Cooling Capacity of Transpulmonary Cooling and Cold-Water Immersion After Exercise-Induced Hyperthermia

ContextCold-water immersion (CWI) may not be feasible in some remote settings, prompting the identification of alternative cooling methods as adjunct treatment modalities for exertional heat stroke (EHS).ObjectiveTo determine the differences in cooling capacities between CWI and the inhalation of cooled air.DesignRandomized controlled clinical trial.SettingLaboratory.Patients or Other ParticipantsA total of 12 recreationally active participants (7 men, 5 women; age = 26 ± 4 years, height = 170.6 ± 10.1 cm, mass = 76.0 ± 18.0 kg, body fat = 18.5% ± 9.7%, peak oxygen uptake = 42.7 ± 8.9 mL·kg⁻¹·min⁻¹).Intervention(s)After exercise in a hot environment (40°C and 40% relative humidity), participants were randomized to 3 cooling conditions: cooling during passive rest (PASS; control), CWI, and the Polar Breeze thermal rehabilitation machine (PB) with which participants inspired cooled air (22.2°C ± 1.0°C).Main Outcome Measure(s)Rectal temperature (T_REC) and heart rate were continuously measured throughout cooling until T_REC reached 38.25°C.ResultsCooling rates during CWI (0.18°C·min⁻¹ ± 0.06°C·min⁻¹) were greater than those during PASS (mean difference [95% CI] of 0.16°C·min⁻¹ [0.13°C·min⁻¹, 0.19°C·min⁻¹]; P < .001) and PB (0.15°C·min⁻¹ [0.12°C·min⁻¹, 0.16°C·min⁻¹]; P < .001). Elapsed time to reach a T_REC of 38.25°C was also faster with CWI (9.71 ± 3.30 minutes) than PASS (−58.1 minutes [−77.1, −39.9 minutes]; P < .001) and PB (−46.8 minutes [−65.5, −28.2 minutes]; P < .001). Differences in cooling rates and time to reach a T_REC of 38.25°C between PASS and PB were not different (P > .05).ConclusionsTranspulmonary cooling via cooled-air inhalation did not promote an optimal cooling rate (>0.15°C·min⁻¹) for the successful treatment of EHS. In remote settings where EHS is a risk, access and use of treatment methods via CWI or cold-water dousing are imperative to ensuring survival.Trial RegistryClinicalTrials.gov (NCT0419026).     

Age- and Sex-Based Differences in Exertional Heat Stroke Incidence in a 7-Mile Road Race

ContextSex, age, and wet-bulb globe temperature (WBGT) have been proposed risk factors for exertional heat stroke (EHS) despite conflicting laboratory and epidemiologic evidence.ObjectiveTo examine differences in EHS incidence while accounting for sex, age, and environmental conditions.DesignObservational study.SettingFalmouth Road Race, a warm-weather 7-mi (11.26-km) running road race.Patients or Other ParticipantsWe reviewed records from patients treated for EHS at medical tents.Main Outcome Measure(s)The relative risk (RR) of EHS between sexes and across ages was assessed with males as the reference population. Multivariate linear regression analyses were calculated to determine the relative contribution of sex, age, and WBGT to the incidence of EHS.ResultsAmong 343 EHS cases, the female risk of EHS was lower overall (RR = 0.71; 95% confidence interval [CI] = 0.58, 0.89; P = .002) and for age groups 40 to 49 years (RR = 0.43; 95% CI = 0.24, 0.77; P = .005) and 50 to 59 years (RR = 0.31; 95% CI = 0.13, 0.72; P = .005). The incidence of EHS did not differ between sexes in relation to WBGT (P > .05). When sex, age, and WBGT were considered in combination, only age groups <14 years (β = 2.41, P = .008), 15 to 18 years (β = 3.83, P < .001), and 19 to 39 years (β = 2.24, P = .014) significantly accounted for the variance in the incidence of EHS (R² = .10, P = .006).ConclusionsIn this unique investigation of EHS incidence in a road race, we found a 29% decreased EHS risk in females compared with males. However, when sex was considered with age and WBGT, only younger age accounted for an increased incidence of EHS. These results suggest that road race medical organizers should consider participant demographics when organizing the personnel and resources needed to treat patients with EHS. Specifically, organizers of events with greater numbers of young runners (aged 19 to 39 years) and males should prioritize ensuring that medical personnel are adequately prepared to handle patients with EHS.     

Cold-Water Immersion and the Treatment of Hyperthermia: Using 38.6��C as a Safe Rectal Temperature Cooling Limit

Context:

Cold-water immersion is recommended for the immediate field treatment of exertional heat stroke. However, concerns exist over potential overcooling of hyperthermic individuals during cold-water immersion.

