| Part I Effect of Positive End Expiratory Pressure guided by esophageal pressure on hemodynamic and gas exchange in pig model with acute respiratory distress syndromeObjective To observe the effect of PEEP guided by esophageal pressure compared with the optimal oxygenation-directed PEEP on hemodynamic and gas exchange in pigs with acute respiratory distress syndrome. Methods 12 ordinary pigs were randomly divided into esophageal pressure group (n=6) and the optimal oxygenation group (n=6), the two groups were given tracheal intubation, mechanical ventilated, PiCCO hemodynamics monitored and right internal jugular vein catheter to test CVP, stable after the operation for 3ominutes, all animals were given lung lavage with normal saline to induce ARDS pigs. The optimal PEEP were set by esophageal pressure titration or optimal oxygenationl after lung recruitment, thereafter, ventilation continued 4 h. Hemodynamics, gas exchange were recorded before saline lung lavage (PEEP 5 cm H2O) (Tbase), after stabilization of ARDS model (PEEP 5 cmH2O) (TO) and after using optimal PEEP for 0,1,2,3 and 4 h (T1-T4). Results The level of PEEP in esophageal pressure group was significantly lower than that in the optimal oxygenation group (P<0.05). In terms of hemodynamics, compared with ARDS model, during mechanical ventilation seted by optimal PEEP in two groups, the changes of heart rate (HR),mean artery pressure (MAP),central venous pressure (CVP).cardiac Index (CI),stroke volume index (SVI),systemic vascular resistance index (SVRI),index of left ventricular contractility (dPmax),global end diastolic volume index (GEDI) and intrathoracic blood volume index (ITBI) showed no significant difference as well as the changes between the two groups (P>0.05). In terms of gas exchanges, the oxygenation index (PaO2/FiO2), arterial oxygen saturation (SaO2) and oxygen delivery (DO2) were significantly higher while the intrapulmonary shunt fraction (Qs/Qt) were significantly lower than that in ARDS model (P<0.05), but the arterial PH (PHa) showed no significant difference (P>0.05). After using optimal PEEP two hours, the level of lactic acid (Lac) in two groups were significantly lower than that in ARDS model (P<0.05). In the optimal oxygenation group, the level of partial pressure of carbon dioxide (PaCO2) was significantly lower than that in ARDS model in the 1h,2h,3h when using optimal PEEP (P<0.05). Finally, there was no significant difference between the two groups of all index (all P>0.05). Conclusion PEEP guided by esophageal pressure can increase oxygen delivery, decrease the intrapulmonary shunt, improve oxygenation and reduce hypoxia with no significant effects on hemodynamics.Part Ⅱ Experimental study of Positive End Expiratory Pressure guided by esophageal pressure on lung injury in pig model with acute respiratory distress syndromeObjective To investigate the effect of PEEP guided by esophageal pressure compared with the optimal oxygenation-directed PEEP on lung injury in pig model with acute respiratory distress syndrome. Methods 12 ordinary pigs were randomly divided into esophageal pressure group (n=6) and the optimal oxygenation group (n=6), the two groups were given tracheal intubation, mechanical ventilated, PiCCO hemodynamics monitored and right internal jugular vein catheter to test CVP, stable after the operation for 3ominutes, all animals were given lung lavage with normal saline to induce ARDS pigs. The optimal PEEP were set by esophageal pressure titration or optimal oxygenationl after lung recruitment, thereafter, ventilation continued 4 h. PVPI, EVLWI and respiratory mechanics changes were recorded before saline lung lavage (PEEP 5 cmH2O) (Tbase), after stabilization of ARDS model (PEEP 5 cmH2O) (TO) and after using optimal PEEP for 0,1,2,3 and 4 h (T1-T4). At the time of Tbase,T0 and T4,blood was collected to detect interleukin-1β and interleukin-6, at the end the experiment, take the right upper, the right lower ventral, the right lower dorsal lung tissue for the immunohistochemical test of NF-KB,IL-1β and IL-6, the lung homogenates were prepared to detect myeloperoxidase (MPO), at the same time, take the lung tissue to observe the pathological changes and record the lung wet/dry weight ratio (W/D). Results In terms of respiratory mechanics, the level of PEEP, Pm, Paw-exp, Ptrans-exp in esophageal pressure group were significantly lower than that in the optimal oxygenation group (P<0.05), while the level of Ptrans-ins at the time of T3 and T4 were also significantly lower than that in the optimal oxygenation group (P<0.05), but the level of Paw-ins, PES-ins, PES-exp, Crs, CCw and CL showed no significant difference between the two group (P>0.05). In the inflammatory indexes, the level of the NF-κB in the right upper lung tissue, the IL-6 in the right lung tissue and the MPO in the right lower dorsal lung were all significantly lower in esophageal pressure group than that in the optimal oxygenation group (P<0.05), while the level of the IL-1β in lung tissue or in blood, IL-6 in blood showed no difference between the two group (P>0.05). In terms of pulmonary edema, during mechanical ventilation seted by optimal PEEP in two groups, the level of PVPI, EVLWI showed no significant difference than that in ARDS model (P<0.05), also the level of PVPI, EVLWI and W/D showed no significant difference between the two group (P>0.05). In terms of pathological changes, the pathological score of the right upper, the right lower dorsal and the right lung tissue all significantly lower in esophageal pressure group than that in the optimal oxygenation group (P<0.05). Conclusion PEEP guided by esophageal pressure can open the lung, reduce the inflammatory response, prevent the ventilator-associated lung injury, and then reach the effect of lung protective.
|
PDF Full Text Request