The American Journal of Surgery (2014) -, -–-
Delayed admission to intensive care unit for critically surgical patients is associated with increased mortality Y. U. Bing-Hua, M.D.* Department of Anesthesiology, Central Hospital of Yiwu City, Yiwu, Zhejiang Province, China KEYWORDS: Surgical patients; Postanesthesia care; Intensive care unit; Survival
Abstract BACKGROUND: Shortage of beds in intensive care units (ICUs) is an increasing common phenomenon worldwide. Consequently, many critically ill patients have to be cared for in other hospital areas without specialized staff, such as general wards, emergency department, post anesthesia care unit (PACU). However, boarding critically ill patients in general wards or emergency department has been associated with higher mortality. The purpose of this study was to evaluate if a delay in ICU admission, waiting in PACU and managed by anesthesiologists, affects their ICU outcomes for critically surgical patients. METHODS: A retrospective cohort of adult critically surgical patients admitted to our ICU between January 2010 and June 2012 were analyzed. ICU admission was classified as either immediate or delayed (waiting in PACU). A general estimation equation was used to examine the relationship of PACU waiting hours before ICU admission with ICU outcomes by adjusting for age, patient sex, comorbidities, surgical categories, end time of operation, operation hours, and clinical conditions. RESULTS: A total of 2,279 critically surgical patients were evaluated. Two thousand ninety-four (91.9%) patients were immediately admitted and 185 (8.1%) patients had delayed ICU admission. There was a significant increase in ICU mortality rates with a delay in ICU admission (P , .001). Prolonged waiting hours in PACU (R6 hours) was associated with higher ICU mortality (adjusted odds ratio 5.32; 95% confidence interval 1.25 to 22.60, P 5 .024). However, longer PACU waiting times was not associated with mechanical ventilation days, ICU length of stay, and ICU cost. CONCLUSION: Prolonged waiting hours in PACU because of ICU bed shortage was associated with higher ICU mortality for critically surgical patients. Ó 2014 Elsevier Inc. All rights reserved.
Currently, the demand for intensive care beds far exceeds their availability in many countries, and the shortage of beds in intensive care units (ICUs) is an increasing common phenomenon. Consequently, many critically ill patients have to be cared for in other hospital areas without specialized staff, such as general wards,
The authors declare no conflicts of interest. * Corresponding author. Tel.: 186-1385-8998-778; fax: 186-5798209-618. E-mail address: [email protected] Manuscript received March 15, 2013; revised manuscript August 25, 2013 0002-9610/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjsurg.2013.08.044
emergency department, post anesthesia care unit (PACU). Since critically ill patients need early interventions to improve their outcomes, delayed or deferred ICU admission has been suggested to be associated with higher mortality.1,2 Four or more hours of delay to treatment after physiological deterioration is associated with a 3.5 times higher mortality.3 However, few studies have investigated the influence of delayed admission to ICU on hospital outcomes for critically surgical patients who had to wait in PACU because of ICU beds shortage. When there are no ICU beds available, some critically surgical patients have to wait for ICU beds in PACUs, which are commonly staffed with anesthesiologists rather
2
The American Journal of Surgery, Vol -, No -, - 2014
than intensivists. Generally, PACU staffs are not trained in critical care and are not experienced in caring for ICU patients. Moreover, they are often challenged with the responsibility of both caring for critically ill boarders and treating routine postoperative recovery patients. This means that PACUs boarding critically surgical patients are in competition with new patients requiring routine recovery. Thus, they tend to be less closely monitored or treated less aggressively as staff attention is diverted to the flow of new postoperative patients. Given this, the likelihood that outcomes would be worse for critically surgical patients boarding in PACU for ICU beds and managed by anesthesiologists during high ICU occupancy is an idea with intuitive appeal, yet few empirical data are available about this. Hence, the aim of this study is to compare the outcome of critically surgical patients immediately admitted to the ICU post operation with those who were required to wait for ICU bed availability in PACU.
days available at midnight once per day. We identified possible confounding factors that may affect the immediate admission to ICU after operation. Thus, for every included patient, the following data were extracted: (1) demographic characteristics (age, sex); (2) type of operations; (3) reasons of admission and comorbidities; (4) The American Society of Anesthesiologists (ASA) level; (5) operation hours and end time of the operation; (6) whether they had waited in PACU for ICU beds and their waiting hours; (7) Acute Physiology and Chronic Health Evaluation (APACHE) II score on ICU admission; (8) daily ICU occupancy; (9) mechanical ventilation hours in ICU; (10) ICU length of stay; (11) ICU cost; and (12) ICU outcome. With reference to the modification of APACHE III diagnostic codes,6 all the operations were categorized into 9 surgical categories: ‘‘Gastrointestinal,’’ ‘‘Cardiovascula,’’ ‘‘Respiratory,’’ ‘‘Neurological,’’ ‘‘Trauma,’’ ‘‘Genitourinary,’’ ‘‘Gynecological,’’ ‘‘Musculoskeletal/Skin,’’ and ‘‘Others.’’ End time of operation was divided at an interval of 4 hours, ie 00:00 AM to 04:00 AM, 04:00 AM to 08:00 AM, 08:00 AM to 12:00 AM, 12:00 AM to 16:00 PM, 16:00 AM to 20:00 PM, and 20:00 AM to 24:00 PM. For the immediate admission group, PACU waiting time was considered zero. While for those who had boarded in PACU before ICU admission, the waiting hours were grouped into 0 to 2, 2 to 4, 4 to 6, and ,6 hours, respectively. Patients discharged from ICU but expected to die imminently were categorized as ‘‘died in ICU.’’
