Results from the International Conference of Experts on Intra-abdominal Hypertension and Abdominal Compartment Syndrome. II. Recommendations

Correlation between intra-abdominal pressure and pulmonary volumes after superior and inferior abdominal surgery

OBJECTIVE

Patients undergoing abdominal surgery are at risk for pulmonary complications. The principal cause of postoperative pulmonary complications is a significant reduction in pulmonary volumes (FEV1 and FVC) to approximately 65-70% of the predicted value. Another frequent occurrence after abdominal surgery is increased intra-abdominal pressure. The aim of this study was to correlate changes in pulmonary volumes with the values of intra-abdominal pressure after abdominal surgery, according to the surgical incision in the abdomen (superior or inferior).

METHODS

We prospectively evaluated 60 patients who underwent elective open abdominal surgery with a surgical time greater than 240 minutes. Patients were evaluated before surgery and on the 3rd postoperative day. Spirometry was assessed by maximal respiratory maneuvers and flow-volume curves. Intra-abdominal pressure was measured in the postoperative period using the bladder technique.

RESULTS

The mean age of the patients was 56 ± 13 years, and 41.6% 25 were female; 50 patients (83.3%) had malignant disease. The patients were divided into two groups according to the surgical incision (superior or inferior). The lung volumes in the preoperative period showed no abnormalities. After surgery, there was a significant reduction in both FEV1 (1.6 ± 0.6 L) and FVC (2.0 ± 0.7 L) with maintenance of FEV1/FVC of 0.8 ± 0.2 in both groups. The maximum intra-abdominal pressure values were similar (p=0.59) for the two groups. There was no association between pulmonary volumes and intra-abdominal pressure measured in any of the groups analyzed.

CONCLUSIONS

Our results show that superior and inferior abdominal surgery determines hypoventilation, unrelated to increased intra-abdominal pressure. Patients at high risk of pulmonary complications should receive respiratory care even if undergoing inferior abdominal surgery.

Temporary abdominal closure with polytetrafluoroethylene prosthetic mesh in critically ill non-trauma patients

BACKGROUND

Survival in critically ill non-trauma patients may be improved by performing temporary abdominal closure using different surgical techniques. We describe the use of expanded polytetrafluoroethylene (ePTFE) mesh for temporary abdominal closure in a group of critical patients. We also evaluate definitive abdominal wall closure in these patients once they are in a stable condition.

METHOD

We conducted a study of 29 critically ill non-trauma patients who underwent temporary abdominal closure due to sepsis or abdominal compartment syndrome over 7 years at two university hospitals. We analysed factors related to surgical wound type and definitive abdominal wall closure. We evaluated the SAPS 3 severity score and used it to obtain expected mortality. We used the Clavien-Dindo System for Surgical Complications and the Ventral Hernia Working Group Classification during follow-up.

RESULTS

Performing temporary abdominal closure with expanded polytetrafluoroethylene mesh was associated with a mortality rate of 20.68%, which was lower than the expected mortality calculated from the SAPS 3 severity score (38.87 ± 21.60). There was no fistula formation related with this type of prosthetic material. In our study group, definitive abdominal wall closure was performed in the 16 patients who survived (69.5%), and six of them underwent this procedure during the original hospital stay.

CONCLUSION

Temporary abdominal closure with ePTFE mesh is an effective alternative in some circumstances. We observed a higher survival rate than the predicted figure and there were no cases of enteroatmospheric fistulae using this particular surgical technique. ePTFE facilitates definitive abdominal wall closure, once the patient is in a stable condition.

Prospective study examining clinical outcomes associated with a negative pressure wound therapy system and Barker's vacuum packing technique

BACKGROUND

The open abdomen has become a common procedure in the management of complex abdominal problems and has improved patient survival. The method of temporary abdominal closure (TAC) may play a role in patient outcome.

METHODS

A prospective, observational, open-label study was performed to evaluate two TAC techniques in surgical and trauma patients requiring open abdomen management: Barker's vacuum-packing technique (BVPT) and the ABThera(TM) open abdomen negative pressure therapy system (NPWT). Study endpoints were days to and rate of 30-day primary fascial closure (PFC) and 30-day all-cause mortality.

RESULTS

Altogether, 280 patients were enrolled from 20 study sites. Among them, 168 patients underwent at least 48 hours of consistent TAC therapy (111 NPWT, 57 BVPT). The two study groups were well matched demographically. Median days to PFC were 9 days for NPWT versus 12 days for BVPT (p = 0.12). The 30-day PFC rate was 69 % for NPWT and 51 % for BVPT (p = 0.03). The 30-day all-cause mortality was 14 % for NPWT and 30 % for BVPT (p = 0.01). Multivariate logistic regression analysis identified that patients treated with NPWT were significantly more likely to survive than the BVPT patients [odds ratio 3.17 (95 % confidence interval 1.22-8.26); p = 0.02] after controlling for age, severity of illness, and cumulative fluid administration.

CONCLUSIONS

Active NPWT is associated with significantly higher 30-day PFC rates and lower 30-day all-cause mortality among patients who require an open abdomen for at least 48 h during treatment for critical illness.

Early enteral nutrition prevents intra-abdominal hypertension and reduces the severity of severe acute pancreatitis compared with delayed enteral nutrition: a prospective pilot study

BACKGROUND

To investigate the effects of early enteral nutrition (EEN) on intra-abdominal pressure (IAP) and disease severity in patients with severe acute pancreatitis (SAP).

METHODS

Enteral nutrition (EN) was started within 48 h after admission in the EEN group and from the 8th day in the delayed enteral nutrition (DEN) group. The IAP and intra-abdominal hypertension (IAH) incidence were recorded for 2 weeks. The caloric intake and feeding intolerance (FI) incidence were recorded daily after EN was started. The severity markers and clinical outcome variables were also recorded.

RESULTS

Sixty patients were enrolled to this study. No difference about IAP was found. The IAH incidence of the EEN group was significantly lower than that of the DEN group from the 9th day (8/30 versus 18/30; P = 0.009) after admission. The FI incidence of the EEN group was higher than that of the DEN group during the initial 3 days of feeding (25/30 versus 12/30; P = 0.001; 22/30 versus 9/30; P = 0.001; 15/30 versus 4/30; P = 0.002). Patients with an IAP <15 mmHg had lower FI incidence than those with an IAP ≥15 mmHg on the 1st day (20/22 versus 17/38; P < 0.001), the 3rd day (11/13 versus 8/47; P < 0.001), and the 7th day (3/5 versus 3/55; P = 0.005) of feeding. The severity markers and clinical outcome variables of the EEN group were significantly improved.

CONCLUSIONS

Early enteral nutrition did not increase IAP. In contrast, it might prevent the development of IAH. In addition, EEN might be not appropriate during the initial 3-4 days of SAP onset. Moreover, EN might be of benefit to patients with an IAP <15 mmHg. Early enteral nutrition could improve disease severity and clinical outcome, but did not decrease mortality of SAP.

The conjoint effect of reduced crystalloid administration and decreased damage-control laparotomy use in the development of abdominal compartment syndrome

BACKGROUND

Anticipation of abdominal compartment syndrome (ACS) is a factor for performing damage-control laparotomy (DCL). Recent years have seen changes in resuscitation patterns and a decline in the use of DCL. We hypothesized that reductions in both crystalloid resuscitation and the use of DCL is associated with a reduced rate of ACS in trauma patients.

