Maintaining higher sedation in patients undergoing ECMO therapy is crucial. Currently no definite sedation strategy has been proposed in the literature, as the pharmacokinetics of the medications in these patients is still not clear. We would like to report a case of a patient with uncontrollable diverse clinical response to medications during arteriovenous (AV) compared to venovenous (VV) ECMO.
Few reports from the literature provided in this study show increased requirement to sedation due to differences in PKa, hemodilution, drug sequestration, tolerance, genetic factors etc. and are mostly done in children. Heparin requirement has been variable for the similar reasons and the antithrombin deficiency due to prolonged use. It is also well known that perfusion and oxygenation are different in two extremities while on AV ECMO. Unfortunately most of these studies show higher drug requirements for sedation and the hypertension is more pronounced in VV compared to AV ECMO.
Contrary to the findings, the patient had hypertension requiring magnanimous doses of sedation and the risk of bleeding and vascular complication necessitating the change of VA to VV. The excessive heparin requirements with normal antithrombin levels slowed down after few days while on AV ECMO. The role of heparin sequestration is questionable as we have used heparin coated standard sized PVC tubes. Further research is necessary to understand the mechanism and to identify the most suitable drugs during ECMO.