Journal of Perinatology (2015) 35, 142–145 © 2015 Nature America, Inc. All rights reserved 0743-8346/15 www.nature.com/jp
ORIGINAL ARTICLE
Rescuer fatigue during simulated neonatal cardiopulmonary resuscitation ES Li1,2,3, P-Y Cheung2,3, M O'Reilly2,3, K Aziz2,3 and GM Schmölzer2,3,4 OBJECTIVE: To assess development of fatigue during chest compressions (CCs) in simulated neonatal cardiopulmonary resuscitation (CPR). STUDY DESIGN: Prospective randomized manikin crossover study. Thirty neonatal healthcare professionals who successfully completed the Neonatal Resuscitation Program performed CPR using (i) 3:1 compression:ventilation (C:V) ratio, (ii) continuous CC with asynchronous ventilation (CCaV) at a rate of 90 CC per min and (iii) CCaV at 120 CC per min for a duration of 10 min on a neonatal manikin. Changes in peak pressure (a surrogate of fatigue) and CC rate were continuously recorded and fatigue among groups was compared. Participants were blinded to pressure tracings and asked to rate their level of comfort and fatigue for each CPR trial. RESULT: Compared with baseline, a significant decrease in peak pressure was observed after 72, 96 and 156 s in group CCaV-120, CCaV-90 and 3:1 C:V, respectively. CC depth decreased by 50% within the first 3 min during CCaV-120, 30% during CCaV-90 and 20% during 3:1 C:V. Moreover, 3:1 C:V and CCaV were similarly preferred by healthcare professionals. CONCLUSION: Similarly, 3:1 C:V and CCaV CPR were also fatiguing. We recommend that rescuers should switch after every second cycle of heart rate assessment during neonatal CPR. Journal of Perinatology (2015) 35, 142–145; doi:10.1038/jp.2014.165; published online 11 September 2014
INTRODUCTION About 0.08% of near-term and term infants and up to 10% of very preterm deliveries require chest compressions (CCs) at birth.1 In addition, outcome studies of preterm infants requiring cardiopulmonary resuscitation (CPR) or CC reported high rates of mortality and neurodevelopmental impairment in surviving children.2 The poor prognosis associated with resuscitations requiring CCs and/ or medications in the delivery room raises questions as to whether improved CPR techniques that are specifically tailored to the newborn could improve the outcomes.2–4 Current resuscitation guidelines recommend delivering coordinated CC and ventilation using a 3:1 compression:ventilation (C:V) ratio; however, the most effective method of delivering CC remains to be controversial.5 Adult animal studies and adult human randomized trials have demonstrated that continuous CC without rescue breaths increase return of spontaneous circulation (ROSC) and survival after sudden cardiac collapse.6,7 We recently demonstrated in our animal model that continuous CC at a rate of 90 per min with 30 asynchronous inflations had similar ROSC when compared with 3:1 CPR.8 In addition, we also recently showed that performing CC at a rate of 120 per min, which were superimposed by sustained inflation, significantly improved ROSC in our animal model compared with 3:1 CPR.9 Several studies assessed the quality of CC depth and reported alarmingly low adequacy; however, in the majority of studies they were within normal resuscitation guideline limits.10–15 In a study of in-hospital rescuers, CC quality deteriorates similarly in child and adult manikin models with comparable peak work per compression cycle, although peak power output was more intense and significantly higher in the adult model.11 This has led to changes
in current adult and pediatric resuscitation guidelines suggesting that healthcare professionals should switch every 2 min during pediatric or adult CPR.16 Conversely, there is a lack of information regarding switching resuscitators during neonatal CPR. Hemway et al.15 compared CC depth using different C:V ratios during 2-min simulated CPR and reported higher depth in the 3:1 group. Furthermore, a decay in CC depth in all three groups was observed.15 Christman et al.17 recently reported that the twothumb compared with the two-finger method is associated with greater depth during 3:1 C:V CPR. Although two studies have reported decay during brief periods of CC, no study has investigated rescuer fatigue over a longer period of CC. Current neonatal CPR guidelines do not address the issue of rescuer fatigue during CC nor have any recommendations regarding the switching of rescuers while performing CC. The aim of the study was to assess development of fatigue during CC in simulated neonatal CPR performed by neonatal healthcare professionals. METHODS Study design This study was carried out at the Royal Alexandra Hospital, Edmonton, AB, Canada, a tertiary perinatal center. The Royal Alexandra Hospital Research Committee and Health Ethics Research Board, University of Alberta approved the study. A neonatal resuscitation baby manikin (Neonatal Resuscitation Baby, Laerdal, Stavanger, Norway) was modified with a 50 ml normal saline infusion bag placed under the manikin’s chest. The infusion bag was connected to a pressure transducer via intravenous catheter and tubing. The pressure transducer was connected to an IntelliVue MP50 monitor (Philips Healthcare, Philips Electronics, Markham, ON, Canada). Peak CC
1 Faculty of Science, McGill University, Montreal, QC, Canada; 2Neonatal Research Unit, Royal Alexandra Hospital, Edmonton, AB, Canada; 3Division of Neonatology, Department of Pediatrics, University of Alberta, Edmonton, AB, Canada and 4Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria. Correspondence: Professor GM Schmölzer, Neonatal Research Unit, Royal Alexandra Hospital, 10240 Kingsway Avenue NW, Edmonton, Canada AB T5H 3V9. E-mail: [email protected] Received 16 April 2014; revised 29 July 2014; accepted 29 July 2014; published online 11 September 2014
