Chilled IV treatment for HI

1. Exertional Heat Injury: Effects of Adding Cold
(4-C) Intravenous Saline to Prehospital Protocol
Gordon Mok, DO1
; David DeGroot, PhD, FACSM2
; Nathanael E. Hathaway, MD3
; Daniel P. Bigley, DO4
;
and Christopher S. McGuire, MD5
Abstract
This article reviews current prehospital treatment for heat casualties and
introduces a retrospective study on the addition of cold (4 -C) intravenous
(IV) saline to prehospital treatment and its effect on morbidity. The study is
a retrospective cohort reviewing electronic medical records of 290 heat
casualties admitted to Martin Army Community Hospital, Ft. Benning, GA,
comparing two treatment groups; U.S. Army Training and Doctrine Com-
mand (ice-sheeting and ambient temperature IV saline) versus Benning
(ice-sheeting and cold IV saline). U.S. Army Training and Doctrine Com-
mand group significantly differed from Benning group on a number of mea-
sures, the median length of stay in the hospital was 3 and 2 d, respectively
(P G 0.0001); pCr were 1.8 to 1.4 mgIdLj1
, respectively (difference of
0.4 mgIdLj1
pCr, P G 0.0001). However, creatine phosphokinase, aspar-
tate aminotransferase, and alanine aminotransferase were not signifi-
cantly different across groups. Findings demonstrate that adding cold IV
saline to ice-sheeting as a protocol reduces the length of hospitalization of
heat casualties and lowers their peak creatinine values.
Introduction
Exertional heat illness (EHI) spans a continuum of severity,
ranging from relatively minor heat exhaustion, to heat injury,
and more serious and potentially fatal exertional heat stroke
(EHS). Heat exhaustion is characterized by hyperthermia and
an inability to sustain cardiac output. Heat injury is a mod-
erate to severe illness characterized by hyperthermia and
indications of organ injury. The definitive feature of EHS is
central nervous system dysfunction accompanied by hyper-
thermia, often but not always in excess of 40-C core body
temperature. The severity and clinical outcome for an EHS
casualty has a strong correlation with
the area under the time and temperature
curve for heat exposure (16). Although
the Army has instituted preventive strat-
egies and increased awareness of EHI,
incidence rates have remained relatively
unchanged in recent years. In 2014,
the U.S. military reported 344 cases of
heat stroke and more than 2000 cases of
heat illness (1).
The consensus from a number of
position statements and review articles
is that the most effective method for
rapidly cooling an EHS casualty is by
cold water immersion (2,7,9,16,27,30,34).
However, often in military training envi-
ronments and in situations where cold
water immersion is not feasible, ‘‘ice
sheets’’ are used to treat EHIs as the
preferred method for initial cooling.
The U.S. Army Training and Doctrine
Command (TRADOC) Regulation 350-29 established that
‘‘ice sheets’’ wrapped around the patient should be used as the
first-line treatment of EHI upon its identification. ‘‘Ice sheets’’
are bed linens stored in a cooler filled with ice and water.
Upon identification of a potential EHS casualty, the cold, wet
bed linens are wrapped around the casualty to facilitate rapid
cooling (35). Other methods of cooling, such as misting with
cool water, fanning (with or without shade), tap water im-
mersion, application of ice packs, and helicopter downdraft,
result in slower cooling rates (9,31). Evidence suggests that
rapid, immediate cooling to a body core temperature
G38.9-C within 30 min results in the best clinical outcome
(7), which reinforces the consensus that cold water immer-
sion is the gold-standard of EHS treatment. There have been
few case reports and no studies representing the utilization of
cold intravenous (IV) saline treatment of EHI casualties in the
prehospital setting.
In 2010, a panel of physicians, paramedics, and exercise
physiologists met at Fort Benning, Georgia, to discuss treat-
ment methods for soldiers potentially experiencing heat illness
in an effort to reduce morbidity and mortality. Consequently,
in 2011, Fort Benning implemented an updated prehospital
protocol whereby IV cold (4-C) saline infusion was added to
ENVIRONMENTAL CONDITIONS
www.acsm-csmr.org Current Sports Medicine Reports 103
1
CPT, U.S. Army Health Clinic Hohenfels, Hohenfels, Bavaria, Germany;
2
MAJ, Tripler Army Medical Center, Honolulu, HI 96859; 3
MAJ, 173rd
IBCT(A) Brigade, Vincenza, Italy; 4
LTC, DiLorenzo TRICARE Health Clinic,
Washington, DC; and 5
MAJ, Martin Army Community Hospital, Ft.
