Page 24 - JSOM Spring 2021

FIGURE 4 Proportion of time as a percentage that temperature at the end of the outlet tubing was ≥32°C for all devices on battery power.

NS = normal saline, PRBC = packed red blood cells, NER = nonemergent rate, ER = emergent rate, ground level = ambient barometric pressure,
8K = 8,000-ft altitude, 16K = 16,000-ft altitude.

TABLE 3 Mean Battery Life (minutes ± SD) and Mean Temperature flow, which may be attributed to the flow (125mL/h) being
(°C ± SD) With All Emergent Flow Rate Using Pressure Bag With sufficiently low that the temperature exiting the devices was
Iced NS cooled toward ambient temperature by the time the measure-
Buddy Buddy M Thermal ment was made at the end of the extension tubing on the exit
Liter Lite AC Warmer Angel side of the warmers. We did not measure the temperature im-
Battery life (min) mediately exiting the warmer due to lack of clinical relevance.
nonemergent rate 634 ± 31 1,177 ± 25 890 ± 14 503 ± 7
Mean temperature We believe the fluid temperature at the point at which it would
(°C) 34.1 ± 0.5 33.8 ± 0.7 34.3 ± 0.4 32.5 ± 0.6 enter a patient’s circulation is clinically relevant and therefore
Battery life (min) a better measure of capability.
emergent rate 74 ± 9 47 ± 4 9 ± 2 10 ± 0.1
Mean temperature A literature review revealed three relevant studies that evalu-
(°C) 12.3 ± 2.4 15.5 ± 2.4 30.5 ± 3.3 21.5 ± 3.5 ated battery operated, portable fluid warmer technology. 13–15
These studies included the Buddy Lite in the evaluations. Con-
ability and is a more accurate indicator of performance due sistent with these studies, our study showed that the warming
to the differences in the time to warm the fluids to the mean capability of the Buddy Lite decreased with increases in flows
temperature. as did the Thermal Angel in studies performed by Weatherall
et al. and Dubick et al. 13,12 Dubick et al. also found that device

Contrary to the study by Dubick et al., time to mean fluid performance decreased significantly when using cold fluids at
temperature was not a good indicator of device performance both high and low flows.
due to inconsistencies with change in temperature within each
device type and between devices. This may be due to the very Battery life is an important consideration for deploying any
12
low and high flows used in the present study. The M Warmer device in prehospital and austere environments when electrical
consistently produced the highest mean temperature and tem- power is unavailable. Battery life with the warmers in this study
perature change but often did not have the fastest time to varied widely among each brand and within brands depending
mean temperature. The reason for these inconsistencies could on the testing profile used. As shown in Table 3, when using
be attributed to the higher temperature change produced by the nonemergent flows with room temperature NS, the tem-
the M Warmer, which may have resulted in a longer time to peratures produced with each type of device showed a small
reach the mean temperature, and because the mean tempera- variance although none of them produced mean temperatures
ture was always higher than with the other devices. ≥35°C, and battery life differences were highly significant (p <
.001). Under this condition, the Buddy Lite had a much lon-
Warming cold PRBCs at the emergent flow and, to a lesser ger battery life than the other devices. This can be attributed
degree, NS at the same flow, clearly showed the differences to the extremely low flow, which allowed the warmed fluid
in heating ability of the devices under extreme conditions. exiting the warmers to cool while traveling through the ex-
Temperature differences were not as great at the nonemergent tension tubing to the measurement point, simulating entering

22 | JSOM Volume 21, Edition 1 / Spring 2021