Primary and secondary intra-abdominal hypertension--different impact on ICU outcome.

OBJECTIVE

To investigate the differences in incidence, time course and outcome of primary versus secondary intra-abdominal hypertension (IAH), and to evaluate IAH as an independent risk factor of mortality in a presumable risk population of critically ill patients.

DESIGN

Prospective observational study.

SETTING

General intensive care unit of a university hospital.

PATIENTS

A total of 257 mechanically ventilated patients at presumable risk for the development of IAH were studied during their ICU stay and followed up for 90-day survival.

INTERVENTIONS

Repeated measurements of intra-abdominal pressure (IAP).

MEASUREMENTS AND RESULTS

IAP was measured intermittently, via bladder. IAH (sustained or repeated IAP > or = 12 mmHg) developed in 95 patients (37.0%). Primary IAH was observed in 60 and secondary IAH in 35 patients. Patients with secondary IAH demonstrated a significant increase of mean IAP during the first three days (mean DeltaIAP was 2.2 +/- 4.7 mmHg), whilst IAP decreased (mean DeltaIAP -1.1 +/- 3.7 mmHg) in the patients with primary IAH. The patients with IAH had a significantly higher ICU- (37.9 vs. 19.1%; P = 0.001), 28-day (48.4 vs. 27.8%, P = 0.001), and 90-day mortality (53.7 vs. 35.8%, P = 0.004) compared to the patients without the syndrome. Patients with secondary IAH had a significantly higher ICU mortality than patients with primary IAH (P = 0.032). Development of IAH was identified as an independent risk factor for death (OR 2.52; 95% CI 1.23-5.14).

CONCLUSIONS

Secondary IAH is less frequent, has a different time course and worse outcome than primary IAH. Development of IAH during ICU period is an independent risk factor for death.