Benning, GA
Address for correspondence: Gordon Mok, DO, CPT, U.S. Army Health
Clinic Hohenfels, Hohenfels, Bavaria, 09173; E-mail:
gordon.mok.mil@mail.mil.
1537-890X/1602/103Y108
Current Sports Medicine Reports
Copyright * 2017 by the American College of Sports Medicine
Copyright © 2017 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.

2. the preestablished TRADOC protocol of ice-sheeting. Addi-
tionally, a series of case reports from the Israeli Defense Force
suggested that cold saline infusion may be an effective method
of cooling an EHS casualty (16). The revised Fort Benning
protocol directs that the cold saline infusion be initiated by
Emergency Medical Services (EMS) during patient transport
to the hospital. The present work examines whether the
addition of IV cold saline to the prehospital management ice-
sheeting protocol improves morbidity of EHI. The key
markers of morbidity that were compared in this study are
hospital length of stay (LOS) and degree of change of serum
biomarkers.
While cold water immersion is the widely accepted criterion
standard of treatment, this is not without contention; there
have been some studies that suggest tepid water immersion
has similar cooling rates as cold water immersion and other
smaller studies that suggest equivalent efficacy of evaporative
cooling with warm water (8). Cold gastric and peritoneal la-
vage is believed to be less efficacious due to required technical
skill of the practitioner. The research indicates that regardless
of application of the gold-standard cold water immersion
therapy, early cooling and resuscitation minimize severe
multiorgan dysfunction and death for patients with suspected
heat illness (3,4,9,11,13,14,16Y18,23,24,26,29,32,34,39).
Indeed, case reports suggest that intravascular cooling and
cold hemofiltration treatment benefits heat stroke patients
experiencing multiorgan dysfunction (5,14,37). However, these
case reports assessed patients who received this treatment in the
hospital setting. The practice of intravascular cooling in treat-
ment of suspected heat illness in a prehospital setting remains
anecdotal. While there may be concerns over administering
cold IV saline outside of the hospital setting, research has
shown that noncontinuously infused cold (4-C) IV saline is
unlikely to induce hypothermic core temperatures (22,25). It
thus appears unlikely that administering cold IV saline out-
side of the hospital setting could be dangerous to patients.
Materials and Methods
This nonrandomized, retrospective cohort study assessed
morbidity outcomes for heat casualties in two consecutive
protocol groups. The first group received ice-sheeting pro-
tocol without cold IV saline while the latter group received
ice-sheeting protocol that included cold IV saline infusion.
Morbidity was assessed via duration of patients’ hospital
stays and via serum biomarkers. A total of 314 heat casu-
alties were admitted to Martin Army Community Hospital
(MACH) at Fort Benning, between the years 2009 and
2012. These heat casualties were identified by the Interna-
tional Classification of Diseases (ICD-9) codes 992.0 through
992.9. This method of identifying heat casualties allowed for
the spectrum of EHI ranging from minor heat exhaustion
(admitted for observation) to severe heat stroke to be in-
cluded in the study. This ensured that the study could account
for any diagnosis within the heat illness spectrum that may
have received an incorrect ICD-9 code.
Exclusion of heat casualties younger than 18 yr and older
than 45 yr is to limit underlying disease and classic heat
illness as a confounding variable. Because the population is
exclusively active duty soldiers, who have received medical
screenings and evaluations before enlistment or commis-
sioning, the concern for medical conditions predisposing the
heat injury was minimized, though not completely eliminated.
Heat casualties admitted to MACH in the winter months
(between November and March) also were excluded to ac-
count for underlying genetic predisposition to sensitivity to
production of heat shock proteins and inflammatory cyto-
kines (6). However, those with a history of previous heat
illness were not excluded. In fact, two casualties had been
admitted to MACH for repeat heat illness during the 4 yr
observed in the study (Table 1).