METHODS

We reviewed the records of all patients who underwent trauma laparotomies at our Level 1 trauma center over a 6-year period (2006-2011). We defined DCL as a trauma laparotomy in which the fascia was not closed at the initial operation. We defined ACS by elevated intravesical pressures and end-organ dysfunction. Our primary outcome measure was a development of ACS.

RESULTS

A total of 799 patients were included. We noted a significant decrease in the DCL rate (39% in 2006 vs. 8% in 2011, p < 0.001), the crystalloid volume per patient (mean [SD], 12.8 [7.8] L in 2006 vs. 6.6 [4.2] L in 2011; p < 0.001), rate of ACS (7.4% in 2006 vs. 0% in 2011, p < 0.001), and mortality rate (22.8% in 2006 vs. 10.6% in 2011, p < 0.001). However, we noted no significant changes in the mean Injury Severity Score (ISS) (p = 0.09), in the mean abdominal Abbreviated Injury Scale (AIS) score (p = 0.17), and in the mean blood product volume per patient (p = 0.67). On multivariate regression analysis, crystalloid resuscitation (p = 0.01) was the only significant factor associated with the development of ACS.

CONCLUSION

Minimizing the use of crystalloids and DCL was associated with better outcomes and virtual elimination of ACS in trauma patients. With the adaption of new resuscitation strategies, goals for a trauma laparotomy should be definitive surgical care with abdominal closure. ACS is a rare complication in the era of damage-control resuscitation and may have been iatrogenic.

LEVEL OF EVIDENCE

Epidemiologic/therapeutic study, level IV.

Planned re-laparotomy and the need for optimization of physiology and immunology

Planned re-laparotomy or damage control laparotomy (DCL), first described by Dr. Harlan Stone in 1983, has become a widely utilized technique in a broad range of patients and operative situations. Studies have validated the use of DCL by demonstrating decreased mortality and morbidity in trauma, general surgery and abdominal vascular catastrophes. Indications for planned re-laparotomy include severe physiologic derangements, coagulopathy, concern for bowel ischemia, and abdominal compartment syndrome. The immunology of DCL patients is not well described in humans, but promising animal studies suggest a benefit from the open abdomen (OA) and several human trials on this subject are currently underway. Optimal critical care of patients with OA's, including sedation, paralysis, nutrition, antimicrobial and fluid management strategies have been associated with improved closure rates and recovery.

Is intra-abdominal hypertension a missing factor that drives multiple organ dysfunction syndrome?

In a recent issue of Critical Care, Cheng and colleagues conducted a rabbit model study that demonstrated that intra-abdominal hypertension (IAH) may damage both gut anatomy and function. With only 6 hours of IAH at 25 mmHg, these authors observed an 80% reduction in mucosal blood flow, an exponential increase in mucosal permeability, and erosion and necrosis of the jejunal villi. Such dramatic findings should remind all caring for the critically ill that IAH may severely damage the normal gut barrier functions and thus may be reasonably expected to facilitate bacterial and mediator translocation. The potential contribution of IAH as a confounding factor in the efficacy of selective decontamination of the digestive tract should be considered.

Abdominal hypertension and decompression: the effect on peritoneal metabolism in an experimental porcine study

OBJECTIVE

The aim of this study was to investigate the abdominal metabolic response and circulatory changes after decompression of intra-abdominal hypertension in a porcine model.

METHODS

This was an experimental study with controls. Three-month-old domestic pigs of both sexes were anesthetized and ventilated. Nine animals had a pneumoperitoneum-induced IAH of 30 mmHg for 6 hours. Twelve animals had the same IAH for 4 hours followed by decompression, and were monitored for another 2 hours. Hemodynamics, including laser Doppler-measured mucosal blood flow, urine output, and arterial blood samples were analyzed every hour along with glucose, glycerol, lactate and pyruvate concentrations, and lactate-pyruvate (l/p) ratio, measured by microdialysis.

RESULTS

Laser Doppler-measured mucosal blood flow and urine output decreased with the induction of IAH and showed a statistically significant resolution after decompression. Both groups developed distinct metabolic changes intraperitoneally on induction of IAH, including an increased l/p ratio, as signs of organ hypoperfusion. In the decompression group the intraperitoneal l/p ratio normalized during the second decompression hour, indicating partially restored perfusion.

CONCLUSION

Decompression after 4 hours of IAH results in an improved intestinal blood flow and a normalized intraperitoneal l/p ratio.

Position paper: timely interventions in severe acute pancreatitis are crucial for survival

Severe acute pancreatitis has high mortality, but multiple and timely interventions can improve survival. Early in the course of the disease aggressive fluid resuscitation is needed for the prevention and treatment of shock. In conjunction with leaking capillaries this results in increased tissue edema, which may lead to intra-abdominal hypertension and abdominal compartment syndrome. Invasive hemodynamic monitoring is essential for optimizing fluid therapy while monitoring of intra-abdominal pressure is necessary for identification patients at risk of developing abdominal compartment syndrome. Abdominal compartment syndrome develops usually within the first days after hospitalization. Conservative treatment modalities are useful in prevention but also in the treatment of abdominal compartment syndrome. If conservative management fails surgical decompression of abdomen may be needed. Multiple organ dysfunction syndrome and increased intra-abdominal pressure predispose patients with severe pancreatitis to secondary infections. Extrapancreatic infections predominate during the first week of the disease, whereas infection of pancreatic necrosis usually develops later. Early enteral nutrition reduces the risk of infections whereas advantage of prophylactic antibiotics is lacking evidence. Surgery for infected pancreatic necrosis is associated with high mortality when performed within the first two weeks of the disease. Therefore surgery should be postponed as late as possible, preferably later than four weeks after disease onset.

Management of intra-abdominal hypertension and abdominal compartment syndrome: a review

Patients in the intensive care unit (ICU) are at risk of developing of intra abdominal hypertension (IAH) and abdominal compartment syndrome (ACS).

AIM

This review seeks to define IAH and ACS, identify the aetiology and presentation of IAH and ACS, identify IAP measurement techniques, identify current management and discuss the implications of IAH and ACS for nursing practice. A search of the electronic databases was supervised by a health librarian. The electronic data bases Cumulative Index of Nursing and Allied Health Literature (CINAHL); Medline, EMBASE, and the World Wide Web was undertaken from 1996- January 2011 using MeSH and key words which included but not limited to: abdominal compartment syndrome, intra -abdominal hypertension, intra-abdominal pressure in adult populations met the search criteria and were reviewed by three authors using a critical appraisal tool. Data derived from the retrieved material are discussed under the following themes: (1) etiology of intra-abdominal hypertension; (2) strategies for measuring intra-abdominal pressure (3) the manifestation of abdominal compartment syndrome; and (4) the importance of nursing assessment, observation and interventions. Intra-abdominal pressure (IAP) and abdominal compartment syndrome (ACS) have the potential to alter organ perfusion and compromise organ function.

Intra-abdominal pressure as a predictor of acute kidney injury in postoperative abdominal surgery

OBJECTIVES

The purpose of this study was to determine if intra-abdominal pressure (IAP) could predict acute renal injury (AKI) in the postoperative period of abdominal surgeries, and which would be its cutoff value.