Patients and Methods The study was a retrospective review of all postoperative surgical patients admitted to our ICU from January 1, 2010 to June 31, 2012, to examine whether boarding some critically surgical patients in PACU and managed by anesthesiologist during ICU overflow was associated with worse outcomes. The institutional review board of our hospital approved the study protocol and waived from the need for a consent form. Our ICU is a closed unit staffed by fully trained intensivists, while the PACU was managed by anesthesiologists. We had consensus ICU admission criteria, which were based mainly on the Task Force of the Society of Critical Care Medicine guidelines.4,5 Decisions to admit patients to the ICU were made by the fellow or attending intensive care physician on a case-by-case basis. Patients were immediately admitted if there was an ICU bed available. For patients who underwent operations at full ICU census or who had prior assured access to the ICU but the previous ICU patient was not discharged, they had to wait in PACU before ICU admission. Although ICU consultation in these cases was routinely part of the treatments, on most occasions, treatments for these patients were provided by the PACU nurses and anesthesiologists. Thus, anesthesiologists in PACU were required to care for not only routine postoperative patients, but also the critical patients awaiting ICU beds. Once the patients were admitted to ICU, all aspects of patient care were carried out at the discretion of the treating intensive care physicians.
Data collection and definition The hospital’s information system was queried to identify all the ICU operation admissions. The daily ICU occupancy was calculated as bed days used divided by bed
Statistical analysis Descriptive data were reported as either mean 6 standard deviation, median (interquartile range), or number (percentage). Patients were grouped into ‘‘Immediate ICU admission’’ group and ‘‘Waiting in PACU before admission’’ group. With respect to the differences between the groups, categorical variables were compared using chisquare analysis. Continuous variables were compared using independent sample t test for normally distributed data and Mann–Whitney U test for non-normally distributed data. Since one focus of the study was to examine whether delayed ICU admission for critically surgical patients is associated with worse outcomes, the median values of the mechanical ventilation hours, ICU length of stay, and ICU cost were used as cutoffs to transform the data into categorical variables (long/short mechanical ventilation hours, long/short ICU length of stay, and high/low ICU cost, respectively) for regression analysis. To identify potential correlation between delay in ICU admission and ICU outcomes, binary regression analysis was performed using ICU outcomes (long/short ventilation hours [yes/no], long/short ICU length of stay [yes/no], high/ low ICU cost [yes/no], died within ICU, respectively) as the dependent variable and other confounding factors as the independent variables. Of them, the ‘‘Surgical categories,’’ ‘‘End time of operation,’’ and ‘‘PACU waiting hours before
Y.U. Bing-Hua Table 1
Delayed admission to ICU
3
Characteristics of postsurgical ICU admissions
Variables
Immediate ICU admission (n 5 2,094)
Waiting in PACU before admission (n 5 185)
Male (%) Age (y) Comorbidities Diabetes mellitus Chronic lung disease Hypertension Surgical categories Gastrointestinal Cardiovascula Respiratory Neurological Trauma Genitourinary Gynecological Musculoskeletal/skin Others ASA level Operation hours End time of operation 12:00 AM to 16:00 PM 16:00 AM to 20:00 PM 20:00 AM to 24:00 PM 00:00 AM to 04:00 AM 04:00 AM to 08:00 AM 08:00 AM to 12:00 AM APACHE II score
1,115 (53.2%) 56.1 6 16.0
100 (54.1%) 58.7 6 15.5
37 11 75
9 5 9
P value .833 .035 .004 .001 .375
456 829 26 495 132 69 29 33 25 2.73 6 .78 3.84 6 3.41
64 25 20 34 5 20 2 9 6 2.81 6 .62 4.47 6 4.35
,.001
772 620 349 188 65 100 13.3 6 6.8
45 28 27 12 9 64 13.5 6 6.6
,.001
.282 .053
.707
APACHE 5 acute physiology and chronic health evaluation; ASA 5 American Society of Anesthesiologists; ICU 5 intensive care unit; PACU 5 post anesthesia care unit.
ICU admission’’ were categorical covariates. Because ‘‘Gastrointestinal’’ operation accounted for the top ICU admissions for many years, thus, it was defined as ‘‘reference.’’ Since most elective operations were theoretically expected to be finished within ‘‘12:00 AM to 16:00 PM,’’ hence, it was defined as ‘‘reference. While for the ‘‘PACU waiting hours before ICU admission,’’ immediate admission (0 hours) to ICU was defined as ‘‘reference.’’ The generalized estimating equation regression model was used to account for the effects of clustering of patients among surgeons, which may make the observations not independently. Odds ratios (OR) and their 95% confidence intervals (95% CIs) were calculated. Statistical analysis was performed using SPSS version 16.0 (SPSS, Inc, Chicago, IL). A P value of ,.05 was considered statistically significant.
Results The study cohort comprised 2,279 surgical ICU admissions, and 185 (8.1%) of them had waited in PACU because of ICU bed unavailability. Patients who had boarded in PACU were older (58.7 6 15.5 vs 56.1 6 16.0, P 5 .035), with a higher incidence of diabetes (P 5 .004) or chronic lung disease (P 5 .001) (Table 1). Patients underwent ‘‘Gastrointestinal,’’ ‘‘Respiratory,’’ or ‘‘Genitourinary’’
operations were more likely to be waited in PACU (Table 1, Fig. 1). Critically surgical patients whose operations were ended within ‘‘08:00 AM to 12:00 AM’’ would highly possible to be waited in PACU for ICU beds (Table 1, Fig. 2). There was no significant difference with respect to the sex, ASA level, operation hours, and APACHE II score on ICU admission between the 2 groups (Table 1). With respect to the ICU occupancy and surgical patients waiting in PACU before ICU admission, approximately 12% happened in days when ICU occupancy was ,90%, while two thirds of the events occurred when ICU was at very high occupancy (R95%) (Fig. 3). ICU mortality rates increased with prolonged delay in ICU admission (P , .001) (Fig. 4). In the univariate analysis, there was no significant difference as to the ICU outcomes between the 2 groups (Table 2). The median mechanical ventilation hours, ICU length of stay, and ICU cost were 18 hours, 44 hours, and $3,273, respectively. Thus, the mechanical ventilation hours, ICU length of stay, and ICU cost were dichotomized into long (,median) and short mechanical ventilation hours, long (,median) and short ICU length of stay, and high (,median) and low ICU cost, respectively. The association between waiting in PACU for ICU beds and ICU outcomes were further assessed by regression analysis with adjustment for age, comorbidities, surgical categories,
The American Journal of Surgery, Vol -, No -, - 2014
4
Figure 1
Percentage of postoperative patients waiting in PACU before ICU admission by the surgical categories.
