ORIGINAL ARTICLES
Perioperative Adverse Respiratory Events in Overweight/Obese Children: Systematic Review Panagiotis Kiekkas, PhD, RN, Nikolaos Stefanopoulos, PhD, RN, Nick Bakalis, PhD, RN, Antonios Kefaliakos, PhD, RN, Evangelos Konstantinou, PhD, RN Childhood obesity is associated with numerous respiratory disorders, which may be aggravated when general anesthesia is administered. This systematic review aimed to investigate and synthesize the published literature on the associations between childhood obesity and perioperative adverse respiratory events (PAREs). By using key terms, observational studies published between 1990 and 2014 in English-language journals indexed by Cumulative Index for Nursing and Allied Health Literature, PubMed, Web of Science, Cochrane Database, and EMBASE were searched for reports of relevant associations. Nine articles were considered eligible for inclusion. In all studies, significant univariate and multivariate associations were reported between obesity and increased risk for PAREs in pediatric patients, mainly for hypoxemia, upper airway obstruction, and difficult mask ventilation. Appropriate strategies for preventing PAREs in obese children need to be followed by health care professionals. Multicenter studies are also recommended for ensuring high generalizability of reported associations and elucidating underlying mechanisms that link obesity to PAREs. Keywords: obesity, childhood, perioperative care, respiratory adverse events, systematic review. Ó 2016 by American Society of PeriAnesthesia Nurses
Panagiotis Kiekkas, PhD, RN, is an Assistant Professor, Nursing Department, Technological Educational Institute of Western Greece, Patras, Greece; Nikolaos Stefanopoulos, PhD, RN, is an Assistant Professor, Nursing Department, Technological Educational Institute of Western Greece, Patras, Greece; Nick Bakalis, PhD, RN, is an Assistant Professor, Nursing Department, Technological Educational Institute of Western Greece, Patras, Greece; Antonios Kefaliakos, PhD, RN, is the Scientific Cooperator, Nursing Department, Technological Educational Institute of Western Greece, Patras, Greece; and Evangelos Konstantinou, PhD, RN, is an Associate Professor in Nurse Anesthesia, Nursing Department, National and Kapodistrian Athens University, Athens, Greece. Conflict of interest: None to report. Address correspondence to Panagiotis Kiekkas, 76 Stratigou Konstantinopoulou Str., Aroi, Patras 263-31, Greece; e-mail address: [email protected]. Ó 2016 by American Society of PeriAnesthesia Nurses 1089-9472/$36.00 http://dx.doi.org/10.1016/j.jopan.2014.11.018
Journal of PeriAnesthesia Nursing, Vol 31, No 1 (February), 2016: pp 11-22
EXCESSIVE BODY WEIGHT in childhood constitutes an ongoing major public health concern. In the United States, obesity prevalence has increased from 7% in 1980 to 18% in 2012 in children ages 6 to 11 years, and from 5% to 21% in ages 12 to 19 years over the same period.1 Likewise, in European countries, almost 20% of children and adolescents are overweight and 7% of them are obese, with the current annual rate increases being 10 times higher than those in the 1970s.2 Considerable increases in childhood obesity prevalence have also been reported in developing countries.3 In this context, the World Health Organization has identified the global epidemic of childhood obesity and has proposed recommendations for its control.4 These recommendations are based on the preventable nature
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of childhood obesity as more than 90% of cases are attributed to excessive calorie consumption along with low energy expenditure.5 Because body mass index (BMI) values substantially change with age, excessive weight disorders are determined by age-specific reference growth charts for BMI during childhood. Children are therefore classified as overweight, obese, or severely obese according to established reference percentiles.6,7 Alternatively, centile curves passing through established cutoff points at the age of 18 years in BMI charts based on pooled international data have been suggested to provide less arbitrary definitions for overweight and obesity.8 However, BMI use is limited by its inability to describe adiposity distribution (regional or overall).9 Thus, considering that abdominal (central) obesity is associated with increased risk for pathologic conditions in childhood, indices of abdominal obesity, such as neck and waist circumference (WC), could be better predictors of adverse health consequences than BMI.9-11 Obese children and adolescents are prone to numerous comorbidities, which can be followed by medical complications and poor health status in adult life.12,13 Respiratory comorbidity is the most common and includes bronchial hyperreactivity and symptoms of severe asthma, increased risk for obstructive sleep apnea and obesity-hypoventilation syndrome, and impaired lung function indicated by decreased respiratory variables.14-17 With regard to the upper airway, it can be narrowed by subcutaneous fat deposition on palatal and pharyngeal soft tissues along with fleshy cheeks and a large tongue. Obese children are also vulnerable to airway infections and gastroesophageal reflux.18,19 Perioperative adverse respiratory events (PAREs) have long been a primary safety concern for health care professionals because they can be followed by increased risk for cardiac arrest, prolonged hospital stay, and increased long-term mortality.20,21 Despite difficulty in defining what a PARE entails, PAREs are more common in obese than normal weight adult surgical patients undergoing general anesthesia.22,23 Considering that airway and respiratory complications are major causes of perioperative morbidity and
mortality in anesthetized children,24,25 and that overweight/obese children represent an increasing proportion of surgical pediatric patients,26 a crucial question is whether overweight/obese children could be more prone to PAREs. In this patient group, compromised airway and respiratory function, along with altered pharmacokinetics of drugs used in general anesthesia because of excessive weight can plausibly lead to complicated recovery and be followed by increased risk for PAREs.5,17,18 The purpose of this systematic literature review was to identify, appraise, and synthesize the existing empirical evidence on the association between overweight/obesity and the occurrence of PAREs in surgical pediatric patients receiving general anesthesia.
Methods Definition of Search Terms This systematic review was structured according to the guidelines set out in Preferred Reporting Items for Systematic reviews and Meta-Analyses statement.27 To determine the eligibility of studies for inclusion in this review, the concepts of overweight/obesity in childhood and PAREs were defined. The following criteria were used for the exact definitions of overweight/obesity7-9: Overweight, obesity, and severe obesity for 85th , BMI , 95th percentile, BMI . 95th percentile, and BMI . 98th percentile, respectively; Overweight and obesity for BMI on or above the BMI curve passing through the 25 and 30 kg/m2 cutoff point at age 18, respectively; and Abdominal obesity for WC . 90th percentile. A PARE was defined as any major unanticipated airway or respiratory problem, which was generally identified by attending expert health care professionals and required physical or pharmacologic interventions. The following criteria were used for the exact definitions of PAREs28-31: Hypoxemia, defined as oxygen desaturation of arterial blood hemoglobin (, 90% or lower);
RESPIRATORY EVENTS IN OVERWEIGHT/OBESE CHILDREN
Airway obstruction, identified by difficulty in breathing or speaking, inspiratory stridor, or expiratory wheeze; Need for airway support, including jaw thrust maneuvers, oropharyngeal or nasopharyngeal airway insertion, laryngeal mask airway placement, or reintubation; Laryngospasm, identified by stridor, or requiring treatment with positive pressure ventilation or drugs (eg, epinephrine); Bronchospasm, identified by auscultated wheezing, or requiring treatment with bronchodilation; Major coughing, continuous coughing requiring repositioning or suction; Difficult mask ventilation, defined as the use of two-handed mask ventilation, or the use of oropharyngeal airway; Difficult laryngoscopy, defined as more than one attempt at laryngoscopy; Difficult tracheal intubation, defined as the use of techniques other than direct laryngoscopy; Pulmonary aspiration, evidenced from chest radiogram; Respiratory depression, identified by low breathing rate (, 10 breaths per minute), or requiring treatment with reversal agent; Apnea, identified by the absence of respiratory function; and Need for supplemental oxygen, administered by nasal cannula or face mask.