PATIENTS AND METHODS

A prospective observational study was conducted in the period from January 2010 to March 2011 in the Intensive Care Units (ICUs) of the University Hospital of Botucatu Medical School, UNESP. Consecutive patients undergoing abdominal surgery were included in the study. Initial evaluation, at admission in ICU, was performed in order to obtain demographic, clinical surgical and therapeutic data. Evaluation of IAP was obtained by the intravesical method, four times per day, and renal function was evaluated during the patient's stay in the ICU until discharge, death or occurrence of AKI.

RESULTS

A total of 60 patients were evaluated, 16 patients developed intra-abdominal hypertension (IAH), 45 developed an abnormal IAP (>7 mmHg) and 26 developed AKI. The first IAP at the time of admission to the ICU was able to predict the occurrence of AKI (area under the receiver-operating characteristic curve was 0.669; p=0.029) with the best cutoff point (by Youden index method) ≥ 7.68 mmHg, sensitivity of 87%, specificity of 46% at this point. The serial assessment of this parameter did not added prognostic value to initial evaluation.

CONCLUSION

IAH was frequent in patients undergoing abdominal surgeries during ICU stay, and it predicted the occurrence of AKI. Serial assessments of IAP did not provided better discriminatory power than initial evaluation.

Management of abdominal compartment syndrome and the open abdomen

OBJECTIVES

The management of the abdominal compartment syndrome (ACS) and the open abdomen (OA) are important to improve survival after major vascular surgery, in particular ruptured abdominal aortic aneurysm (RAAA). The aim is to summarize contemporary knowledge in this field.

METHODS

The consensus definitions of the World Society of the Abdominal Compartment Syndrome (WSACS) that were published in 2006 and the clinical practice guidelines published in 2007 were updated in 2013. Structured clinical questions were formulated (modified Delphi method), and the evidence base to answer those questions was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) guidelines.

RESULTS

Most of the previous definitions were kept untouched, or were slightly modified. Four new definitions were added, including a definition of OA and of lateralization of the abdominal wall, an important clinical problem to approach during prolonged OA treatment. A classification system of the OA was added. Seven recommendations were formulated, in summary: Trans-bladder intra-abdominal pressure (IAP) should be monitored in patients at risk. Protocolized monitoring and management are recommended, and decompression laparotomy if ACS. When OA, protocolized efforts to obtain an early abdominal fascial closure, and strategies utilizing negative pressure wound therapy should be used, versus not. In most cases the evidence was graded as weak or very weak. In six of the structured clinical questions, no recommendation could be made.

CONCLUSION

This review summarizes changes in definitions and management guidelines of relevance to vascular surgery, and data on the incidence of ACS after open and endovascular aortic surgery.

Abdominal damage control surgery and reconstruction: world society of emergency surgery position paper

Damage control laparotomy was first described by Dr. Harlan Stone in 1983 when he suggested that patients with severe trauma should have their primary procedures abbreviated when coagulopathy was encountered. He recommended temporizing patients with abdominal packing and temporary closure to allow restoration of normal physiology prior to returning to the operating room for definitive repair. The term damage control in the trauma setting was coined by Rotondo et al., in 1993. Studies in subsequent years have validated this technique by demonstrating decreased mortality and immediate post-operative complications. The indications for damage control laparotomy have evolved to encompass abdominal compartment syndrome, abdominal sepsis, vascular and acute care surgery cases. The perioperative critical care provided to these patients, including sedation, paralysis, nutrition, and fluid management strategies may improve closure rates and recovery. In the rare cases of inability to primarily close the abdomen, there are a number of reconstructive strategies that may be used in the acute and chronic phases of abdominal closure.

[«Surgical» analysis of the new clinical practice guide on compartmental syndrome]

The new published guidelines of compartment syndrome are supposed to be a helpful tool in order to make decisions in patients with abdominal hypertension. From a surgical perspective of view, an important effort has been made in order to reach consensus in different phases in which there is no clear answer in evidence-based medicine. It is mandatory the use of a universal classification of open abdomen and there are three main concepts that must be observed: make a decompressive laparotomy when conservative measures have failed, attempt to closure the abdomen as soon as possible and the use of negative-pressure treatments that facilitates the management of an open abdomen. Although most of recommendations that have been delivered are not high grades, the present guide is an important assistant for the management of intra-abdominal hypertension and several lines of investigation are opened in order to answer the doubts that have been addressed.

The role of intestinal mucosa injury induced by intra-abdominal hypertension in the development of abdominal compartment syndrome and multiple organ dysfunction syndrome

Introduction

Abdominal distension is common in critical illness. There is a growing recognition that intra-abdominal hypertension (IAH) may complicate nonsurgical critical illness as well as after abdominal surgery. However, the pathophysiological basis of the injury to the intestinal mucosal barrier and its influence on the onset of abdominal compartment syndrome (ACS) and multiorgan dysfunction syndrome (MODS) remain unclear. We measured intestinal microcirculatory blood flow (MBF) during periods of raised intra-abdominal pressure (IAP) and examined how this influenced intestinal permeability, systemic endotoxin release, and histopathological changes.

Methods

To test different grades of IAH to the injury of intestinal mucosa, 96 New Zealand white rabbits aged 5 to 6 months were exposed to increased IAP under nitrogen pneumoperitoneum of 15 mmHg or 25 mmHg for 2, 4 or 6 hours. MBF was measured using a laser Doppler probe placed against the jejunal mucosa through a small laparotomy. Fluorescein isothiocyanate (FITC)-conjugated dextran was administered by gavage. Intestinal injury and permeability were measured using assays for serum FITC-dextran and endotoxin, respectively, after each increase in IAP. Structural injury to the intestinal mucosa at different levels of IAH was confirmed by light and transmission electron microscopy.

Results

MBF reduced from baseline by 40% when IAP was 15 mmHg for 2 hours. This doubled to 81% when IAP was 25 mmHg for 6 hours. Each indicator of intestinal injury increased significantly, proportionately with IAP elevation and exposure time. Baseline serum FITC-dextran was 9.30 (± SD 6.00) μg/ml, rising to 46.89 (±13.43) μg/ml after 15 mmHg IAP for 4 hours (P <0.01), and 284.59 (± 45.18) μg/ml after 25 mmHg IAP for 6 hours (P <0.01). Endotoxin levels showed the same pattern. After prolonged exposure to increased IAP, microscopy showed erosion and necrosis of jejunal villi, mitochondria swelling and discontinuous intracellular tight junctions.

Conclusions

Intra-abdominal hypertension can significantly reduce MBF in the intestinal mucosa, increase intestinal permeability, result in endotoxemia, and lead to irreversible damage to the mitochondria and necrosis of the gut mucosa. The dysfunction of the intestinal mucosal barrier may be one of the important initial factors responsible for the onset of ACS and MODS.

Abdominal compartment syndrome in children

Abdominal compartment syndrome is defined as sustained intra-abdominal pressure greater than 20 mm Hg (with or without abdominal perfusion pressure <60 mm Hg) associated with new organ failure or dysfunction. The syndrome is associated with 90% to 100% mortality if not recognized and treated in a timely manner. Nurses are responsible for accurately measuring intra-abdominal pressure in children with abdominal compartment syndrome and for alerting physicians about important changes. This article provides relevant definitions, outlines risk factors for abdominal compartment syndrome developing in children, and discusses an instructive case involving an adolescent with abdominal compartment syndrome. Techniques for measuring intra-abdominal pressure, normal ranges, and the importance of monitoring in the critical care setting for timely identification of intra-abdominal hypertension and abdominal compartment syndrome also are discussed.

