Daily intra-abdominal pressure, Sequential Organ Failure Score and fluid balance predict duration of mechanical ventilation.

BACKGROUND: Elevated intra-abdominal pressure (IAP) is a common occurrence in mechanically ventilated patients in the intensive care unit (ICU). This study was undertaken to determine the relationship between IAP, pulmonary compliance and the duration of mechanical ventilation. METHODS: A prospective study of 220 consecutively enrolled mechanically ventilated patients admitted to a mixed surgical-medical ICU in a tertiary referral hospital. The IAP was measured at least twice daily, benchmarked against consensus guidelines. Dynamic pulmonary compliance was calculated together with admission Acute Physiology and Chronic Health Evaluation (APACHE III) score and daily Sequential Organ Failure Assessment (SOFA) score. RESULTS: No relationship between highest IAP for the day and pulmonary compliance (P = 0.61) was found. For each 5 mm Hg increase in IAP, the risk of remaining intubated increased 19% (HR = 1.19, 95% CI: 0.98-1.44); for each standard deviation increase in SOFA score (3.7 points), the risk of remaining intubated increased by 14% (HR = 1.14, 95% CI: 0.98-1.33); and for each 1 L increase in fluid balance, the risk of remaining intubated increased by 11% (HR = 1.11, 95% CI: 1.04-1.19). A nomogram was developed to predict the probability of extubation based on daily highest IAP for the day, SOFA score and fluid balance. CONCLUSION: IAPs did not correlate with pulmonary compliance in critically ill patients. Increased IAP was associated with a longer duration of mechanical ventilation. A nomogram integrating daily IAP, SOFA score and fluid balance may be used to predict the duration of mechanical ventilation.

Intra-abdominal hypertension in postoperative cardiac surgery patients.

OBJECTIVE: To investigate screening variables identifying patients at risk of developing intra-abdominal hypertension (IAH) after cardiac surgery. DESIGN AND SETTING: Prospective observational study in a tertiary general intensive care unit. PARTICIPANTS: One hundred and eight patients admitted to the ICU after cardiac surgery, with measurements of intraabdominal pressure (IAP). MAIN OUTCOME MEASURES: Routinely collected clinical, physiological and biochemical variables were analysed with at least twice-daily measurements of IAP during the postoperative stay in the ICU. Variables available within 24 hours of admission to the ICU were evaluated against the incidence of IAH using logistic regression analysis to develop a set of screening criteria to identify patients at risk. RESULTS: Fifty patients (46%) developed IAH during their stay in the ICU and were ventilated for longer, needed more vasopressors and stayed one more day in the ICU. Plasma albumin concentration, central venous pressure, minimal abdominal perfusion pressure, cardiopulmonary and aortic cross-clamp times and the presence of abdominal distension within the first 24 hours were associated with the occurrence of IAH. A logistic regression model using these variables correctly identified 85% of patients who developed IAH. CONCLUSIONS: A set of screening criteria routinely available within the first 24 hours of admission to the ICU after cardiac surgery could correctly identify most patients at risk of IAH.