Is the evolving management of intra-abdominal hypertension and abdominal compartment syndrome improving survival?*

Continuing Medical Education Article Is the evolving management of intra-abdominal hypertension and abdominal compartment syndrome improving survival?* Michael L. Cheatham, MD, FCCM; Karen Safcsak, RN LEARNING OBJECTIVES After participating in this activity, the participant should be better able to: 1. Distinguish intra-abdominal hypertension from intra-abdominal compartment syndrome. 2. Explain consensus definition and recommendations proposed by the World Society of the Abdominal Compartment Syndrome. 3. Use this information in a clinical setting. Unless otherwise noted below, each faculty or staff s spouse/life partner (if any) has nothing to disclose. Dr. Cheatam has disclosed that he was/is a consultant/advisor for Kinetic Corporation, Inc. Ms. Safcsak has disclosed that she has no financial relationships with or interests in any commercial companies pertaining to this educational activity. All faculty and staff in a position to control the content of this CME activity have disclosed that they have no financial relationship with, or financial interests in, any commercial companies pertaining to this educational activity. Lippincott CME Institute has identified and resolved all faculty conflicts of interest regarding this educational activity. Visit the Critical Care Medicine Web site (www.ccmjournal.org) for information on obtaining continuing medical education credit. Objective: The diagnosis and management of intra-abdominal hypertension and abdominal compartment syndrome have changed significantly over the past decade with improved understanding of the pathophysiology and appropriate treatment of these disease processes. Serial intra-abdominal pressure measurements, nonoperative pressure-reducing interventions, and early abdominal decompression for refractory intra-abdominal hypertension or abdominal compartment syndrome are all key elements of this evolving strategy. Design: Prospective, observational study. Setting: Tertiary referral/level I trauma center. Patients: Four hundred seventy-eight consecutive patients requiring an open abdomen for the management of intra-abdominal hypertension or abdominal compartment syndrome. Interventions: Patients were managed by a defined group of surgical intensivists using established definitions and an evidence-based management algorithm. Both univariate and multivariate analyses were performed to identify patient and management factors associated with improved survival. Measurements and Main Results: Whereas patient demographics and severity of illness remained unchanged over the 6-yr study period, the use of a continually revised intra-abdominal hypertension/abdominal compartment syndrome management algorithm significantly increased patient survival to hospital discharge from 50% to 72% (p.015). Clinically significant decreases in resource utilization and an increase in same-admission primary fascial closure from 59% to 81% were recognized. Development of abdominal compartment syndrome, prophylactic use of an open abdomen to prevent development of intra-abdominal hypertension/abdominal compartment syndrome, and use of a multi-modality surgical/medical management algorithm were identified as independent predictors of survival. Conclusions: A comprehensive evidence-based management strategy that includes early use of an open abdomen in patients at risk significantly improves survival from intra-abdominal hypertension/abdominal compartment syndrome. This improvement is not achieved at the cost of increased resource utilization and is associated with an increased rate of primary fascial closure. (Crit Care Med 2010; 38:402 407) KEY WORDS: open abdomen; intra-abdominal pressure; intraabdominal hypertension; abdominal compartment syndrome; survival *See also p. 692. Director (MLC), Surgical/Trauma Intensive Care Units, Orlando Regional Medical Center, Orlando, FL; and Project Manager (KS), Surgical Critical Care Research, Orlando Regional Medical Center, Orlando, FL. For information regarding this article, E-mail: michael.cheatham@orlandohealth.com Copyright 2010 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins DOI: 10.1097/CCM.0b013e3181b9e9b1 402 Crit Care Med 2010 Vol. 38, No. 2

