Michael L. Cheatham

Intra-abdominal hypertension and the abdominal compartment syndrome: updated consensus definitions and clinical practice guidelines from the World Society of the Abdominal Compartment Syndrome

PurposeTo update the World Society of the Abdominal Compartment Syndrome (WSACS) consensus definitions and management statements relating to intra-abdominal hypertension (IAH) and the abdominal compartment syndrome (ACS).MethodsWe conducted systematic or structured reviews to identify relevant studies relating to IAH or ACS. Updated consensus definitions and management statements were then derived using a modified Delphi method and the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) guidelines, respectively. Quality of evidence was graded from high (A) to very low (D) and management statements from strong RECOMMENDATIONS (desirable effects clearly outweigh potential undesirable ones) to weaker SUGGESTIONS (potential risks and benefits of the intervention are less clear).ResultsIn addition to reviewing the consensus definitions proposed in 2006, the WSACS defined the open abdomen, lateralization of the abdominal musculature, polycompartment syndrome, and abdominal compliance, and proposed an open abdomen classification system. RECOMMENDATIONS included intra-abdominal pressure (IAP) measurement, avoidance of sustained IAH, protocolized IAP monitoring and management, decompressive laparotomy for overt ACS, and negative pressure wound therapy and efforts to achieve same-hospital-stay fascial closure among patients with an open abdomen. SUGGESTIONS included use of medical therapies and percutaneous catheter drainage for treatment of IAH/ACS, considering the association between body position and IAP, attempts to avoid a positive fluid balance after initial patient resuscitation, use of enhanced ratios of plasma to red blood cells and prophylactic open abdominal strategies, and avoidance of routine early biologic mesh use among patients with open abdominal wounds. NO RECOMMENDATIONS were possible regarding monitoring of abdominal perfusion pressure or the use of diuretics, renal replacement therapies, albumin, or acute component-parts separation.ConclusionAlthough IAH and ACS are common and frequently associated with poor outcomes, the overall quality of evidence available to guide development of RECOMMENDATIONS was generally low. Appropriately designed intervention trials are urgently needed for patients with IAH and ACS.

Abdominal perfusion pressure: a superior parameter in the assessment of intra-abdominal hypertension.

OBJECTIVE To assess the clinical utility of abdominal perfusion pressure (mean arterial pressure minus intra-abdominal pressure) as both a resuscitative endpoint and predictor of survival in patients with intra-abdominal hypertension. METHODS 144 surgical patients treated for intra-abdominal hypertension between May 1997 and June 1999 were retrospectively reviewed. Multivariate logistic regression and receiver operating characteristic curve analysis of common physiologic variables and resuscitation endpoints were performed to determine the decision thresholds for each variable that predict patient survival. RESULTS Abdominal perfusion pressure was statistically superior to both mean arterial pressure and intravesicular pressure in predicting patient survival from intra-abdominal hypertension and abdominal compartment syndrome. Multiple regression analysis demonstrated that abdominal perfusion pressure was also superior to other common resuscitation endpoints, including arterial pH, base deficit, arterial lactate, and hourly urinary output. CONCLUSION Abdominal perfusion pressure appears to be a clinically useful resuscitation endpoint and predictor of patient survival during treatment for intra-abdominal hypertension and abdominal compartment syndrome.

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

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.

Right ventricular end-diastolic volume index as a predictor of preload status in patients on positive end-expiratory pressure

OBJECTIVE To evaluate the clinical utility of right ventricular end-diastolic volume index (RVEDVI) and pulmonary artery occlusion pressure (PAOP) as measures of preload status in patients with acute respiratory failure receiving treatment with positive end-expiratory pressure. DESIGN Prospective, cohort study. SETTING Surgical intensive care unit in a Level I trauma center/university hospital. PATIENTS Sixty-four critically ill surgical patients with acute respiratory failure. INTERVENTIONS All patients were treated for acute respiratory failure with titrated levels of positive end-expiratory pressure (PEEP) with the goal of increasing arterial oxygen saturation to > or =0.92, reducing FIO2 to <0.5, and reducing intrapulmonary shunt to < or =0.2. Serial determinations of RVEDVI, PAOP, and cardiac index (CI) were recorded. MEASUREMENTS AND MAIN RESULTS Two hundred-fifty sets of hemodynamic variables were measured in 64 patients. The level of PEEP ranged from 5 to 50 cm H2O (mean 12+/-9 [SD] cm H2O). At all levels of PEEP, CI correlated significantly better with RVEDVI than with PAOP. At levels of PEEP > or =15 cm H2O, CI was inversely correlated with PAOP, but remained positively correlated with RVEDVI. CONCLUSIONS CI correlates significantly better with RVEDVI than PAOP at all levels of PEEP up to 50 cm H2O. RVEDVI is a more reliable predictor of volume depletion and preload recruitable increases in CI, especially in patients receiving higher levels of PEEP where PAOP is difficult to interpret.

