To the Editor:
We thank Dr Mortimer and Mr Hurtt for their interest in our study. 1 They provide data indicating that putting a 500 mL bag of cold intravenous fluid next to the body can warm it but does not achieve a temperature close to the typically described desired range of 40°C to 42°C for a patient with or at risk for hypothermia. 2 Their results are credible and their conclusions appropriate.
We also agree that, regardless of warming method, achieving a predictable infusion temperature is likely to be difficult in a remote environment. One way to get around this problem is to broaden the range of acceptable infusion temperatures. Studies in dogs have shown that 65°C intravenous fluid given through a central line was an effective and safe means of treating hypothermia.3,4 This has not been studied in humans. If 60°C peripheral intravenous fluid was shown to be safe in humans, the range of acceptable infusion temperatures could be broadened to 35 to 60°C, allowing a much bigger target for those heating fluids in a remote setting. In this case, preheating fluids as described by Dr Mortimer and Mr Hurtt or heating fluids on a stove, as we describe, 1 would be a much more reasonable proposition. The other benefit of demonstrating the safety of supraphysiologic temperature intravenous fluid in humans is that such fluid would have a greater potential to rewarm a cold patient. We look forward to seeing additional research on this subject.