Inclusion and Exclusion Criteria Full-text articles published between January 1990 and April 2014 in English-language peer-reviewed journals were included. Specific criteria for considering studies for this review include the following: 1. Types of study subjects: surgical pediatric patients aged 1 to 19 years receiving general anesthesia; studies conducted in adult patients, or in pediatric patients not receiving general anesthesia, were excluded; 2. Types of study design: observational studies conducted in the hospital environment, prospective or retrospective; 3. Types of exposure: overweight/obesity measured before anesthesia and surgery;
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4. Types of outcome measures: PAREs documented during induction, maintenance, or emergence from anesthesia, postanesthesia care unit stay, or the first 24 hours after anesthesia; and 5. Types of associations reported: associations between overweight/obesity and PAREs, by comparing the incidence of PAREs between obese, overweight, and normal weight patients. Database Search Two authors (NS and NB) independently searched for primary studies indexed in the Cumulative Index for Nursing and Allied Health Literature, PubMed (National Library of Medicine), Web of Science, Cochrane Library, and EMBASE. Key search terms used included ‘‘childhood obesity,’’ ‘‘children obesity,’’ ‘‘childhood overweight,’’ ‘‘overweight children,’’ ‘‘childhood body mass index,’’ and ‘‘obese children,’’ which were combined with ‘‘perioperative adverse respiratory events,’’ ‘‘respiratory complications,’’ ‘‘perioperative complications,’’ ‘‘perioperative morbidity,’’ ‘‘perioperative hypoxemia,’’ ‘‘perioperative airway obstruction,’’ and ‘‘anesthetic morbidity.’’ Database searches took place the last week of April 2014, and duplicate entries were removed. In the first stage, retrieved studies were screened for inclusion according to titles and abstracts. In the second stage, full text of selected articles was obtained and read for a final determination regarding eligibility for inclusion. Reference lists of the eligible articles were reviewed to identify additional potentially relevant articles not found in the online searches. Data Extraction and Quality Appraisal Two authors with long clinical experience in perianesthesia nursing (PK and EK) independently extracted data from included studies. Extracted data included year of publication, country, study design, study population (patient number, type of surgery, and age range), study duration, definitions and incidence of overweight/obesity, exclusion criteria used, use of power analysis, types of PAREs studied, and detected associations between overweight/
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obesity and PAREs at the univariate and multivariate levels. The reviewers re-examined articles in which their data extractions were discordant and discussed differences until consensus was reached. Study characteristics and findings were summarized in tables. Although methodological quality of studies was not a criterion for their inclusion in this review, selected studies were critically appraised and differences regarding their quality were evaluated. Specifically, quality of included studies was evaluated according to study design, types of operative procedures included, population size, use of a power analysis, exclusion criteria, and statistical analysis used.32
Results Search Outcome Initial online searches revealed 169 nonduplicate titles; of which 25 potentially relevant citations evaluated by title were identified (Figure 1). Based on abstract evaluation, 16 articles were selected for full-text review; nine of them were further
25 articles retrieved by title for abstract review 9 citations excluded based on abstract evaluation (not meeting eligibility criteria) 16 articles retrieved for full text review 7 articles excluded based on full text evaluation: - associations between overweight/obesity and PAREs not reported, n=4 - only morbidly obese pts enrolled (not compared with normal weight pts), n=1 - overweight/obesity and sleep disordered breathing used together for comparisons, n=1 - data on pt weight not reported, n=1 9 articles selected - 2 additional articles identified from reference list searches and evaluated by full text review Additional articles excluded based on full text evaluation: - only morbidly obese pts enrolled, n=2 A total of 9 articles met inclusion criteria
Figure 1. Flow diagram of literature search results. PAREs, perioperative adverse respiratory events; pts, patients.
selected based on full-text evaluation. There were two discrepancies during abstract review and one discrepancy during full-text review, all resolved by discussion. Two more potential citations were revealed through reference list searches, but were excluded after full-text evaluation. Thus, nine articles were finally considered appropriate for inclusion in this review.29–31,33–38 Study Characteristics Selected studies were published between 2007 and 2014 (Table 1). There were seven cohort studies,29,30,33,34,36–38 one case-control study,35 and one matched cohort study.31 All studies were single centered. Six studies were conducted in the United States (main author and hospital site were the same in three of them), with the remaining studies conducted in Canada,35 China,38 and Egypt.34 In all studies, associations between overweight/obesity and PAREs were among primary endpoints. Study duration ranged between 1 and 5 years. Overweight/obesity definitions varied among studies (Table 1). An overweight definition was used in four studies; overweight was defined as 85th , BMI , 95th percentile in two of them,29,30 and as BMI on or above the BMI curve passing through the 25 kg/m2 cutoff point at age 18 in another two studies.34,37 An obesity definition was used in eight studies; obesity was defined as BMI . 95th percentile in four studies,29,30,35,38 as BMI on or above the BMI curve passing through the 30 kg/m2 cutoff point at age 18 in another three studies,34,36,37 and as WC . 90th percentile (abdominal obesity) in one study.33 A severe obesity definition was used in one study,31 and this was defined as BMI . 98th percentile. In cohort studies, overweight incidence ranged between 14.4% and 17.3%; similarly, obesity incidence ranged between 4.7% and 17.2%, with abdominal obesity reaching up to 23.1% in one study. Overall incidence of PAREs was reported in five studies31,34,35,37,38 (Table 2). Hypoxemia (its definition ranged between SpO2 , 70% to , 90%) and airway obstruction were included among studied PAREs in eight studies. Laryngospasm, bronchospasm, and difficult mask ventilation were included in five studies; difficult
Author (Y)
Country/Study Design
Study Population/Duration
El-Metainy et al34 (2011)
Egypt/prospective, cohort, single-center
1,465 pts aged 2 to 16 y undergoing elective general surgery/2 y
Fung et al35 (2010)
Canada/prospective, casecontrol, single-center
49 obese pts with SDB aged 2 to 17 y undergoing adenotonsillectomy (pairmatched to pts with BMI , 85th percentile)/5 y 100 severely obese pts aged 2 to 18 y undergoing tonsillectomy (matched to 200 nonseverely obese pts)/1 y 6,094 pts aged 2 to 19 y undergoing elective general surgery/5 y
Gleich et al31 (2012) United States/retrospective, matched cohort, singlecenter Nafiu et al30 (2007)
United States/retrospective, cohort, single-center
Nafiu et al29 (2009)
United States/retrospective, cohort, single-center
Nafiu & Onyewuche33 (2014) Setzer and Saade36 (2007)
United States/prospective, cohort, single-center
Tait et al37 (2008)
United States/prospective, cohort, single-center
United States/retrospective, cohort, single-center
Excessive Weight Disorders: Definitions—Incidence Overweight (BMI $ curve passing through 25 kg/m2 point at age 18)—15.2% Obesity (BMI $ curve passing through 30 kg/m2 point at age 18)—10.5% Obesity (BMI . 95th percentile)
Severe obesity (BMI $ 98th percentile)
Exclusion Criteria/Power Analysis Conducted Secondary causes of obesity, laryngotracheomalacia, neuromuscular disorders/no
Incomplete BMI data, genetic, metabolic, neurologic, and syndromic conditions, craniofacial abnormalities, hypotonia/no Inconsistencies in weight measurement, multiple surgical procedures/no
(Continued )
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Incomplete BMI data, secondary Overweight (85th , BMI, 95th causes of obesity (syndromes), percentile)—14.4% obesogenic medications used/no Obesity (BMI . 95th percentile)— 17.2% 2,170 pts aged 3 to 19 y Overweight (85th , BMI , 95th Incomplete BMI data, secondary causes of obesity, chronic lung, undergoing adenotonsillectomy/ percentile)—13.1% or neuromuscular disease, 3y Obesity (BMI . 95th percentile)— laryngotracheomalacia, multiple 7.5% surgical procedures/no 1,102 pts aged 6 to 18 y Abdominal obesity (WC . 90th Cardiac surgery, ascites, pregnancy, undergoing elective general percentile)—23.1% intra-abdominal masses, severe surgery/2 y cardiorespiratory disease/no 1,133 pts aged 2 to 12 y Obesity (BMI $ curve passing ASA physical status . II/no undergoing dental surgery/1 y through 30 kg/m2 point at age 18)—8.8% 2,025 pts aged 2 to 18 y Overweight (BMI $ curve passing Cardiac surgery/yes undergoing elective general through 25 kg/m2 point at age surgery/20 mo 18)—17.3% Obesity (BMI $ curve passing through 30 kg/m2 point at age 18)—14.5%
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Table 1. Main Characteristics of Included Studies
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Table 1. Continued Author (Y) Ye et al38 (2009)
Country/Study Design
Study Population/Duration
Excessive Weight Disorders: Definitions—Incidence
Exclusion Criteria/Power Analysis Conducted
China/retrospective, cohort, 321 pts with OSAS aged 4 to 14 y Obesity (BMI . 95th percentile)— ASA physical status . III, 4.7% concomitant surgery, genetic single-center undergoing adenotonsillectomy/ disorders, craniofacial 4.5 y abnormalities, severe cardiorespiratory or neuromuscular disease, Down syndrome, contraindications to general anesthesia/no
pts, patients; BMI, body mass index; SDB, sleep disordered breathing; WC, waist circumference; ASA, American Society of Anesthesiologists; OSAS, obstructive sleep apnea syndrome.