Fatigue during neonatal resuscitation ES Li et al
143 Table 1.
Level of fatigue and comfort during each trial—based on a Likert scale rating
Participants’ perception of fatigue 3:1 C:V CCaV-90 CCaV-120 Participants’ level of comfort 3:1 C:V CCaV-90 CCaV-120
Not fatigued
Slightly fatigued
Somewhat fatigued
Moderately fatigued
Extremely fatigued
1 (3%) 1 (3%) —
10 (33%) 5 (17%) —
13 (43%) 13 (43%) 2 (7%)
5 (17%) 9 (30%) 17 (57%)
1 (3%) 2 (7%) 11 (36%)
Very uncomfortable
Moderately uncomfortable
Neutral
Moderately comfortable
Very comfortable
1 (4%) 2 (7%) 7 (23%)
2 (7%) 7 (23%) 12 (40%)
6 (20%) 8 (27%) 3 (10%)
16 (53%) 11 (37%) 5 (17%)
5 (17%) 2 (7%) 3 (10%)
Abbreviations: C, compression; CCaV, continuous chest compressions with asynchronous ventilations; V, ventilation.
pressure was measured continuously and was used as a surrogate for rescuer fatigue, which was the primary outcome of this study. Rescuer fatigue was defined as a significant decrease in peak CC pressure compared with baseline. The rate of CC was also continuously recorded. The manikin was placed on an adjustable resuscitation incubator (Giraffe Incubator, General Electric Healthcare, Burnaby, BC, Canada) to allow for height adjustments for each participant corresponding to their own comfort level. We used the same setup as previously reported by Dorfsman et al.,18 who compared blood pressures of two-thumb vs two-finger CC during prolonged CPR.
Study participants All study subjects were recruited using Health Ethics Research Boardapproved study posters, which were displayed throughout the Neonatal Intensive Care Unit at the Royal Alexandra Hospital over a period of 4 weeks. Registered Neonatal Resuscitation Program (NRP) healthcare professionals were included in the study. No participants were recruited from NRP classes. Exclusion criteria were expired NRP registration or any medical condition contraindicating the exertion required for CPR. Demographic information including age, gender, time since of last certification, field of work, experience and written informed consent were also obtained. A convenient sample of 30 subjects was recruited.
Study protocol Participants were instructed to deliver three sets of CC using the twothumb encircling method, delivered to the lower third of the sternum with a depth of approximately one-third of the anterior–posterior diameter of the manikin’s chest. Participants were asked to perform (i) the currently recommended 3:1 C:V ratio; (ii) continuous CC with asynchronous ventilation (CCaV) at a rate of 90 CC per min (CCaV-90); and (iii) CCaV at a rate of 120 CC per min (CCaV-120) for 10 min each. 3:1 C:V CPR was performed according to the current neonatal resuscitation guidelines, providing 90 CC and 30 inflations per min.5 A metronome was used to assist the rescuer for the duration of the each trial. One investigator (GMS) provided mask ventilation in all trials. In the 3:1 C:V group, after three CCs an inflation was provided. In the CCaV-90 group, 30 inflations were provided during continuous CC without interrupting CC. In the CCaV-120 group, sustained inflations of a 30-s duration were provided, as previously described in our animal study.9 The sequence of trials was randomized using an online randomizer. Each participant was only allowed to perform one trial per day to reduce any potential bias of fatigue. Rescuers were blinded to pressure tracings and no feedback was given regarding their performance. The rescuers were able to adjust the height of the resuscitation incubator before the study. After height adjustment, the entire system was calibrated by zeroing the pressure transducer. After completing all three trials, each rescuer was asked to complete a questionnaire with a Likert scale concerning the level of fatigue and comfort while performing each technique, and the method of CPR they preferred (Table 1).
Data collection and analysis Data are presented as the mean ± s.d. for normally distributed continuous variables. Peak pressure was continuously recorded for the 10-min duration of each trial. We defined baseline as the average peak pressures generated in the first 10 s after the commencement of CC, and compared © 2015 Nature America, Inc.
baseline pressure with all subsequent measurements using a two-way repeated-measures analysis of variance (two-factor repetition) with a generalized linear model and post hoc Tukey's test. Chi-square was used for analysis of the level of comfort and fatigue as determined by participant questionnaire. A P-value of o0.05 was considered to be statistically significant.
RESULTS A total of 35 healthcare professionals were invited to participate; 5 declined consent, leaving 30 healthcare professionals (neonatologists (n = 5), neonatal–perinatal fellows (n = 3), neonatal nurse practitioners (n = 7) and registered nurses (n = 15)). Twenty-four (80%) of the participants were female. Participants had 14 ± 9 years of neonatal experience, and 9 ± 8 months had passed since their last NRP update. Each trial was separated by 4 ± 3 days. Overall, 15 (50%) of the rescuers preferred the 3:1 group, 14 (47%) and 1 (3%) the CCaV-90 and CCaV-120 groups, respectively. Selfreported levels of comfort and fatigue for each method are presented in Table 1. Overall, rates of CC were 94 ± 3 CC per min in the 3:1 group, 92 ± 10 and 120 ± 4 CC per min in the CCaV-90 and CCaV-120 groups, respectively. No significant decrease was detected in CC rate over time. The demographics of the healthcare professionals were not related to their performance. We observed a gradual decrease in peak CC pressure from baseline in all three groups over the 10-min study period. Compared with the respective baseline, peak pressure significantly decreased at 156, 96 and 72 s after commencement of CC in the 3:1, CCaV-90, and CCaV-120 groups, respectively. However, CCaV-120 and CCaV-90 had higher peak pressure throughout the resuscitation compared with 3:1 group. After 3 min, CC depth reduced by 50% in the CCaV-120 group, 30% in the CCaV-90 group and 20% in the 3:1 group (Figure 1). Participants perceived more fatigue while performing CCaV-120 compared with 3:1 C:V CPR or CCaV-90 (P = 0.006). There was a trend to be more fatigued when participants performed CCaV-90 compared with 3:1 C:V CPR (P = 0.083). DISCUSSION In the current study we compared three different techniques of neonatal resuscitation, and their effect on rescuer fatigue over a 10-min period. Our rationale behind having 10-min trials was threefold (i) no other studies have considered rescuer fatigue during CC over a long period of time; (ii) current resuscitation guidelines advise that it is appropriate to consider stopping resuscitation if heart rate remains undetectable for 10 min;5 (iii) this method allowed us to reliably induce fatigue. We compared the currently recommended approach of neonatal resuscitation, 3:1 C:V CPR,5 with two recently described experimental approaches.8,9 The two experimental approaches were continuous CC at a rate of 90 CC per min with 30 inflations per min (CCaV-90),8,19 Journal of Perinatology (2015), 142 – 145
Fatigue during neonatal resuscitation ES Li et al
144
Figure 1.