Over the past decade, intraabdominal hypertension (IAH) and abdominal compartment syndrome (ACS) have evolved from being obscure and poorly understood diseases of the traumatically injured patient to recognized causes of significant morbidity and mortality among the critically ill of all disciplines (1 24). Elevated intraabdominal pressure (IAP) has been identified as an independent predictor of mortality during critical illness (5, 20). Recently, evidence-based consensus definitions and recommendations for the resuscitation and management of patients with IAH and ACS have been published (1, 2). Central to this evolving strategy are the use of serial IAP measurements to detect the presence of IAH, application of comprehensive medical management strategies to reduce elevated IAP and restore end-organ perfusion, and timely surgical decompression of the abdomen for refractory organ dysfunction (1, 2, 23, 24). Whereas numerous retrospective studies and reviews have suggested that patient survival is significantly improved by the time and resource intensive approach outlined, prospective interventional trials confirming these benefits have been lacking. Many physicians remain skeptical regarding the clinical importance of elevated IAP and hesitant to use the open abdomen to treat IAH and ACS. We therefore sought to determine whether the currently recommended evidence-based medicine strategy for managing IAH/ACS improves patient survival. MATERIALS AND METHODS In January 2002, we began a prospective, observational study to confirm the survival efficacy of our evidence-based medicine approach to the management of patients with IAH/ACS. The study was approved by our Institutional Review Board with a waiver of informed consent. All patients aged 15 yrs or older who are admitted to the surgical teaching service of our institution and require an open abdomen during their resuscitation and management are screened and evaluated daily by a single individual. Patients are enrolled within 24 hrs of requiring an open abdomen and are subsequently followed-up prospectively on a daily basis throughout their hospitalization using a standardized data collection sheet. Data are entered into a computerized database to record patient demographics, mechanism and severity of injury, temporary abdominal closure method, duration of open abdomen, subsequent abdominal wall reconstruction technique, resource utilization, and survival to hospital discharge among other variables. All patients are managed by a defined group of five board-certified surgical intensivists according to continually revised evidence-based medicine guidelines. Patients are followed-up until discharge from the hospital with subsequent follow-up in our outpatient clinic. For the purposes of this study, patients requiring an open abdomen because of fascial dehiscence or existing enteric fistula have been excluded. At the time of study initiation in 2002, our management algorithm consisted of serial IAP measurements to diagnose IAH/ACS, fluid and vasopressor resuscitation to maintain systemic and visceral perfusion, and emergent abdominal decompression with temporary abdominal closure when IAP reached 30 to 40 mm Hg (16). Attempts to achieve abdominal closure were generally delayed until the patient s critical illness had resolved, commonly necessitating either split-thickness skin grafting of the viscera or closure of skin and subcutaneous tissue only, resulting in a fascial defect and need for subsequent incisional hernia repair (15, 16, 18). As the years progressed and new advances in the management of IAH/ ACS became known, we revised our management algorithm to reflect these findings. This included adoption of decreasing IAP thresholds for surgical intervention (IAP 25 30 mm Hg) and increased use of the open abdomen at the time of initial laparotomy to avoid detrimental IAP elevations in patients at risk for IAH/ACS (16). Temporary abdominal closure was performed almost universally using the vacuum-pack technique (2, 8, 23). Faced with a number of open-abdomen patients requiring subsequent hernia repair, we began an aggressive strategy to close the open abdomen as soon as physiologically feasible (25, 26). In January 2005, the consensus definitions and recommendations proposed by the World Society of the Abdominal Compartment Syndrome were incorporated into our management algorithm (27). These comprehensive surgical and medical management guidelines emphasize: (1) the need for early serial IAP monitoring when IAH/ACS risk factors are