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laryngoscopy in four studies; need for supplemental oxygen in three studies; pulmonary aspiration and major coughing in two studies; and need for airway support, difficult tracheal intubation, respiratory depression, apnea, and reintubation in one study. Study Quality Differences in methodological quality of included studies were identified (Table 1). First, only four studies were prospective.33–35,37 Second, elective general surgery patients were enrolled in four cohort studies30,33,34,37; only adenotonsillectomy patients were enrolled in two cohort studies,29,38 in the case-control35 and the matched cohort study,31 whereas only dental surgery patients were enrolled in one cohort study.36 Third, six cohort studies used large patient population sizes, which exceeded 6,000 patients in one study,30 2,000 patients in two studies,29,37 and 1,000 patients in the rest three studies.33,34,36 The rest studies used considerably smaller patient numbers.31,35,38 Fourth, power analysis for determining required minimum population size was conducted in only one cohort study.37 Fifth, five cohort studies as well as the case-control and the matched cohort study used a considerable number of exclusion criteria for establishing precision and avoiding confounding effects; the rest two cohort studies36,37 used only one criterion each. Sixth, only five studies31,33,35,37,38 tested the associations between overweight/obesity and PAREs at the multivariate level (Table 2). Study Findings Significant associations between overweight/ obesity and PAREs were detected in all included studies (Table 2). Obesity was significantly associated with increased risk for overall PAREs in four studies,34,35,37,38 increased risk for airway obstruction in four studies,30,34,35,37 increased risk for hypoxemia in three studies,34,36,37 increased risk for difficult mask ventilation in three studies,30,34,37 increased risk for bronchospasm in two studies,34,37 increased risk for major coughing in one study,37 increased risk for difficult laryngoscopy in one study,30 and increased risk for the need for supplemental oxygen in one study.35
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Overweight/obesity was significantly associated with increased risk for airway obstruction, hypoxemia, difficult laryngoscopy, difficult mask ventilation, and laryngospasm in one study.29 Severe obesity was significantly associated with increased risk for overall PAREs, airway obstruction, hypoxemia, and laryngospasm in one study.31 Abdominal obesity was significantly associated with increased risk for airway obstruction, hypoxemia, and difficult mask ventilation in one study.33 The five studies in which the associations between obesity and PAREs were tested in the multivariate level reported that obesity,37,38 severe obesity,31 abdominal obesity,33 and BMI35 were significant predictors of increased risk for overall PAREs, whereas BMI was a significant predictor of increased risk for airway obstruction as well.35
Discussion Existing research on overweight/obesity in childhood has focused on its associations with chronic diseases and its effects on adult health status, with few recent studies having explored its contribution to perioperative complications and outcomes. The findings of studies included in this review provided considerable evidence that childhood overweight/obesity is linked to increased risk for overall PAREs, airway obstruction, hypoxemia, and difficult mask ventilation, whereas associations with difficult laryngoscopy, laryngospasm, bronchospasm, major coughing, and need for supplemental oxygen were also reported. Similar associations between obesity and PAREs have been reported for adult surgical patients, mainly for difficult laryngoscopy, difficult mask ventilation, and aspiration.39,40 Reported incidence of PAREs varied considerably among studies, depending on definitions used, anesthetic drugs administered, pre-existing respiratory disorders of patients enrolled, and operative procedures included. Only four studies enrolled general surgery patients, who sustained diverse operative procedures, and were highly representative of the pediatric surgical population. In addition, only few types of PAREs were investigated in most studies, raising the possibility that significant associations between overweight/ obesity and separate types of PAREs have actually been underdetected. It is also worth noting that
Author (Y)
PAREs Studied
Univariate Associations Between Overweight/Obesity and PAREs
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Table 2. Types of PAREs Studied and Main Findings of Included Studies Multivariate Associations Between Overweight/Obesity and PAREs
Hypoxemia (SpO2 , 90%), airway obstruction, difficult mask ventilation, difficult laryngoscopy, bronchospasm, and pulmonary aspiration
Overall PAREs (40.9% vs 32.6%, P , .05), hypoxemia (14.9% vs 8.0%, P , .05), airway obstruction (24.0% vs 17.2%, P , .05), difficult mask ventilation (20.8% vs 3.2%, P , .01), and bronchospasm (7.8% vs 2.2%, P , .01) were more common in obese pts (compared with normal weight and overweight pts)
—
Fung et al35 (2010)
Hypoxemia (minor SpO2 81% to 90%, major SpO2 # 80%), bronchospasm, airway obstruction, need for airway support, respiratory depression, major coughing, need for supplemental oxygen leaving PACU
Overall PAREs (75.5% vs 26.5%, P , .01), airway obstruction (38.8% vs 8.2%, P , .01), and need for supplemental oxygen leaving PACU (36.7% vs 16.3%, P , .05) were more common in obese pts (compared with normal weight pts)
Higher BMI was independently associated with increased risk for airway obstruction (P , .01) and overall PAREs (P , .01)
Gleich et al31 (2012)
Difficult tracheal intubation, hypoxemia (mild SpO2 , 90%, severe SpO2 , 70%), bronchospasm, laryngospasm, airway obstruction, pulmonary aspiration, need for supplemental oxygen in PACU, and reintubation in PACU
Overall PAREs (15.0% vs 2.0%, P , .01), intraoperative hypoxemia (mild [19.0% vs 9.5%, P , .05] and severe [0.05% vs 0.005%, P , .05]), laryngospasm (0.04% vs 0.005%, P , .05), and airway obstruction (intraoperative [0.07% vs 0%, P , .01] and in PACU [0.03% vs 0%, P , .05]) were more common in severely obese pts (compared with normal weight pts)
Severe obesity was independently associated with increased risk for overall PAREs, both with (OR, 7.7; P , .01) and without adjusting (OR, 8.8; P , .01) for preoperative respiratory disorders
Nafiu et al30 (2007)
Airway obstruction in PACU, difficult laryngoscopy, and difficult mask ventilation
Difficult laryngoscopy (1.3% vs 0.4%, P , .01), difficult mask ventilation (7.4% vs 2.2%, P , .01), and airway obstruction in PACU (1.6% vs 0.1%, P , .01) were more common in obese pts (compared with normal weight pts)
—
Nafiu et al29 (2009)
Hypoxemia (SpO2 , 90%), airway obstruction, difficult laryngoscopy,
Hypoxemia (40.4% vs 30.9%, P , .01), airway obstruction (intraoperative [5.9%
—
KIEKKAS ET AL
El-Metainy et al34 (2011)
vs 0.2%, P , .01] and in PACU [3.7% vs 0.3%, P , .01]), difficult laryngoscopy (27.4% vs 11.9%, P , .01), difficult mask ventilation (31.6% vs 15.7%, P , .01), and laryngospasm (2.1% vs 0.2%, P , .01) were more common in overweight/obese pts (compared with normal weight pts)
Nafiu and Onyewuche33 (2014)
Hypoxemia (SpO2 , 90%), airway obstruction, difficult mask ventilation, difficult laryngoscopy, laryngospasm, and bronchospasm
Hypoxemia (3.5% vs 1.3%, P , .05), airway obstruction (intraoperative [14.9% vs 3.5%, P , .01] and in PACU [9.6% vs 3.3%, P , .01]), and difficult mask ventilation (26.0% vs 11.0%, P , .01) were more common in pts with abdominal obesity (compared with pts without abdominal obesity)
Abdominal obesity was independently associated with increased risk for overall PAREs (OR, 2.4; P , .01)
Setzer and Saade36 (2007)
Hypoxemia (SpO2 , 85%), laryngospasm, and need for supplemental oxygen in PACU
Intraoperative hypoxemia (2.0% vs 0.2%, P , .01) was more common in obese pts (compared with normal weight and overweight pts)
—
Tait et al37 (2008)
Hypoxemia (minor SpO2 5% to 10% decrease from baseline, major SpO2 . 10% decrease from baseline), apnea (minor , 30 s and major .30 s), airway obstruction, difficult mask ventilation, laryngospasm, bronchospasm, and major coughing
Overall PAREs (39.8% vs 25.1%, P , .01), major hypoxemia (16.8% vs 9.1%, P , .01), airway obstruction (18.9% vs 11.2%, P , .01), difficult mask ventilation (8.7% vs 2.1%, P , .01), bronchospasm (6.1% vs 2.0%, P , .01), and major coughing (7.1% vs 4.3%, P , .05) were more common in obese pts (compared with normal weight and overweight pts)
Obesity was independently associated with increased risk for overall PAREs (OR, 2.0; P , .05)
Ye et al38 (2009)
Postoperative hypoxemia (SpO2 , 95%) and postoperative airway obstruction (including apnea)
Overall PAREs (11.1% vs 3.9%, P , .05) were more common in obese pts (compared with normal weight and overweight pts)
Obesity was independently associated with increased risk for overall PAREs (OR, 1.5; P , .05)
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difficult mask ventilation, and laryngospasm
PAREs, perioperative adverse respiratory events; pts, patients; PACU, postanesthesia care unit; BMI, body mass index; OR, odds ratio.