Reduction of compression depth in percentage for each group over the 10-min period of CC.
and continuous CC at a rate of 120 CC per min, which were superimposed by a sustained inflation (CCaV-120).9 We observed a gradual decrease in peak pressure throughout the 10-min study period in all three groups, with a significant decrease from baseline at 156, 96 and 72 s after commencement of CC in the 3:1, CCaV-90 and CCaV-120 groups, respectively. CCaV compared with 3:1 CPR achieved higher peak pressure at baseline, which resulted in a larger percentage decrease in pressure during the 10-min CPR period. Although we observed a higher initial decay in pressures, peak pressure remained stable throughout the study period. Several studies of simulated adult and pediatric CPR reported an impact of fatigue on quality of CC;10–13,20,21 however, the evidence in newborn infants is limited.14,15 Peak power output generated during pediatric resuscitation is comparable to power generated during intense exercise (for example, running 9 km h − 1).11 In addition, peak work per compression cycle and deterioration of CC quality is comparable between adult and pediatric resuscitation.11 The depth of CC can be translated into compression force, which is related to changes in intrathoracic pressure.22 Manikin studies demonstrated that adequate CC depths are infrequently achieved, implying that CC depth should be emphasized more during CPR training and real-life resuscitations.1 During CPR it is imperative that CC are delivered with an adequate pressure and depth,5 as rescuer fatigue causes deterioration of CC quality, potentially leading to reduced cardiac output and increased mortality. Therefore, current pediatric resuscitation guidelines suggest that professionals should be switched every 2 min while performing CC.16 Badaki-Makun et al.11 reported similar rates of fatigue in adult and child CPR, with a decrease in CC depth after 42 min of CPR. In comparison, two studies examined the rate of fatigue within 2 min of CPR in pediatric and neonatal healthcare professionals and reported no significant decay in CC, which is comparable to our results.10,15 Hemway et al. also observed a significant decay in CC depth between the first and last 25 s of the 2-min CC period, which is similar to our results, suggesting that after 2 min of CC, a significant decay in CC depth can be observed. Interestingly, in the CCaV-90 group, fatigue occurred ~ 60 s earlier compared with 3:1 C:V and time to fatigue was further halved in the CCaV-120 group (Figure 1). Indeed, asynchronous ventilations may work against the compressions being delivered and thereby may have potential to increase the workload and fatigue of the healthcare professional, which could be decreased by the interruptions during synchronous ventilation and compressions. Our results suggest CC quality improved when healthcare professionals were provided with a rest as exemplified in 3:1 C:V Journal of Perinatology (2015), 142 – 145
CPR. Min et al.23 reported that CC quality improved when rescuers were provided with a resting period at a particular time during CC compared with CC without rest. Current neonatal CPR guidelines recommend that heart rate should be reassessed after 45 to 60 s of CC, and CC should be continued until heart rate is 460 min − 1. We observed fatigue after 96 s in the CCaV-90 and 156 s in the 3:1 group, suggesting that rescuers should switch after every second heart rate evaluation cycle. Studies examining changes in CC rate during prolonged CPR report an increase or decrease in CC rate over time.11,24 In the current study, all participants continued to deliver CC at a constant rate throughout the 10-min study period despite observed fatigue. We believe that the aid of a metronome contributed to the constant CC rate. Data from in-hospital adult CPR observed no change in CC rate during 3 min of CPR with real-time audio-visual feedback.25 Alternatively, Dold et al.26 reported more accurate CC rates when participants listened to a musical prompt during CPR. In addition, Binder et al.27 reported that visual or verbal feedback significantly reduced mask leak during simulated neonatal CPR. However, no study has assessed real-time neonatal CPR in the delivery room or the neonatal intensive care unit. Further research is required to identify whether audio, visual, audio-visual feedback or musical prompts might be beneficial during neonatal resuscitation training or real-life resuscitation. Although adult human and animal studies have shown that continuous CC increases ROSC and survival, it is important to note that the etiology of neonatal cardiovascular collapse is asphyxia compared to ventricular fibrillation in adults. In addition, newborns must also undergo postnatal adaptation, which might hinder translation of adult data to newborns.28 In this study we delivered ventilations without interrupting CC to minimize interference between compressions and ventilations. There were concerns that CCaV impeded tidal volume delivery during CC. In a recent animal study, we demonstrated that o 30% of inflations are impeded by CC resulting in a lower tidal volume delivery during CCaV or 3:1 C:V CPR.8 Our data also show that it increases fatigue of the healthcare professional delivering CC. Limitations Manikin studies do not fully resemble real-life scenarios of neonatal resuscitation including the psycho-physical stress and environmental factors, which are limitations for clinical translation. Although we did not assess whether the placement of a salinefilled bag under the manikin’s chest potentially changed the force required to provide CC, a similar study did not report any concerns © 2015 Nature America, Inc.
