Acute Experimental Study
The mean weight of the 6 dogs was 20.1 ±1.0 kg. Veno-RV ECMO remained stable throughout the 1-h experiment. During veno-RV ECMO, the mean nasopharyngeal temperature was 29±2°C and the extracorporeal blood flow rate was 100 mL/kg/min without respiratory ventilation.
The oxygen saturation levels of the PA (Spa02), LA (Sla02), FA (Sfa02) and oxygenator inlet (Sint02) during the acute experiment are shown in Figure 2. Spa02 increased during veno-RV ECMO compared with the level before veno-RV ECMO (p = 0.05) and was maintained at more than 99% during veno-RV ECMO. After the oxygenator was disconnected, the Spa02 level decreased to that recorded before veno-RV ECMO. Despite total lung collapse during veno-RV ECMO, both Sfa02 and Sla02 were maintained at more than 98% and there was no significant difference between them. There was also no significant difference between Spa02 and Sfa02 during veno-RV ECMO and, therefore, the aorta was perfused with blood that had been oxygenated by the veno-RV ECMO system. Sint02, which represents the mixed venous blood oxygen saturation during veno-RV ECMO, was elevated from 69.9±7.4% at baseline to 78.6±23.8% 15 min after veno-RV ECMO, and satisfactory oxygenation of >80% was maintained thereafter despite total lung collapse during veno-RV ECMO. canadian health mall
The changes in pH, PaC02, bicarbonate (HC03~) levels, and RE are presented in Table 1. Up to the end of the acute experiment, none of these parameters underwent significant changes during veno-RV ECMO compared with measurements taken prior to veno-RV ECMO.
The HR, mean PAP, mean LAP, and mean AP values at each measurement time are shown in Figure 3. Despite the use of veno-RV ECMO, the mean PAP remained below 25 mm Hg and the values before and during veno-RV ECMO did not differ significantly; the mean AP and LAP were maintained at greater than 100 mm Hg and less than 10 mm Hg, respectively, during veno-RV ECMO. There were no significant differences between the HR, mean AP, or mean LAP values measured before and during veno-RV ECMO. Therefore, the systemic and pulmonary hemodynamics of all the dogs remained stable during veno-RV ECMO support. Additionally, 60 min after the start of veno-RV ECMO, all the animals were weaned easily from veno-RV ECMO without inotropic support. Histopathologic examination of tissues stained with hematoxylin-eosin demonstrated neither pulmonary edema nor intra-alveolar hemorrhage at the end of this acute study (Fig 4).
Figure 2. Oxygen saturation percentages of the FA, LA, PA, and the oxygenator inlet before veno-RV ECMO, during veno-RV ECMO, and after restarting ventilation in the acute experiment. There were no significant differences in the oxygen saturation percentages of the FA, LA, or PA during veno-RV ECMO. Each value represents the mean±SD.
Figure 3. Hemodynamic parameters before veno-RV ECMO, during veno-RV ECMO, and after restarting ventilation in the acute experiment. There were no significant differences in the HR, mean AP, mean PAP, or mean LAP values before veno-RV ECMO, during veno-RV ECMO, and after restarting ventilation. Each value represents the mean±SD.
Figure 4. Histologic findings showing neither pulmonary edema nor intra-alveolar hemorrhage after veno-RV ECMO (hematox-ylin-eosin, original X40).
Table 1—Changes in Femoral Arterial Blood Gas Values Before Veno-RV ECMO, During Veno-RV ECMO, and After Restarting Ventilation in the Acute Experiment (n=6)
|Before Veno-RV ECMO||During Veno-RV ECMO||AfterRestartingVentilation|
|15 min||30 min||45 min||60 min|
|PaC02, mm Hg||27.2±5.11||34.3±9.24||33.9±9.94||29.3±4.76||23.7±7.26||34.2±6.36|
|HC03“, mEq/L||19.5±3.17||28.7±4.73||23.3 ±5.58||23.8±4.91||23.2±2.81||26.6±2.35|