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significant univariate and multivariate associations between obesity and overall PAREs were identified in all studies that tested this association. PAREs are closely inter-related (eg, airway obstruction or pulmonary aspiration may lead to hypoxemia, whereas laryngospasm or bronchospasm may result in airway obstruction), thus their overall incidence might better reflect obesity effects on patient airway and respiratory function.41 Although excessive weight seems plausible to contribute to increased risk for PAREs, it is difficult to define whether this risk increases in a progressive manner or if there is a weight threshold above which this risk emerges. Among existing studies, significant differences were reported when obese patients were compared with overweight/normal weight ones33,34,36–38 or to only normal weight ones,30,35 when severely obese patients were compared with normal weight ones,31 and when overweight/obese patients were compared with normal weight ones.29 Thus, because comparisons among excessive weight groups are missing, it remains questionable whether overweight children are at increased risk for PAREs or whether severely obese children are at higher risk than obese ones. In addition, risk for PAREs might not be uniformly increased for the whole childhood spectrum. According to recent findings, younger children are more susceptible to intraoperative hypoxemia than older ones irrespective of body weight,42 whereas obese children below 13 years are at higher risk for PAREs compared with those aged 13 to 16 years.34 To our knowledge, whether abdominal obesity could be more pathogenic for airway and respiratory function of children than BMI-defined obesity remains unknown. However, WC of young adults was reported to be a significantly better predictor of compromised pulmonary function than BMI.43 In case central fat distribution proves to better predict compromised airway and respiratory function in childhood than excessive weight per se, reported associations between BMI-defined obesity and PAREs are expected to have underestimated the actual contribution of obesity on the risk for PAREs. Anatomic and metabolic mechanisms account for the potential of childhood obesity to contribute to PAREs.33 Excessive adipose tissue may directly derange respiratory parameters and airway func-
tion, which are expected to be aggravated by general anesthesia administration toward adverse events. Alternatively, obesity-associated respiratory disorders can act as mediators for the manifestation of PAREs. Bronchial asthma is not only more common among obese children but also followed by increased risk for bronchospasm after general anesthesia with tracheal intubation.44,45 Likewise, sleep-related breathing disorders are strongly associated with both obesity and increased risk for hypoxemia.46,47 It should, however, be highlighted that obesity was independently associated with PAREs in studies that asthma, sleep-disordered breathing, and obstructive sleep apnea were included in the multivariate analysis.31,33,37 Study Limitations The small number of studies meeting the inclusion criteria, more than half of which were retrospective, was a major limitation of this review. Second, single-center conduct of all studies, three of them by the same research team, and the focus of five studies on specific operative procedures (adenotonsillectomy or dental surgery) limited generalizability of their findings. Third, some criteria used for defining PAREs were inevitably of subjective nature and depended on health care professionals’ expertise. Fourth, only published studies were considered for inclusion, thus the gray literature (theses or conference abstracts) was not covered. Fifth, established instruments used for study quality appraisal in systematic reviews were not used. Sixth, heterogeneous definitions of both overweight/obesity and PAREs did not allow extracted data to be combined in a meta-analysis. Implications for Clinical Practice and Research Major complications of pediatric anesthesia are by far associated with patients’ airway and respiratory function. Considering the increased risk for PAREs among obese children, health professionals employed in anesthesiology or surgical departments need to be aware of possible negative effects of obesity, especially in case of coexisting respiratory disorders or after high-risk operative procedures. Preoperative examination of obese pediatric surgical patients is recommended to include BMI, airway assessment, and pulse oximetry, along with pulmonary function tests if necessary. Within
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the operating room, 3-minute preoxygenation and tracheal intubation in head-up or sniffing position, stomach desufflation, regular auscultation of breath sounds, and availability of difficult intubation equipment are expected to decrease risk for PAREs.48,49 Particular attention is needed during the postoperative phase for improving safety of obese pediatric patients. Appropriate care includes careful selection of pharmacologic agents and doses used.50 In contrast to opioids, administration of nonsteroidal anti-inflammatory drugs is not followed by respiratory depression and should thus be preferred. Alternatively, opioid doses have to be carefully titrated to avoid heavy sedation. With regard to patient positioning, head-up position increases vital capacity, semi-recumbent position decreases risk for atelectasis and improves oxygenation, whereas recovery position decreases risk for airway obstruction or aspiration.48,51 Finally, supplemental oxygen administration along with continuous pulse oximetry and surveillance until complete recovery from anesthesia offer the potential of preventing or timely detecting PAREs. Future research on childhood overweight/obesity has yet to address many issues related to PAREs. Prospective and multicenter cohort studies enrolling diverse pediatric surgical populations need to be conducted to ensure high generalizability of findings. These studies are called to further investigate the scarcely reported associations of obesity with difficult laryngoscopy,
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laryngospasm, bronchospasm, major coughing, and need for supplemental oxygen. Underlying mechanisms that link obesity with PAREs (ie, obstructive sleep apnea), as well as whether abdominal obesity can be more predictive of the risk for PAREs than BMI-defined obesity, are important to be elucidated. Meaningful questions for research also include whether the continuum of childhood overweight, obesity, and severe obesity corresponds to gradually increasing risk for PAREs, as well as whether the obesity-PAREs association differs significantly among specific age groups.
Conclusion This review summarizes the existing evidence about the role of overweight/obesity on the risk for PAREs in pediatric patients receiving general anesthesia. Associations of obesity with overall PAREs, hypoxemia, airway obstruction, and difficult mask ventilation have been strongly supported, whereas associations with laryngoscopy, laryngospasm, bronchospasm, major coughing, and need for supplemental oxygen have been reported but remain inconclusive. Although many factors related to the patient, anesthesia, or surgery predispose to PAREs, identifying obesity effects, anticipating adverse respiratory events in obese children during the entire perioperative phase, and appropriately managing this patient population is expected to contribute to the prevention or timely detection of PAREs. Additional research of better methodological quality is recommended for confirming and defining the exact nature of associations between childhood obesity and PAREs.
References 1. Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of childhood and adult obesity in the United States, 2011-2012. JAMA. 2014;311:806-814. 2. World Health Organization Europe. The challenge of obesity in the WHO European Region and the strategies for response. (Edited by Branca F, Nikogosian H, Lobstein T). Available at: http://www.euro.who.int/__data/assets/pdf_file/0008/ 98243/E89858.pdf?ua=1. Accessed May 2, 2014. 3. Flynn MA, McNeil DA, Maloff B, et al. Reducing obesity and related chronic disease risk in children and youth: A synthesis of evidence with ‘best practice’ recommendations. Obes Rev. 2006;7:7-66. 4. World Health Organization. What can be done to fight the childhood obesity epidemic? Available at: http://www.who.int/ dietphysicalactivity/childhood_what_can_be_done/en/. Accessed May 2, 2014.
5. Veyckemans F. Child obesity and anaesthetic morbidity. Curr Opin Anaesthesiol. 2008;21:308-312. 6. Dietz WH, Robinson TN. Use of the body mass index (BMI) as a measure of overweight in children and adolescents. J Pediatr. 1998;132:191-193. 7. Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC growth charts for the United States: Methods and development. Vital Health Stat 11. 2002;246:1-190. 8. Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: International survey. BMJ. 2000;320:1-6. 9. Nafiu OO, Burke C, Gupta R, et al. Association of neck circumference with perioperative adverse respiratory events in children. Pediatrics. 2011;127:e1198-e1205. 10. Garnett SP, Baur LA, Srinivasan S, et al. Body mass index and waist circumference in mid-childhood and adverse
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cardiovascular disease risk clustering in adolescence. Am J Clin Nutr. 2007;86:549-555. 11. Walls HL, Stevenson CE, Mannan HR, et al. Comparing trends in BMI and waist circumference. Obesity (Silver Spring). 2011;19:216-219. 12. Yanovski JA. Pediatric obesity. Rev Endocr Metab Disord. 2001;2:371-383. 13. Berenson GS, Bogalusa Heart Study Group. Health consequences of obesity. Pediatr Blood Cancer. 2012;58:117-121. 14. Davidson WJ, Mackenzie-Rife KA, Witmans MB, et al. Obesity negatively impacts lung function in children and adolescents. Pediatr Pulmonol. 2014;49:1003-1010. 15. Deane S, Thomson A. Obesity and the pulmonologist. Arch Dis Child. 2006;91:188-191. 16. Murugan AT, Sharma G. Obesity and respiratory diseases. Chron Respir Dis. 2008;5:233-242. 17. Fiorino EK, Brooks LJ. Obesity and respiratory diseases in childhood. Clin Chest Med. 2009;30:601-608. 18. Smith HL, Meldrum DJ, Brennan LJ. Childhood obesity: A challenge for the anesthetist? Peadiatr Anaesth. 2002;12: 750-761. 19. Pulgaron ER. Childhood obesity: A review of increased risk for physical and psychological co-morbidities. Clin Ther. 2013;35:A18-A32. 20. Watson CB. Respiratory complications associated with anesthesia. Anesthesiol Clin North America. 2002;20:513-537. 21. Quaseem A, Snow V, Fitterman N, et al. Risk assessment for and strategies to reduce perioperative pulmonary complications for patients undergoing noncardiothoracic surgery: A guideline from the American College of Physicians. Ann Intern Med. 2006;144:575-580. 22. Pelosi P, Gregoretti C. Perioperative management of obese patients. Best Pract Res Clin Anaesthesiol. 2010;24: 211-225. 23. Uakritdathikarn T, Chongsuvivatwong V, Geater AF, et al. Perioperative desaturation and risk factors in general anesthesia. J Med Assoc Thai. 2008;91:1020-1029. 24. Brambrink AM, Braun U. Airway management in infants and children. Best Pract Res Clin Anaesthesiol. 2005;19:675-697. 25. Bhananker SM, Ramamoorthy C, Geiduschek JM, et al. Anesthesia-related cardiac arrest in children: Update from the Pediatric Perioperative Cardiac Arrest Registry. Anesth Analg. 2007;105:344-350. 26. Nafiu OO, Ndao-Brumlay KS, Bamgbade OA, et al. Prevalence of overweight and obesity in a U.S. pediatric surgical population. J Natl Med Assoc. 2007;99:46-51. 27. Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. BMJ. 2009;339:332-336. 28. Nicholau D. The Postanesthesia Care Unit. In: Miller RD, ed. Miller’s Anesthesia, 7th ed. Philadelphia, PA: Elsevier/ Churchill Livingstone; 2010:2707-2728. 29. Nafiu OO, Green GE, Walton S, et al. Obesity and risk of peri-operative complications in children presenting for adenotonsillectomy. Int J Pediatr Otorhinolaryngol. 2009;73:89-95. 30. Nafiu OO, Reynolds PI, Bamgbade OA, et al. Childhood body mass index and perioperative complications. Peadiatr Anaesth. 2007;17:426-430. 31. Gleich SJ, Olson MD, Sprung J, et al. Perioperative outcomes of severely obese children undergoing tonsillectomy. Peadiatr Anaesth. 2012;22:1171-1178.
