The effect of non-invasive ventilation on intra-abdominal pressure

Background
Non-invasive ventilation is a well-established treatment modality in patients with respiratory failure of different aetiologies. A previous case report described how non-invasive ventilation caused gastric distension and intra-abdominal hypertension with subsequent cardio-respiratory arrest and clinical recovery following resuscitative efforts including gastric decompression with a nasogastric tube.

Methods
The aim of this prospective multicentre observational study was to assess the effect of non-invasive ventilation on intra-abdominal pressure. Following informed consent, intra-abdominal pressure and PaCO2 were measured before and after the application of non-invasive ventilation for up to three days in critically ill patients requiring non-invasive ventilation.

Results
Thirty-five patients were enrolled; mean (±SD) age of 67.8 (±12.5) years, median (interquartile range) body mass index of 27.9 (24.5–30.0) kg m–2, Acute Physiology and Chronic Health Evaluation II score of 15.8 (±6.4). On admission and after 24 hours of non-invasive ventilation, intra-abdominal pressure was 11.0 (7.5–15.0) mm Hg and 11.0 (8.5–14.5) mm Hg (P = 0.82) and PaCO2 was 44.4 (±11.4) mm Hg and 51.3 (±14.3) mm Hg (P = 0.19), respectively.

Conclusions
The application of non-invasive ventilation was not associated with an increase in intra-abdominal pressure over 72 hours in this small observational study. Thus, it appears that intra-abdominal pressure does not frequently increase when applying non-invasive ventilation in critically ill patients with respiratory failure.