ASA level, operation hours, and end time of operations (Table 3). Prolonged waiting hours in PACU (R6 hours) was associated with higher ICU mortality (adjusted OR 5.32, 95% CI 1.25 to 22.60, P 5 .024). However, longer PACU waiting times was not associated with other ICU outcomes (Table 3).
Comments This study demonstrated that critically surgical patients who underwent ‘‘Gastrointestinal,’’ ‘‘Respiratory,’’ and ‘‘Genitourinary’’ operations, and those whose operations ended within ‘‘08:00 AM to 12:00 AM’’ or high ICU occupancy were more likely to be waiting in PACU before ICU admission. Prolonged waiting hours in PACU (R6 hours) was associated with higher ICU mortality (adjusted OR 5.32, 95% CI 1.25 to 22.60, P 5 .024) for critically surgical patients. The PACU is primarily established to minimize the incidence of complications immediately after anesthesia
Figure 2
and surgery, while providing the best quality of safe care. PACUs were not designed, staffed, or equipped to serve as an ICU.7 Nevertheless, with the ongoing problems with ICU bed shortage, it is a common practice to board critically ill patients outside ICU such as PACU and emergency department.7–9 A study by Ziser et al7 demonstrated the overflow admission to the PACU over 33 months, and 350 postsurgery patients were admitted to PACU because of the lack of available ICU beds. Approximately three quarters were critically ill patients with either mechanical ventilation or invasive monitoring. The most common surgical procedures were abdominal and orthopedic surgeries, and busiest admission hours were 01 to 11 AM, which were consistent with our findings. Simchen et al10 compared the outcomes of critically ill patients allocated in 3 different types of hospital departments. Admission to an ICU was associated with better survival during the first 3 days compared to regular wards and special care units including PACU. In another recent study, Cardoso et al9 demonstrated that each hour of waiting before ICU admission was
Percentage of postoperative patients waiting in PACU before ICU admission by the end time of operation.
Y.U. Bing-Hua
Delayed admission to ICU
Figure 3
Number of postoperative patients waiting in PACU for ICU beds grouped by ICU occupancy.
independently associated with a 1.5% increased risk of ICU death. However, nearly 70% of the ICU admissions in their study were from the emergency department. To our knowledge, few studies have evaluated if a delay in ICU admission, ie waiting in PACU for ICU beds and managed by anesthesiologists, affects the outcomes for critically surgical patients. In our study, we demonstrated that prolonged waiting hours in PACU (R6 hours) were associated with higher ICU mortality (adjusted OR 5.32, 95% CI 1.25 to 22.60, P 5 .024). Thus, to some extent, boarding critically surgical patients in PACU would subject them to poor outcomes. Moreover, delayed admission to ICU for postoperative critical patients would slow or cancel surgical schedule, thereby causing dissatisfaction to surgeons, staff in operating theatre, and patients and their families. Effective access to health care systems is composed of 3 components, which must be equally adequate: care, timing, and location.9 Given our findings, some innovative ways should be developed to address the problem of reduced
Figure 4
5
access to intensive care for critically surgical patients and improve their outcomes. Since the ICU capacity is inextricably linked with the throughput of critically ill patients, some would propose expanding ICU capacity as a solution. However, simply expanding ICU capacity is not feasible because of space limitations within hospitals, workforce shortages, and government regulations. Nevertheless, in the face of variable demand, expanding ICU capacity can ultimately result in higher fixed costs, excess capacity, and long-term inefficiencies.11 Instead, we could improve the efficiency of ICU bed allocation by eliminating nonbeneficial admissions and expediting ICU discharges under high census times.12 Too much inappropriate ICU admissions would consume ICU resources, reduce the capacity for new patients, premature discharge from ICU, and increase readmission and mortality, and precipitate a vicious cycle.13 In our study, approximately two thirds of boarding critically surgical patients in PACU occurred when the ICU was at very high occupancy (R95%) (Fig. 3). Likewise, ICUs can improve throughput by reducing the time waiting
ICU mortality rate among postoperative patients grouped by PACU waiting hours before ICU admission.
The American Journal of Surgery, Vol -, No -, - 2014
6 Table 2
Outcomes for critically postoperative patients grouped by whether waiting in PACU before ICU admission
Outcomes
Immediate ICU admission (n 5 2094)
Boarding in PACU before admission (n 5 185)
P value
Mortality (%) Mechanical ventilation hours ICU length of stay (d) ICU cost ($)
140 18.0 1.8 3,206
16 13.0 1.92 3,429
.311 .751 .996 .237
(6.7%) (5.0–88.0) (.96–3.13) (1,135–9,697)
(8.6%) (5.0–74.5) (.96–3.0) (1,362–11,483)
Data are presented as median (interquartile range). ICU 5 intensive care unit; PACU 5 post anesthesia care unit.
