Abstract
Background
Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is a supportive therapy for acute respiratory failure with increased risk of packed red blood cells (PRBC) transfusion. Blood cell salvage (BCS) aims to reduce blood transfusion, but its efficacy is unclear. This study aimed to estimate the effect of BCS at the time of removal of the ECMO circuit (ECMO decannulation) on PRBC transfused.
Methods
To compare BCS to non-blood cell salvage (n-BCS), we conducted an emulated trial of patients at two ECMO centres in the United Kingdom. We used inverse propensity of treatment weighting to control for confounding and estimated the average treatment effect of BCS on PRBC transfused within two days of decannulation, and on changes in haemoglobin (Hb).
Results
We included 841 patients who underwent VV-ECMO decannulation. The estimated marginal mean number of PRBC transfused when using BCS was 0·2 (95%CI: 0·16, 0·25) units compared to 0·51 (95%CI: 0·44, 0·59) units with n-BCS; an average treatment effect of −0·31 (95%CI: −0·40, −0·22) units. BCS reduced the risk of receiving any PRBC transfusion by 17·1% (95%CI: 11·1%, 22·9%) equating to a number needed to treat for any PRBC transfusion of 6 (95%CI: 5, 9). The difference in expected Hb levels after decannulation between BCS and n-BCS was 5·0 (95%CI: 4·2, 5·8) g/L.
Conclusions
The use of BCS during VV-ECMO decannulation may be an effective strategy to augment haemoglobin levels and reduce PRBC transfusions.
Key Points:
- VV-ECMO and Transfusion Risk: VV-ECMO patients often require PRBC transfusions during decannulation due to blood loss, posing risks of complications and resource challenges.
- Study Design: A retrospective emulated trial analyzed data from two UK ECMO centers with differing BCS practices.
- BCS Process: The system retrieves and re-infuses a patient’s own red blood cells, reducing dependency on external PRBC transfusions.
- Primary Outcome: BCS reduced PRBC transfusion requirements significantly, with an average reduction of 0.31 units per patient.
- Improved Hb Levels: Patients undergoing BCS had an average Hb increase of 5 g/L compared to non-BCS patients, suggesting better blood conservation.
- Number Needed to Treat (NNT): Six patients need BCS during decannulation to prevent one additional PRBC transfusion.
- No Effect on Other Markers: BCS had no significant impact on inflammatory, coagulation, or platelet markers, indicating safety.
- Resource Implications: Findings highlight the cost-effectiveness of BCS by reducing reliance on transfusion supplies and associated risks.
- Limitations: Observational nature, short follow-up period, and variability in local transfusion practices warrant caution in generalizing results.
- Clinical Implications: BCS offers a practical and effective approach to reducing transfusion needs in ECMO decannulation, supporting its broader adoption in critical care protocols.
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