Individuals were identified as potential heat illness casu-
alties if they had been exposed to high environmental tem-
peratures, if they had physically collapsed, and/or if they had
altered mental status. For casualties in the TRADOC group,
ice-sheeting was initiated by medics or cadre and EMS initi-
ated ambient temperature IV normal saline infusion for re-
suscitation. The TRADOC Protocol was in accordance with
TRADOC Regulation 350-29, which outlines the identifi-
cation of suspected heat casualties and their prehospital
management (35). Heat casualties in the Benning group also
received a protocol treatment in accordance with TRADOC
Regulation 350-29; however, rather than initiate ambient
temperature saline, EMS initiated cold (4-C) IV saline infu-
sion en route to the hospital.
In accordance with Martin Army Community Hospital’s
standard of care procedures, all heat casualties in the study
received a standardized order set of labs trended every 6 to
8 h, beginning upon arrival to the emergency room (ER). This
set of labs included a hemogram, a complete metabolic panel,
initial cardiac enzymes, creatine phosphokinase (CPK), co-
agulation panel, lactate dehydrogenase, uric acid and uri-
nalysis, including urine myoglobin. Outcome measures of
interest included initial presenting creatinine (iCr), initial CPK
(iCPK), aspartate aminotransferase (iAST), and alanine ami-
notransferase (iALT), trough creatinine (tCr), peak values of
CPK (pCPK), aspartate aminotransferase (pAST), and alanine
aminotransferase (pALT). Heat stroke has the complication
risk of multiple organ failure including liver failure, dissemi-
nated intravascular coagulation (DIC), rhabdomyolysis, acute
kidney injury (AKI), neurologic dysfunction, metabolic aci-
dosis, circulatory collapses, and electrolyte abnormalities that
may lead to dysrhythmias. Elevation in biomarkers of creati-
nine, CPK and transaminases (alanine aminotransferase
[ALT] and aspartate aminotransferase [AST]) are associated
with the development of these complications, increasing
morbidity and potentially mortality (36,38).
Serum creatinine data was collected to monitor AKI. Serum
CPK data were collected to monitor musculoskeletal damage
or inflammation. Serum alanine aminotransferase and aspar-
tate aminotransferase data were collected as markers for liver
capsular inflammation, a surrogate marker used to measure
Table 1.
Demographics.
TRADOC group Benning group
Study Years 2009, 2010 2011, 2012
Male 149 135
Female 4 2
Age (Range,
Median, Mean)
18 to 44, 25, 25.7 18 to 42, 22, 23.7
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3. liver failure secondary to accumulated heat stress. The other
laboratory values within the standard order set trended for
heat casualties were not collected for analyses because they
are clinical indicators of complications rather than markers of
heat illness morbidity.
Rates of change also were calculated as an additional
variable for each of the collected data points and labeled as
rCr, rCPK, rAST, and rALT. Dates of admittance and dis-
charge were recorded and the LOS was calculated. LOS,
used as an indirect marker of morbidity, was defined as the
period from when a heat casualty’s first laboratory was
drawn until 12:00 p.m. the day of his or her documented
discharge. Any data points with non-normal distributions
were analyzed using the Mann-Whitney-Wilcoxon Ranked
Sum Test using IBM SPSS Statistics software and STATA
Data Analysis and Statistical software. This study was
reviewed and approved by the Eisenhower Army Medical
Center Human Use Review Committee. Because this study
was retrospective and involved the analysis of preexisting
medical records, informed consent was not required.
Results
There were 290 EHI casualties during the study period,
153 (149 men, 4 women) in the TRADOC cohort and 137
(135 men, 2 women) in the Benning cohort (Table 2).
LOS
For the TRADOC group, LOS ranged from 1 to 9 d, and
median LOS was 3 d. For the Benning group, LOS ranged
from 1 to 7 d, and median LOS was 2 d (P G 0.0001 vs
TRADOC).
Creatinine
The median iCr (also noted to be peak creatinine (Cr) or
pCr) was 1.8 mgIdLj1
in TRADOC, which was signifi-
cantly higher (P G 0.0001) than Benning group, where the
median iCr was 1.4 mgIdLj1
. The tCr also was significantly
lower across groups: Benning had lower tCr levels than
TRADOC group (difference of 0.1 mgIdLj1
, P G 0.0001).
However, no significant differences were found between
groups’ median rates of rCr change. A median rate of rCr
change was 0.033 mgIdLj1
Ihj1
for TRADOC group and
0.032 mgIdLj1
Ihj1
for Benning group.
CPK
There were no significant differences in iCPK, pCPK, and
rCPK between groups.