for a floor bed after a patient’s critical care needs have resolved. Moreover, improving ICU throughput is not just optimizing a given process or capacity allocation decision, it is also about improving process through innovation, thereby improving both the quality and efficiency of critical care.14 For example, the ‘‘daily interruption of sedation and spontaneous breathing trial’’ strategy would allow an ICU to take care of 847 more patients per year without building additional beds or increasing ICU capacity.14 Furthermore, allowing greater flexibility of critical care bed use by expanding the hospital’s high dependent capacity is another solution. For instance, less dependent patients may be transferred from the ICU to high dependent area, to make space for more seriously ill patients.15 Finally, PACU should be an integral part of the patients’ care, and surgical consultants and a specified anesthetist should be available any time.7 Also, during overflow time, appropriate trained staff, such as ICU nurses, and medical care should therefore be provided for critically surgical patients boarded in
Table 3
PACU.16 A patient-centered model, not location, needs to be the emphasis of the delivery of care.8 Recently, Kastrup et al17 demonstrated that introduction of a round-the-clock intensivist staffing to PACU could shorten the hospital length of stay, from 8.3 days to 7.7 days, for surgical patients. Moreover, the revenues for the hospital increased because of a better use of resources. Therefore, therapeutic interventions that are traditionally initiated after ICU admission could be started on PACU while the patients were waiting for an ICU bed. Our study has several limitations. First, our study demonstrated the findings by retrospective cohort in a single institution, which may raise concerns about the generalization of the study. However, our results were consistent with other publications.7,9 Second, we did not evaluate the staffing of PACU and ICU in the study. Staffing levels have been shown to affect patients’ outcome. However, on most occasions in our institute, only the PACU nurses and anesthesiologists on shift cared for the study patients. This staffing
Association between PACU waiting hours and ICU outcomes among critically postoperative patients*
Outcomes
PACU waiting hours before ICU admission (h)
OR (95% CI)
P value
Long mechanical ventilation days
0(immediate admission) 0–2 2–4 4–6 .6 0 (immediate admission) 0–2 2–4 4–6 .6 0 (immediate admission) 0–2 2–4 4–6 .6 0 (immediate admission) 0–2 2–4 4–6 .6
Reference .37 (.10–1.42) .79 (.32–1.95) .67 (.19–2.34) 1.11 (.27–4.63) Reference 1.43 (.57–3.55) 1.15 (.55–2.41) .59 (.23–1.53) 1.71 (.23–2.20) Reference .66 (.26–1.65) 1.31 (.61–2.79) .72 (.28–1.87) 1.87 (.60–5.82) Reference 1.45 (.30–6.89) 2.77 (.87–8.85) .50 (.05–5.52) 5.32 (1.25–22.60)
– .147 .602 .532 .890 – .447 .718 .278 .552 – .373 .485 .503 .279 – .642 .086 .574 .024
Long ICU length of stay
High ICU cost
Died within ICU
CI 5 confidence interval; ICU 5 intensive care unit; OR 5 odds ratio; PACU 5 post anesthesia care unit. *Regression model adjusted for age, patient sex, comorbidities, surgical categories, end time of operation, operation hours, and clinical condition. General estimation equation was used to account for the clustering of patients among surgeons.
Y.U. Bing-Hua
Delayed admission to ICU
model remained constant during the study period. Third, our designation of delay in the immediate admission group as zero may have caused an underestimation of the association between PACU waiting time and mortality, because this method was actually a lack of measurement of real time to admission when an ICU bed was available.9 Finally, although intraoperative events may also affect patient’s outcome, we did not include that in the analysis because we cannot get all the information about intraoperative events singly through charts review as a retrospective study. In summary, delay in ICU admission for critically surgical patients because of unavailability of beds is common. Prolonged waiting hours in PACU (R6 hours) was associated with higher ICU mortality for critically surgical patients who had to wait in PACU because of ICU bed shortage and be managed by anesthesiologists.
References 1. Liu V, Kipnis P, Rizk NW, et al. Adverse outcomes associated with delayed intensive care unit transfers in an integrated healthcare system. J Hosp Med 2012;7:224–30. 2. Phua J, Ngerng WJ, Lim TK. The impact of a delay in intensive care unit admission for community-acquired pneumonia. Eur Respir J 2010;36:826–33. 3. Young MP, Gooder VJ, McBride K, et al. Inpatient transfers to the intensive care unit: delays are associated with increased mortality and morbidity. J Gen Intern Med 2003;18:77–83. 4. Task Force on Guidelines. Society of Critical Care Medicine. Recommendations for intensive care unit admission and discharge criteria. Crit Care Med 1988;16:807–8.
7 5. Task Force of the American College of Critical Care Medicine. Society of Critical Care Medicine. Guidelines for intensive care unit admission, discharge, and triage. Crit Care Med 1999;27:633–8. 6. Slater A, Shann F, McEniery J. The ANZPIC registry diagnostic codes: a system for coding reasons for admitting children to intensive care. Intensive Care Med 2003;29:271–7. 7. Ziser A, Alkobi M, Markovits R, et al. The postanaesthesia care unit as a temporary admission location due to intensive care and ward overflow. Br J Anaesth 2002;88:577–9. 8. Zhou JC, Pan KH, Zhou DY, et al. High hospital occupancy is associated with increased risk for patients boarding in the emergency department. Am J Med 2012;125:416.e1–7. 9. Cardoso LT, Grion CM, Matsuo T, et al. Impact of delayed admission to intensive care units on mortality of critically ill patients: a cohort study. Crit Care 2011;15:R28. 10. Simchen E, Sprung CL, Galai N, et al. Survival of critically ill patients hospitalized in and out of intensive care units under paucity of intensive care unit beds. Crit Care Med 2004;32:1654–61. 11. Terwiesch C, Diwas KC, Kahn JM. Working with capacity limitations: operations management in critical care. Crit Care 2011;15:308. 12. Wagner J, Halpern SD. Deferred admission to the intensive care unit: rationing critical care or expediting care transitions? Arch Intern Med 2012;172:474–6. 13. Chrusch CA, Olafson KP, McMillan PM, et al. High occupancy increases the risk of early death or readmission after transfer from intensive care. Crit Care Med 2009;37:2753–8. 14. Howell MD. Managing ICU throughput and understanding ICU census. Curr Opin Crit Care 2011;17:626–33. 15. Jones AG, Harper SJ. ‘Ventilating in recovery’–the way forward: intensive therapy or postoperative critical care? Br J Anaesth 2002; 88:473–4. 16. Odom-Forren J. The PACU as critical care unit. J Perianesth Nurs 2003;18:431–3. 17. Kastrup M, Seeling M, Barthel S, et al. Effects of intensivist coverage in a post-anaesthesia care unit on surgical patients’ case mix and characteristics of the intensive care unit. Crit Care 2012;16:R126.
