Effekte des intraabdominellen Drucks auf respiratorische Parameter und den Gasaustausch unter druckkontrollierter versus assistierter Beatmung mit BIPAP

PURPOSE: Ventilation problems are common in critically ill patients with intra-abdominal hypertension. The aim of this study was to investigate the effects of preserved spontaneous breathing during mechanical ventilation on hemodynamics, respiratory function and lung injury in experimental intra-abdominal hypertension.METHODS: 20 anesthetized pigs were intubated and ventilated for 24h with biphasic positive airway pressure without (BIPAPPC) or with additional, unsynchronized spontaneous breathing (BIPAPSB). In 12 animals, intra-abdominal pressure was increased to 30mmHg for two 9h periods followed by a 3h pressure relief. Eight animals served as controls and were ventilated for 24h. Hemodynamics, gas exchange and respiratory mechanics were measured and lung injury was determined histologically.RESULTS: Intra-abdominal hypertension caused significant impairment of hemodynamics and respiratory mechanics in both modes. In the presence of intra-abdominal hypertension, BIPAPSB did not demonstrate superior respiratory mechanics and cardiovascular stability as compared to BIPAPPC. Although the decrease of dynamic compliance and the increase of airway pressures were mitigated, BIPAPSB failed to lower pulmonary vascular resistance and caused increased dead space ventilation (p=0.007). Blood pressures and cardiac output increased in BIPAPSB, caused by an increase in heart rate (p