present; (2) improving abdominal wall compliance through sedation, analgesia, and pharmacologic paralysis; (3) evacuating intraluminal contents through nasogastric or rectal decompression; (4) evacuating abdominal fluid collections via percutaneous drainage; (5) correcting positive fluid balance through the use of hypertonic fluids, colloids, and careful diuresis; (6) supporting organ function with vasopressors and judicious goal-directed fluid resuscitation to maintain an abdominal perfusion pressure (calculated as mean arterial pressure IAP) 60 mm Hg; and (7) early surgical intervention when IAP exceeds 25 mm Hg (2, 24, 27). These guidelines highlight the importance of both nonoperative therapies, to prevent and reduce elevated IAP, as well as operative intervention for refractory organ dysfunction and failure. We defined IAH as a sustained or repeated pathologic elevation of IAP 12 mm Hg (1). ACS was defined as a sustained IAP 20 mm Hg associated with new organ dysfunction or failure. Primary ACS was considered to be ACS associated with injury or disease in the abdomino-pelvic region, whereas secondary ACS was considered to be ACS that did not originate from the abdomino-pelvic region. Recurrent ACS was used to identify conditions in which ACS re-developed after previous surgical or medical treatment of primary or secondary ACS. IAP was measured using the intra-vesicular technique as recommended in the World Society of the Abdominal Compartment Syndrome consensus guidelines (1, 2). IAP measurements are not performed in the operating room or the emergency department in our institution. IAP measurements and abdominal perfusion pressure calculations were performed every 4 hrs in the intensive care unit (ICU) in patients at risk for IAH/ACS and were used to guide both resuscitative therapy, as well as the need for emergent abdominal decompression in the setting of ACS. Predecompression IAP and abdominal perfusion pressure values were recorded as an indicator of the severity of IAH/ACS prompting open abdomen management. The primary clinical reason for use of an open abdomen was carefully evaluated with all patients being assigned one of four indications. Damage control laparotomy represented patients who either required abdominal packing for hemorrhage control or had hemodynamic instability, hypothermia, coagulopathy, or metabolic acidosis intra-operatively requiring an abbreviated surgical intervention. Surgeon suspicion for IAH identified otherwise stable patients who were believed to be at high risk for elevated IAP if primary fascial closure was performed (such as patients with markedly edematous bowel), were anticipated to require a large volume fluid resuscitation because of their shock, or required a planned re-exploration not accounted for by the damage control laparotomy indication. ACS represented those patients who required emergent abdominal decompression after the development of documented primary, secondary, or recurrent ACS. Septic abdomen denoted patients in whom intra-abdominal abscess, gross contamination, or intestinal perforation (including new-onset fistula) warranted staged laparotomy for serial washout of the abdominal cavity. The timing of open abdomen management was also assessed. A prophylactic open abdo- Crit Care Med 2010 Vol. 38, No. 2 403

Table 1. Demographics by study year men was defined as one in which the surgeon intentionally left the patient s abdomen open during the initial operative procedure for one of the four clinical indications outlined. Emergent decompression was defined as the need for an open abdomen in a patient exhibiting organ dysfunction or failure (i.e., ACS) who had either not undergone laparotomy or had been closed primarily after previous laparotomy. The patient s abdominal status at hospital discharge was further defined as: (1) primary fascial closure with or without supplemental prosthetic mesh; (2) splitthickness skin graft of the viscera; or (3) skin and subcutaneous tissue closure leaving the fascia open. Both of the latter two methods resulted in an incisional hernia requiring subsequent repair. Patient demographics were assessed using age, gender, and surgical service. Patient severity of illness was determined using Acute Physiology and Chronic Health Evaluation Score version II, Simplified Acute Physiology Score version 2, and injury severity score (for trauma patients). Resource utilization was