Delayed admission to intensive care unit for critically surgical patients is associated with increased mortality Y. U. Bing-Hua, M.D.* Department of Anesthesiology, Central Hospital of Yiwu City, Yiwu, Zhejiang Province, China KEYWORDS: Surgical patients; Postanesthesia care; Intensive care unit; Survival
Abstract BACKGROUND: Shortage of beds in intensive care units (ICUs) is an increasing common phenomenon worldwide. Consequently, many critically ill patients have to be cared for in other hospital areas without specialized staff, such as general wards, emergency department, post anesthesia care unit (PACU). However, boarding critically ill patients in general wards or emergency department has been associated with higher mortality. The purpose of this study was to evaluate if a delay in ICU admission, waiting in PACU and managed by anesthesiologists, affects their ICU outcomes for critically surgical patients. METHODS: A retrospective cohort of adult critically surgical patients admitted to our ICU between January 2010 and June 2012 were analyzed. ICU admission was classified as either immediate or delayed (waiting in PACU). A general estimation equation was used to examine the relationship of PACU waiting hours before ICU admission with ICU outcomes by adjusting for age, patient sex, comorbidities, surgical categories, end time of operation, operation hours, and clinical conditions. RESULTS: A total of 2,279 critically surgical patients were evaluated. Two thousand ninety-four (91.9%) patients were immediately admitted and 185 (8.1%) patients had delayed ICU admission. There was a significant increase in ICU mortality rates with a delay in ICU admission (P , .001). Prolonged waiting hours in PACU (R6 hours) was associated with higher ICU mortality (adjusted odds ratio 5.32; 95% confidence interval 1.25 to 22.60, P 5 .024). However, longer PACU waiting times was not associated with mechanical ventilation days, ICU length of stay, and ICU cost. CONCLUSION: Prolonged waiting hours in PACU because of ICU bed shortage was associated with higher ICU mortality for critically surgical patients. Ó 2014 Elsevier Inc. All rights reserved.
Currently, the demand for intensive care beds far exceeds their availability in many countries, and the shortage of beds in intensive care units (ICUs) is an increasing common phenomenon. Consequently, many critically ill patients have to be cared for in other hospital areas without specialized staff, such as general wards,
The authors declare no conflicts of interest. * Corresponding author. Tel.: 186-1385-8998-778; fax: 186-5798209-618. E-mail address: [email protected] Manuscript received March 15, 2013; revised manuscript August 25, 2013 0002-9610/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjsurg.2013.08.044
emergency department, post anesthesia care unit (PACU). Since critically ill patients need early interventions to improve their outcomes, delayed or deferred ICU admission has been suggested to be associated with higher mortality.1,2 Four or more hours of delay to treatment after physiological deterioration is associated with a 3.5 times higher mortality.3 However, few studies have investigated the influence of delayed admission to ICU on hospital outcomes for critically surgical patients who had to wait in PACU because of ICU beds shortage. When there are no ICU beds available, some critically surgical patients have to wait for ICU beds in PACUs, which are commonly staffed with anesthesiologists rather
2
The American Journal of Surgery, Vol -, No -, - 2014
than intensivists. Generally, PACU staffs are not trained in critical care and are not experienced in caring for ICU patients. Moreover, they are often challenged with the responsibility of both caring for critically ill boarders and treating routine postoperative recovery patients. This means that PACUs boarding critically surgical patients are in competition with new patients requiring routine recovery. Thus, they tend to be less closely monitored or treated less aggressively as staff attention is diverted to the flow of new postoperative patients. Given this, the likelihood that outcomes would be worse for critically surgical patients boarding in PACU for ICU beds and managed by anesthesiologists during high ICU occupancy is an idea with intuitive appeal, yet few empirical data are available about this. Hence, the aim of this study is to compare the outcome of critically surgical patients immediately admitted to the ICU post operation with those who were required to wait for ICU bed availability in PACU.
days available at midnight once per day. We identified possible confounding factors that may affect the immediate admission to ICU after operation. Thus, for every included patient, the following data were extracted: (1) demographic characteristics (age, sex); (2) type of operations; (3) reasons of admission and comorbidities; (4) The American Society of Anesthesiologists (ASA) level; (5) operation hours and end time of the operation; (6) whether they had waited in PACU for ICU beds and their waiting hours; (7) Acute Physiology and Chronic Health Evaluation (APACHE) II score on ICU admission; (8) daily ICU occupancy; (9) mechanical ventilation hours in ICU; (10) ICU length of stay; (11) ICU cost; and (12) ICU outcome. With reference to the modification of APACHE III diagnostic codes,6 all the operations were categorized into 9 surgical categories: ‘‘Gastrointestinal,’’ ‘‘Cardiovascula,’’ ‘‘Respiratory,’’ ‘‘Neurological,’’ ‘‘Trauma,’’ ‘‘Genitourinary,’’ ‘‘Gynecological,’’ ‘‘Musculoskeletal/Skin,’’ and ‘‘Others.’’ End time of operation was divided at an interval of 4 hours, ie 00:00 AM to 04:00 AM, 04:00 AM to 08:00 AM, 08:00 AM to 12:00 AM, 12:00 AM to 16:00 PM, 16:00 AM to 20:00 PM, and 20:00 AM to 24:00 PM. For the immediate admission group, PACU waiting time was considered zero. While for those who had boarded in PACU before ICU admission, the waiting hours were grouped into 0 to 2, 2 to 4, 4 to 6, and ,6 hours, respectively. Patients discharged from ICU but expected to die imminently were categorized as ‘‘died in ICU.’’
