Intravenous Fluids as a Heat Stroke Treatment

Intravenous (IV) infusion of cold fluids is often considered a heat stroke treatment, particularly during transport. But what does the evidence say about its efficacy?

In short, the evidence supports the principle of "cool first, transport second." We have a critical 30-minute window to lower core temperature below 39ºC. To achieve this, a minimal cooling rate of 0.78ºC per 10 minutes is generally required. This rate is deemed acceptable according to research by McDermott et al. (2009). For cold IV fluids to be considered a suitable treatment for heat stroke, they must meet this minimal acceptable cooling rate, regardless of their feasibility during transport.

The three studies summarized in Table 1 reveal modest cooling rates. These rates were either at the low end of the acceptable range or deemed unacceptable. For instance, infusing fluids at 4ºC versus 22ºC improved the cooling rate by 14.3% (0.72ºC versus 0.63ºC per 10 minutes), but it still fell within the unacceptable range. Overall, based on the published data, cold IV infusion appears inadequate as a stand-alone or primary treatment for heat stroke, even when infusing 2L of fluid.

Table 1. Summary of three studies assessing intravenous infusion to rapidly lower core temperature

Core Temp. Cooling Rate (ºC/10mins)	IV Temp. (ºC)	IV Volume (L)	IV Infusion Rate (mL/min)	Pre IV Core Temp (ºC)	Reference
0.39 ± 0.05	2	0.84	28	38.8	McDermott et al., 2023
0.63  ± 0.05	22	2.00	66	39.4	Morrison et al., 2018
0.72 ± 0.06	4	2.00	66	39.3	Morrison et al., 2018
0.80 ± 0.11	20	2.00	84	39.9	Sinclair et al., 2009

This conclusion is further supported by the Wilderness Medical Society Clinical Practice Guidelines (2024 update), which state:

"Cold intravenous fluids may supplement cooling but have not been shown to adequately serve as a primary treatment for heat stroke. We recommend not using cold intravenous fluids as a primary cooling modality for the treatment of heat stroke" (Eifling et al., 2024).

Moreover, the November 2024 Consensus Statement on the Pre-Hospital Management of Exertional Heat Illness from the Royal College of Surgeons of Edinburgh emphasises that:

"Current evidence does not support the routine use of IV fluids, cold or otherwise, to reduce core temperature in exertional heat illness patients in a pre-hospital setting" (Hemingway et al, 2025).

The evidence strongly supports alternative cooling methods over IV infusion as the primary treatment for heat stroke. Regardless, administering IV fluids is still utilised in some field settings as part of the prevention or treatment of heat stroke. This is demonstrated in practice through various training videos and demonstrations that highlight effective cooling techniques. An example from Phoenix Fire Department is profiled in the video below.

https://www.youtube.com/watch?v=BZjf11sF1QI

In conclusion, while intravenous cold fluids may have a role in managing heat stress, they should not be relied upon as the primary treatment for heat stroke. Instead, we should focus on alternative cooling methods that have demonstrated effective core temperature cooling rates.

References

Eifling KP, Gaudio FG, Dumke C, Lipman GS, Otten EM, Martin AD, Grissom CK. Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2024 Update. Wilderness & Environmental Medicine. 2024;35(1_suppl):112S-27S

Hemingway R, Stourton F, Leckie T, Fitzpatrick D, Jones G, Wood F, Boalch A, McNulty-Ackroyd J, Thurgood A, Boulter M, Hartle A, Walter E, Pynn HJ, Kipps C, Stacey MJ. Faculty of Pre-Hospital Care: consensus statement on the prehospital management of exertional heat illness. Emerg Medicine Journal. 2025;42(6):390-395

McDermott BP, Atkins WC. Whole-body cooling effectiveness of cold intravenous saline following exercise hyperthermia: A randomized trial. The American Journal of Emergency Medicine. 2023; 72:188-92

McDermott BP, Casa DJ, Ganio MS, Lopez RM, Yeargin SW, Armstrong LE, Maresh CM. Acute whole-body cooling for exercise-induced hyperthermia: a systematic review. J Athl Train. 2009 Jan-Feb;44(1):84-93.

Morrison KE, Desai N, McGuigan C, Lennon M, Godek SF. Effects of intravenous cold saline on hyperthermic athletes representative of large football players and small endurance runners. Clinical Journal of Sport Medicine. 2018; 28(6):493-9

Sinclair WH, Rudzki SJ, Leicht AS, Fogarty AL, Winter SK, Patterson MJ. Efficacy of field treatments to reduce body core temperature in hyperthermic subjects. Medicine and Science in Sports and Exercise. 2009; 41(11):1984-90