Fatigue during neonatal resuscitation ES Li et al
using this method.18 Comparable manikin studies reported compression depth in millimeters,17 but no study compared either technique with real-life resuscitations. There was no reliable way to measure arterial pressures as the mechanism of antegrade blood flow during CPR is complex and cannot be simulated in a manikin. Therefore, we cannot accurately determine which group delivered more accurate pressures. Nonetheless, it was evident that there was fatigue in all groups. Further, in this study there was no goal peak pressure for the participants, as they were blinded to pressure tracings. The participants were asked to perform compressions according to CPR guidelines: compress one-third of the anterior–posterior diameter of the chest on the lower onethird of the sternum. Thus it is uncertain whether our findings could be translated in some novel pressure-targeted resuscitation techniques.29 We did not observe a change in CC rate throughout the 10-min period, which we attribute to the use of a metronome. Unfortunately, we did not predetermine a sample size before the study, which is a limitation of the current study.
145 9
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12
13
14
15
CONCLUSIONS Overall, 3:1 C:V CPR was the least fatiguing and the most preferred method of neonatal CPR. We recommend that rescuers should switch after every second cycle of heart rate assessment during neonatal CPR. CONFLICT OF INTEREST
16 17
18
The authors declare no conflict of interest. 19
ACKNOWLEDGEMENTS
20
We would like to thank all participating neonatal healthcare professionals who contributed to this study with their own enthusiasm and effort, and Tze-Fun Lee for statistical assistance. ESL is supported in part by the Northern Alberta Clinical Trials and Research Centre Faculty of Medicine and Dentistry, University of Alberta, and Neonatal Research Fund, Northern Alberta Neonatal Program, Alberta Health Services. GMS is a recipient of a Banting Postdoctoral Fellowship, Canadian Institutes of Health Research and an Alberta Innovates–Health Solutions Clinical Fellowship.
22
REFERENCES
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1 Wyckoff MH, Perlman JM, Finer NN, Horbar JD. Cardiopulmonary resuscitation in very low birth weight infants. Pediatrics 2000; 106: 618–620. 2 Wyckoff MH, Salhab WA, Heyne RJ, Kendrick DE, Stoll BJ, Laptook AR. Outcome of extremely low birth weight infants who received delivery room cardiopulmonary resuscitation. J Pediatr 2012; 160: 239–244. 3 Kapadia V, Wyckoff MH. Chest compressions for bradycardia or asystole in neonates. Clin Perinatol 2012; 39: 833–842. 4 Wyckoff MH. Improving neonatal cardiopulmonary resuscitation hemodynamics: are sustained inflations during compressions the answer? Circulation 2013; 128: 2468–2469. 5 Kattwinkel J, Perlman JM, Aziz K, Colby C, Fairchild K, Gallagher J et al. Part 15: neonatal resuscitation: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2010; 122: S909–S919. 6 Berg RA, Hilwig RW, Kern KB, Ewy GA. "Bystander" chest compressions and assisted ventilation independently improve outcome from piglet asphyxial pulseless “Cardiac Arrest”. Circulation 2000; 101: 1743–1748. 7 Kern KB, Berg RA, Hilwig RW, Sanders AB, Ewy GA. Importance of continuous chest compressions during cardiopulmonary resuscitation improved outcome during a simulated single lay-rescuer scenario. Circulation 2002; 105: 645–649. 8 Schmölzer G, O’Reilly M, LaBossiere J, Lee T-F, Cowan S, Nicoll J et al. 3:1 compression to ventilation ratio versus continuous chest compression with
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asynchronous ventilation in a porcine model of neonatal resuscitation. Resuscitation 2014; 85: 270–275. Schmölzer G, OReilly M, LaBossiere J, Lee TF, Cowan S. Cardiopulmonary resuscitation with chest compressions during sustained inflations: a new technique of neonatal resuscitation That Improves Recovery and Survival in a Neonatal Porcine Model. Circulation 2013; 128: 2495–2503. Hamrick JT, Fisher B, Quinto KB, Foley J. Quality of external closed-chest compressions in a tertiary pediatric setting: Missing the mark. Resuscitation 2010; 81: 718–723. Badaki-Makun O, Nadel F, Donoghue A, McBride M, Niles D, Seacrist Tet al. Chest compression quality over time in pediatric resuscitations. Pediatrics 2013; 131: e797–e804. Ashton A, McCluskey A, Gwinnutt CL, Keenan AM. Effect of rescuer fatigue on performance of continuous external chest compressions over 3 min. Resuscitation 2002; 55: 151–155. Abella BS, Alvarado JP, Sandbo N, Vassilatos P, O'Hearn N, Wigder HN et al. Chest compression rates during cardiopulmonary resuscitation are suboptimal: a prospective study during in-hospital cardiac arrest. Circulation 2005; 111: 428–434. Wyckoff MH, Christman C, Hemway RJ, Perlman JM. The two-thumb is superior to the two-finger method for administering chest compressions in a manikin model of neonatal resuscitation. Arch Dis Child Fetal Neonatal Ed 2011; 96: F99–F101. Hemway RJ, Christman C, Perlman JM. The 3:1 is superior to a 15:2 ratio in a newborn manikin model in terms of quality of chest compressions and number of ventilations. Arch Dis Child Fetal Neonatal Ed 2012; 98: F42–F45. Kleinman ME, de AR, Chameides L, Atkins DL, Berg R, Berg M et al. Part 10: Paediatric basic and advanced