Session 2: Viability Index Scoring For Critical Cardiopulmonary and Extracorporeal Support Patients

CO2 Gradient & Weaning: Survivor

The venoarterial CO₂ gradient is the most reliable indicator of a patient’s ability to wean from extracorporeal support (IABP, VAD, CPB or ECMO). As an example, a patient was placed on ECMO after failing to wean from CPB. After allowing the heart to recover on ECMO for several days, the ECMO blood flow is weaned over 30 hours as illustrated in the case above. During that time, the venoarterial CO₂ remained below 10 mmHg. As the ECMO flow was slowed, the patient’s own cardiac output increased, preventing the CO₂ gradient from increasing. This indicates survivability off mechanical support.