AST
For TRADOC group, iAST ranged from 18 to 795 UILj1
,
with a median iAST of 49 UILj1
. For Benning group, iAST
ranged from 19 to 748 UILj1
, with a median iAST of
59 UILj1
. Median iAST was significantly higher (P G 0.05)
in Benning group compared to TRADOC group. TRADOC
group, pAST ranged from 25 to 6193 UILj1
, with a median
pAST of 105 UILj1
. Benning group, pAST ranged from 20
to 1510 UILj1
, with a median pAST of 87 UILj1
. While no
significant differences were found between groups’ median
pCPK levels (P 9 0.05), Benning group had a significantly
higher (P G 0.05) median rAST, declining more rapidly by
0.9 UILj1
Ihj1
than the TRADOC group.
ALT
For TRADOC group, iALT ranged from 25 to 302 UILj1
,
with a median iALTof 54 UILj1
. Benning group, iALTranged
from 6 to 318 UILj1
, with a median iALT of 36 UILj1
.
Benning group had significantly lower (P G 0.0001) median
iALT than TRADOC group. TRADOC group, pALT ranged
from 34 to 6147 UILj1
, with a median pALT of 84 UILj1
.
Benning group, pALT ranged from 9 to 922 UILj1
, with a
median pALT of 106.3 UILj1
. Benning group had signifi-
cantly higher (P G 0.05) median rALT, declining more rapidly
by 0.33 UILj1
Ihj1
TRADOC group.
Table 2.
Results.
Variables TRADOC Range Benning Range TRADOC Median Benning Median ¸Median MWW Test
Hospital LOS 1 to 9 d 1 to 7 d 3 d 2 d 1 d p G 0.0001
Cr Peak 0.9 to 3.7 mgIdLj1
0.8 to 4.4 mgIdLj1
1.8 mgIdLj1
1.4 mgIdLj1
0.4 mgIdLj1
p G 0.0001
Cr Trough 0.7 to 1.5 mgIdLj1
0.6 to 2.5 mgIdLj1
1.0 mgIdLj1
0.9 mgIdLj1
0.1 mgIdLj1
p G 0.0001
Cr Rate j0.033 mgIdLj1
Ihj1
j0.032 mgIdLj1
Ihj1
0.001 mgIdLj1
Ihj1
p=0.5320
CPK Initial 82 to 110,080 UILj1
95 to 50,027 UILj1
855 UILj1
827 UILj1
58 UILj1
p=0.5897
CPK Peak 99 to 249,088 UILj1
155 to 56,441 UILj1
2335 UILj1
1530 UILj1
805 UILj1
p=0.1200
CPK Rate j27.3 UILj1
Ihj1
j9.8 UILj1
Ihj1
17.5 UILj1
Ihj1
p=0.4477
AST Initial 18 to 795 UILj1
19 to 748 UILj1
49 UILj1
59 UILj1
10 UILj1
p=0.0426
AST Peak 25 to 6.193 UILj1
20 to 1510 UILj1
105 UILj1
87 UILj1
18 UILj1
p=0.1311
AST Rate j1.3 UILj1
Ihj1
j0.4 UILj1
Ihj1
0.9 UILj1
Ihj1
p=0.0068
ALT Initial 25 to 302 UILj1
6 to 318 UILj1
54 UILj1
36 UILj1
18 UILj1
p G 0.0001
ALT Peak 34 to 6147 UILj1
9 to 922 UILj1
84 UILj1
51 UILj1
33 UILj1
p G 0.0001
ALT Rate 0.56 UILj1
Ihj1
j0.22 UILj1
Ihj1
0.33 UILj1
Ihj1
p=0.0059
MWW, Mann-Whitney-Wilcoxon.
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4. Discussion
This retrospective cohort study aimed to examine whether
the morbidity of suspected EHI patients would improve by
adding cold (4-C) IV saline infusion to the established pre-
hospital management protocol of ice-sheeting. To examine
this question empirically, we compared outcome measures
for heat casualties who received an ice-sheeting protocol in-
cluding cold IV saline infusion with casualties who received
the same established ice-sheeting protocol that instead in-
fused ambient temperature IV saline. Results demonstrated
that heat casualties receiving the protocol that included cold
IV saline infusion had significantly shorter hospitalization,
lower peak creatinine values, and more rapidly declining
rALT and rAST than casualties whose protocol included
ambient IV saline infusions. These findings suggest that a
protocol including cold (4-C) IV saline infusion would
improve the morbidity of exertional heat injury or heat
stroke casualties.