evaluated using both ICU and hospital days, as well as days of mechanical ventilation. These data were compared to that of the contemporaneous surgical/trauma ICU patients who did not require an open abdomen to identify changes in general ICU care over time that might represent a potential confounding factor during data analysis. This included calculation of annual survival rates for both the study (open abdomen) and surgical/trauma ICU (non-open abdomen) patients using Simplified Acute Physiology Score version 2 scores to calculate severity-adjusted survival. Descriptive statistics are reported as either mean SD or percentage. Categorical data were analyzed using chi-square analysis. Continuous data were assessed using Student s t test for normally distributed data and Mann- Whitney U test for non-normally distributed data. Multiple comparison analysis between study years was performed using log-linear analysis for categorical data and either analysis of variance or Kruskal-Wallis analysis of variance by ranks for normally distributed and non-normally distributed continuous data respectively. Tukey s test was utilized for post hoc comparisons. To identify potential causative factors that lead to improved survival, univariate multiple regression analysis was performed using patient survival as the dependent variable and patient demographics, management algorithm complexity (defined by each individual study year), and timing and indications for open abdomen management as the independent variables. Significant variables identified in the univariate analysis were subsequently entered into a binomial logistic regression analysis to identify factors independently predictive of survival. Significance was defined as a p.05. RESULTS Between January 2002 and December 2007, 478 consecutive patients were managed with an open abdomen in our institution. The demographics of the study patients remained similar without significant differences throughout the 6 Open-abdomen patients 58 75 114 65 85 81 Age, yrs 47 17 45 18 42 18 43 17 39 17 45 21 Male, % 59 76 71 77 80 74 Trauma, % 81 61 80 75 74 68 General/vascular surgery, % 19 39 19 25 24 27 Burns, % 0 0 1 0 2 5 p.05 for all variables. Table 2. Severity of illness by study year APACHE II 23 9 20 8 22 8 22 8 20 9 20 9 SAPS-2 48 17 41 16 44 15 51 15 41 15 41 17 ISS 25 12 22 10 26 12 24 13 26 14 28 12 APACHE II, Acute Physiology and Chronic Health Evaluation, version II; SAPS 2, Simplified Acute Physiology Score, version 2; ISS, injury severity score. p.05 for all variables. Table 3. Resource utilization by study year Intensive care 16.6 18.1 14.8 15.1 14.6 15.6 15.8 13.7 13.8 14.1 12.5 15.4 unit days Hospital days 35.6 41.8 27.7 28.7 26.7 24.9 32.7 29.0 28.7 25.6 25.7 22.5 Mechanical ventilator days 16.3 19.0 14.1 16.0 13.1 13.4 14.3 15.5 12.6 14.4 10.8 13.7 p.05 for all variables. Table 4. Indications for open abdomen management Study patients, n 58 75 114 65 85 81 Open abdomen utilization, % 8.8 10.2 14.9 a 8.0 8.8 7.4 Damage control laparotomy, % 41 27 47 46 53 40 Surgeon suspicion for IAH, % 24 29 26 31 29 38 Septic abdomen, % 5 12 7 6 5 8 ACS, % Primary 7 9 4 3 2 1 Secondary 21 23 12 14 10 12 Recurrent b 7 7 6 9 5 4 IAH, intra-abdominal hypertension; ACS, abdominal compartment syndrome. a p.03 compared to all other study years. Comparisons statistically insignificant unless otherwise noted; b percentages add up to 100% because of the development of recurrent ACS. Utilization is calculated as the number of open-abdomen patients divided by the total surgical/trauma intensive care unit population for that year. yrs of the study (Table 1). Patient severity of illness demonstrated no significant differences from year to year (Table 2). Resource utilization over the study period demonstrated nonsignificant trends toward decreased ICU, hospital, and mechanical ventilator days (Table 3). Pre decompression IAP measurements and abdominal perfusion pressure calcu- 404 Crit Care Med 2010 Vol. 38, No. 2