Gastric tonometry supplements information provided by systemic indicators of oxygen transport.

HYPOTHESIS Assessment of splanchnic perfusion by gastric intramucosal pH (pHi) adds to the information provided by systemic indicators of oxygen transport. SETTING University Hospital level I trauma center. DESIGN Prospective study in 20 critically ill trauma patients comparing pHi with base deficit, lactate, oxygen delivery, and oxygen consumption (indexed to body surface area), mixed venous oxygen saturation (Svo2), oxygen utilization coefficient, and arterial pH. All measurements were obtained at admission, 1, 2, 4, 8, 16, and 24 hours, or at death. MAIN OUTCOME MEASURES Correlation of pHi with the measured systemic variables, prediction of organ dysfunction, development of multiple organ dysfunction syndrome, and mortality. RESULTS There was a poor correlation between pHi and the systemic hemodynamic and oxygen transport variables. Patients with a low pHi (< 7.32) on admission who did not correct within the initial 24 hours had a higher mortality (50% vs. 0.0%, p = 0.03) and incidence of organ dysfunction (2.6 organs/patient vs. 0.62 organs/patient, p = 0.02) than those who did. Using logistic regression analysis, only pHi, base deficit, and Svo2 were significantly associated with mortality during the study period. At 24 hours, only pHi was different between patients who developed multiple organ dysfunction syndrome and those who did not. There was a threshold value for pHi (7.10) which identified those patients who would go on to develop multiple organ dysfunction syndrome. CONCLUSIONS Uncorrected splanchnic malperfusion is associated with a higher incidence of organ dysfunction and mortality. Gastric tonometry supplements information provided by systemic indicators of oxygen transport during resuscitation of critically ill trauma patients.

Classification—Important Step to Improve Management of Patients with an Open Abdomen

This short report is a distillation of the proceedings from a consensus group meeting in January 2009. It outlines a proposed classification system for patients with an open abdomen (OA). The classification allows (1) a description of the patient’s clinical course; (2) standardized clinical guidelines for improving OA management; and (3) improved reporting of OA status, which will facilitate comparisons between studies and heterogeneous patient populations. The following grading is suggested: grade 1A, clean OA without adherence between bowel and abdominal wall or fixity of the abdominal wall (lateralization); grade 1B, contaminated OA without adherence/fixity; grade 2A, clean OA developing adherence/fixity; grade 2B, contaminated OA developing adherence/fixity; grade 3, OA complicated by fistula formation; grade 4, frozen OA with adherent/fixed bowel, unable to close surgically, with or without fistula. We propose that this classification system will facilitate communication, clarify OA management, and potentially improve patient care.

Percutaneous dilational tracheostomy: a comparison of single- versus multiple-dilator techniques.

Objective To compare the safety and efficacy of single- vs. multiple-dilator techniques in the performance of percutaneous dilational tracheostomy. Design Prospective randomized trial. Setting Intensive care units at a level 1 trauma center. Patients Fifty consecutive patients requiring tracheostomy for airway control or prolonged mechanical ventilatory support. Interventions Patients were randomized to receive a percutaneous dilational tracheostomy by either the single- or multiple-dilator technique described by Ciaglia. Measurements and Main Results Percutaneous dilational tracheostomy was performed using the single-dilator technique in 6:01 ± 3:03 mins and by the multiple-dilator technique in 10:01 ± 4:26 mins (p < .0006). There were no statistically significant differences in complication rates between the two techniques. No major complications occurred with either technique. Conclusion The single-dilator percutaneous tracheostomy technique is a safe, cost-effective, and more rapidly performed method for bedside tracheostomy in the intensive care unit.

CONSENSUS CONFERENCE DEFINITIONS AND RECOMMENDATIONS ON INTRA-ABDOMINAL HYPERTENSION (IAH) AND THE ABDOMINAL COMPARTMENT SYNDROME (ACS) - THE LONG ROAD TO THE FINAL PUBLICATIONS, HOW DID WE GET THERE?