life support. Circulation 2010; 122: S466–S515. Christman C, Hemway RJ, Wyckoff MH, Perlman JM. The two-thumb is superior to the two-finger method for administering chest compressions in a manikin model of neonatal resuscitation. Arch Dis Child Fetal Neonatal Ed 2011; 96: F99–F10. Dorfsman ML, Menegazzi JJ, Wadas RJ, Auble TE. Two-thumb vs. two-finger chest compression in an infant model of prolonged cardiopulmonary resuscitation. Acad Emerg Med 2000; 7: 1077–1082. Li ES, Cheung PY, Pichler G, Aziz K, Schmölzer GM. Respiratory function and near infrared spectroscopy recording during cardiopulmonary resuscitation in an extremely preterm Newborn. Neonatology 2014; 105: 200–204. Bjørshol CA, Søreide E, Torsteinbø TH, Lexow K, Nilsen OB, Sunde K. Quality of chest compressions during 10 min of single-rescuer basic life support with different compression: ventilation ratios in a manikin model. Resuscitation 2008; 77: 95–100. Haque IU, Udassi JP, Udassi S, Theriaque DW, Shuster JJ, Zaritsky AL. Chest compression quality and rescuer fatigue with increased compression to ventilation ratio during single rescuer pediatric CPR. Resuscitation 2008; 79: 82–89. Cheung P-Y, Schmölzer G. Learning not to lean when you push … some hardpressed issues of cardiac compressions during cardiopulmonary resuscitation of neonates. Resuscitation 2013; 84: 1637–1638. Min MK, Yeom SR, Ryu JH, Kim YI, Park MR, Han SK et al. A 10-s rest improves chest compression quality during hands-only cardiopulmonary resuscitation: A prospective, randomized crossover study using a manikin model. Resuscitation 2013; 84: 1279–1284. Solevåg A, Dannevig I, Wyckoff M, Saugstad O, Nakstad B. Return of spontaneous circulation with a compression:ventilation ratio of 15:2 versus 3:1 in newborn pigs with cardiac arrest due to asphyxia. Arch Dis Child Fetal Neonatal Ed 2011; 96: F417–F421. Sugerman NT, Edelson DP, Leary M, Weidman EK, Herzberg DL, Vanden Hoek TL et al. Rescuer fatigue during actual in-hospital cardiopulmonary resuscitation with audiovisual feedback: A prospective multicenter study. Resuscitation 2009; 80: 981–984. Dold S, Schmölzer GM, Kelm M, Davis PG, Schmalisch G, Roehr CC. Training Neonatal Cardiopulmonary Resuscitation: Can It Be Improved by Playing a Musical Prompt? A Pilot Study. Amer J Perinatol 2013; 31: 245–248. Binder C, Urlesberger B, Schmölzer G, O’Reilly M, Pichler G. Human or monitor feedback to improve mask ventilation during simulated neonatal cardiopulmonary resuscitation. Arch Dis Child Fetal Neonatal Ed 2014; 99: F120–F123. Wyllie J. Resuscitation of the depressed newborn. Semin Fetal Neonatal Med 2006; 11: 158–165. Friess SH, Sutton RM, Bhalala U, Maltese MR, Naim MY, Bratinov G et al. Hemodynamic directed cardiopulmonary resuscitation improves short-term survival from ventricular fibrillation cardiac arrest. Crit Care Med 2013; 41: 2698–2704.
Journal of Perinatology (2015), 142 – 145
ORIGINAL ARTICLE
Rescuer fatigue during simulated neonatal cardiopulmonary resuscitation ES Li1,2,3, P-Y Cheung2,3, M O'Reilly2,3, K Aziz2,3 and GM Schmölzer2,3,4 OBJECTIVE: To assess development of fatigue during chest compressions (CCs) in simulated neonatal cardiopulmonary resuscitation (CPR). STUDY DESIGN: Prospective randomized manikin crossover study. Thirty neonatal healthcare professionals who successfully completed the Neonatal Resuscitation Program performed CPR using (i) 3:1 compression:ventilation (C:V) ratio, (ii) continuous CC with asynchronous ventilation (CCaV) at a rate of 90 CC per min and (iii) CCaV at 120 CC per min for a duration of 10 min on a neonatal manikin. Changes in peak pressure (a surrogate of fatigue) and CC rate were continuously recorded and fatigue among groups was compared. Participants were blinded to pressure tracings and asked to rate their level of comfort and fatigue for each CPR trial. RESULT: Compared with baseline, a significant decrease in peak pressure was observed after 72, 96 and 156 s in group CCaV-120, CCaV-90 and 3:1 C:V, respectively. CC depth decreased by 50% within the first 3 min during CCaV-120, 30% during CCaV-90 and 20% during 3:1 C:V. Moreover, 3:1 C:V and CCaV were similarly preferred by healthcare professionals. CONCLUSION: Similarly, 3:1 C:V and CCaV CPR were also fatiguing. We recommend that rescuers should switch after every second cycle of heart rate assessment during neonatal CPR. Journal of Perinatology (2015) 35, 142–145; doi:10.1038/jp.2014.165; published online 11 September 2014
INTRODUCTION About 0.08% of near-term and term infants and up to 10% of very preterm deliveries require chest compressions (CCs) at birth.1 In addition, outcome studies of preterm infants requiring cardiopulmonary resuscitation (CPR) or CC reported high rates of mortality and neurodevelopmental impairment in surviving children.2 The poor prognosis associated with resuscitations requiring CCs and/ or medications in the delivery room raises questions as to whether improved CPR techniques that are specifically tailored to the newborn could improve the outcomes.2–4 Current resuscitation guidelines recommend delivering coordinated CC and ventilation using a 3:1 compression:ventilation (C:V) ratio; however, the most effective method of delivering CC remains to be controversial.5 Adult animal studies and adult human randomized trials have demonstrated that continuous CC