Page 14 - JSOM Spring 2026

during trauma care. Existing studies have primarily evalu- Responses were recorded using a 5-point Likert scale, rang-
ated these systems under laboratory conditions using crystal- ing from “strongly disagree” to “strongly agree.” Additionally,
loid or packed red blood cells, with performance varying by medics were asked to identify which one device they would
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heating mechanism and flow rate. The Buddy Lite has not prefer to deploy with, and to explain their choice using open-
performed adequately at elevated flow rates, showing outlet ended responses. The full survey instrument is provided in the
temperatures near 24–25°C at 100mL/min and operational Supplemental Information.
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failures above 100–200mL/min. 9–11 The MEQU M Warmer
has maintained outlet temperatures ≥35°C up to 200mL/min Quantitative Likert-based data were transformed to integers
without evidence of hemolysis in vitro. 11,12 The Thermal An- in sequence (i.e., Likert ratings [LRs]), ranging from “strongly
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gel performs effectively at lower flow rates (<100mL/min) disagree” (–2) to “neutral” (0) and “strongly agree” (+2). LRs
but demonstrates reduced warming capacity at higher flow were summarized as median (interquartile range [IQR]) and
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rates. 9,11 The QinFlow devices have achieved outlet tempera- compared using the Kruskal-Wallis test with Dunn’s multiple
tures of approximately 34°C when warming 10°C saline at comparisons test for post-hoc analysis. Multiplicity-adjusted
200mL/min, while the NAR Quantum has reported similar P values were reported with statistical significance established
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specifications, though independent peer-reviewed validation is at P<.05.
not yet available. 9,13,14 Across all devices, increased flow rates
reduce contact time with the heating element, leading to lower Qualitative free-response data regarding blood warmer device
outlet temperatures. 11,12,15 preferences were qualitatively summarized. All available free-
text comments were compiled. Each respondent’s preference
While the role of fluid warmers in trauma resuscitation has comments were examined line-by-line to identify keywords
been previously evaluated, little is known about the experi- and phrases (e.g., “compact,” “easy to use,” “packability”)
ences and preferences of medics who operate these devices that reflected the respondents’ reasoning. Comments were
in austere and unpredictable environments. Accordingly, the then compiled into broader categories with conceptual sim-
present study aimed to evaluate the self-perceived ease of use, ilarities. These categories were then selectively coded into a
ruggedness, and efficacy of five commonly used blood warm- final core theoretical construct that captured the overall ratio-
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ing devices—the QinFlow , M Warmer, Buddy Lite , Thermal nale behind respondents’ preferences.
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Angel , and the North American Rescue (NAR) Quantum —
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based on direct user feedback. This study aims to provide hu- Results
man factor–driven insights to guide optimal device selection
for trauma resuscitation in austere deployed settings. Prod- A total of 35 NSW HMs based in the state of Virginia were
ucts were selected based on the biomedical market’s current surveyed in this study. The surveyed HMs had a median of 5
available prehospital fluid warmers. All devices were operated (IQR 3–12) years of experience and 73% had reported de-
according to manufacturer instructions. Devices used are sum- ployment experience. Of those who had previously deployed
marized in Table 1. and managed combat casualties (n=26), 27% (7/26) reported
managing a casualty using a blood warming device. Although
the data were normally distributed, the Brown-Forsythe test
Methods
suggested a violation of the assumption of variance homoge-
All experiments were approved by the Naval Medical Cen- neity (P<.05). Therefore, the Kruskal-Wallis H-test was used
ter Portsmouth Institutional Review Board, and the study was to compare results due to its increased robustness against vari-
conducted in accordance with ethical standards and applicable ance inequality.
Department of Defense regulations.
Quantitative analysis of the Likert-based questions demon-
After initial hands-on equipment familiarization, a convenience strated that there were statistically significant differences in all
sample of active-duty Naval Special Warfare (NSW) Corpsmen questions asked (Table 2). There were significantly different an-
(HMs) was surveyed to evaluate the perceived usability of five swers with regards to perceived warmers’ ease of use (P<.0001).
different blood warming devices. The survey was developed The M Warmer attained the highest perceived ease of use scores
by a multidisciplinary panel of physicians and special warfare (LR=2.00 [IQR 1.00–2.00]) compared to all other warmers,
medics with extensive deployment and prehospital resuscita- including the Buddy Lite (LR=1.00 [IQR 0.00–1.50], P=.0005),
tion backgrounds. It was designed to capture medics’ perspec- NAR Quantum (LR=1.00 [IQR –1.00 to 2.00], P=.0003), and
tives on critical human factors that influence performance and the QinFlow (LR=0.00 [IQR –1.00 to 1.00], P<.0001). There
device preference in austere environments. were no significant differences between the M Warmer and the
Thermal Angel (LR=1.00 [IQR 1.00–2.00], P=.134).
Specifically, three domains were emphasized in the survey: ease
of use, ruggedness, and perceived efficacy/confidence. These Perceptions of device efficacy also differed significantly be-
domains were chosen based on their direct relevance to oper- tween devices (P=.0006), with the M Warmer again ranking
ational decision-making and the real-world constraints medics the highest (LR=2.00 [IQR 1.00–2.00]). This was signifi-
face in forward-deployed, resource-limited settings. Ease of use cantly higher than the Buddy Lite (LR=1.00 [IQR 0.00–1.00],
reflected the need for intuitive interfaces and rapid device de- P=.0002). All other ratings were nonsignificant compared
ployment during medical resuscitation. Ruggedness captured to the QinFlow (LR=1.00 [IQR 0.00–2.00], P=.1300), NAR
the medics’ perceptions of a device’s durability and ability to Quantum (LR=1.00 [IQR 0.00–2.00], P=.1327), and Thermal
withstand environmental extremes experienced in far forward Angel (1.00 [IQR 1.00–2.00], P>.999).
prehospital environments. Perceived efficacy and confidence
were included to assess the psychological and clinical trust Finally, there were also significant differences in perceived re-
medics placed in their equipment. liability of device construction (P<.0001), with the M Warmer

12 | JSOM Volume 26, Edition 1 / Spring 2026