Delayed Abdominal Compartment Syndrome as a Complication of Spinal Surgery: Literature Review and Case Report

Posterior spinal fusion surgery for neuromuscular scoliosis is associated with favorable outcomes and high caregiver satisfaction scores. However, these patients represent a medically fragile patient population prone to complications. One of the more unpredictable complications is abdominal compartment syndrome (ACS), the etiology of which is not fully understood. This case report represents the first case report of delayed ACS to develop 3 days after spinal fusion in a patient with no history of previous abdominal surgeries undergoing correction for neuromuscular scoliosis. This case outlines the clinical course, risk factors for ACS, and indications for urgent surgical decompression of the abdomen. Given the high mortality, it is important for orthopedic surgeons to understand prevention, presentation, and timely management associated with ACS.

[Abdominal compartment syndrome]

Abdominal compartment syndrome is defined as a pathological elevation of intraabdominal pressure associated with significant organ dysfunction and failure. Organ dysfunction mainly affects the renal, pulmonary, cardiac, gastrointestinal, and central nervous system. A high level of suspicion for this condition and early identification of patients at risk are mandatory for the successful management of abdominal compartment syndrome, which includes conservative and operative strategies.

Early management of acute pancreatitis

Acute pancreatitis is the most common gastro-intestinal indication for acute hospitalization and its incidence continues to rise. In severe pancreatitis, morbidity and mortality remains high and is mainly driven by organ failure and infectious complications. Early management strategies should aim to prevent or treat organ failure and to reduce infectious complications. This review addresses the management of acute pancreatitis in the first hours to days after onset of symptoms, including fluid therapy, nutrition and endoscopic retrograde cholangiography. This review also discusses the recently revised Atlanta classification which provides new uniform terminology, thereby facilitating communication regarding severity and complications of pancreatitis.

Value and limitations of transpulmonary pressure calculations during intra-abdominal hypertension

OBJECTIVE

To clarify the effect of progressively increasing intra-abdominal pressure on esophageal pressure, transpulmonary pressure, and functional residual capacity.

DESIGN

Controlled application of increased intra-abdominal pressure at two positive end-expiratory pressure levels (1 and 10 cm H2O) in an anesthetized porcine model of controlled ventilation.

SETTING

Large animal laboratory of a university-affiliated hospital.

SUBJECTS

Eleven deeply anesthetized swine (weight 46.2 ± 6.2 kg).

INTERVENTIONS

Air-regulated intra-abdominal hypertension (0-25 mm Hg).

MEASUREMENTS

Esophageal pressure, tidal compliance, bladder pressure, and end-expiratory lung aeration by gas dilution.

MAIN RESULTS

Functional residual capacity was significantly reduced by increasing intra-abdominal pressure at both positive end-expiratory pressure levels (p ≤ 0.0001) without corresponding changes of end-expiratory esophageal pressure. Above intra-abdominal pressure 5 mm Hg, plateau airway pressure increased linearly by ~ 50% of the applied intra-abdominal pressure value, associated with commensurate changes of esophageal pressure. With tidal volume held constant, negligible changes occurred in transpulmonary pressure due to intra-abdominal pressure. Driving pressures calculated from airway pressures alone (plateau airway pressure--positive end-expiratory pressure) did not equate to those computed from transpulmonary pressure (tidal changes in transpulmonary pressure). Increasing positive end-expiratory pressure shifted the predominantly negative end-expiratory transpulmonary pressure at positive end-expiratory pressure 1 cm H2O (mean -3.5 ± 0.4 cm H2O) into the positive range at positive end-expiratory pressure 10 cm H2O (mean 0.58 ± 1.2 cm H2O).

CONCLUSIONS

Despite its insensitivity to changes in functional residual capacity, measuring transpulmonary pressure may be helpful in explaining how different levels of positive end-expiratory pressure influence recruitment and collapse during tidal ventilation in the presence of increased intra-abdominal pressure and in calculating true transpulmonary driving pressure (tidal changes of transpulmonary pressure). Traditional interpretations of respiratory mechanics based on unmodified airway pressure were misleading regarding lung behavior in this setting.

Compression of the inferior vena cava in bowel obstruction

INTRODUCTION

We investigated whether (a) the inferior vena cava (IVC) is compressed in bowel obstruction and (b) some tracts are more compressed than others.

METHODS

Two groups of abdominal computed tomography (CT) examinations were collected retrospectively. Group O (N = 69) scans were positive for bowel obstruction, group C (N = 50) scans were negative for diseases. IVC anteroposterior and lateral diameters (APD, LAD) were assessed at seven levels.

RESULTS

In group C, IVC section had an elliptic shape (APD/LAD: .76 ± .14), the area of which increased gradually from 1.9 (confluence of the iliac veins) to 3.1 cm²/m² of BSA (confluence of the hepatic veins) with a significant narrowing in the hepatic section. In group O, bowel obstruction caused a compression of IVC (APD/LAD: .54 ± .17). Along its course, IVC section area increased from 1.3 to 2.5 cm²/m². At ROC curve analysis, an APD/LAD ratio lower than 0.63 above the confluence of the iliac veins discriminated between O and C groups with sensitivity of 74% and specificity of 96%.

CONCLUSIONS

Bowel obstruction caused a compression of IVC, which involved its entire course except for the terminal section. APD/LAD ratio may be useful to monitor the degree of compression.

The preventive effect of dopamine infusion in rats with abdominal compartment syndrome

BACKGROUND

The most significant perfusion disorder of the intra-abdominal viscera occurs in the abdominal compartment syndrome (ACS). Free oxygen radicals diffuse into the body during the reperfusion phase of ACS. Our aim was to determine the effects of dopamine infusion (3 μg/kg/min) on renal perfusion, cytokine levels, free oxygen radicals, and renal histopathological changes in the presence of ACS in a prospective randomized manner.

METHODS

Twenty-four male Sprague-Dawley rats were randomly divided into four groups (n = 6). Group 1 was used as control. In group 2, air was inflated until the intra-abdominal pressure (IAP) reached 20 mmHg. In group 3, dopamine was infused for 60 min meanwhile IAP was kept at 20 mmHg. In group 4, dopamine was infused for 60 min before IAP rise. After this phase, renal artery (RA) perfusion was measured continuously. Myeloperoxidase activity (MPO), glutathione (GSH), and lipid peroxidation (MDA) levels were measured in tissue samples and histopathological scoring was performed.

RESULTS

Dopamine treatment before and during ACS significantly decreased MPO and MDA levels and also increased renal blood flow and GSH levels. However, histopathological damage was improved simultaneously.

CONCLUSION

Dopamine infusion before and during ACS, increases renal perfusion and decreases free oxygen radicals. According to our findings, dopamine infusion may be proposed for the treatment of ACS and perfusion disorders in critically ill patients.

Abdominal catastrophes in the intensive care unit setting

Patients in the setting of the intensive care unit can develop intra-abdominal complications that may worsen outcome. Clinical suspicion of such complications coupled with early diagnosis and treatment may reduce morbidity and mortality associated with these processes. This article addresses the diagnosis and management of some of the common causes of intra-abdominal catastrophes.