without rescue breaths increase return of spontaneous circulation (ROSC) and survival after sudden cardiac collapse.6,7 We recently demonstrated in our animal model that continuous CC at a rate of 90 per min with 30 asynchronous inflations had similar ROSC when compared with 3:1 CPR.8 In addition, we also recently showed that performing CC at a rate of 120 per min, which were superimposed by sustained inflation, significantly improved ROSC in our animal model compared with 3:1 CPR.9 Several studies assessed the quality of CC depth and reported alarmingly low adequacy; however, in the majority of studies they were within normal resuscitation guideline limits.10–15 In a study of in-hospital rescuers, CC quality deteriorates similarly in child and adult manikin models with comparable peak work per compression cycle, although peak power output was more intense and significantly higher in the adult model.11 This has led to changes
in current adult and pediatric resuscitation guidelines suggesting that healthcare professionals should switch every 2 min during pediatric or adult CPR.16 Conversely, there is a lack of information regarding switching resuscitators during neonatal CPR. Hemway et al.15 compared CC depth using different C:V ratios during 2-min simulated CPR and reported higher depth in the 3:1 group. Furthermore, a decay in CC depth in all three groups was observed.15 Christman et al.17 recently reported that the twothumb compared with the two-finger method is associated with greater depth during 3:1 C:V CPR. Although two studies have reported decay during brief periods of CC, no study has investigated rescuer fatigue over a longer period of CC. Current neonatal CPR guidelines do not address the issue of rescuer fatigue during CC nor have any recommendations regarding the switching of rescuers while performing CC. The aim of the study was to assess development of fatigue during CC in simulated neonatal CPR performed by neonatal healthcare professionals. METHODS Study design This study was carried out at the Royal Alexandra Hospital, Edmonton, AB, Canada, a tertiary perinatal center. The Royal Alexandra Hospital Research Committee and Health Ethics Research Board, University of Alberta approved the study. A neonatal resuscitation baby manikin (Neonatal Resuscitation Baby, Laerdal, Stavanger, Norway) was modified with a 50 ml normal saline infusion bag placed under the manikin’s chest. The infusion bag was connected to a pressure transducer via intravenous catheter and tubing. The pressure transducer was connected to an IntelliVue MP50 monitor (Philips Healthcare, Philips Electronics, Markham, ON, Canada). Peak CC
1 Faculty of Science, McGill University, Montreal, QC, Canada; 2Neonatal Research Unit, Royal Alexandra Hospital, Edmonton, AB, Canada; 3Division of Neonatology, Department of Pediatrics, University of Alberta, Edmonton, AB, Canada and 4Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria. Correspondence: Professor GM Schmölzer, Neonatal Research Unit, Royal Alexandra Hospital, 10240 Kingsway Avenue NW, Edmonton, Canada AB T5H 3V9. E-mail: [email protected] Received 16 April 2014; revised 29 July 2014; accepted 29 July 2014; published online 11 September 2014
Fatigue during neonatal resuscitation ES Li et al
143 Table 1.
Level of fatigue and comfort during each trial—based on a Likert scale rating
Participants’ perception of fatigue 3:1 C:V CCaV-90 CCaV-120 Participants’ level of comfort 3:1 C:V CCaV-90 CCaV-120
Not fatigued
Slightly fatigued
Somewhat fatigued
Moderately fatigued
Extremely fatigued
1 (3%) 1 (3%) —
10 (33%) 5 (17%) —
13 (43%) 13 (43%) 2 (7%)
5 (17%) 9 (30%) 17 (57%)
1 (3%) 2 (7%) 11 (36%)
Very uncomfortable
Moderately uncomfortable
Neutral
Moderately comfortable
Very comfortable
1 (4%) 2 (7%) 7 (23%)
2 (7%) 7 (23%) 12 (40%)
6 (20%) 8 (27%) 3 (10%)
16 (53%) 11 (37%) 5 (17%)
5 (17%) 2 (7%) 3 (10%)
Abbreviations: C, compression; CCaV, continuous chest compressions with asynchronous ventilations; V, ventilation.
pressure was measured continuously and was used as a surrogate for rescuer fatigue, which was the primary outcome of this study. Rescuer fatigue was defined as a significant decrease in peak CC pressure compared with baseline. The rate of CC was also continuously recorded. The manikin was placed on an adjustable resuscitation incubator (Giraffe Incubator, General Electric Healthcare, Burnaby, BC, Canada) to allow for height adjustments for each participant corresponding to their own comfort level. We used the same setup as previously reported by Dorfsman et al.,18 who compared blood pressures of two-thumb vs two-finger CC during prolonged CPR.
Study participants All study subjects were recruited using Health Ethics Research Boardapproved study posters, which were displayed throughout the Neonatal Intensive Care Unit at the Royal Alexandra Hospital over a period of 4 weeks. Registered Neonatal Resuscitation Program (NRP) healthcare professionals were included in the study. No participants were recruited from NRP classes. Exclusion criteria were expired NRP registration or any medical condition contraindicating the exertion required for CPR. Demographic information including age, gender, time since of last certification, field of work, experience and written informed consent were also obtained. A convenient sample of 30 subjects was recruited.