Patients and Methods The study was a retrospective review of all postoperative surgical patients admitted to our ICU from January 1, 2010 to June 31, 2012, to examine whether boarding some critically surgical patients in PACU and managed by anesthesiologist during ICU overflow was associated with worse outcomes. The institutional review board of our hospital approved the study protocol and waived from the need for a consent form. Our ICU is a closed unit staffed by fully trained intensivists, while the PACU was managed by anesthesiologists. We had consensus ICU admission criteria, which were based mainly on the Task Force of the Society of Critical Care Medicine guidelines.4,5 Decisions to admit patients to the ICU were made by the fellow or attending intensive care physician on a case-by-case basis. Patients were immediately admitted if there was an ICU bed available. For patients who underwent operations at full ICU census or who had prior assured access to the ICU but the previous ICU patient was not discharged, they had to wait in PACU before ICU admission. Although ICU consultation in these cases was routinely part of the treatments, on most occasions, treatments for these patients were provided by the PACU nurses and anesthesiologists. Thus, anesthesiologists in PACU were required to care for not only routine postoperative patients, but also the critical patients awaiting ICU beds. Once the patients were admitted to ICU, all aspects of patient care were carried out at the discretion of the treating intensive care physicians.
Data collection and definition The hospital’s information system was queried to identify all the ICU operation admissions. The daily ICU occupancy was calculated as bed days used divided by bed
Statistical analysis Descriptive data were reported as either mean 6 standard deviation, median (interquartile range), or number (percentage). Patients were grouped into ‘‘Immediate ICU admission’’ group and ‘‘Waiting in PACU before admission’’ group. With respect to the differences between the groups, categorical variables were compared using chisquare analysis. Continuous variables were compared using independent sample t test for normally distributed data and Mann–Whitney U test for non-normally distributed data. Since one focus of the study was to examine whether delayed ICU admission for critically surgical patients is associated with worse outcomes, the median values of the mechanical ventilation hours, ICU length of stay, and ICU cost were used as cutoffs to transform the data into categorical variables (long/short mechanical ventilation hours, long/short ICU length of stay, and high/low ICU cost, respectively) for regression analysis. To identify potential correlation between delay in ICU admission and ICU outcomes, binary regression analysis was performed using ICU outcomes (long/short ventilation hours [yes/no], long/short ICU length of stay [yes/no], high/ low ICU cost [yes/no], died within ICU, respectively) as the dependent variable and other confounding factors as the independent variables. Of them, the ‘‘Surgical categories,’’ ‘‘End time of operation,’’ and ‘‘PACU waiting hours before
Y.U. Bing-Hua Table 1
Delayed admission to ICU
3
Characteristics of postsurgical ICU admissions
Variables
Immediate ICU admission (n 5 2,094)
Waiting in PACU before admission (n 5 185)
Male (%) Age (y) Comorbidities Diabetes mellitus Chronic lung disease Hypertension Surgical categories Gastrointestinal Cardiovascula Respiratory Neurological Trauma Genitourinary Gynecological Musculoskeletal/skin Others ASA level Operation hours End time of operation 12:00 AM to 16:00 PM 16:00 AM to 20:00 PM 20:00 AM to 24:00 PM 00:00 AM to 04:00 AM 04:00 AM to 08:00 AM 08:00 AM to 12:00 AM APACHE II score
1,115 (53.2%) 56.1 6 16.0
100 (54.1%) 58.7 6 15.5
37 11 75
9 5 9
P value .833 .035 .004 .001 .375
456 829 26 495 132 69 29 33 25 2.73 6 .78 3.84 6 3.41
64 25 20 34 5 20 2 9 6 2.81 6 .62 4.47 6 4.35
,.001
772 620 349 188 65 100 13.3 6 6.8
45 28 27 12 9 64 13.5 6 6.6
,.001
.282 .053
.707
APACHE 5 acute physiology and chronic health evaluation; ASA 5 American Society of Anesthesiologists; ICU 5 intensive care unit; PACU 5 post anesthesia care unit.
ICU admission’’ were categorical covariates. Because ‘‘Gastrointestinal’’ operation accounted for the top ICU admissions for many years, thus, it was defined as ‘‘reference.’’ Since most elective operations were theoretically expected to be finished within ‘‘12:00 AM to 16:00 PM,’’ hence, it was defined as ‘‘reference. While for the ‘‘PACU waiting hours before ICU admission,’’ immediate admission (0 hours) to ICU was defined as ‘‘reference.’’ The generalized estimating equation regression model was used to account for the effects of clustering of patients among surgeons, which may make the observations not independently. Odds ratios (OR) and their 95% confidence intervals (95% CIs) were calculated. Statistical analysis was performed using SPSS version 16.0 (SPSS, Inc, Chicago, IL). A P value of ,.05 was considered statistically significant.
Results The study cohort comprised 2,279 surgical ICU admissions, and 185 (8.1%) of them had waited in PACU because of ICU bed unavailability. Patients who had boarded in PACU were older (58.7 6 15.5 vs 56.1 6 16.0, P 5 .035), with a higher incidence of diabetes (P 5 .004) or chronic lung disease (P 5 .001) (Table 1). Patients underwent ‘‘Gastrointestinal,’’ ‘‘Respiratory,’’ or ‘‘Genitourinary’’
operations were more likely to be waited in PACU (Table 1, Fig. 1). Critically surgical patients whose operations were ended within ‘‘08:00 AM to 12:00 AM’’ would highly possible to be waited in PACU for ICU beds (Table 1, Fig. 2). There was no significant difference with respect to the sex, ASA level, operation hours, and APACHE II score on ICU admission between the 2 groups (Table 1). With respect to the ICU occupancy and surgical patients waiting in PACU before ICU admission, approximately 12% happened in days when ICU occupancy was ,90%, while two thirds of the events occurred when ICU was at very high occupancy (R95%) (Fig. 3). ICU mortality rates increased with prolonged delay in ICU admission (P , .001) (Fig. 4). In the univariate analysis, there was no significant difference as to the ICU outcomes between the 2 groups (Table 2). The median mechanical ventilation hours, ICU length of stay, and ICU cost were 18 hours, 44 hours, and $3,273, respectively. Thus, the mechanical ventilation hours, ICU length of stay, and ICU cost were dichotomized into long (,median) and short mechanical ventilation hours, long (,median) and short ICU length of stay, and high (,median) and low ICU cost, respectively. The association between waiting in PACU for ICU beds and ICU outcomes were further assessed by regression analysis with adjustment for age, comorbidities, surgical categories,
The American Journal of Surgery, Vol -, No -, - 2014
4
Figure 1
Percentage of postoperative patients waiting in PACU before ICU admission by the surgical categories.