Intra-abdominal pressure in the early phase of severe acute pancreatitis: canary in a coal mine? Results from a rigorous validation protocol

Background/Aims

Intra-abdominal hypertension (IAH) is being increasingly reported in patients with severe acute pancreatitis (SAP) with worsened outcomes. The present study was undertaken to evaluate intra-abdominal pressure (IAP) as a marker of severity in the entire spectrum of acute pancreatitis and to ascertain the relationship between IAP and development of complications in patients with SAP.

Methods

IAP was measured via the transvesical route by measurements performed at admission, once after controlling pain and then every 4 hours. Data were collected on the length of the hospital stay, the development of systemic inflammatory response syndrome (SIRS), multiorgan failure, the extent of necrosis, the presence of infection, pleural effusion, and mortality.

Results

In total, 40 patients were enrolled and followed up for 30 days. The development of IAH was exclusively associated with SAP with an APACHE II score ≥8 and/or persistent SIRS, identifying all patients who were going to develop abdominal compartment syndrome (ACS). The presence of ACS was associated with a significantly increased extent of pancreatic necrosis, multiple organ failure, and mortality. The mean admission IAP value did not differ significantly from the value obtained after pain control or the maximum IAP measured in the first 5 days.

Conclusions

IAH is reliable marker of severe disease, and patients who manifest organ failure, persistent SIRS, or an Acute Physiology and Chronic health Evaluation II score ≥8 should be offered IAP surveillance. Severe pancreatitis is not a homogenous entity.

Blood flow response in small intestinal loops at different depths during negative pressure wound therapy of the open abdomen

High closure rates of the open abdomen have been reported following negative pressure wound therapy (NPWT). However, the method has occasionally been associated with increased development of intestinal fistulae. We have previously shown that the application of NPWT to the open abdomen causes a decrease in microvascular blood flow in the small intestinal loop and the omentum adjacent to the visceral protective layer of the dressing. In this study we investigate whether the negative pressure affects only small intestinal loops lying directly below the dressing or if it also affects small intestinal loops that are not in direct contact with the dressing. Six pigs underwent midline incision and application of NPWT to the open abdomen. The microvascular blood flow was measured in four intestinal loops at different depths from the visceral protective layer, at two different locations: beneath the dressing and at the anterior abdominal wall, before and after the application of NPWT of -50, -70, -100, -120, -150 and -170 mmHg, using laser Doppler velocimetry. Negative pressures between -50 and -170 mmHg caused a significant decrease in the microvascular blood flow in the intestinal loops in direct contact with the visceral protective layer. A slight, but significant, decrease in blood flow was also seen in the intestinal loops lying beneath these loops. The decrease in microvascular blood flow increased with the amount of negative pressure applied. No difference in blood flow was seen in the intestinal loops lying deeper in the abdominal cavity. A decrease in blood flow was seen in the upper two intestinal loops located apically and anteriorly, but not in the lower two, indicating that this is a local effect and that pressure decreases with distance from the source. A long-term decrease in blood flow in the intestinal wall may induce ischaemia and secondary necrosis in the intestinal wall, which could promote the development of intestinal fistulae. We believe that NPWT of the open abdomen is a very effective treatment, but that it could be improved by gaining more knowledge on the mechanisms involved.

Surgical treatment of acute pancreatitis

BACKGROUND

Acute pancreatitis remains an unpredictable, potentially lethal disease with significant morbidity and mortality rates. New insights in the pathophysiology of acute pancreatitis have changed management concepts. In the first phase, characterized by a systemic inflammatory response syndrome, organ failure, not related to infection but rather to severe inflammation, dominates the focus of treatment. In the second phase, secondary infectious complications largely determine the clinical outcome. As infection is associated with increased mortality in acute pancreatitis, numerous prophylactic strategies have been explored in the past two decades.

PURPOSE

This review describes the strategies that have been developed to lower the infection rate, in an attempt to lower mortality. Antibiotic prophylaxis has been the subject of many RCT's without showing convincing evidence of their efficacy. Probiotics, although theoretically capable of lowering the rate of infection, also had no effect on infectious complications, and consequently, no effective strategy to lower the rate of infectious complications is currently available. In the second part of this review, new approaches for necrosectomy that have been designed by different centers around the world are discussed. All the interventional techniques have in common their aim to lower the invasive character, hypothesizing that lowering the surgical trauma will improve survival and lower complication rates. Recent advances include postponing intervention as a strategy to facilitate necrosectomy and improve prognosis and the "step-up approach" in case of infected necrosis. The step-up approach includes percutaneous catheter drainage as the first step, to be followed by necrosectomy, either through a minimally invasive approach or by open necrosectomy, as the next step.

CONCLUSIONS

All attempts to develop treatment strategies to lower the infection rate in acute pancreatitis have failed. Accumulating evidence is emerging to show that the combination of centralization, the use of catheter drainage as the first step of invasive treatment, and the development of minimally invasive techniques, improve the outlook for patients with infected necrosis. It is uncertain at this point in time as to which of the three effects is dominant in the improvement of prognosis.

Experimental intra-abdominal hypertension influences airway pressure limits for lung protective mechanical ventilation

BACKGROUND

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) may complicate monitoring of pulmonary mechanics owing to their impact on the respiratory system. However, recommendations for mechanical ventilation of patients with IAH/ACS and the interpretation of thoracoabdominal interactions remain unclear. Our study aimed to characterize the influence of elevated intra-abdominal pressure (IAP) and positive end-expiratory pressure (PEEP) on airway plateau pressure (PPLAT) and bladder pressure (PBLAD).

METHODS

Nine deeply anesthetized swine were mechanically ventilated via tracheostomy: volume-controlled mode at tidal volume (VT) of 10 mL/kg, frequency of 15, inspiratory-expiratory ratio of 1:2, and PEEP of 1 and 10 cm H2O (PEEP1 and PEEP10, respectively). A tracheostomy tube was placed in the peritoneal cavity, and IAP levels of 5, 10, 15, 20, and 25 mm Hg were applied, using a continuous positive airway pressure system. At each IAP level, PBLAD and airway pressure measurements were performed during both PEEP1 and PEEP10.

RESULTS

PBLAD increased as experimental IAP rose (y = 0.83x + 0.5; R = 0.98; p < 0.001 at PEEP1). Minimal underestimation of IAP by PBLAD was observed (-2.5 ± 0.8 mm Hg at an IAP of 10-25 mm Hg). Applying PEEP10 did not significantly affect the correlation between experimental IAP and PBLAD. Approximately 50% of the PBLAD (in cm H2O) was reflected by changes in PPLAT, regardless of the PEEP level applied. Increasing IAP did not influence hemodynamics at any level of IAP generated.

CONCLUSION

With minimal underestimation, PBLAD measurements closely correlated with experimentally regulated IAP, independent of the PEEP level applied. For each PEEP level applied, a constant proportion (approximately 50%) of measured PBLAD (in cm H2O) was reflected in PPLAT. A higher safety threshold for PPLAT should be considered in the setting of IAH/ACS as the clinician considers changes in VT. A strategy of reducing VT to cap PPLAT at widely recommended values may not be warranted in the setting of increased IAP.

Surgical treatment of acute pancreatitis

BACKGROUND

Acute pancreatitis remains an unpredictable, potentially lethal disease with significant morbidity and mortality rates. New insights in the pathophysiology of acute pancreatitis have changed management concepts. In the first phase, characterized by a systemic inflammatory response syndrome, organ failure, not related to infection but rather to severe inflammation, dominates the focus of treatment. In the second phase, secondary infectious complications largely determine the clinical outcome. As infection is associated with increased mortality in acute pancreatitis, numerous prophylactic strategies have been explored in the past two decades.