KIEKKAS ET AL 32. Polit DF, Beck CT. Essentials of Nursing Research: Appraising Evidence for Nursing Practice. Philadelphia, PA: Wolters Kluwer/Lippincott, Williams & Wilkins; 2010. 33. Nafiu OO, Onyewuche V. Association of abdominal obesity in children with perioperative respiratory adverse events. J Perianesth Nurs. 2014;29:84-93. 34. El-Metainy S, Ghoneim T, Aridae E, Abdel Wahab M. Incidence of perioperative adverse events in obese children undergoing elective general surgery. Br J Anaesth. 2011;106:359-363. 35. Fung E, Cave D, Witmans M, et al. Postoperative respiratory complications and recovery in obese children following adenotonsillectomy for sleep-disordered breathing: A case-control study. Otolaryngol Head Neck Surg. 2010;142:898-905. 36. Setzer N, Saade E. Childhood obesity and anesthetic morbidity. Peadiatr Anaesth. 2007;17:321-326. 37. Tait AR, Voepel-Lewis T, Burke C, et al. Incidence and risk factors for perioperative adverse respiratory events in children who are obese. Anesthesiology. 2008;108:375-380. 38. Ye J, Liu H, Zhang G, et al. Postoperative respiratory complications of adenotonsillectomy for obstructive sleep apnea syndrome in older children: Prevalence, risk factors, and impact on clinical outcome. J Otolaryngol Head Neck Surg. 2009;38:49-58. 39. Juvin P, Lavaut E, Dupont H, et al. Difficult tracheal intubation is more common in obese than in lean patients. Anesth Analg. 2003;97:595-600. 40. Kheterpal S, Han R, Tremper KK, et al. Incidence and predictors of difficult and impossible mask ventilation. Anesthesiology. 2006;105:885-891. 41. Scott B. Airway management in post anaesthetic care. J Perioper Pract. 2012;22:135-138. 42. de Graaff JC, Bijker JB, Kappen TH, et al. Incidence of intraoperative hypoxemia in children in relation to age. Anesth Analg. 2013;117:169-175. 43. Saxena Y, Sidhwani G, Upmanyu R. Abdominal obesity and pulmonary functions in young Indian adults: A prospective study. Indian J Physiol Pharmacol. 2009;53:318-326. 44. Silvanus MT, Groeben H, Peters J. Corticosteroids and inhaled salbutamol in patients with reversible airway obstruction markedly decrease the incidence of bronchospasm after tracheal intubation. Anesthesiology. 2004;100: 1052-1057. 45. Boulet LP. Asthma and obesity. Clin Exp Allergy. 2013;43: 8-21. 46. Strauss SG, Lynn AM, Bratton SL, Nespeca MK. Ventilatory response to CO2 in children with obstructive sleep apnea from adenotonsillar hypertrophy. Anesth Analg. 1999;89: 328-332. 47. Patino M, Sadhasivam S, Mahmoud M. Obstructive sleep apnoea in children: Perioperative considerations. Br J Anaesth. 2013;111:i83-95. 48. Mortensen A, Lenz K, Abildstrom H, Lauritsen TLB. Anesthetizing the obese child. Peadiatr Anaesth. 2011;21: 623-629. 49. Murphy C, Wong DT. Airway management and oxygenation in obese patients. Can J Anaesth. 2013;60: 929-945. 50. Russell P, von Ungern-Sternberg BS, Schug SA. Perioperative analgesia in pediatric surgery. Curr Opin Anaesthesiol. 2013;26:420-427. 51. Noble KA. The obesity epidemic: The impact of obesity on the perianesthesia patient. J Perianesth Nurs. 2008;23: 418-425.
Perioperative Adverse Respiratory Events in Overweight/Obese Children: Systematic Review Panagiotis Kiekkas, PhD, RN, Nikolaos Stefanopoulos, PhD, RN, Nick Bakalis, PhD, RN, Antonios Kefaliakos, PhD, RN, Evangelos Konstantinou, PhD, RN Childhood obesity is associated with numerous respiratory disorders, which may be aggravated when general anesthesia is administered. This systematic review aimed to investigate and synthesize the published literature on the associations between childhood obesity and perioperative adverse respiratory events (PAREs). By using key terms, observational studies published between 1990 and 2014 in English-language journals indexed by Cumulative Index for Nursing and Allied Health Literature, PubMed, Web of Science, Cochrane Database, and EMBASE were searched for reports of relevant associations. Nine articles were considered eligible for inclusion. In all studies, significant univariate and multivariate associations were reported between obesity and increased risk for PAREs in pediatric patients, mainly for hypoxemia, upper airway obstruction, and difficult mask ventilation. Appropriate strategies for preventing PAREs in obese children need to be followed by health care professionals. Multicenter studies are also recommended for ensuring high generalizability of reported associations and elucidating underlying mechanisms that link obesity to PAREs. Keywords: obesity, childhood, perioperative care, respiratory adverse events, systematic review. Ó 2016 by American Society of PeriAnesthesia Nurses
Panagiotis Kiekkas, PhD, RN, is an Assistant Professor, Nursing Department, Technological Educational Institute of Western Greece, Patras, Greece; Nikolaos Stefanopoulos, PhD, RN, is an Assistant Professor, Nursing Department, Technological Educational Institute of Western Greece, Patras, Greece; Nick Bakalis, PhD, RN, is an Assistant Professor, Nursing Department, Technological Educational Institute of Western Greece, Patras, Greece; Antonios Kefaliakos, PhD, RN, is the Scientific Cooperator, Nursing Department, Technological Educational Institute of Western Greece, Patras, Greece; and Evangelos Konstantinou, PhD, RN, is an Associate Professor in Nurse Anesthesia, Nursing Department, National and Kapodistrian Athens University, Athens, Greece. Conflict of interest: None to report. Address correspondence to Panagiotis Kiekkas, 76 Stratigou Konstantinopoulou Str., Aroi, Patras 263-31, Greece; e-mail address: [email protected]. Ó 2016 by American Society of PeriAnesthesia Nurses 1089-9472/$36.00 http://dx.doi.org/10.1016/j.jopan.2014.11.018
Journal of PeriAnesthesia Nursing, Vol 31, No 1 (February), 2016: pp 11-22
EXCESSIVE BODY WEIGHT in childhood constitutes an ongoing major public health concern. In the United States, obesity prevalence has increased from 7% in 1980 to 18% in 2012 in children ages 6 to 11 years, and from 5% to 21% in ages 12 to 19 years over the same period.1 Likewise, in European countries, almost 20% of children and adolescents are overweight and 7% of them are obese, with the current annual rate increases being 10 times higher than those in the 1970s.2 Considerable increases in childhood obesity prevalence have also been reported in developing countries.3 In this context, the World Health Organization has identified the global epidemic of childhood obesity and has proposed recommendations for its control.4 These recommendations are based on the preventable nature
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of childhood obesity as more than 90% of cases are attributed to excessive calorie consumption along with low energy expenditure.5 Because body mass index (BMI) values substantially change with age, excessive weight disorders are determined by age-specific reference growth charts for BMI during childhood. Children are therefore classified as overweight, obese, or severely obese according to established reference percentiles.6,7 Alternatively, centile curves passing through established cutoff points at the age of 18 years in BMI charts based on pooled international data have been suggested to provide less arbitrary definitions for overweight and obesity.8 However, BMI use is limited by its inability to describe adiposity distribution (regional or overall).9 Thus, considering that abdominal (central) obesity is associated with increased risk for pathologic conditions in childhood, indices of abdominal obesity, such as neck and waist circumference (WC), could be better predictors of adverse health consequences than BMI.9-11 Obese children and adolescents are prone to numerous comorbidities, which can be followed by medical complications and poor health status in adult life.12,13 Respiratory comorbidity is the most common and includes bronchial hyperreactivity and symptoms of severe asthma, increased risk for obstructive sleep apnea and obesity-hypoventilation syndrome, and impaired lung function indicated by decreased respiratory variables.14-17 With regard to the upper airway, it can be narrowed by subcutaneous fat deposition on palatal and pharyngeal soft tissues along with fleshy cheeks and a large tongue. Obese children are also vulnerable to airway infections and gastroesophageal reflux.18,19 Perioperative adverse respiratory events (PAREs) have long been a primary safety concern for health care professionals because they can be followed by increased risk for cardiac arrest, prolonged hospital stay, and increased long-term mortality.20,21 Despite difficulty in defining what a PARE entails, PAREs are more common in obese than normal weight adult surgical patients undergoing general anesthesia.22,23 Considering that airway and respiratory complications are major causes of perioperative morbidity and
mortality in anesthetized children,24,25 and that overweight/obese children represent an increasing proportion of surgical pediatric patients,26 a crucial question is whether overweight/obese children could be more prone to PAREs. In this patient group, compromised airway and respiratory function, along with altered pharmacokinetics of drugs used in general anesthesia because of excessive weight can plausibly lead to complicated recovery and be followed by increased risk for PAREs.5,17,18 The purpose of this systematic literature review was to identify, appraise, and synthesize the existing empirical evidence on the association between overweight/obesity and the occurrence of PAREs in surgical pediatric patients receiving general anesthesia.