Length of hospital stay was used as a primary measure of
overall morbidity. As the results demonstrated, the addition
of cold IV saline to prehospital management protocol of ice-
sheeting had a positive impact on morbidity as measured by 1
median hospital day. A potential confounder was the general
discharge criteria of when AKI was resolved (defined as Cr
lower than 1.3 mgIdLj1
) and transaminases (ALT and AST)
lower than three to five times the upper limit of normal, and a
CPK lower than 10,000 UILj1
. Though a clear consensus of
Cr lower than 1.3 mgIdLj1
was observed, there appeared to
be some minor variations in CPK, ALT, and AST values at the
time of discharge. These variations are believed to be due to
the clinical preference of the attending physician, because
there is no literature to date suggesting any particular value of
CPK, ALT, or AST that is a safe ‘‘cutoff’’ for discharge. Data
were collected from cases during the 2009 to 2012 time-
frame, during which there was no known initiative as a hos-
pital system to reduce LOS of admitted patients.
Acute kidney injury has a strong association with EHS.
Factors related to AKI may include prerenal azotemia, heat
storage, inflammation, and rhabdomyolysis (19,36,38).
There are a number of factors that may have influenced the
difference in initial (peak) creatinine between protocols.
There may have been a greater duration of heat exposure
and storage in the body of heat casualties in the TRADOC
group compared with the Benning group. This would be
assuming that an IV cold saline infusion lowers core body
temperature faster than ambient temperature saline. Other
confounding factors include incidences of rhabdomyolysis,
environmental temperature and humidity at time of EHI,
timeliness of identification of illness, and an individual’s
history of prior heat illness or time spent in the area to ac-
climatize. We are thus unable to account for all potential
factors that may contribute to differences in initial (peak)
creatinine across conditions. We also do not have baseline
creatinine values for heat casualties. However, given our
strict exclusion criteria, we assumed that all baseline creat-
inine values were normal. The hourly rate of return to
baseline creatinine levels was equivalent in both groups,
which is consistent with the primary treatment for AKI be-
ing aggressive fluid resuscitation. Lowest recovery creati-
nine values before discharge were clinically equivalent and
thus, the data suggest that degree of kidney injury is the
factor that most strongly relates to and influences duration
of hospitalization. Moreover, these findings suggest that
adding IV cold saline infusion before hospital admission for
heat casualties likely reduces morbidity.
Serum CPK is a marker of muscular damage and in-
flammation that has been used to predict the severity of heat
illness, the development of multiple organ dysfunction, and
poor prognosis (36). Multiple case studies have found re-
lations between elevated CPK and complications of rhab-
domyolysis as well as with AKI; however, no consistent
correlation has been found between a particular threshold
level of serum CPK and either rhabdomyolysis complica-
tions or AKI (19,21,28,33). Excessive heat storage itself
may be a cause for biomarker release as elevated CPK has
been observed in the classic, non-EHIs. Though rhabdo-
myolysis may be a complication of heat illness, we chose not
to collect data on its frequency of occurrence given that the
nature of its treatment would not cause any clinical devia-
tion from our protocols. The difference in ranges of pCPK
could suggest a clinically significant difference in musculo-
skeletal inflammation between heat casualties receiving IV
cold saline in addition to ice sheeting. However, this was not
reflected in the median pCPK values between groups. It is
possible that no significant differences were found across
the groups’ mean and median pCPK values because heat
casualties included in the study only had mild to moderate
severity heat illnesses. Given this possibility, we conducted a
subsequent analysis to examine whether there exists a sig-
nificant difference in mean and median pCPK values for heat
casualties with more severe heat illness (defined as having
serum biomarkers for creatinine greater than 1.2 mgIdLj1
,
CPK levels above 10,000 UILj1
, and ALT and AST values
above five times the upper limit of normal). Results, however,
demonstrated no significant differences between groups,
possibly because only a subpopulation of heat casualties from
each protocol group was included (i.e., those with more se-
vere symptoms).