PURPOSE

This review describes the strategies that have been developed to lower the infection rate, in an attempt to lower mortality. Antibiotic prophylaxis has been the subject of many RCT's without showing convincing evidence of their efficacy. Probiotics, although theoretically capable of lowering the rate of infection, also had no effect on infectious complications, and consequently, no effective strategy to lower the rate of infectious complications is currently available. In the second part of this review, new approaches for necrosectomy that have been designed by different centers around the world are discussed. All the interventional techniques have in common their aim to lower the invasive character, hypothesizing that lowering the surgical trauma will improve survival and lower complication rates. Recent advances include postponing intervention as a strategy to facilitate necrosectomy and improve prognosis and the "step-up approach" in case of infected necrosis. The step-up approach includes percutaneous catheter drainage as the first step, to be followed by necrosectomy, either through a minimally invasive approach or by open necrosectomy, as the next step.

CONCLUSIONS

All attempts to develop treatment strategies to lower the infection rate in acute pancreatitis have failed. Accumulating evidence is emerging to show that the combination of centralization, the use of catheter drainage as the first step of invasive treatment, and the development of minimally invasive techniques, improve the outlook for patients with infected necrosis. It is uncertain at this point in time as to which of the three effects is dominant in the improvement of prognosis.

Acute limb ischemia due to abdominal compartment syndrome

Acute limb ischemia (ALI) is caused by embolisms or progressive atherosclerosis. We report the case of a 68-year-old female who presented with acute total occlusion of left iliac artery due to remarkably massive ascites from pancreatic cancer. To our knowledge, no other case reports of ALI caused by acute compartment syndrome have been published. We treated our case successfully by draining the ascites fluid without any balloon angioplasty or stent implantation. The removal of extrinsic compression may be the best treatment for cases of this type.

Effect of obesity and decompressive laparotomy on mortality in acute pancreatitis requiring intensive care unit admission

Background

Controversy still exists on the effect that obesity has on the morbidity and mortality in severe acute pancreatitis (SAP). The primary purpose of this study was to compare the mortality rate of obese versus nonobese patients admitted to the ICU for SAP. Secondary goals were to assess the potential risk factors for abdominal compartment syndrome (ACS) and to investigate the performance of validated scoring systems to predict ACS and in-hospital mortality.

Methods

A retrospective cohort of adults admitted to the ICU for SAP was stratified by their body mass index (BMI) as obese and nonobese. The rates of morbidity, mortality, and ACS were compared by univariate and multivariate regression analyses. Areas under the curve (AUC) were used to evaluate the discriminating performance of severity scores and other selected variables to predict mortality and the risk of ACS.

Result

Forty-five patients satisfied the inclusion criteria and 24 (53 %) were obese with similar characteristics to nonobese patients. Among all the subjects, 11 (24 %) died and 16 (35 %) developed ACS. In-hospital mortality was significantly lower for obese patients (12.5 vs. 38 %; P = 0.046) even though they seemed to develop ACS more frequently (41 vs. 28 %; P = 0.533). At multivariable analysis, age was the most significant factor associated with in-hospital mortality (odds ratio (OR) = 1.273; 95 % confidence interval (CI) 1.052–1.541; P = 0.013) and APACHE II and Glasgow-Imrie for the development of ACS (OR = 1.143; 95 % CI 1.012–1.292; P = 0.032 and OR = 1.221; 95 % CI 1.000–1.493; P = 0.05) respectively. Good discrimination for in-hospital mortality was observed for patients’ age (AUC = 0.846) and number of comorbidities (AUC = 0.801). ACS was not adequately predicted by any of the clinical severity scores (AUC = 0.548–0.661).

Conclusions

Patients’ age was the most significant factor associated with mortality in patients affected by SAP. Higher APACHE II and Glasgow-Imrie scores were associated with the development of ACS, but their discrimination performance was unsatisfactory.

Intra-abdominal hypertension in cardiac surgery

OBJECTIVES

The occurrence of intra-abdominal hypertension (IAH), as well as its promoting factors in cardiac surgery, has been poorly explored. The aim of the present study was to characterize intra-abdominal pressure (IAP) variations in patients undergoing cardiac surgical procedures, and to identify the risk factors for IAH in this setting.

METHODS

All consecutive adult patients requiring postoperative intensive care unit admission for >24 h were enrolled. Demographic data, pre-existing comorbidities, type and duration of surgery, cardiopulmonary bypass (CPB) use and duration, perioperative IAP, organ function and fluid balance were recorded. IAH was defined as a sustained increase in IAP >12 mmHg. Multivariate logistic regression and stepwise analyses identified the baseline and perioperative variables associated with IAH.

RESULTS

Of 69 patients, 22 (31.8%) developed IAH. In the logistic model, baseline IAP, high central venous pressure, vasoactive drugs administration, positive fluid balance, AKI, CPB, total sequential organ failure assessment score and age were all promoting factors for IAH (Hosmer-Lemeshow χ(2) = 7.23; P = 0.843). Baseline IAP, high central venous pressure and positive fluid balance were independent risk factors for IAH in the stepwise analysis. The ROC curve analysis, obtained by plotting the occurrence of IAH vs the IAP baseline value, showed an AUC of 0.75 (SE 0.064; 99% CI 0.62-0.87; P < 0.0001). The best IAP cut-off value was at 8 mmHg (sensitivity 63% and specificity 76%). Considering on- and off-pump surgery groups, fluid balance and vasoactive drugs use were significantly higher in the on-pump group. Linear regression analysis showed a positive correlation (P = 0.0001) between IAP changes and fluid balance only in the on-pump group.

CONCLUSIONS

IAH develops in one-third of cardiac surgery patients and is strongly associated with higher baseline IAP values, higher central venous pressure, positive fluid balance, extracorporeal circulation, use of vasoactive drugs and AKI. Determinants of IAH should be accurately assessed before and after surgery, and patients presenting risk factors must be monitored properly during the perioperative period. In this context, the baseline value of IAP may be a valuable and early warning parameter for IAH occurrence.

A novel nonoperative approach to abdominal compartment syndrome after abdominal wall reconstruction

INTRODUCTION

Intraabdominal hypertension and abdominal compartment syndrome have been increasingly recognized as significant causes of morbidity and mortality in both medical and surgical patients. The gold standard remains surgical intervention; however, nonoperative approaches have been investigated less. Here, we describe the successful treatment of a severe acute case by intubation, nasogastric decompression, and paralysis--a novel approach not previously described in the literature.

CASE DESCRIPTION

After the patient underwent laparoscopic bilateral component separation and repair of a large recurrent ventral hernia with a 20 30-cm Strattice mesh (LifeCell Corp, Branchburg, NJ), acute renal failure developed within 12 hours postoperatively, and was associated with oliguria, hyperkalemia, and elevated peak airway and bladder pressures. The patient was treated nonoperatively with intubation, nasogastric tube decompression, and paralysis with a vecuronium drip. Rapid reversal was seen, avoiding further surgery. Within 2 hours after intubation and paralysis, our patient's urine output improved dramatically with an initial diuresis of approximately 1 L, his bladder pressures decreased, and within 12 hours his creatinine level had normalized.