Methods Definition of Search Terms This systematic review was structured according to the guidelines set out in Preferred Reporting Items for Systematic reviews and Meta-Analyses statement.27 To determine the eligibility of studies for inclusion in this review, the concepts of overweight/obesity in childhood and PAREs were defined. The following criteria were used for the exact definitions of overweight/obesity7-9: Overweight, obesity, and severe obesity for 85th , BMI , 95th percentile, BMI . 95th percentile, and BMI . 98th percentile, respectively; Overweight and obesity for BMI on or above the BMI curve passing through the 25 and 30 kg/m2 cutoff point at age 18, respectively; and Abdominal obesity for WC . 90th percentile. A PARE was defined as any major unanticipated airway or respiratory problem, which was generally identified by attending expert health care professionals and required physical or pharmacologic interventions. The following criteria were used for the exact definitions of PAREs28-31: Hypoxemia, defined as oxygen desaturation of arterial blood hemoglobin (, 90% or lower);
RESPIRATORY EVENTS IN OVERWEIGHT/OBESE CHILDREN
Airway obstruction, identified by difficulty in breathing or speaking, inspiratory stridor, or expiratory wheeze; Need for airway support, including jaw thrust maneuvers, oropharyngeal or nasopharyngeal airway insertion, laryngeal mask airway placement, or reintubation; Laryngospasm, identified by stridor, or requiring treatment with positive pressure ventilation or drugs (eg, epinephrine); Bronchospasm, identified by auscultated wheezing, or requiring treatment with bronchodilation; Major coughing, continuous coughing requiring repositioning or suction; Difficult mask ventilation, defined as the use of two-handed mask ventilation, or the use of oropharyngeal airway; Difficult laryngoscopy, defined as more than one attempt at laryngoscopy; Difficult tracheal intubation, defined as the use of techniques other than direct laryngoscopy; Pulmonary aspiration, evidenced from chest radiogram; Respiratory depression, identified by low breathing rate (, 10 breaths per minute), or requiring treatment with reversal agent; Apnea, identified by the absence of respiratory function; and Need for supplemental oxygen, administered by nasal cannula or face mask.
Inclusion and Exclusion Criteria Full-text articles published between January 1990 and April 2014 in English-language peer-reviewed journals were included. Specific criteria for considering studies for this review include the following: 1. Types of study subjects: surgical pediatric patients aged 1 to 19 years receiving general anesthesia; studies conducted in adult patients, or in pediatric patients not receiving general anesthesia, were excluded; 2. Types of study design: observational studies conducted in the hospital environment, prospective or retrospective; 3. Types of exposure: overweight/obesity measured before anesthesia and surgery;
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4. Types of outcome measures: PAREs documented during induction, maintenance, or emergence from anesthesia, postanesthesia care unit stay, or the first 24 hours after anesthesia; and 5. Types of associations reported: associations between overweight/obesity and PAREs, by comparing the incidence of PAREs between obese, overweight, and normal weight patients. Database Search Two authors (NS and NB) independently searched for primary studies indexed in the Cumulative Index for Nursing and Allied Health Literature, PubMed (National Library of Medicine), Web of Science, Cochrane Library, and EMBASE. Key search terms used included ‘‘childhood obesity,’’ ‘‘children obesity,’’ ‘‘childhood overweight,’’ ‘‘overweight children,’’ ‘‘childhood body mass index,’’ and ‘‘obese children,’’ which were combined with ‘‘perioperative adverse respiratory events,’’ ‘‘respiratory complications,’’ ‘‘perioperative complications,’’ ‘‘perioperative morbidity,’’ ‘‘perioperative hypoxemia,’’ ‘‘perioperative airway obstruction,’’ and ‘‘anesthetic morbidity.’’ Database searches took place the last week of April 2014, and duplicate entries were removed. In the first stage, retrieved studies were screened for inclusion according to titles and abstracts. In the second stage, full text of selected articles was obtained and read for a final determination regarding eligibility for inclusion. Reference lists of the eligible articles were reviewed to identify additional potentially relevant articles not found in the online searches. Data Extraction and Quality Appraisal Two authors with long clinical experience in perianesthesia nursing (PK and EK) independently extracted data from included studies. Extracted data included year of publication, country, study design, study population (patient number, type of surgery, and age range), study duration, definitions and incidence of overweight/obesity, exclusion criteria used, use of power analysis, types of PAREs studied, and detected associations between overweight/
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obesity and PAREs at the univariate and multivariate levels. The reviewers re-examined articles in which their data extractions were discordant and discussed differences until consensus was reached. Study characteristics and findings were summarized in tables. Although methodological quality of studies was not a criterion for their inclusion in this review, selected studies were critically appraised and differences regarding their quality were evaluated. Specifically, quality of included studies was evaluated according to study design, types of operative procedures included, population size, use of a power analysis, exclusion criteria, and statistical analysis used.32
Results Search Outcome Initial online searches revealed 169 nonduplicate titles; of which 25 potentially relevant citations evaluated by title were identified (Figure 1). Based on abstract evaluation, 16 articles were selected for full-text review; nine of them were further
25 articles retrieved by title for abstract review 9 citations excluded based on abstract evaluation (not meeting eligibility criteria) 16 articles retrieved for full text review 7 articles excluded based on full text evaluation: - associations between overweight/obesity and PAREs not reported, n=4 - only morbidly obese pts enrolled (not compared with normal weight pts), n=1 - overweight/obesity and sleep disordered breathing used together for comparisons, n=1 - data on pt weight not reported, n=1 9 articles selected - 2 additional articles identified from reference list searches and evaluated by full text review Additional articles excluded based on full text evaluation: - only morbidly obese pts enrolled, n=2 A total of 9 articles met inclusion criteria
Figure 1. Flow diagram of literature search results. PAREs, perioperative adverse respiratory events; pts, patients.
selected based on full-text evaluation. There were two discrepancies during abstract review and one discrepancy during full-text review, all resolved by discussion. Two more potential citations were revealed through reference list searches, but were excluded after full-text evaluation. Thus, nine articles were finally considered appropriate for inclusion in this review.29–31,33–38 Study Characteristics Selected studies were published between 2007 and 2014 (Table 1). There were seven cohort studies,29,30,33,34,36–38 one case-control study,35 and one matched cohort study.31 All studies were single centered. Six studies were conducted in the United States (main author and hospital site were the same in three of them), with the remaining studies conducted in Canada,35 China,38 and Egypt.34 In all studies, associations between overweight/obesity and PAREs were among primary endpoints. Study duration ranged between 1 and 5 years. Overweight/obesity definitions varied among studies (Table 1). An overweight definition was used in four studies; overweight was defined as 85th , BMI , 95th percentile in two of them,29,30 and as BMI on or above the BMI curve passing through the 25 kg/m2 cutoff point at age 18 in another two studies.34,37 An obesity definition was used in eight studies; obesity was defined as BMI . 95th percentile in four studies,29,30,35,38 as BMI on or above the BMI curve passing through the 30 kg/m2 cutoff point at age 18 in another three studies,34,36,37 and as WC . 90th percentile (abdominal obesity) in one study.33 A severe obesity definition was used in one study,31 and this was defined as BMI . 98th percentile. In cohort studies, overweight incidence ranged between 14.4% and 17.3%; similarly, obesity incidence ranged between 4.7% and 17.2%, with abdominal obesity reaching up to 23.1% in one study. Overall incidence of PAREs was reported in five studies31,34,35,37,38 (Table 2). Hypoxemia (its definition ranged between SpO2 , 70% to , 90%) and airway obstruction were included among studied PAREs in eight studies. Laryngospasm, bronchospasm, and difficult mask ventilation were included in five studies; difficult
Author (Y)
Country/Study Design
Study Population/Duration
El-Metainy et al34 (2011)
Egypt/prospective, cohort, single-center
1,465 pts aged 2 to 16 y undergoing elective general surgery/2 y
Fung et al35 (2010)
Canada/prospective, casecontrol, single-center
49 obese pts with SDB aged 2 to 17 y undergoing adenotonsillectomy (pairmatched to pts with BMI , 85th percentile)/5 y 100 severely obese pts aged 2 to 18 y undergoing tonsillectomy (matched to 200 nonseverely obese pts)/1 y 6,094 pts aged 2 to 19 y undergoing elective general surgery/5 y
Gleich et al31 (2012) United States/retrospective, matched cohort, singlecenter Nafiu et al30 (2007)
United States/retrospective, cohort, single-center
Nafiu et al29 (2009)
United States/retrospective, cohort, single-center
Nafiu & Onyewuche33 (2014) Setzer and Saade36 (2007)
United States/prospective, cohort, single-center
Tait et al37 (2008)
