Establishment and transfer management of veno-arterial extracorporeal membrane oxygenation in patients with difficult downtime during cardiopulmonary bypass surgery

Abstract

To investigate the establishment method, coordination points and safe transport management strategy of vena-arterial extracorporeal membrane oxygenation (VA-ECMO) in patients with downtime difficulties during cardiopulmonary bypass (CPB). A observation study was conducted. The patients admitted to the department of critical care medicine of the First Affiliated Hospital of Wannan Medical College (Yijishan Hospital) from January 2020 to October 2022 were enrolled. These patients could not be separated from CPB and received VA-ECMO-assisted CPB surgery. The clinical data of the patients were recorded, including the basic information of the patients, the data of VA-ECMO establishment and transport process, the clinical indicators before and after VA-ECMO installation, the operation data of VA-ECMO and clinical outcomes. The experience was summarized from the aspects of extracorporeal membrane oxygenation (ECMO) establishment, transport process, team cooperation, and adverse events during transport. The clinical indicators before and after ECMO operation were compared. According to whether ECMO was successfully weaned, the patients were divided into a successful weaning group and a failure weaning group, and the clinical data between the two groups were compared. Eighteen patients who underwent VA-ECMO-assisted CPB were enrolled, including 10 males and 8 females. The average age was (56.7±12.3) years old. Preoperative left ventricular ejection fraction (LVEF) was 0.46±0.10, and the main reasons for switching to VA-ECMO assistance included right ventricular systolic weakness in 6 cases, total cardiac systolic weakness in 5 cases, left ventricular systolic weakness in 4 cases, high pulmonary arterial pressure in 2 cases, and intractable ventricular fibrillation in 1 case. Among the 18 patients transferred from CPB to VA-ECMO, 10 cases were successfully weaned and 8 cases failed. In ICU, 8 cases survived, 5 cases died, and 5 cases gave up treatment and discharged. The average time for successful CPB to VA-ECMO establishment was (24.6±7.4) minutes, initial blood flow was (3.3±0.4) L/min, and transit time was (8.4±1.5) minutes. ECMO-assisted duration averaged (82.0±69.3) hours. Adverse events occurred in 9 patients during ECMO establishment and transfer. Post-ECMO onboarding for 4 hours, significant improvements were noted in blood lactic acid (Lac), pH value, mean arterial pressure (MAP), central venous oxygen saturation (ScvO2) as compared with pre-ECMO onboarding [Lac (mmol/L): 10.5±7.0 vs. 15.2±6.8, pH value: 7.38±0.92 vs. 7.26±0.87, MAP (mmHg, 1 mmHg ≈ 0.133 kPa): 74.9±13.7 vs. 58.4±17.0, ScvO2: 0.678±0.065 vs. 0.611±0.061, all P < 0.01], and vasoactive-inotropic score (VIS) was also decreased (39.8±29.8 vs. 68.9±64.4, P < 0.01). Compared with successful weaning group, the patients in the failed weaning group exhibited higher pre-machine Lac (mmol/L: 18.8±7.8 vs. 12.3±4.3, P < 0.05), longer CPB time [minutes: 238.0 (208.8, 351.2) vs. 200.0 (185.8, 217.0), P < 0.05], and shorter ECMO-assisted time [hours: 19.5 (11.0, 58.8) vs. 94.5 (65.8, 179.8), P < 0.01]. However, there was no statistically significant difference in pre-machine pH value, ScvO2, MAP, VIS score, and initial blood flow and establishment time of ECMO between the two groups. VA-ECMO is an effective circulatory aid for CPB surgery that cannot be weaned after CPB. The establishment and transfer of CPB "bridge" to ECMO aid depends on multi-disciplinary treatment (MDT) cooperation. The success rate of ECMO weaning is related to the Lac and CPB duration. If it is not possible to detach from the CPB successfully, VA-ECMO should be initiated as early as possible.