Table 5. Outcome lations were available for the 110 patients who underwent IAP monitoring in the ICU before emergent decompression for ACS. IAP immediately before decompression was 28 8 mm Hg and did not vary significantly by study year. Abdominal perfusion pressure was 46 15 mm Hg Mean days to abdominal 20 14 17 19 17 14 16 17 13 16 10 10 b closure Median days to abdominal 20 8 13 12 6 a 6 a closure Entero-atmospheric fistula 8.6 8.0 1.8 6.2 4.7 3.6 rate, % Abdominal closure type, % Primary fascial closure 59 72 68 72 77 81 mesh Split-thickness skin 12 23 15 19 12 3 b graft Skin only 29 5 17 9 11 16 Survival to hospital discharge, % 50 57 52 63 69 72 a All other comparisons are statistically insignificant. a p.05; b p.01. Table 6. Univariate predictors of survival Survivors Non-Survivors Significance Patients, n 289 189 Age, yrs 40 17 49 19.00001 Gender, male 77% 67%.016 Traumatic injury 81% 63%.00001 APACHE-II score 18 9 27 9.00001 SAPS-2 score 39 12 53 17.00001 ISS score 23 11 30 14.00002 Prophylactic open abdomen 84% 63%.00001 Open abdomen indications Damage control laparotomy 45% 40%.25 Surgeon suspicion for IAH 33% 25%.07 ACS 13% 30%.00001 Septic abdomen 13% 8%.06 APACHE II, Acute Physiology and Chronic Health Evaluation, version II; SAPS-2, Simplified Acute Physiology Score, version 2; ISS, injury severity score; IAH, intra-abdominal hypertension; ACS, abdominal compartment syndrome. Table 7. Multivariate predictors of improved survival Coefficient Significance Odds Ratio 95% Confidence Interval ACS 1.69335.0001 0.18 0.09 0.37 Prophylactic open 1.17098.0001 3.23 1.78 5.85 abdomen APACHE-II score 25 1.10534.001 0.33 0.18 0.62 Study year, per yr 0.151142.018 0.86 0.76 0.97 Age, per yr 0.0096016.13 0.99 0.98 1.00 SAPS-2 score 52 0.450669.15 1.45 0.85 2.89 Traumatic injury 0.231176.37 1.26 0.76 2.10 Gender, male 0.0226406.93 0.98 0.61 1.57 ACS, abdominal compartment syndrome; APACHE II, Acute Physiology and Chronic Health Evaluation, version II; SAPS-2, Simplified Acute Physiology Score, version 2. Crit Care Med 2010 Vol. 38, No. 2 and similarly demonstrated no annual changes over the course of the study. Although there was a significant increase in open abdomen utilization in 2004 (p.03) that coincided with our initial adoption of lower IAP thresholds for surgical intervention, use of the open abdomen otherwise remained unchanged with the final year of the study demonstrating the lowest open abdomen utilization rate (Table 4). In contrast, the timing of open abdomen management did change significantly. With lower IAP thresholds, patients underwent open abdomen management earlier in their disease process resulting in a significant decrease in the number of emergent abdominal decompressions required for ACS (p.009). Both the mean and median days to abdominal closure decreased significantly over the duration of the study (Table 5). With both earlier use of an open abdomen and earlier abdominal closure, the entero-atmospheric fistula rate decreased during the study, but did not achieve statistical significance. The percentage of patients achieving definitive abdominal closure during their initial hospital admission increased such that by 2007, 81% of surviving open-abdomen patients (50% of all study patients) were discharged from the hospital with their abdomen closed. The percentage of patients who required split-thickness skin grafting of their exposed viscera as management of their open abdomen decreased significantly from a peak of 23% in 2003 to 3% in 2007 (p.01). There was a significant improvement in patient survival to hospital discharge from 50% in 2002 to 72% in 2007 (p.015). Both univariate and multivariate analyses were performed to determine which factors were predictive of improved survival. In the univariate analysis, openabdomen survivors were significantly more likely to be younger, male, traumatically injured, less critically ill, and to have undergone a prophylactic open abdomen rather than emergent decompression for ACS (Table 6). After severity of illness adjustment using Simplified Acute Physiology Score version 2 scores, there remained a significant difference in survival between patients receiving a prophylactic versus emergent open abdomen (p.0006). In the multivariate analysis, development of ACS, use of a prophylactic open abdomen at the time of initial laparotomy in patients at risk, Acute Physiology and Chronic Health Evaluation Score version II score 25, and study year (indicating the complexity of the management algorithm) were identified as independent predictors of improved survival with a Hosmer-Leme show goodness-of-fit statistic of 11.5 (p.18), indicating that the model accurately predicted patient outcome (Table 7). 405