Study protocol Participants were instructed to deliver three sets of CC using the twothumb encircling method, delivered to the lower third of the sternum with a depth of approximately one-third of the anterior–posterior diameter of the manikin’s chest. Participants were asked to perform (i) the currently recommended 3:1 C:V ratio; (ii) continuous CC with asynchronous ventilation (CCaV) at a rate of 90 CC per min (CCaV-90); and (iii) CCaV at a rate of 120 CC per min (CCaV-120) for 10 min each. 3:1 C:V CPR was performed according to the current neonatal resuscitation guidelines, providing 90 CC and 30 inflations per min.5 A metronome was used to assist the rescuer for the duration of the each trial. One investigator (GMS) provided mask ventilation in all trials. In the 3:1 C:V group, after three CCs an inflation was provided. In the CCaV-90 group, 30 inflations were provided during continuous CC without interrupting CC. In the CCaV-120 group, sustained inflations of a 30-s duration were provided, as previously described in our animal study.9 The sequence of trials was randomized using an online randomizer. Each participant was only allowed to perform one trial per day to reduce any potential bias of fatigue. Rescuers were blinded to pressure tracings and no feedback was given regarding their performance. The rescuers were able to adjust the height of the resuscitation incubator before the study. After height adjustment, the entire system was calibrated by zeroing the pressure transducer. After completing all three trials, each rescuer was asked to complete a questionnaire with a Likert scale concerning the level of fatigue and comfort while performing each technique, and the method of CPR they preferred (Table 1).
Data collection and analysis Data are presented as the mean ± s.d. for normally distributed continuous variables. Peak pressure was continuously recorded for the 10-min duration of each trial. We defined baseline as the average peak pressures generated in the first 10 s after the commencement of CC, and compared © 2015 Nature America, Inc.
baseline pressure with all subsequent measurements using a two-way repeated-measures analysis of variance (two-factor repetition) with a generalized linear model and post hoc Tukey's test. Chi-square was used for analysis of the level of comfort and fatigue as determined by participant questionnaire. A P-value of o0.05 was considered to be statistically significant.
RESULTS A total of 35 healthcare professionals were invited to participate; 5 declined consent, leaving 30 healthcare professionals (neonatologists (n = 5), neonatal–perinatal fellows (n = 3), neonatal nurse practitioners (n = 7) and registered nurses (n = 15)). Twenty-four (80%) of the participants were female. Participants had 14 ± 9 years of neonatal experience, and 9 ± 8 months had passed since their last NRP update. Each trial was separated by 4 ± 3 days. Overall, 15 (50%) of the rescuers preferred the 3:1 group, 14 (47%) and 1 (3%) the CCaV-90 and CCaV-120 groups, respectively. Selfreported levels of comfort and fatigue for each method are presented in Table 1. Overall, rates of CC were 94 ± 3 CC per min in the 3:1 group, 92 ± 10 and 120 ± 4 CC per min in the CCaV-90 and CCaV-120 groups, respectively. No significant decrease was detected in CC rate over time. The demographics of the healthcare professionals were not related to their performance. We observed a gradual decrease in peak CC pressure from baseline in all three groups over the 10-min study period. Compared with the respective baseline, peak pressure significantly decreased at 156, 96 and 72 s after commencement of CC in the 3:1, CCaV-90, and CCaV-120 groups, respectively. However, CCaV-120 and CCaV-90 had higher peak pressure throughout the resuscitation compared with 3:1 group. After 3 min, CC depth reduced by 50% in the CCaV-120 group, 30% in the CCaV-90 group and 20% in the 3:1 group (Figure 1). Participants perceived more fatigue while performing CCaV-120 compared with 3:1 C:V CPR or CCaV-90 (P = 0.006). There was a trend to be more fatigued when participants performed CCaV-90 compared with 3:1 C:V CPR (P = 0.083). DISCUSSION In the current study we compared three different techniques of neonatal resuscitation, and their effect on rescuer fatigue over a 10-min period. Our rationale behind having 10-min trials was threefold (i) no other studies have considered rescuer fatigue during CC over a long period of time; (ii) current resuscitation guidelines advise that it is appropriate to consider stopping resuscitation if heart rate remains undetectable for 10 min;5 (iii) this method allowed us to reliably induce fatigue. We compared the currently recommended approach of neonatal resuscitation, 3:1 C:V CPR,5 with two recently described experimental approaches.8,9 The two experimental approaches were continuous CC at a rate of 90 CC per min with 30 inflations per min (CCaV-90),8,19 Journal of Perinatology (2015), 142 – 145
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Figure 1.
Reduction of compression depth in percentage for each group over the 10-min period of CC.
