[Effect of transpulmonary pressure-directed mechanical ventilation on respiration in severe acute pancreatitis patient with intraabdominal hypertension].

OBJECTIVE: To assess the effect of mehanical ventilation (MV) guided by transpulmonary pressure (Ptp) on respiratory mechanics and gas exchange in severe acute pancreatitis patient with intraabdominal hypertension.

METHODS: Twelve severe acute pancreatitis patient with intraabdominal hypertension and acute respiratory distress syndrome(ARDS) underwent mechanical ventilation were involved from Jan to Dec 2013. PEEP levels were set to achieve a Ptp of 0 to 10 cm of water at end expiration. We also limited tidal volume to keep Ptp at less than 25 cm of water at end inspiration. Respiratory mechanics and gas-exchange were measured.

RESULTS: Plat pressure (Pplat) increased and the compliance of chest wall (Ccw) decreased when intraabdominal pressure (IAP) increased. Pplat correlated with IAP positively (r2=0.741 9, P<0.05) and Ccw correlated with IAP negtively (r2=0.722 2, P<0.05), respectively.There were not corrletions between IAP and end-expiratory Ptp (Ptp-e) and end-inspiratory Ptp (Ptp-i) (P>0.05). Compared with baseline, after guiding MV with Ptp, the Level of PEEP (14.6±4.2) cmH2O vs (8.3±2.0) cmH2O, and Ptp-e (1.5±0.5) cmH2O vs (-2.3±1.4) cmH2O increased (P<0.05) and Ptp-i did not increase significantly (P>0.05). Ptp-e correlated with PEEP (r2=0.549, P<0.05) and end-expiratory esophageal pressure (Pes-e) (r2=0.260, P<0.05). Ptp-i correlated with Pplat (r2=0.523, P<0.05) and end-inspiratory esophageal pressure (Pes-i) (r2=0.231, P<0.05), but did not correlate with Tidal volume(VT) (r2=0.052 4, P>0.05). Compared with baseline, lung compliance (CL) (48.1±10.3) cmH2O vs (25.7±6.4) cmH2O and oxygenation index (PaO2/FiO2) (235±48) mmHg vs (160±35) mmHg improved obviously (P<0.05), dead space fraction (VD/VT) (0.48±0.07) vs (0.59±0.06) decreased (P<0.05), but Ccw and respiratory compliance(Cr) didn't improve (P>0.05).

CONCLUSIONS: Transpulmonary pressure-directed mechanical ventilation in ARDS secondary to severe acute pancreatitis patient with intraabdominal hypertension could not only recruit the collapsed alveoli, improve lung compliance, increase oxygenation index and decrease dead space ventilation but also monitor lung stress to avoid alveoli overinflation, which might be lung protective.