Figure 1. Severity-adjusted patient survival. To determine whether improvements in general ICU care over the course of the study could have resulted in the improved patient survival independent of our IAH/ ACS management algorithm, annual study patient survival was compared to that of the surgical/trauma ICU patients who did not require an open abdomen. Whereas study patient survival was seen to increase annually, non-open-abdomen patient survival remained unchanged with similar demographics (Fig. 1). Using Simplified Acute Physiology Score version 2 scores for both patient populations, severity-adjusted annual survival rates were calculated to remove patient acuity as a possible confounding factor. After accounting for these potential differences in severity of illness, study patient survival is seen to improve significantly when the 2002 to 2004 (precomprehensive management algorithm) versus 2005 to 2007 (post-comprehensive management algorithm) time periods are compared (p.001). DISCUSSION This prospective, observational study represents the largest trial to-date evaluating the benefits of a comprehensive, evidence-based medicine approach to the management of patients with IAH or ACS. As our management algorithm has changed based on the evolving medical literature, we have witnessed significant decreases in the incidence of ACS, clinically significant decreases in ICU, ventilator, and hospital days, and a marked improvement in the rate of and time to same-admission definitive abdominal closure. Most importantly, we have seen significant increases in both raw and severity-adjusted patient survival to discharge. These improvements appear to be temporally related to changes in our management algorithm that were made after the December 2004 International Consensus Conference on IAH and ACS (1, 2). This combined, multi-modality management strategy is based on four general principles: (1) serial IAP monitoring; (2) goal-directed optimization of systemic perfusion and organ function; (3) institution of medical interventions to reduce IAP and the end-organ consequences of IAH/ ACS; and (4) prompt surgical decompression for IAH/ACS refractory to these therapeutic interventions (24). Of these, the institution of broad-ranging nonoperative medical interventions to reduce IAP and earlier use of the open abdomen represent the greatest changes to our evolving management algorithm. Patient demographics, severity of illness, and the indications for open abdomen management remained unchanged throughout the duration of this 6-yr study. As a result, the marked improvement in abdominal closure rate and significant increase in patient survival to discharge do not appear to be related to a general improvement in overall ICU care, a less critically ill patient population, or a routine practice to leave the abdomen open after laparotomy. In fact, our use of the open abdomen has actually decreased by 50% since implementation of the World Society of the Abdominal Compartment Syndrome guidelines. When open abdomen management is used, it is most commonly performed either prophylactically at the time of initial laparotomy or for lower IAP thresholds before development of ACS when nonoperative management strategies to reduce IAP and improve systemic perfusion have failed. The open abdomen thus becomes a therapeutic intervention rather than just a method of abdominal management after development of ACS, a condition to be avoided with its five-fold increase in mortality (Table 7). Given the stable patient population throughout the study and the finding that a prophylactic open abdomen is associated with a greater than threefold increase in survival from IAH/ACS, we propose that a prophylactic open abdomen to avoid ACS, rather than delayed emergent decompression once ACS has developed, represents a key contributing factor to the significant improvement in survival recognized in this study. Through earlier abdominal decompression in selected patients at risk for IAH/ACS, we have also found that patients do not have the severity of IAH/ACS seen in years past and are thus able to tolerate earlier and more definitive abdominal wall closure. Primary fascial closure before hospital discharge is now possible in the majority of our patients. Such improvements are not related to changes in temporary abdominal closure technique as we almost exclusively used the vacuum-pack technique throughout the study period. Splitthickness skin grafting is now relegated only to either those few patients who have decompression late in the course of