DISCUSSION

Although surgical intervention has traditionally been thought of as the most effective--and thus the gold standard--for abdominal compartment syndrome, this preliminary experience demonstrates nonoperative management as highly efficacious, with the added benefit of decreased morbidity. Therefore, nonoperative management could be considered first-line therapy, with laparotomy reserved for refractory cases only. This suggests a more complex pathology than the traditional teaching of congestion and edema alone.

Decompressive laparotomy for abdominal compartment syndrome in children on ECMO: effect on support and survival

PURPOSE

Abdominal compartment syndrome (ACS) may complicate ECMO due to significant fluid shifts resulting in tense ascites and interstitial edema. This compromises venous cannula flow leading to inadequate patient support. It is debatable whether decompressive laparotomy should be performed in these patients due to the risk of bleeding and poor prognosis. We sought to evaluate the effect of decompressive laparotomy on ECMO support and patient survival.

METHODS

We reviewed our tertiary care children's hospital ECMO registry (2000-2011) identifying those who underwent decompressive laparotomy. All had ACS as characterized by abdominal hypertension with abdominal distention, hemodynamic instability, oliguria, rising central venous pressures, and inadequate venous return to the ECMO circuit. Physiologic parameters immediately before and 60 min after laparotomy were compared using a signed rank test.

RESULTS

Seven patients were identified. ACS developed within 8 h of initiating ECMO in 6 patients. Decompressive laparotomy resulted in significant improvement of patient physiologic parameters and ECMO venous return. One patient had significant bleeding following laparotomy. There were no survivors but three were organ donation candidates after stabilization via decompressive laparotomy.

CONCLUSION

Decompressive laparotomy for ACS in patients on ECMO markedly improves support and tissue perfusion. While in our series ECMO complicated by ACS carries a poor prognosis, we cannot confidently define this as futile therapy due to the limited sample size.

Respiratory functions of burn patients undergoing decompressive laparotomy due to secondary abdominal compartment syndrome

INTRODUCTION

The development of secondary abdominal compartment syndrome (ACS) is associated with multiple organ dysfunction. There is little information about the effects of decompressive laparotomy (DL) on respiratory function (RF) in burn patients developing ACS.

PATIENTS AND METHODS

We retrospectively obtained data characterising RF from the database of an adult burn intensive care unit (BICU). Peak inspiratory pressure (Pip), PaO2/FiO2-ratio (P/F), static compliance (Cstat) and airway resistance (Raw) were analysed over the course of 60 h at 8 time points relative to DL.

RESULTS

Thirty-five patients with ACS underwent DL with a mean percentage of total burned body surface area (TBSA) 39 ± 23% and mean intra-abdominal pressure 33 ± 7 mmHg. All patients presented with significantly deteriorating RF within 12h of DL (Pip 33 ± 4 to 39 ± 7 cm/H2O, p=0.003; P/F 232 ± 59 to 160 ± 55 mmHg, p<0.001, Cstat 34 ± 5 to 26 ± 6 mL/cmH2O, p<0.001; Raw 18 ± 3 to 24 ± 9 cm H2O/L/s, p=0.02). All these parameters improved significantly (p<0.001) after DL, regardless of the presence of inhalation injury or torso burns. Mortality was 71.4%.

CONCLUSIONS

Variables characterising RF demonstrated a rapid deterioration before and a significant and sustained improvement after DL in burn patients developing ACS. Despite these respiratory improvements, DL was associated with low survival rates. Secondary ACS remains a challenge in burn patients and thus warrants particular attention during intensive care treatment.

Acute kidney injury following acute pancreatitis: A review

BACKROUND. Acute kidney injury (AKI) is a common serious complication of severe acute pancreatitis (SAP) and an important marker of morbidity and mortality in critically ill septic patients. AKI due to severe acute pancreatitis can be the result of hypoxemia, release of pancreatic amylase from the injured pancreas with impairment of renal microcirculation, decrease in renal perfusion pressure due to abdominal compartment syndrome, intraabdominal hypertension or hypovolemia. Endotoxins and reactive oxygen species (ROS) also play an important role in the pathophysiology of SAP and AKI. Knowledge of the pathophysiology and diagnosis of AKI following SAP might improve the therapeutic outcome of critically ill patients.

METHODS AND RESULTS

An overview of the pathophysiology, diagnosis and potential treatment options based on a literature search of clinical human and experimental studies from 1987 to 2013.

CONCLUSIONS

Early recognition of AKI and SAP in order to prevent severe complication like septic shock, intraabdominal hypertension or abdominal compartment syndrome leading to multiple organ dysfunction syndrome is a crucial tool of therapeutic measures in intensive care.

Factors associated with survival in patients who undergo peritoneal dialysis catheter placement following cardiac surgery

PURPOSE

Pediatric post-cardiac surgery patients are at risk for acute kidney injury and intraabdominal hypertension. The present study assesses indications and outcomes of postoperative peritoneal dialysis catheter (PDC) placement in this population.

METHODS

We retrospectively reviewed single-institution patients who underwent PDC placement post-cardiac surgery between 1999 and 2011 (n=55). Baseline, clinical course, and outcome data were recorded pre- and post-PDC. We used multivariable logistic and Cox analyses to assess factors associated with mortality.

RESULTS

In-hospital mortality of the study cohort was 67.3% (n=37). Peritoneal dialysis was performed in 21 patients (38.2%). Five patients (9.1%) experienced adverse events related to PDC placement. Greater post-PDC decreases in abdominal girth (adjusted odds ratio [OR]=2.43; P=0.02) and BUN (OR=1.06; P=0.04) were associated with survival. Additionally, preoperative ventilator independence (hazard ratio [HR]=1.18; P<0.01) and lower creatinine (HR=8.32; P<0.01), as well as greater post-PDC decrease in inotrope score (HR=1.33; P<0.02) were associated with survival.

CONCLUSIONS

In-hospital mortality of the study cohort was 67%. Less severe pre-PDC renal impairment, increased pre-PDC abdominal girth, and greater post-PDC improvement of abdominal girth, renal function, and inotrope requirements were associated with survival. Prospective trials are needed to assess appropriate indications and timing of PDC placement, with consideration of more aggressive treatment for intraabdominal hypertension.

Intra-abdominal hypertension in the critically ill: interrater reliability of bladder pressure measurement

PURPOSE

Intra-abdominal hypertension is frequently underdiagnosed and defined by intra-abdominal pressure (IAP) 12 mm Hg or higher. Increasing IAP may compromise organ viability and culminate in abdominal compartment syndrome. Bladder pressure measurement is a surrogate for IAP, but measurement properties are unknown in the intensive care unit. Our primary objective was to assess the agreement of bladder pressure measurements in critically ill patients.

METHODS

We conducted an observational study examining the correlation of measurement variability of bladder pressure. Four raters (2 nurses and 2 physicians) measured IAP. Patient's age, Acute Physiology and Chronic Health Evaluation II, body mass index, mechanical ventilation parameters, and demographics were collected.

RESULTS

Fifty-one patients had bladder pressures measured in quadruplicate, producing 204 measurements. Among 51 patients, the mean age was 61.9 years, Acute Physiology and Chronic Health Evaluation II was 23.8, and body mass index was 27.8 kg/m2. The average bladder pressure was 12.4 (SD, ±6.2) mm Hg. The interrater agreement by intraclass correlation coefficient was 0.745 (95% confidence interval [CI], 0.637-0.825), 0.804 (95% CI, 0.684-0.882), and 0.626 (95% CI, 0.428-0.767) among all raters, physicians, and nurses, respectively.