Abstract Objective: There has been an exponentially increasing interest in intraabdominal hypertension (IAH) and the abdominal compartment syndrome (ACS) over the last decade, and different definitions have been suggested. Nevertheless, there has been an impetus from experts in the field to modify these definitions to reflect our current understanding of the pathophysiology of these syndromes. An international multidisciplinary group of interested doctors met with the goal of agreeing on a set of definitions that could be applied to patients with IAH and ACS. The goal of this consensus group was to provide a conceptual and practical framework to further define ACS, a progressive injurious process that falls under the generalized term ‘IAH’ and that includes IAH-associated organ dysfunction. Design: In total, 21 North American, Australasian and European surgical, trauma and critical care specialists agreed to standardize the current definitions for IAH, ACS and related conditions in preparation for the second World Congress on Abdominal Compartment Syndrome (WCACS). The WCACS-meeting was endorsed by the European Society of Intensive Care Medicine (ESICM) and the World Society on Abdominal Compartment Syndrome (WSACS). Methods: The consensus conference (Noosa, Australia; December 7, 2004) was attended by 21 specialists from Europe, Australasia and North America and approximately 70 other congress participants. In advance of the conference, a blueprint for the various definitions was suggested. After the conference the participants corresponded electronically with feedback. A writing committee was formed at the conference and developed the final manuscript based on executive summary documents generated by each participant. The final report of the 2004 International ACS Consensus Definitions Conference has recently been published. This article will describe the long road towards this final publication with the evolution of the different definitions and recommendations from the initial suggestions in 2004 to the further refinement and final publications in 2006 and 2007. It will try to explain how we got there and will also give the percentage of agreement with each proposed definition by the participants. Results: New definitions were offered for some terms, while others were discarded and not kept in the final manuscript. Different cut-offs for defining IAH and ACS were given, as well as broad definitions of primary, secondary and recurrent IAH/ACS. A classification system was introduced taking into account the duration, origin, and etiology of IAH. The use of an organ severity scoring method, by means of the Sequential Organ Failure Assessment (SOFA) score when dealing with ACS patients was not recommended as an adjunctive tool to assess morbidity in the final publication. Conclusion: This document reflects a process whereby a group of experts and opinion leaders suggested definitions for IAH and ACS. This document should be used as a reference for the next consensus definitions conference in March 2007.

Preload assessment in patients with an open abdomen.

BACKGROUND Intra-abdominal hypertension and abdominal compartment syndrome cause significant morbidity and mortality in surgical and trauma patients. Maintenance of intravascular preload and use of open abdomen techniques are essential. The accuracy of pulmonary artery occlusion pressure (PAOP) and central venous pressure (CVP) in patients with intra-abdominal hypertension has been questioned. METHODS Twenty surgical and trauma patients with intra-abdominal hypertension requiring open abdominal decompression were monitored using volumetric thermodilution pulmonary artery catheters. Hemodynamic, oxygenation, inspiratory, and intravesicular pressure measurements were collected prospectively. PAOP, CVP, and right ventricular end-diastolic volume index (RVEDVI) were compared as estimates of preload status. RESULTS Multiple regression analysis demonstrated that cardiac index correlated significantly better with RVEDVI (r = 0.69) than with PAOP (r = -0.27) or CVP (r = -0.28) during resuscitation after open abdominal decompression (p < 0.0001). CONCLUSION RVEDVI is superior to PAOP and CVP as an estimate of preload status in patients with an open abdomen.

Negative-pressure wound therapy for critically ill adults with open abdominal wounds: A systematic review

BACKGROUND Open abdominal management with negative-pressure wound therapy (NPWT) is increasingly used for critically ill trauma and surgery patients. We sought to determine the comparative efficacy and safety of NPWT versus alternate temporary abdominal closure (TAC) techniques in critically ill adults with open abdominal wounds. METHODS We conducted a systematic review of published and unpublished comparative studies. We searched MEDLINE, PubMed, EMBASE, Scopus, Web of Science, the Cochrane Database, the Center for Reviews and Dissemination, clinical trials registries, and bibliographies of included articles. Two authors independently abstracted data on study design, methodological quality, patient characteristics, and outcomes. RESULTS Among 2,715 citations identified, 2 randomized controlled trials and 9 cohort studies (3 prospective/6 retrospective) met inclusion criteria. Methodological quality of included prospective studies was moderate. One randomized controlled trial observed an improved fascial closure rate (relative risk [RR], 2.4; 95% confidence interval [CI], 1.0–5.3) and length of hospital stay after addition of retention sutured sequential fascial closure to the Kinetic Concepts Inc. (KCI) vacuum-assisted closure (VAC). Another reported a trend toward enhanced fascial closure using the KCI VAC versus Barker’s vacuum pack (RR, 2.6; 95% CI, 0.95–7.1). A prospective cohort study observed improved mortality (RR, 0.48; 95% CI, 0.25–0.92) and fascial closure (RR, 1.5; 95% CI, 1.1–2.0) for patients who received the ABThera versus Barker’s vacuum pack. Another noted a reduced arterial lactate, intra-abdominal pressure, and hospital stay for those fitted with the KCI VAC versus Bogotá bag. Most included retrospective studies exhibited low methodological quality and reported no mortality or fascial closure benefit for NPWT. CONCLUSION Limited prospective comparative data suggests that NPWT versus alternate TAC techniques may be linked with improved outcomes. However, the clinical heterogeneity and quality of available studies preclude definitive conclusions regarding the preferential use of NPWT over alternate TAC techniques. LEVEL OF EVIDENCE Systematic review, level III.