their critical illness and have severe visceral edema develop or those in whom enteroatmospheric fistulas develop and cannot be primarily closed. Such an aggressive approach to primary fascial closure might be anticipated to result in an increased incidence of recurrent ACS (27, 28). As a result of earlier open abdomen management, however, we have not witnessed such an occurrence. Despite the proven morbidity and mortality of IAH/ACS, some physicians remain reluctant to use open abdomen management out of concern for causing permanent disability or mortality to their patients. Vidal et al recently identified the mortality of IAH to be 53% and ACS 80% in a prospective study in which the treatment algorithm did not include open abdomen management (20). Our current mortality of 28% suggests that open abdomen management is an important factor in improving survival from IAH/ACS. This is further supported by a recent prospective observational trial of ACS patients by Parsak et al, in which the odds ratio for increased mortality associated with nonoperative management alone was 5.2 (22). We have recently prospectively demonstrated that long-term phys- 406 Crit Care Med 2010 Vol. 38, No. 2

ical and mental health perception are not negatively impacted by the open abdomen and that such a procedure does not limit subsequent employment or decrease quality of life (26). Early open abdomen management, as part of a comprehensive evidence-based management strategy, should be strongly considered in patients with IAH/ACS that is refractory to less invasive interventions because of the significant associated survival advantage and lack of long-term morbidity. Our study does have several limitations. Given that IAP is typically measured in intensive care units, 80% of our patients who received their initial care in the emergency department or operating room did not have IAP measurements available before open abdomen management. Whereas universal pre-decompression IAP measurements might have provided a greater sense of the severity of the study population s IAH, they would primarily serve only to clarify the grades of IAH present from year to year. Postdecompression IAP measurements in the ICU remain an important part of our algorithm for guiding resuscitation and preventing organ dysfunction attributable to IAH/ACS. Another limitation of the study is that it does not directly include IAH/ACS patients who did not require abdominal decompression. To have included such patients would have greatly increased the complexity of the trial. In this initial study, we chose to focus on those patients with higher grades of IAH/ACS who required open abdomen management. The evaluation of patients with lower severities of IAH that do not require an open abdomen is soon to be investigated through two prospective, randomized, multicenter trials. Such trials are necessary to confirm our findings and we look forward to participating in these investigations. Finally, we do not have data regarding the volume of fluid resuscitation received by each individual patient. Positive fluid balance has been demonstrated to be an independent predictor of ACS in several studies and the negative impact of overresuscitation is well-recognized (19, 20). There is little doubt that a more restrictive fluid resuscitation strategy was utilized in the latter years of the trial in accordance with the World Society of the Abdominal Compartment Syndrome guidelines. If such a difference in fluid resuscitation volume exists and significantly impacted on our patient survival, it only further supports the efficacy of our current management algorithm. CONCLUSIONS In conclusion, a comprehensive evidence-based management strategy that incorporates both operative and nonoperative interventions designed to reduce IAP significantly improved survival among patients treated with an open abdomen for IAH/ACS. Such improvements were not achieved at the cost of increased resource utilization. We encourage other institutions to adopt such an evidence-based approach to the patient with IAH/ACS. REFERENCES 1. Malbrain MLNG, Cheatham ML, Kirkpatrick A, et al: Results from the conference of experts on intra-abdominal hypertension and abdominal compartment syndrome. Part I: Definitions. Intensive Care Med 2006; 32:1722 1732 2. Cheatham ML, Malbrain MLNG, Kirkpatrick A, et al: Results from the conference of experts on intra-abdominal hypertension