Khaya-warmer: blood warming in a resource-constrained setting

Abstract

Background: Blood warming poses a challenge for healthcare workers in a resource-constrained setting due to financial limitations. Various blood-warming methods have been studied, but to our knowledge, none have investigated inline gravitational blood warming using a preheated water bath. We aimed to test the efficiency of an improvised blood warmer (named the Khaya-warmer) to warm cold packed red blood cells (PRBC) to a mean temperature of 35°C, utilising consumables readily available in a resourceconstrained setting. The primary outcome was the outflow temperature–time profile; secondary outcomes included flow rates and cost comparisons with standard methods.
Methods: This was a laboratory-based, experimental, proof-of-concept study. We ran 20 cold PRBC units through extended blood transfusion lines, each immersed in a 1 000 ml water bath preheated to 46°C. Using a 4-probe electronic thermometer, we measured the following temperatures: ambient, PRBC bag, water bath and outflow.
Results: Mean outflow temperature was 35.2°C (95% CI 35.1–35.4); mean emptying time 9.0 minutes (95% CI 8.7–10.2) with a mean flow rate of 25.4 ml.min-1 (95% CI 24.1–26.6).
Conclusion: The Khaya-warmer proved to be effective in safely warming cold PRBC units to a mean temperature of 35.2°C using a cost-effective method. Future studies include investigating various flow rates using a pressure bag or a flow regulating device, and to replace the preheated water bath with a thermally insulated flask.