ASA level, operation hours, and end time of operations (Table 3). Prolonged waiting hours in PACU (R6 hours) was associated with higher ICU mortality (adjusted OR 5.32, 95% CI 1.25 to 22.60, P 5 .024). However, longer PACU waiting times was not associated with other ICU outcomes (Table 3).
Comments This study demonstrated that critically surgical patients who underwent ‘‘Gastrointestinal,’’ ‘‘Respiratory,’’ and ‘‘Genitourinary’’ operations, and those whose operations ended within ‘‘08:00 AM to 12:00 AM’’ or high ICU occupancy were more likely to be waiting in PACU before ICU admission. Prolonged waiting hours in PACU (R6 hours) was associated with higher ICU mortality (adjusted OR 5.32, 95% CI 1.25 to 22.60, P 5 .024) for critically surgical patients. The PACU is primarily established to minimize the incidence of complications immediately after anesthesia
Figure 2
and surgery, while providing the best quality of safe care. PACUs were not designed, staffed, or equipped to serve as an ICU.7 Nevertheless, with the ongoing problems with ICU bed shortage, it is a common practice to board critically ill patients outside ICU such as PACU and emergency department.7–9 A study by Ziser et al7 demonstrated the overflow admission to the PACU over 33 months, and 350 postsurgery patients were admitted to PACU because of the lack of available ICU beds. Approximately three quarters were critically ill patients with either mechanical ventilation or invasive monitoring. The most common surgical procedures were abdominal and orthopedic surgeries, and busiest admission hours were 01 to 11 AM, which were consistent with our findings. Simchen et al10 compared the outcomes of critically ill patients allocated in 3 different types of hospital departments. Admission to an ICU was associated with better survival during the first 3 days compared to regular wards and special care units including PACU. In another recent study, Cardoso et al9 demonstrated that each hour of waiting before ICU admission was
Percentage of postoperative patients waiting in PACU before ICU admission by the end time of operation.
Y.U. Bing-Hua
Delayed admission to ICU
Figure 3
Number of postoperative patients waiting in PACU for ICU beds grouped by ICU occupancy.
independently associated with a 1.5% increased risk of ICU death. However, nearly 70% of the ICU admissions in their study were from the emergency department. To our knowledge, few studies have evaluated if a delay in ICU admission, ie waiting in PACU for ICU beds and managed by anesthesiologists, affects the outcomes for critically surgical patients. In our study, we demonstrated that prolonged waiting hours in PACU (R6 hours) were associated with higher ICU mortality (adjusted OR 5.32, 95% CI 1.25 to 22.60, P 5 .024). Thus, to some extent, boarding critically surgical patients in PACU would subject them to poor outcomes. Moreover, delayed admission to ICU for postoperative critical patients would slow or cancel surgical schedule, thereby causing dissatisfaction to surgeons, staff in operating theatre, and patients and their families. Effective access to health care systems is composed of 3 components, which must be equally adequate: care, timing, and location.9 Given our findings, some innovative ways should be developed to address the problem of reduced
Figure 4
5
access to intensive care for critically surgical patients and improve their outcomes. Since the ICU capacity is inextricably linked with the throughput of critically ill patients, some would propose expanding ICU capacity as a solution. However, simply expanding ICU capacity is not feasible because of space limitations within hospitals, workforce shortages, and government regulations. Nevertheless, in the face of variable demand, expanding ICU capacity can ultimately result in higher fixed costs, excess capacity, and long-term inefficiencies.11 Instead, we could improve the efficiency of ICU bed allocation by eliminating nonbeneficial admissions and expediting ICU discharges under high census times.12 Too much inappropriate ICU admissions would consume ICU resources, reduce the capacity for new patients, premature discharge from ICU, and increase readmission and mortality, and precipitate a vicious cycle.13 In our study, approximately two thirds of boarding critically surgical patients in PACU occurred when the ICU was at very high occupancy (R95%) (Fig. 3). Likewise, ICUs can improve throughput by reducing the time waiting
ICU mortality rate among postoperative patients grouped by PACU waiting hours before ICU admission.
The American Journal of Surgery, Vol -, No -, - 2014
6 Table 2
Outcomes for critically postoperative patients grouped by whether waiting in PACU before ICU admission
Outcomes
Immediate ICU admission (n 5 2094)
Boarding in PACU before admission (n 5 185)
P value
Mortality (%) Mechanical ventilation hours ICU length of stay (d) ICU cost ($)
140 18.0 1.8 3,206
16 13.0 1.92 3,429
.311 .751 .996 .237
(6.7%) (5.0–88.0) (.96–3.13) (1,135–9,697)
(8.6%) (5.0–74.5) (.96–3.0) (1,362–11,483)
Data are presented as median (interquartile range). ICU 5 intensive care unit; PACU 5 post anesthesia care unit.
