Objective To investigate the effects of different levels of intra-abdominal pressure ( IAP) on respiration and hemodynamics in a porcine model of acute lung injury( ALI) .Methods A total of 8 domestic swine received mechanical ventilation. Following baseline observations, oleic acid 0. 1mL/kg in 20mL of normal saline was infused via internal jugular vein. Using a nitrogen gas pneumoperitongum, the IAP increased from0 to 15 and 25mmHg, and the groups were named IAP0 , IAP15 and IAP25 , respectively. During the experimental period, hemodynamic parameters including heart rate ( HR) , cardiac output ( CO) , mean arterial pressure( MAP) , central venous pressure( CVP) , intrathoracic blood volume index( ITBVI) and so on were obtained by using thermodilution technique of pulse induced continuous cardiac output( PiCCO) . The esophageal pressure( Pes) was dynamicly monitored by the esophageal catheter. Results Pes and peak airway pressure( Ppeak) increased and static lung compliance( Cstat) decreased significantly in IAP15 and IAP25 groups compared with IAP0 group( all P lt;0. 01) . Transpulmonary pressure( Ptp) showed a downward trend( P gt;0. 05) . PO2 and oxygenation index showed a downward trend while PCO2 showed a upward trend ( P gt;0. 05) . HR and CVP increased significantly, cardiac index( CI) and ITBV index decreased significantly ( all P lt;0. 05) ,MAP didn′t change significantly( P gt;0. 05) . The changes in Pes were negatively correlated with the changes in CI( r = - 0. 648, P = 0. 01) . Conclusion In the porcine model of ALI, Pes increases because of a rise in IAP which decreased pulmonary compliance and CI.
ObjectiveTo explore whether positive end-expiratiory pressure (PEEP) guided by the esophageal balloon manometry is better than the ARDS Network standard of care recommendations during treating traumatic acute respiratory distress syndrome (ARDS) patients with mechanical ventilation. MethodsTwelve traumatic ARDS patients selected from September 2013 to March 2015 in ICU of Xiamen No. 3 Hospital were administrated esophageal balloor catheter and underwent mechanical ventilation with PEEP adjusted according to measurements of esophageal pressure and the ARDS Network standard of care recommendations simultaneously. According to the selection method of PEEP, the patients were divided into two groups:the esophageal pressure guided group and the ARDS Network recommendations guided group (the control group). The changes of peak inspiratory pressure, esophageal pressure, transpulmonary end-expiratory pressure, transpulmonary end-inpiratory pressure, lung compliance at 0 h, 24 h, 48 h, 72 h following different PEEP treatments were observed and compared between two groups of patients. ResultsA mean PEEP in the esophageal pressure guided group of (10.98±4.36)cm H2O was significantly higher than the control group of (7.13±2.21)cm H2O (P<0.01). The transpulmonary end-expiratory pressure was significantly higher in the esophageal pressure guided group (0.71±0.62)cm H2O than the control group (-2.29±3.49) cm H2O. And all of the mean transpulmonary end-expiratory pressure remained above zero in the esophageal pressure guided group, whereas in the control group 73% patients remained negative (P<0.01). ConclusionsEsophageal pressure method adjusts PEEP for traumatic ARDS patients with mechanical ventilation through estimating pleural pressure so as to calculate transpulmonary pressure. It can identify traumatic ARDS patients who would benefit from the high PEEP, adjust PEEP individually and meet patients' need more satisfactorily.