CONCLUSIONS

Agreement on bladder pressure was high among 4 clinicians and were not significantly different between physicians and nurses. Given that medical/surgical treatments are considered on bladder pressure values, understanding their reliability is essential to monitor critically ill patients.

Efficacy and safety of active negative pressure peritoneal therapy for reducing the systemic inflammatory response after damage control laparotomy (the Intra-peritoneal Vacuum Trial): study protocol for a randomized controlled trial

Background

Damage control laparotomy, or abbreviated initial laparotomy followed by temporary abdominal closure (TAC), intensive care unit resuscitation, and planned re-laparotomy, is frequently used to manage intra-abdominal bleeding and contamination among critically ill or injured adults. Animal data suggest that TAC techniques that employ negative pressure to the peritoneal cavity may reduce the systemic inflammatory response and associated organ injury. The primary objective of this study is to determine if use of a TAC dressing that affords active negative pressure peritoneal therapy, the ABThera Open Abdomen Negative Pressure Therapy System, reduces the extent of the systemic inflammatory response after damage control laparotomy for intra-abdominal sepsis or injury as compared to a commonly used TAC method that provides potentially less efficient peritoneal negative pressure, the Barker’s vacuum pack.

Methods/Design

The Intra-peritoneal Vacuum Trial will be a single-center, randomized controlled trial. Adults will be intraoperatively allocated to TAC with either the ABThera or Barker’s vacuum pack after the decision has been made by the attending surgeon to perform a damage control laparotomy. The study will use variable block size randomization. On study days 1, 2, 3, 7, and 28, blood will be collected. Whenever possible, peritoneal fluid will also be collected at these time points from the patient’s abdomen or TAC device. Luminex technology will be used to quantify the concentrations of 65 mediators relevant to the inflammatory response in peritoneal fluid and plasma. The primary endpoint is the difference in the plasma concentration of the pro-inflammatory cytokine IL-6 at 24 and 48 h after TAC dressing application. Secondary endpoints include the differential effects of these dressings on the systemic concentration of other pro-inflammatory cytokines, collective peritoneal and systemic inflammatory mediator profiles, postoperative fluid balance, intra-abdominal pressure, and several patient-important outcomes, including organ dysfunction measures and mortality.

Discussion

Results from this study will improve understanding of the effect of active negative pressure peritoneal therapy after damage control laparotomy on the inflammatory response. It will also gather necessary pilot information needed to inform design of a multicenter trial comparing clinical outcomes among patients randomized to TAC with the ABThera versus Barker’s vacuum pack.

Trial registration

ClinicalTrials.gov identifier http://www.clicaltrials.gov/ct2/show/NCT01355094

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

Purpose

To 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).

Methods

We 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).

Results

In 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.

Conclusion

Although 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.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-013-2906-z) contains supplementary material, which is available to authorized users.

The importance of timing of decompression in severe acute pancreatitis combined with abdominal compartment syndrome

BACKGROUND

Surgical decompression is widely considered as an important treatment in patients with severe acute pancreatitis (SAP) and abdominal compartment syndrome (ACS). Until now, the indication and optimal time of decompression remain unknown, and no experimental data exist, although extremely high mortality has been repeatedly reported in these patients. The aim of this study was to evaluate the effects of three different time points for decompression in a 24-hour lasting porcine model.

METHODS

Following baseline registrations, 32 animals were divided into four groups (8 animals each group) as follows: one SAP-alone group and three SAP + ACS groups, which received decompression at 6, 9, and 12 hours. We used a N2 pneumoperitoneum to increase the intra-abdominal pressure to 25 mm Hg and retrograde intra-ductal infusion of sodium taurocholate to induce SAP. Global hemodynamic profiles, urine output, systemic oxygenation, and serum biochemical parameters of the animals were studied. At the end of the experiment, histologic examination of the intestine and lung was performed.

RESULTS

The survival time of the 12-hour group was significantly shortened (p = 0.037 vs. 9 hours and p = 0.008 vs. 6 hours). In SAP + ACS animals, decompression at 6 hours restored systemic hemodynamics, oxygen-derived parameters, organ function, and inflammatory intensity to a level comparable with that of the SAP-alone group. In contrast, animals in the 9 hours and 12 hours developed more severe hemodynamic and organ dysfunction. The histopathologic analyses also revealed higher grade injury of the intestine and lung in animals receiving delayed decompression.

CONCLUSION

Well-timed decompression in a porcine model of SAP incorporating 25-mm Hg intra-abdominal hypertension/ACS was associated with significantly reduced mortality, improved systemic hemodynamics and organ function, as well as alleviated histologic injury and inflammatory intensity. According to our results and previous reports, both too early and too late decompression should be avoided owing to significant morbidity for the former and unfavorable outcomes for the latter.

Effect of intra-abdominal pressure on respiratory function in patients undergoing ventral hernia repair

AIM

To determine the influence of intra-abdominal pressure (IAP) on respiratory function after surgical repair of ventral hernia and to compare two different methods of IAP measurement during the perioperative period.

METHODS

Thirty adult patients after elective repair of ventral hernia were enrolled into this prospective study. IAP monitoring was performed via both a balloon-tipped nasogastric probe [intragastric pressure (IGP), CiMON, Pulsion Medical Systems, Munich, Germany] and a urinary catheter [intrabladder pressure (IBP), UnoMeterAbdo-Pressure Kit, UnoMedical, Denmark] on five consecutive stages: (1) after tracheal intubation (AI); (2) after ventral hernia repair; (3) at the end of surgery; (4) during spontaneous breathing trial through the endotracheal tube; and (5) at 1 h after tracheal extubation. The patients were in the complete supine position during all study stages.

RESULTS

The IAP (measured via both techniques) increased on average by 12% during surgery compared to AI (P < 0.02) and by 43% during spontaneous breathing through the endotracheal tube (P < 0.01). In parallel, the gradient between РаСО2 and EtCO2 [Р(а-et)CO2] rose significantly, reaching a maximum during the spontaneous breathing trial. The PаO2/FiO2 decreased by 30% one hour after tracheal extubation (P = 0.02). The dynamic compliance of respiratory system reduced intraoperatively by 15%-20% (P < 0.025). At all stages, we observed a significant correlation between IGP and IBP (r = 0.65-0.81, P < 0.01) with a mean bias varying from -0.19 mmHg (2SD 7.25 mmHg) to -1.06 mm Hg (2SD 8.04 mmHg) depending on the study stage. Taking all paired measurements together (n = 133), the median IGP was 8.0 (5.5-11.0) mmHg and the median IBP was 8.8 (5.8-13.1) mmHg. The overall r (2) value (n = 30) was 0.76 (P < 0.0001). Bland and Altman analysis showed an overall bias for the mean values per patient of 0.6 mmHg (2SD 4.2 mmHg) with percentage error of 45.6%. Looking at changes in IAP between the different study stages, we found an excellent concordance coefficient of 94.9% comparing ΔIBP and ΔIGP (n = 117).

CONCLUSION

During ventral hernia repair, the IAP rise is accompanied by changes in Р(а-et)CO2 and PаO2/FiO2-ratio. Estimation of IAP via IGP or IBP demonstrated excellent concordance.