United States/prospective, cohort, single-center
United States/retrospective, cohort, single-center
Excessive Weight Disorders: Definitions—Incidence Overweight (BMI $ curve passing through 25 kg/m2 point at age 18)—15.2% Obesity (BMI $ curve passing through 30 kg/m2 point at age 18)—10.5% Obesity (BMI . 95th percentile)
Severe obesity (BMI $ 98th percentile)
Exclusion Criteria/Power Analysis Conducted Secondary causes of obesity, laryngotracheomalacia, neuromuscular disorders/no
Incomplete BMI data, genetic, metabolic, neurologic, and syndromic conditions, craniofacial abnormalities, hypotonia/no Inconsistencies in weight measurement, multiple surgical procedures/no
(Continued )
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Incomplete BMI data, secondary Overweight (85th , BMI, 95th causes of obesity (syndromes), percentile)—14.4% obesogenic medications used/no Obesity (BMI . 95th percentile)— 17.2% 2,170 pts aged 3 to 19 y Overweight (85th , BMI , 95th Incomplete BMI data, secondary causes of obesity, chronic lung, undergoing adenotonsillectomy/ percentile)—13.1% or neuromuscular disease, 3y Obesity (BMI . 95th percentile)— laryngotracheomalacia, multiple 7.5% surgical procedures/no 1,102 pts aged 6 to 18 y Abdominal obesity (WC . 90th Cardiac surgery, ascites, pregnancy, undergoing elective general percentile)—23.1% intra-abdominal masses, severe surgery/2 y cardiorespiratory disease/no 1,133 pts aged 2 to 12 y Obesity (BMI $ curve passing ASA physical status . II/no undergoing dental surgery/1 y through 30 kg/m2 point at age 18)—8.8% 2,025 pts aged 2 to 18 y Overweight (BMI $ curve passing Cardiac surgery/yes undergoing elective general through 25 kg/m2 point at age surgery/20 mo 18)—17.3% Obesity (BMI $ curve passing through 30 kg/m2 point at age 18)—14.5%
RESPIRATORY EVENTS IN OVERWEIGHT/OBESE CHILDREN
Table 1. Main Characteristics of Included Studies
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Table 1. Continued Author (Y) Ye et al38 (2009)
Country/Study Design
Study Population/Duration
Excessive Weight Disorders: Definitions—Incidence
Exclusion Criteria/Power Analysis Conducted
China/retrospective, cohort, 321 pts with OSAS aged 4 to 14 y Obesity (BMI . 95th percentile)— ASA physical status . III, 4.7% concomitant surgery, genetic single-center undergoing adenotonsillectomy/ disorders, craniofacial 4.5 y abnormalities, severe cardiorespiratory or neuromuscular disease, Down syndrome, contraindications to general anesthesia/no
pts, patients; BMI, body mass index; SDB, sleep disordered breathing; WC, waist circumference; ASA, American Society of Anesthesiologists; OSAS, obstructive sleep apnea syndrome.
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RESPIRATORY EVENTS IN OVERWEIGHT/OBESE CHILDREN
laryngoscopy in four studies; need for supplemental oxygen in three studies; pulmonary aspiration and major coughing in two studies; and need for airway support, difficult tracheal intubation, respiratory depression, apnea, and reintubation in one study. Study Quality Differences in methodological quality of included studies were identified (Table 1). First, only four studies were prospective.33–35,37 Second, elective general surgery patients were enrolled in four cohort studies30,33,34,37; only adenotonsillectomy patients were enrolled in two cohort studies,29,38 in the case-control35 and the matched cohort study,31 whereas only dental surgery patients were enrolled in one cohort study.36 Third, six cohort studies used large patient population sizes, which exceeded 6,000 patients in one study,30 2,000 patients in two studies,29,37 and 1,000 patients in the rest three studies.33,34,36 The rest studies used considerably smaller patient numbers.31,35,38 Fourth, power analysis for determining required minimum population size was conducted in only one cohort study.37 Fifth, five cohort studies as well as the case-control and the matched cohort study used a considerable number of exclusion criteria for establishing precision and avoiding confounding effects; the rest two cohort studies36,37 used only one criterion each. Sixth, only five studies31,33,35,37,38 tested the associations between overweight/obesity and PAREs at the multivariate level (Table 2). Study Findings Significant associations between overweight/ obesity and PAREs were detected in all included studies (Table 2). Obesity was significantly associated with increased risk for overall PAREs in four studies,34,35,37,38 increased risk for airway obstruction in four studies,30,34,35,37 increased risk for hypoxemia in three studies,34,36,37 increased risk for difficult mask ventilation in three studies,30,34,37 increased risk for bronchospasm in two studies,34,37 increased risk for major coughing in one study,37 increased risk for difficult laryngoscopy in one study,30 and increased risk for the need for supplemental oxygen in one study.35
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Overweight/obesity was significantly associated with increased risk for airway obstruction, hypoxemia, difficult laryngoscopy, difficult mask ventilation, and laryngospasm in one study.29 Severe obesity was significantly associated with increased risk for overall PAREs, airway obstruction, hypoxemia, and laryngospasm in one study.31 Abdominal obesity was significantly associated with increased risk for airway obstruction, hypoxemia, and difficult mask ventilation in one study.33 The five studies in which the associations between obesity and PAREs were tested in the multivariate level reported that obesity,37,38 severe obesity,31 abdominal obesity,33 and BMI35 were significant predictors of increased risk for overall PAREs, whereas BMI was a significant predictor of increased risk for airway obstruction as well.35
Discussion Existing research on overweight/obesity in childhood has focused on its associations with chronic diseases and its effects on adult health status, with few recent studies having explored its contribution to perioperative complications and outcomes. The findings of studies included in this review provided considerable evidence that childhood overweight/obesity is linked to increased risk for overall PAREs, airway obstruction, hypoxemia, and difficult mask ventilation, whereas associations with difficult laryngoscopy, laryngospasm, bronchospasm, major coughing, and need for supplemental oxygen were also reported. Similar associations between obesity and PAREs have been reported for adult surgical patients, mainly for difficult laryngoscopy, difficult mask ventilation, and aspiration.39,40 Reported incidence of PAREs varied considerably among studies, depending on definitions used, anesthetic drugs administered, pre-existing respiratory disorders of patients enrolled, and operative procedures included. Only four studies enrolled general surgery patients, who sustained diverse operative procedures, and were highly representative of the pediatric surgical population. In addition, only few types of PAREs were investigated in most studies, raising the possibility that significant associations between overweight/ obesity and separate types of PAREs have actually been underdetected. It is also worth noting that
Author (Y)
PAREs Studied
Univariate Associations Between Overweight/Obesity and PAREs
18
Table 2. Types of PAREs Studied and Main Findings of Included Studies Multivariate Associations Between Overweight/Obesity and PAREs
Hypoxemia (SpO2 , 90%), airway obstruction, difficult mask ventilation, difficult laryngoscopy, bronchospasm, and pulmonary aspiration
Overall PAREs (40.9% vs 32.6%, P , .05), hypoxemia (14.9% vs 8.0%, P , .05), airway obstruction (24.0% vs 17.2%, P , .05), difficult mask ventilation (20.8% vs 3.2%, P , .01), and bronchospasm (7.8% vs 2.2%, P , .01) were more common in obese pts (compared with normal weight and overweight pts)
—
Fung et al35 (2010)
Hypoxemia (minor SpO2 81% to 90%, major SpO2 # 80%), bronchospasm, airway obstruction, need for airway support, respiratory depression, major coughing, need for supplemental oxygen leaving PACU
Overall PAREs (75.5% vs 26.5%, P , .01), airway obstruction (38.8% vs 8.2%, P , .01), and need for supplemental oxygen leaving PACU (36.7% vs 16.3%, P , .05) were more common in obese pts (compared with normal weight pts)
Higher BMI was independently associated with increased risk for airway obstruction (P , .01) and overall PAREs (P , .01)
Gleich et al31 (2012)
Difficult tracheal intubation, hypoxemia (mild SpO2 , 90%, severe SpO2 , 70%), bronchospasm, laryngospasm, airway obstruction, pulmonary aspiration, need for supplemental oxygen in PACU, and reintubation in PACU
Overall PAREs (15.0% vs 2.0%, P , .01), intraoperative hypoxemia (mild [19.0% vs 9.5%, P , .05] and severe [0.05% vs 0.005%, P , .05]), laryngospasm (0.04% vs 0.005%, P , .05), and airway obstruction (intraoperative [0.07% vs 0%, P , .01] and in PACU [0.03% vs 0%, P , .05]) were more common in severely obese pts (compared with normal weight pts)
Severe obesity was independently associated with increased risk for overall PAREs, both with (OR, 7.7; P , .01) and without adjusting (OR, 8.8; P , .01) for preoperative respiratory disorders
Nafiu et al30 (2007)
Airway obstruction in PACU, difficult laryngoscopy, and difficult mask ventilation
Difficult laryngoscopy (1.3% vs 0.4%, P , .01), difficult mask ventilation (7.4% vs 2.2%, P , .01), and airway obstruction in PACU (1.6% vs 0.1%, P , .01) were more common in obese pts (compared with normal weight pts)
—
Nafiu et al29 (2009)
Hypoxemia (SpO2 , 90%), airway obstruction, difficult laryngoscopy,
Hypoxemia (40.4% vs 30.9%, P , .01), airway obstruction (intraoperative [5.9%
—
KIEKKAS ET AL
El-Metainy et al34 (2011)
vs 0.2%, P , .01] and in PACU [3.7% vs 0.3%, P , .01]), difficult laryngoscopy (27.4% vs 11.9%, P , .01), difficult mask ventilation (31.6% vs 15.7%, P , .01), and laryngospasm (2.1% vs 0.2%, P , .01) were more common in overweight/obese pts (compared with normal weight pts)