for a floor bed after a patient’s critical care needs have resolved. Moreover, improving ICU throughput is not just optimizing a given process or capacity allocation decision, it is also about improving process through innovation, thereby improving both the quality and efficiency of critical care.14 For example, the ‘‘daily interruption of sedation and spontaneous breathing trial’’ strategy would allow an ICU to take care of 847 more patients per year without building additional beds or increasing ICU capacity.14 Furthermore, allowing greater flexibility of critical care bed use by expanding the hospital’s high dependent capacity is another solution. For instance, less dependent patients may be transferred from the ICU to high dependent area, to make space for more seriously ill patients.15 Finally, PACU should be an integral part of the patients’ care, and surgical consultants and a specified anesthetist should be available any time.7 Also, during overflow time, appropriate trained staff, such as ICU nurses, and medical care should therefore be provided for critically surgical patients boarded in
Table 3
PACU.16 A patient-centered model, not location, needs to be the emphasis of the delivery of care.8 Recently, Kastrup et al17 demonstrated that introduction of a round-the-clock intensivist staffing to PACU could shorten the hospital length of stay, from 8.3 days to 7.7 days, for surgical patients. Moreover, the revenues for the hospital increased because of a better use of resources. Therefore, therapeutic interventions that are traditionally initiated after ICU admission could be started on PACU while the patients were waiting for an ICU bed. Our study has several limitations. First, our study demonstrated the findings by retrospective cohort in a single institution, which may raise concerns about the generalization of the study. However, our results were consistent with other publications.7,9 Second, we did not evaluate the staffing of PACU and ICU in the study. Staffing levels have been shown to affect patients’ outcome. However, on most occasions in our institute, only the PACU nurses and anesthesiologists on shift cared for the study patients. This staffing
Association between PACU waiting hours and ICU outcomes among critically postoperative patients*
Outcomes
PACU waiting hours before ICU admission (h)
OR (95% CI)
P value
Long mechanical ventilation days
0(immediate admission) 0–2 2–4 4–6 .6 0 (immediate admission) 0–2 2–4 4–6 .6 0 (immediate admission) 0–2 2–4 4–6 .6 0 (immediate admission) 0–2 2–4 4–6 .6
Reference .37 (.10–1.42) .79 (.32–1.95) .67 (.19–2.34) 1.11 (.27–4.63) Reference 1.43 (.57–3.55) 1.15 (.55–2.41) .59 (.23–1.53) 1.71 (.23–2.20) Reference .66 (.26–1.65) 1.31 (.61–2.79) .72 (.28–1.87) 1.87 (.60–5.82) Reference 1.45 (.30–6.89) 2.77 (.87–8.85) .50 (.05–5.52) 5.32 (1.25–22.60)
– .147 .602 .532 .890 – .447 .718 .278 .552 – .373 .485 .503 .279 – .642 .086 .574 .024
Long ICU length of stay
High ICU cost
Died within ICU
CI 5 confidence interval; ICU 5 intensive care unit; OR 5 odds ratio; PACU 5 post anesthesia care unit. *Regression model adjusted for age, patient sex, comorbidities, surgical categories, end time of operation, operation hours, and clinical condition. General estimation equation was used to account for the clustering of patients among surgeons.
Y.U. Bing-Hua
Delayed admission to ICU
model remained constant during the study period. Third, our designation of delay in the immediate admission group as zero may have caused an underestimation of the association between PACU waiting time and mortality, because this method was actually a lack of measurement of real time to admission when an ICU bed was available.9 Finally, although intraoperative events may also affect patient’s outcome, we did not include that in the analysis because we cannot get all the information about intraoperative events singly through charts review as a retrospective study. In summary, delay in ICU admission for critically surgical patients because of unavailability of beds is common. Prolonged waiting hours in PACU (R6 hours) was associated with higher ICU mortality for critically surgical patients who had to wait in PACU because of ICU bed shortage and be managed by anesthesiologists.
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7 5. Task Force of the American College of Critical Care Medicine. Society of Critical Care Medicine. Guidelines for intensive care unit admission, discharge, and triage. Crit Care Med 1999;27:633–8. 6. Slater A, Shann F, McEniery J. The ANZPIC registry diagnostic codes: a system for coding reasons for admitting children to intensive care. Intensive Care Med 2003;29:271–7. 7. Ziser A, Alkobi M, Markovits R, et al. The postanaesthesia care unit as a temporary admission location due to intensive care and ward overflow. Br J Anaesth 2002;88:577–9. 8. Zhou JC, Pan KH, Zhou DY, et al. High hospital occupancy is associated with increased risk for patients boarding in the emergency department. Am J Med 2012;125:416.e1–7. 9. Cardoso LT, Grion CM, Matsuo T, et al. Impact of delayed admission to intensive care units on mortality of critically ill patients: a cohort study. Crit Care 2011;15:R28. 10. Simchen E, Sprung CL, Galai N, et al. Survival of critically ill patients hospitalized in and out of intensive care units under paucity of intensive care unit beds. Crit Care Med 2004;32:1654–61. 11. Terwiesch C, Diwas KC, Kahn JM. Working with capacity limitations: operations management in critical care. Crit Care 2011;15:308. 12. Wagner J, Halpern SD. Deferred admission to the intensive care unit: rationing critical care or expediting care transitions? Arch Intern Med 2012;172:474–6. 13. Chrusch CA, Olafson KP, McMillan PM, et al. High occupancy increases the risk of early death or readmission after transfer from intensive care. Crit Care Med 2009;37:2753–8. 14. Howell MD. Managing ICU throughput and understanding ICU census. Curr Opin Crit Care 2011;17:626–33. 15. Jones AG, Harper SJ. ‘Ventilating in recovery’–the way forward: intensive therapy or postoperative critical care? Br J Anaesth 2002; 88:473–4. 16. Odom-Forren J. The PACU as critical care unit. J Perianesth Nurs 2003;18:431–3. 17. Kastrup M, Seeling M, Barthel S, et al. Effects of intensivist coverage in a post-anaesthesia care unit on surgical patients’ case mix and characteristics of the intensive care unit. Crit Care 2012;16:R126.
