Carboxyhemoglobin Elevation, a Marker for Hemolysis, Is Common in Veno-venous Extracorporeal Membrane Oxygenation

Evolution of Carboxyhemoglobin in Children Supported by Extracorporeal Membrane Oxygenation: An Observational Single-Center Study

Carboxyhemoglobin (COHb) is potentially a novel marker of hemolysis on extracorporeal membrane oxygenation (ECMO) and may be useful as an indicator for circuit-related complication in adults, but little is known about COHb levels in children. An observational single-center study was performed between January 2018 and December 2021. Fifty-eight children were included and COHb levels were obtained along with routine blood gas analysis before, during, and after ECMO support. From the 6th hour of ECMO support, the COHb level increased relative to the pre-ECMO level, with an adjusted mean difference of 0.44 (95% confidence interval [CI], 0.26-0.62; p < 0.001) and remained higher during ECMO run and within 6 hours after weaning ( p < 0.001). Among the 18 children (31%) who experienced at least one circuit-related complication leading to a circuit change, we observed a significant decrease in COHb levels within 24 hours after the circuit change, compared with the 24 hours before (adjusted mean difference, 0.54%; 95% CI, 0.27-0.80; p < 0.001). The maximal daily COHb level was able to predict circuit-related complications within 24 hours following COHb measurement with an area under the receiver operating characteristic (ROC) curve of 0.85 (95% CI, 0.77-0.92; p < 0.001).

Analysis of Bicarbonate-Based Purge Solution in Patients With Cardiogenic Shock Supported Via Impella Ventricular Assist Device

BACKGROUND

The Impella device is a continuous axial flow pump which provides hemodynamic support by expelling blood into the aorta. The manufacturer recommends using dextrose-based heparin containing solutions as the default purge. As an alternative to anticoagulant solutions, a bicarbonate-based purge solution has been proposed with limited data substantiating adequate protection and durability.

OBJECTIVE

To assess the impact of a bicarbonate-based purge solution on Impella pump thrombosis and bleeding outcomes.

METHODS

Single-center, retrospective study of cardiogenic shock patients who received an Impella between December 2020 through September 2021. Patients were evaluated based on whether they received bicarbonate-based purge solutions or remained on heparin-based purge solutions. The primary outcome was the rate of Impella pump thrombosis, defined as multiple purge pressures greater than 800 mm Hg. Secondary outcomes included incidence of bleeding defined as a drop in Hgb of at least 2 g/dL along with use of blood products and supratherapeutic anticoagulation defined as an aPTT of greater than 70 seconds.

RESULTS

Forty-three patients received bicarbonate-based purge solutions and 49 controls received heparin. The incidence of purge thrombosis by purge pressure threshold was similar between the two groups (16.3% vs 12.2%, P = 0.58). The rate of bleeding was lower with bicarbonate-based purge (27.9% vs 65.3%, P < 0.05) driven by a drop in Hgb of more than 2 g/dL. The rate of supratherapeutic anticoagulation was higher in the heparin arm (65.3% vs 27.9%, P < 0.05).

CONCLUSION AND RELEVANCE

Nonanticoagulant purge alternatives offer the potential to reduce bleeding complications and laboratory monitoring burden while maintaining durability.