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.