and abdominal compartment syndrome. Part II: Recommendations. Intensive Care Med 2007; 33:951 962 3. Malbrain MLNG, Chiumello D, Pelosi P, et al: Prevalence of intra-abdominal hypertension in critically ill patients: A multicentre epidemiological study. Intensive Care Med 2004; 30:822 829 4. Malbrain ML, Chiumello D, Pelosi P, et al: Incidence and prognosis of intraabdominal hypertension in a mixed population of critically ill patients: A multiple-center epidemiological study. Crit Care Med 2005; 33:315 322 5. Sugrue M, Jones F, Deane SA, et al: Intraabdominal hypertension is an independent cause of postoperative renal impairment. Arch Surg 1999; 134:1082 1085 6. Sugrue M, Buist MD, Hourihan F, et al: Prospective study of intra-abdominal hypertension and renal function after laparotomy. Br J Surg 2005; 82:235 238 7. Ivatury RR, Porter JM, Simon RJ, et al: Intraabdominal hypertension after life-threatening penetrating abdominal trauma: Prophylaxis, incidence, and clinical relevance to gastric mucosal ph and abdominal compartment syndrome. J Trauma 1998; 44:1016 1021 8. Ivatury RR, Cheatham ML, Malbrain MLNG, et al: Abdominal Compartment Syndrome. Landes Biosciences, Georgetown, 2006 9. Cothren CC, Moore EE, Johnson JL, et al: Outcomes in surgical versus medical patients with the secondary abdominal compartment syndrome. Am J Surg 2007; 194:804 807 10. Ejike JC, Humbert S, Bahjri K, et al: Outcomes of children with abdominal compartment syndrome. Acta Clin Belg Suppl 2007; 141 148 11. Hershberger RC, Hunt JL, Arnoldo BD, et al: Abdominal compartment syndrome in the severely burned patient. J Burn Care Res 2007; 28:708 714 12. Kirkpatrick AW, Balogh Z, Ball CG, et al: The secondary abdominal compartment syndrome: Iatrogenic or unavoidable? J Am Coll Surg 2006; 202:668 679 13. De Waele JJ, Hoste E, Blot SI, et al: Intraabdominal hypertension in patients with severe acute pancreatitis. Crit Care 2005; 9:R452 R457 14. Offner PJ, de Souza AL, Moore EE, et al: Avoidance of abdominal compartment syndrome in damage-control laparotomy after trauma. Arch Surg 2001; 136:676 681 15. Raeburn CD, Moore EE, Biffl WL, et al: The abdominal compartment syndrome is a morbid complication of postinjury damage control surgery. Am J Surg 2001; 182:542 546 16. Cheatham ML, White MW, Sagraves SG, et al: Abdominal perfusion pressure: A superior parameter in the assessment of intra-abdominal hypertension. J Trauma 2000; 49:621 626 17. Balogh Z, McKinley BA, Holcomb JB, et al: Both primary and secondary abdominal compartment syndrome can be predicted early and are harbingers of multiple organ failure. J Trauma 2003; 54:848 859 18. Ertel W, Oberholzer A, Platz A, et al: Incidence and clinical pattern of the abdominal compartment syndrome after damagecontrol laparotomy in 311 patients with severe abdominal and/or pelvic trauma. Crit Care Med 2000; 28:1747 1753 19. McNelis J, Marini CP, Jurkiewicz A, et al: Predictive factors associated with the development of abdominal compartment syndrome in the surgical intensive care unit. Arch Surg 2002; 137:133 136 20. Vidal MD, Weisser JR, Gonzalez F, Toro MA, et al: Incidence and clinical effects of intraabdominal hypertension in critically ill patients. Crit Care Med 2008; 36:1823 1831 21. Hong JJ, Cohn SM, Perez JM, et al: Prospective study of the incidence and outcome of intra-abdominal hypertension and the abdominal compartment syndrome. Br J Surg 2002; 89:591 596 22. Parsak CK, Seydaoglu G, Sakman G, et al: Abdominal compartment syndrome: Current problems and new strategies. World J Surg 2008; 32:13 19 23. Cheatham ML: Abdominal compartment syndrome. Curr Opin Crit Care 2009; 15:154 162 24. Cheatham ML: Nonoperative management of intraabdominal hypertension and abdominal compartment syndrome. World J Surg 2009; 33:1116 1122 25. Cheatham ML, Safcsak K, Llerena LE, et al: Long-term physical, mental, and functional consequences of abdominal decompression. J Trauma 2004; 56:237 242 26. Cheatham ML, Safcsak K: Long-term impact of abdominal decompression: A prospective comparative analysis. J Am Coll Surg 2008; 207:573 579 27. World Society of the Abdominal Compartment Syndrome resuscitation algorithms. Available online at: http://www.wsacs.org. Accessed May 22, 2009 28. Kirkpatrick AW, De Waele JJ, Ball CG, et al: The secondary and recurrent abdominal compartment syndrome. Acta Clinica Belgica 2007; 62(Suppl 1):60 65 Crit Care Med 2010 Vol. 38, No. 2 407