Intra-Abdominal Hypertension in Severe Acute Pancreatitis

Abstract & Commentary

By David J. Pierson, MD, Editor, Director of Pulmonary and Critical Care Medicine, Harborview Medical Center, University of Washington, Seattle, is Editor for Critical Care Alert.

Synopsis: Both intra-abdominal hypertension and evidence for its adverse physiologic effects were common in this retrospective series of ICU patients with severe acute pancreatitis, although there was no association with mortality, and 3 of 4 patients subjected to decompressive laparotomy died.

Source: De Waele JJ, et al. Intra-abdominal hypertension in patients with severe acute pancreatitis. Crit Care. 2005;9:R452-R457; www.ccforum.com/content/9/4/R452. Accessed September 13, 2005.

To examine the incidence of intra-abdominal hypertension (IAH) and physiologic manifestations of the abdominal compartment syndrome (ACS) among patients with severe acute pancreatitis (SAP), De Waele and colleagues from Ghent University Hospital in Belgium performed a retrospective records analysis from patients with SAP admitted to their ICU over a 39-month period. Data collected included patient demographics, the etiology of SAP, C-reactive protein level (an assessment of systemic inflammation), Ranson score (a pancreatitis-specific assessment of illness severity), APACHE II scores, indices of individual organ function, length of ICU stay, and hospital mortality. Intra-abdominal pressure was assessed via catheter after instillation of 50 mL of saline into the bladder, and pressures over 15 mm Hg (20 cm H2O) were considered to indicate IAP.

During the study period, 44 patients were admitted to the ICU with SAP. Their mean age was 57 years and 27 were male. SAP was associated with biliary tract stones in 19 patients, alcohol excess in 12, hyperlipidemia in 4, and trauma in 2; the cause was undetermined in 7 patients. The mean Ranson and APACHE II scores on admission were 5.5 and 18, respectively. Nine of the 44 patients died.

Intra-abdominal pressures were not measured as part of routine monitoring but were assessed when considered clinically indicated. Of the 44 patients, 27 had bladder pressure measurements made, and in 21 of them it exceeded 15 mm Hg. Maximum intra-abdominal pressures in these 21 patients averaged 27 mm Hg (SD, 7.8 mm Hg). Patients who developed IAH had higher Ranson and APACHE II scores than those who did not, and the highest measured pressure correlated significantly with APACHE II score. Patients with IAH had significantly more pulmonary, cardiovascular, and renal function impairment than patients with normal intra-abdominal pressures, and also had more pancreatic necrosis and longer ICU and hospital stays. Mortality was not different in the 2 groups, and there were no differences in age, gender, cause of SAP, or C-reactive protein. Of 4 patients with IAH who underwent decompressive laparotomy, 3 died. DeWaele et al conclude that IAH is frequent among patients admitted to an ICU with SAP, that it is associated with a high rate of organ dysfunction, and that surgical decompression may not be advisable in this condition.

Commentary

Organ dysfunction—particularly respiratory, cardiac, and renal impairment—associated with IAH in critically ill patients has been called the abdominal compartment syndrome (ACS). Although patients with ACS typically have severe systemic inflammatory response syndrome and other reasons for organ dysfunction, the physical effects of raised intra-abdominal pressure on airway pressure, lung expansion, venous return to the heart, and perfusion of the kidneys and other abdominal viscera are believed to be a major contributor to the syndrome. ACS has been reported (or at least recognized) most often in patients with trauma, particularly abdominal injuries, and those who have received massive fluid resuscitation. It also occurs in patients with intestinal ischemia, hernias, and SAP. Although the exact mechanism is unknown, the presence of IAH and the ACS are increasingly associated with multi-organ dysfunction and with adverse outcomes of critical illness.

A recently convened consensus group1 has designated 12 mm Hg as the intra-abdominal pressure above which adverse physiologic effects occur; and using this as the cut-off reports the incidence of IAH and ACS among ICU patients to be 35% and 5%, respectively. Thus, this is by no means a rare disorder. Because the indices used to diagnose ACS—such as peak and static airway pressures, cardiac output, and urine output—typically improve when the pressure is relieved via decompressive laparotomy, the latter has been regarded as the treatment of choice, particularly in patients with trauma or post-surgical IAH, and especially when the intra-abdominal pressure exceeds 20-25 mm Hg. However, there has yet to be a clinical trial of surgical decompression vs non-surgical management.

In the present study little can be said about the effects of abdominal decompression on outcome, although only one survivor out of 4 is hardly encouraging. In fact, the conclusions of this retrospective study are discouraging in 2 respects: IAH appears to be common in patients with SAP, and the usual treatment for it may not work.

This study is of interest because of its examination of an important patient group (those with SAP), in the context of an increasingly important condition (IAH). However, the actual incidence of IAH in SAP cannot be determined from this study because only 27 of 44 patients with SAP had bladder pressures measured. Measurements were done at the discretion of the clinician and thus were presumably more likely to be elevated in the patients in whom they were made. In the discussion DeWaele et al report an overall incidence of IAH of 51%, but I was unable to figure out where that number came from. The incidence in the 27 patients in whom pressure measurements were made was 78% (21 patients). This is undoubtedly higher than would be found in the whole population. At the other extreme, if only those 21 patients out of the total of 44 had had IAH then the incidence would have been 48%. De Waele et al report a very high incidence of respiratory, cardiovascular, and renal failure (95%, 91%, and 86%, respectively) but do not relate this to a particular definition of ACS. These minor issues notwithstanding, this study should heighten the awareness of ICU clinicians with respect to IAH and ACS as possible complications of SAP.

Reference

  1. Sugrue M. Abdominal compartment syndrome. Curr Opin Crit Care. 2005;11:333-338.