Effect of arterial oxygen partial pressure inflection point on Venoarterial extracorporeal membrane oxygenation for emergency cardiac support

Abstract

Background: Temporary circulatory support is a bridge between acute circulatory failure and definitive treatment or recovery. Currently, venoarterial extracorporeal membrane oxygenation (VA-ECMO) is considered to be one of the effective circulatory support methods, although cardiac function monitoring during the treatment still needs further investigation. Inflection point of arterial oxygen partial pressure (IPPaO2) may occur at an early stage in part of patients with a good prognosis after VA-ECMO treatment, and the relationship between time of IPPaO2 (tIPPaO2) and recovery of cardiac function or prognosis remains unclear.

Methods: To investigate this relationship, we retrospectively analyzed the clinical data of 71 patients with different conditions after treatment with VA-ECMO in the emergency center of Jiangsu Province Hospital between May 2015 and July 2020. Spearman's correlation analysis was used for the correlation between tIPPaO₂ and quantitative data, and ROC curve for the predictive effect of tIPPaO₂ on the 28-day mortality.

Results: Thirty-five patients were admitted because of refractory cardiogenic shock (26 of 35 survived) and the remaining 36 patients due to cardiac arrest (13 of 36 survived). The overall survival rate was 54.9% (39 of 71 survived). Acute physiology and chronic health evaluation II, ECMO time, tIPPaO2, continuous renal replacement therapy time, mechanical ventilation time, and bleeding complications in the survival group were lower than those in the non-survival group, with length of stay, intensive care unit stay, and platelet levels were being higher. The tIPPaO₂ was negatively correlated with ejection fraction, and the shorter tIPPaO2 resulted in a higher 28-day survival probability, higher predictive value for acute myocardial infarction and fulminant myocarditis.

Conclusions: Therefore, tIPPaO2 could be a reliable qualitative indicator of cardiac function in patients treated with VA-ECMO, which can reveal appropriate timing for adjusting VA-ECMO flow or weaning.

Trial registration: ChiCTR1900026105 .

Keywords: Cardiac arrest; Cardiac function; Refractory cardiogenic shock; VA-ECMO; tIPPaO2.

Fig. 1

Schematic diagram of the retrograde blood flow from VA-ECMO against the antegrade blood flow pumped by the heart. Legend: The red diamond stands for the ECMO oxygenator, LV for the left ventricle, red vessels for arteries, red lines and arrows for the direction of ECMO oxygenated blood flow, and the blue lines and arrows for the direction of the pumping blood flow from the heart. The black dotted line represents the intersection plane of blood flow, and the black * indicates the IPPaO₂. The intersection plane is located in the front of the opening of the brachiocephalic trunk when the cardiac function is poor (a); When the cardiac function gradually improves, the self-pumping blood flow rate increases, and the intersection plane moves to the distal part of the brachiocephalic trunk opening (b).

Fig. 2

Summary of treatment for CA and RCS patients with VA-ECMO. Legend: VA-ECMO, venoarterial extracorporeal membrane oxygenation; CHD: chronic cardiac dysfunction; RSC, refractory cardiogenic shock; CA, cardiac arrest; EF, ejection fraction; AMI, acute myocardial infarction; FMC, fulminant myocarditis; SACM, sepsis-associated cardiomyopathy; OCCA, other causes related cardiac arrest

Fig. 3

The ROC curve to predict 28-day mortality using tIPPaO2. Legend: The cut-off value was set at 62 h, prediction sensitivity was 92.3%, and specificity was 65.6%. tIPPaO2, time of inflection point of arterial oxygen partial pressure