and continuous CC at a rate of 120 CC per min, which were superimposed by a sustained inflation (CCaV-120).9 We observed a gradual decrease in peak pressure throughout the 10-min study period in all three groups, with a significant decrease from baseline at 156, 96 and 72 s after commencement of CC in the 3:1, CCaV-90 and CCaV-120 groups, respectively. CCaV compared with 3:1 CPR achieved higher peak pressure at baseline, which resulted in a larger percentage decrease in pressure during the 10-min CPR period. Although we observed a higher initial decay in pressures, peak pressure remained stable throughout the study period. Several studies of simulated adult and pediatric CPR reported an impact of fatigue on quality of CC;10–13,20,21 however, the evidence in newborn infants is limited.14,15 Peak power output generated during pediatric resuscitation is comparable to power generated during intense exercise (for example, running 9 km h − 1).11 In addition, peak work per compression cycle and deterioration of CC quality is comparable between adult and pediatric resuscitation.11 The depth of CC can be translated into compression force, which is related to changes in intrathoracic pressure.22 Manikin studies demonstrated that adequate CC depths are infrequently achieved, implying that CC depth should be emphasized more during CPR training and real-life resuscitations.1 During CPR it is imperative that CC are delivered with an adequate pressure and depth,5 as rescuer fatigue causes deterioration of CC quality, potentially leading to reduced cardiac output and increased mortality. Therefore, current pediatric resuscitation guidelines suggest that professionals should be switched every 2 min while performing CC.16 Badaki-Makun et al.11 reported similar rates of fatigue in adult and child CPR, with a decrease in CC depth after 42 min of CPR. In comparison, two studies examined the rate of fatigue within 2 min of CPR in pediatric and neonatal healthcare professionals and reported no significant decay in CC, which is comparable to our results.10,15 Hemway et al. also observed a significant decay in CC depth between the first and last 25 s of the 2-min CC period, which is similar to our results, suggesting that after 2 min of CC, a significant decay in CC depth can be observed. Interestingly, in the CCaV-90 group, fatigue occurred ~ 60 s earlier compared with 3:1 C:V and time to fatigue was further halved in the CCaV-120 group (Figure 1). Indeed, asynchronous ventilations may work against the compressions being delivered and thereby may have potential to increase the workload and fatigue of the healthcare professional, which could be decreased by the interruptions during synchronous ventilation and compressions. Our results suggest CC quality improved when healthcare professionals were provided with a rest as exemplified in 3:1 C:V Journal of Perinatology (2015), 142 – 145
CPR. Min et al.23 reported that CC quality improved when rescuers were provided with a resting period at a particular time during CC compared with CC without rest. Current neonatal CPR guidelines recommend that heart rate should be reassessed after 45 to 60 s of CC, and CC should be continued until heart rate is 460 min − 1. We observed fatigue after 96 s in the CCaV-90 and 156 s in the 3:1 group, suggesting that rescuers should switch after every second heart rate evaluation cycle. Studies examining changes in CC rate during prolonged CPR report an increase or decrease in CC rate over time.11,24 In the current study, all participants continued to deliver CC at a constant rate throughout the 10-min study period despite observed fatigue. We believe that the aid of a metronome contributed to the constant CC rate. Data from in-hospital adult CPR observed no change in CC rate during 3 min of CPR with real-time audio-visual feedback.25 Alternatively, Dold et al.26 reported more accurate CC rates when participants listened to a musical prompt during CPR. In addition, Binder et al.27 reported that visual or verbal feedback significantly reduced mask leak during simulated neonatal CPR. However, no study has assessed real-time neonatal CPR in the delivery room or the neonatal intensive care unit. Further research is required to identify whether audio, visual, audio-visual feedback or musical prompts might be beneficial during neonatal resuscitation training or real-life resuscitation. Although adult human and animal studies have shown that continuous CC increases ROSC and survival, it is important to note that the etiology of neonatal cardiovascular collapse is asphyxia compared to ventricular fibrillation in adults. In addition, newborns must also undergo postnatal adaptation, which might hinder translation of adult data to newborns.28 In this study we delivered ventilations without interrupting CC to minimize interference between compressions and ventilations. There were concerns that CCaV impeded tidal volume delivery during CC. In a recent animal study, we demonstrated that o 30% of inflations are impeded by CC resulting in a lower tidal volume delivery during CCaV or 3:1 C:V CPR.8 Our data also show that it increases fatigue of the healthcare professional delivering CC. Limitations Manikin studies do not fully resemble real-life scenarios of neonatal resuscitation including the psycho-physical stress and environmental factors, which are limitations for clinical translation. Although we did not assess whether the placement of a salinefilled bag under the manikin’s chest potentially changed the force required to provide CC, a similar study did not report any concerns © 2015 Nature America, Inc.
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using this method.18 Comparable manikin studies reported compression depth in millimeters,17 but no study compared either technique with real-life resuscitations. There was no reliable way to measure arterial pressures as the mechanism of antegrade blood flow during CPR is complex and cannot be simulated in a manikin. Therefore, we cannot accurately determine which group delivered more accurate pressures. Nonetheless, it was evident that there was fatigue in all groups. Further, in this study there was no goal peak pressure for the participants, as they were blinded to pressure tracings. The participants were asked to perform compressions according to CPR guidelines: compress one-third of the anterior–posterior diameter of the chest on the lower onethird of the sternum. Thus it is uncertain whether our findings could be translated in some novel pressure-targeted resuscitation techniques.29 We did not observe a change in CC rate throughout the 10-min period, which we attribute to the use of a metronome. Unfortunately, we did not predetermine a sample size before the study, which is a limitation of the current study.
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CONCLUSIONS Overall, 3:1 C:V CPR was the least fatiguing and the most preferred method of neonatal CPR. We recommend that rescuers should switch after every second cycle of heart rate assessment during neonatal CPR. CONFLICT OF INTEREST
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18
The authors declare no conflict of interest. 19
ACKNOWLEDGEMENTS
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We would like to thank all participating neonatal healthcare professionals who contributed to this study with their own enthusiasm and effort, and Tze-Fun Lee for statistical assistance. ESL is supported in part by the Northern Alberta Clinical Trials and Research Centre Faculty of Medicine and Dentistry, University of Alberta, and Neonatal Research Fund, Northern Alberta Neonatal Program, Alberta Health Services. GMS is a recipient of a Banting Postdoctoral Fellowship, Canadian Institutes of Health Research and an Alberta Innovates–Health Solutions Clinical Fellowship.
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REFERENCES
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