Nafiu and Onyewuche33 (2014)
Hypoxemia (SpO2 , 90%), airway obstruction, difficult mask ventilation, difficult laryngoscopy, laryngospasm, and bronchospasm
Hypoxemia (3.5% vs 1.3%, P , .05), airway obstruction (intraoperative [14.9% vs 3.5%, P , .01] and in PACU [9.6% vs 3.3%, P , .01]), and difficult mask ventilation (26.0% vs 11.0%, P , .01) were more common in pts with abdominal obesity (compared with pts without abdominal obesity)
Abdominal obesity was independently associated with increased risk for overall PAREs (OR, 2.4; P , .01)
Setzer and Saade36 (2007)
Hypoxemia (SpO2 , 85%), laryngospasm, and need for supplemental oxygen in PACU
Intraoperative hypoxemia (2.0% vs 0.2%, P , .01) was more common in obese pts (compared with normal weight and overweight pts)
—
Tait et al37 (2008)
Hypoxemia (minor SpO2 5% to 10% decrease from baseline, major SpO2 . 10% decrease from baseline), apnea (minor , 30 s and major .30 s), airway obstruction, difficult mask ventilation, laryngospasm, bronchospasm, and major coughing
Overall PAREs (39.8% vs 25.1%, P , .01), major hypoxemia (16.8% vs 9.1%, P , .01), airway obstruction (18.9% vs 11.2%, P , .01), difficult mask ventilation (8.7% vs 2.1%, P , .01), bronchospasm (6.1% vs 2.0%, P , .01), and major coughing (7.1% vs 4.3%, P , .05) were more common in obese pts (compared with normal weight and overweight pts)
Obesity was independently associated with increased risk for overall PAREs (OR, 2.0; P , .05)
Ye et al38 (2009)
Postoperative hypoxemia (SpO2 , 95%) and postoperative airway obstruction (including apnea)
Overall PAREs (11.1% vs 3.9%, P , .05) were more common in obese pts (compared with normal weight and overweight pts)
Obesity was independently associated with increased risk for overall PAREs (OR, 1.5; P , .05)
RESPIRATORY EVENTS IN OVERWEIGHT/OBESE CHILDREN
difficult mask ventilation, and laryngospasm
PAREs, perioperative adverse respiratory events; pts, patients; PACU, postanesthesia care unit; BMI, body mass index; OR, odds ratio.
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KIEKKAS ET AL
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significant univariate and multivariate associations between obesity and overall PAREs were identified in all studies that tested this association. PAREs are closely inter-related (eg, airway obstruction or pulmonary aspiration may lead to hypoxemia, whereas laryngospasm or bronchospasm may result in airway obstruction), thus their overall incidence might better reflect obesity effects on patient airway and respiratory function.41 Although excessive weight seems plausible to contribute to increased risk for PAREs, it is difficult to define whether this risk increases in a progressive manner or if there is a weight threshold above which this risk emerges. Among existing studies, significant differences were reported when obese patients were compared with overweight/normal weight ones33,34,36–38 or to only normal weight ones,30,35 when severely obese patients were compared with normal weight ones,31 and when overweight/obese patients were compared with normal weight ones.29 Thus, because comparisons among excessive weight groups are missing, it remains questionable whether overweight children are at increased risk for PAREs or whether severely obese children are at higher risk than obese ones. In addition, risk for PAREs might not be uniformly increased for the whole childhood spectrum. According to recent findings, younger children are more susceptible to intraoperative hypoxemia than older ones irrespective of body weight,42 whereas obese children below 13 years are at higher risk for PAREs compared with those aged 13 to 16 years.34 To our knowledge, whether abdominal obesity could be more pathogenic for airway and respiratory function of children than BMI-defined obesity remains unknown. However, WC of young adults was reported to be a significantly better predictor of compromised pulmonary function than BMI.43 In case central fat distribution proves to better predict compromised airway and respiratory function in childhood than excessive weight per se, reported associations between BMI-defined obesity and PAREs are expected to have underestimated the actual contribution of obesity on the risk for PAREs. Anatomic and metabolic mechanisms account for the potential of childhood obesity to contribute to PAREs.33 Excessive adipose tissue may directly derange respiratory parameters and airway func-
tion, which are expected to be aggravated by general anesthesia administration toward adverse events. Alternatively, obesity-associated respiratory disorders can act as mediators for the manifestation of PAREs. Bronchial asthma is not only more common among obese children but also followed by increased risk for bronchospasm after general anesthesia with tracheal intubation.44,45 Likewise, sleep-related breathing disorders are strongly associated with both obesity and increased risk for hypoxemia.46,47 It should, however, be highlighted that obesity was independently associated with PAREs in studies that asthma, sleep-disordered breathing, and obstructive sleep apnea were included in the multivariate analysis.31,33,37 Study Limitations The small number of studies meeting the inclusion criteria, more than half of which were retrospective, was a major limitation of this review. Second, single-center conduct of all studies, three of them by the same research team, and the focus of five studies on specific operative procedures (adenotonsillectomy or dental surgery) limited generalizability of their findings. Third, some criteria used for defining PAREs were inevitably of subjective nature and depended on health care professionals’ expertise. Fourth, only published studies were considered for inclusion, thus the gray literature (theses or conference abstracts) was not covered. Fifth, established instruments used for study quality appraisal in systematic reviews were not used. Sixth, heterogeneous definitions of both overweight/obesity and PAREs did not allow extracted data to be combined in a meta-analysis. Implications for Clinical Practice and Research Major complications of pediatric anesthesia are by far associated with patients’ airway and respiratory function. Considering the increased risk for PAREs among obese children, health professionals employed in anesthesiology or surgical departments need to be aware of possible negative effects of obesity, especially in case of coexisting respiratory disorders or after high-risk operative procedures. Preoperative examination of obese pediatric surgical patients is recommended to include BMI, airway assessment, and pulse oximetry, along with pulmonary function tests if necessary. Within
RESPIRATORY EVENTS IN OVERWEIGHT/OBESE CHILDREN
the operating room, 3-minute preoxygenation and tracheal intubation in head-up or sniffing position, stomach desufflation, regular auscultation of breath sounds, and availability of difficult intubation equipment are expected to decrease risk for PAREs.48,49 Particular attention is needed during the postoperative phase for improving safety of obese pediatric patients. Appropriate care includes careful selection of pharmacologic agents and doses used.50 In contrast to opioids, administration of nonsteroidal anti-inflammatory drugs is not followed by respiratory depression and should thus be preferred. Alternatively, opioid doses have to be carefully titrated to avoid heavy sedation. With regard to patient positioning, head-up position increases vital capacity, semi-recumbent position decreases risk for atelectasis and improves oxygenation, whereas recovery position decreases risk for airway obstruction or aspiration.48,51 Finally, supplemental oxygen administration along with continuous pulse oximetry and surveillance until complete recovery from anesthesia offer the potential of preventing or timely detecting PAREs. Future research on childhood overweight/obesity has yet to address many issues related to PAREs. Prospective and multicenter cohort studies enrolling diverse pediatric surgical populations need to be conducted to ensure high generalizability of findings. These studies are called to further investigate the scarcely reported associations of obesity with difficult laryngoscopy,
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laryngospasm, bronchospasm, major coughing, and need for supplemental oxygen. Underlying mechanisms that link obesity with PAREs (ie, obstructive sleep apnea), as well as whether abdominal obesity can be more predictive of the risk for PAREs than BMI-defined obesity, are important to be elucidated. Meaningful questions for research also include whether the continuum of childhood overweight, obesity, and severe obesity corresponds to gradually increasing risk for PAREs, as well as whether the obesity-PAREs association differs significantly among specific age groups.
Conclusion This review summarizes the existing evidence about the role of overweight/obesity on the risk for PAREs in pediatric patients receiving general anesthesia. Associations of obesity with overall PAREs, hypoxemia, airway obstruction, and difficult mask ventilation have been strongly supported, whereas associations with laryngoscopy, laryngospasm, bronchospasm, major coughing, and need for supplemental oxygen have been reported but remain inconclusive. Although many factors related to the patient, anesthesia, or surgery predispose to PAREs, identifying obesity effects, anticipating adverse respiratory events in obese children during the entire perioperative phase, and appropriately managing this patient population is expected to contribute to the prevention or timely detection of PAREs. Additional research of better methodological quality is recommended for confirming and defining the exact nature of associations between childhood obesity and PAREs.
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