ABSTRACT
Objective:To explore the relationship between respiratory mechanics and right heart function during ARDS mechanical ventilation through the establishment of Beagle dogs acute respiratory distress syndrome (ARDS) animal model and the application of different levels of mechanical ventilation, which will provide theoretical basis for right heart protective ventilation strategy of ARDS.Methods:Beagle dogs were anesthetized successfully and then pulmonary artery floating catheter, esophageal manometric catheter and femoral artery catheter were inserted. Under the pressure control mode, the driving pressure was fixed. After adjustment, PEEP gradually increased from 2 cmH 2O to 14 cmH 2O. The changes of respiratory mechanics, hemodynamics and right heart function were observed. ARDS model was established by injecting oleic acid into central vein, and mechanical ventilation with the same parameters was given after the model was established successfully. In contrast to itself, the changes of respiratory mechanics, hemodynamics and right heart function indexes of experimental dogs before and after modeling were analyzed. In the group, the indexes of different PEEP were compared by ANOVA, and then compared by Student-Newman-Keuls. The difference was statistically significant at a P value <0.05. Results:Before modeling, the peak airway pressure (P peak) and plateau pressure (P plat) increased with the increase of PEEP ( F=232.733,196.33, P<0.05). However, P trans-I, P trans-E, C stat and Vt decreased significantly ( F=4.524, 6.499, 64.803, 2.31, P<0.05). The area of change of right ventricle (FAC) became smaller ( F=3.09, P<0.05); SV first increased and then decreased ( F=3.24, P<0.05), and CVP and MPAP increased ( F=19.07,14.81, P<0.05). There was no significant difference in TAPSE, MAP, HR and SpO 2 ( P>0.05). After modeling, as PEEP increased, P peak, P plat, P ES-I and P ES-E increased significantly ( F=24.829, 41.95, 9.78, 87.86, P<0.05). Vt, P trans-I, P trans-E, C stat and Vt first increased and then decreased ( F=2.91, 4.29, 5.84, 48.890, P<0.05). TAPSE and SV first increased and then decreased ( F=6.22,6.54, P<0.05). CVP and MPAP increased ( F=5.23, 19.24, P<0.05). MAP increased first and then decreased ( F=5.02, P<0.05). SpO 2 increased ( F=2.77, P<0.05). FAC and HR had no statistical significance ( P>0.05). Conclusions:Trans pulmonary pressure and lung compliance can reflect the effectiveness of ARDS lung recruitment, and have good synergy; with the increase of PEEP, the right ventricular systolic function TAPSE is first affected, and SV compensatory increase, but with the increase of PEEP, TAPSE and SV decrease; pulmonary blood flow distribution is more important in improving alveolar oxygenation. Therefore, real-time monitoring of trans pulmonary pressure, TAPSE and intrapulmonary blood flow should be performed in ARDS treatment.