Prognostic value of abdominal perfusion pressure in mechanically ventilated patients

Introduction

Intra-abdominal hypertension (IAH) is an important outcome-predictor in critically ill patients [1][2] Abdominal perfusion pressure (APP = MAP – IAP) is suggested as a better resuscitation endpoint [3]. Until now no prospective data have been available looking at the effect of IAP and APP on outcome in patients with acute respiratory failure (ARF) that are mechanically ventilated (MV).

Methods

Over a 12-month period patients admitted with ARF were studied prospectively. Patients were screened for IAH (defined as IAP >12 mmHg) with the FoleyManometer method (Holtech, Kopenhagen, Denmark). The IAP was recorded four to six times daily together with the highest and lowest APP, fluid balance, and SOFA score. Until now data have been collected on 142 patients (127 medical and 15 surgical). The major endpoint was ICU mortality. Values are the mean ± SD. The unpaired Student t test was used.

Results

BMI was 25.1 ± 5.2, male/female ratio 1/1, age 63.9 ± 16.3 years, APACHE II score 23.8 ± 10.2, SAPS-II 52.3 ± 17.3. The SOFA score on day 1 was 9.4 ± 3.6 with 2 ± 1 organ failures. IAP on day 1 was 10.4 ± 3.9 mmHg, while APP was 58.2 ± 15.5. Intra-abdominal hypertension was present in 33.1%. Mortality was 52.9%. The outcome did not differ between patients with or without IAH. Nonsurvivors had a significantly (P < 0.05) higher IAP by day 4, but the APP was already significantly lower (<55 mmHg) from day 1 onwards. There was a more positive daily and cumulative net fluid balance in nonsurvivors and the extravascular lung water was also significantly higher on admission in the nonsurvivors.

Conclusion

The preliminary results of an ongoing prospective trial, and the first looking at APP in ARF, show that the incidence of IAH is high in ARF. Mortality is also high but in correlation with the severity scores. The persistence of IAH by day 4 was able to discriminate between survivors and nonsurvivors. However, the presence of a low APP (<55 mmHg) was already able to discriminate between survivors and nonsurvivors from day 1 onwards. Close monitoring of IAP and especially APP seems warranted in patients with ARF.