Transaminase elevations also have been used as in-
dicators of heat illness prognosis and are hallmark features
of heat stroke (36), thus it is difficult to diagnose heat stroke
without using transaminase levels (12,15). However, there
is no known correlating threshold between transaminase
levels and encephalopathy or DIC, the two complications of
heat illness directly related to death. In the present study, we
observed no cases of DIC or liver failure that led to en-
cephalopathy and death. ALT values indicated a statistically
significant difference between groups, whereas serum AST
values did not. The significant difference in ALT is unclear
and may require further investigation; however, peak AST
values were higher than peak ALT values, which is consistent
with Sithinamsuwan et al. (32), Mil Med 2009, suggesting that
AST may be a more sensitive marker of hepatic capsular in-
flammation or damage. A confounder to transaminase values
may be the use of over-the-counter medications and supple-
ments not accounted for in the medical documentation. These
also may have led to elevated liver enzymes in heat casualties
or may have predisposed an individual to heat injury. Protocol
groups were not significantly different from one another re-
garding transaminase data. Moreover, no significant differ-
ences were found across groups even when analyses only
included data from casualties with more severe heat illness.
106 Volume 16 & Number 2 & March/April 2017 Exertional Heat Injury Prehospital Treatment
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5. Implications of our data include an overall cost savings due
to shorter hospital stay for all, a more expeditious return to
duty or return to training/play, and improved retention/fewer
medical separations from military service. Data from a sepa-
rate analysis of EHI at Ft. Benning indicated that a heat ca-
sualty admitted to MACH cost U.S. $5000 to U.S. $6800 per
encounter (10). Reducing LOS by 33% (median LOS, 3 vs 2 d)
has significant fiscal implications, when the annual numbers
of EHI across the Department of Defense (DoD) are consid-
ered. Army Regulation 40Y501 contains return to duty
guidance for EHI casualties, based on injury severity and re-
covery time. Further research is needed to determine if the
practice of cold IV saline infusion as part of prehospital
treatment of EHI results in quicker return to duty and re-
duced rate of medical separation from military service.
The present study is not without limitations. Women
were underrepresented in our sample (1.4% of our cases)
but comprise approximately 15% of the total Army end-
strength and suffer EHI at approximately 50% the rate in
men (1,20). However, Ft. Benning is the location for initial
entry training for recruits entering combat arms military
occupational specialties, which until recently were restrict-
ed to men only. Although our sample may be representative
of the population at risk at Ft. Benning, further research is
necessary to confirm our findings in women. We did not
collect ambient humidity and temperature data, which may
have influenced the injury severity of heat casualties, nor
did we collect body core temperature data. Although core
temperature data were available for a limited number of EHI
casualties, data regarding the time of measurement, in rela-
tion to when the individual collapsed, were either missing or
highly variable. Therefore, our ability to calculate the impact
of cold saline infusion on the core temperature cooling rate
was severely limited. We cannot be certain that all prehospital
responders (i.e., medics, cadre, EMS) adhered to these
protocols. In-patient records did not document whether
prehospital protocols were followed by responders, and re-
searchers were unable to review hard-copy records of EMS/
ER run sheets. Future studies should manipulate treatment
type (i.e., cold IV saline or ambient temperature IV saline) to
ensure that all participants receive the intended treatment.
Conclusion
The present study comparing different prehospital man-
agement protocols suggests that adding cold (4-) IV saline
infusion to ice-sheeting in prehospital management of EHI
casualties improves morbidity outcomes when the gold-
standard cold water immersion therapy is not feasible. This
is demonstrated by reduced hospital LOS, lower Cr values,
and improved rates of ALT and AST decline. These findings
suggest that the adjunct of cold IV saline in the prehospital
management of EHI could benefit the military population,
as well as individuals that may suffer from EHI in the civilian
population, that is, occupational workers, marathon runners,
football players, triathletes, etc. Given the increasing ready
availability of cold (4-) IV saline for use in the Return of
Spontaneous Circulation after Cardiopulmonary Resuscita-
tion by EMS, its utilization is practical and cost effective.
This study reinforces the implication of combining cooling
techniques alternative to immersion therapy because field
treatment may safely produce greater rates of cooling (31).
However, a subsequent study comparing core temperature
cooling rates between cold (4-) IV saline alone and in com-
bination with ice-sheeting to that of cold water immersion
therapy would be necessary to verify these implications.
The authors declare no conflict of interest and do not
have any financial disclosures.
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