Objective:

To evaluate the recommendation that removing previously hyperthermic individuals from a cold-water bath at a rectal temperature (T_re) of 38.6°C would attenuate overcooling.

Design:

Controlled laboratory study.

Setting:

University research laboratory.

Patients or Other Participants:

Participants included 6 men and 4 women (age  =  22 ± 3 years, height  =  172 ± 10 cm, mass  =  67.8 ± 10.7 kg, body fat percentage  =  17.1% ± 4.5%, maximum oxygen consumption  =  59.3 ± 8.7 mL·kg⁻¹·min⁻¹).

Intervention(s):

After exercising at an ambient temperature of 40.0°C for 38.5 ± 9.4 minutes, until T_re reached 39.5°C, participants were immersed in a 2.0°C circulated water bath until T_re decreased to either 37.5°C or 38.6°C. Subsequently, participants were removed from the water bath and recovered for 20 minutes at an ambient temperature of 25°C.

Main Outcome Measure(s):

Rectal and esophageal temperatures were measured continuously during the immersion and recovery periods.

Results:

Because of the experimental design, the overall time of immersion was greater during the 37.5°C trial (16.6 ± 5.7 minutes) than the 38.6°C trial (8.8 ± 2.6 minutes) (t₉  =  −4.740, P  =  .001). During the recovery period after cold-water immersion, both rectal (F_1,9  =  50.540, P < .001) and esophageal (F_1,6  =  20.365, P  =  .007) temperatures remained greater in the 38.6°C trial than in the 37.5°C trial. This was evidenced by low points of 36.47°C ± 0.70°C and 37.19°C ± 0.71°C for rectal temperature (t₉  =  2.975, P  =  .016) and of 35.67°C ± 1.27°C and 36.72°C ± 0.95°C for esophageal temperature (t₆  =  3.963, P  =  .007) during the recovery period of the 37.5°C and 38.6°C trials, respectively.

Conclusions:

Immersion for approximately 9 minutes to a rectal temperature cooling limit of 38.6°C negated any risk associated with overcooling hyperthermic individuals when they were immersed in 2°C water.     

Validity of devices that assess body temperature during outdoor exercise in the heat

CONTEXT: Rectal temperature is recommended by the National Athletic Trainers' Association as the criterion standard for recognizing exertional heat stroke, but other body sites commonly are used to measure temperature. Few authors have assessed the validity of the thermometers that measure body temperature at these sites in athletic settings. OBJECTIVE: To assess the validity of commonly used temperature devices at various body sites during outdoor exercise in the heat. DESIGN: Observational field study. SETTING: Outdoor athletic facilities. PATIENTS OR OTHER PARTICIPANTS: Fifteen men and 10 women (age = 26.5 +/- 5.3 years, height = 174.3 +/- 11.1 cm, mass = 72.73 +/- 15.95 kg, body fat = 16.2 +/- 5.5%). INTERVENTION(S): We simultaneously tested inexpensive and expensive devices orally and in the axillary region, along with measures of aural, gastrointestinal, forehead, temporal, and rectal temperatures. Temporal temperature was measured according to the instruction manual and a modified method observed in medical tents at local road races. We also measured forehead temperatures directly on the athletic field (other measures occurred in a covered pavilion) where solar radiation was greater. Rectal temperature was the criterion standard used to assess the validity of all other devices. Subjects' temperatures were measured before exercise, every 60 minutes during 180 minutes of exercise, and every 20 minutes for 60 minutes of postexercise recovery. Temperature devices were considered invalid if the mean bias (average difference between rectal temperature and device temperature) was greater than +/-0.27 degrees C (+/-0.5 degrees F). MAIN OUTCOME MEASURE(S): Temperature from each device at each site and time point. RESULTS: Mean bias for the following temperatures was greater than the allowed limit of +/-0.27 degrees C (+/-0.5 degrees F): temperature obtained via expensive oral device (-1.20 degrees C [-2.17 degrees F]), inexpensive oral device (-1.67 degrees C [-3.00 degrees F]), expensive axillary device (-2.58 degrees C [-4.65 degrees F]), inexpensive axillary device (-2.07 degrees C [-3.73 degrees F]), aural method (-1.00 degrees C [-1.80 degrees F]), temporal method according to instruction manual (-1.46 degrees C [-2.64 degrees F]), modified temporal method (-1.36 degrees C [-2.44 degrees F]), and forehead temperature on the athletic field (0.60 degrees C [1.08 degrees F]). Mean bias for gastrointestinal temperature (-0.19 degrees C [-0.34 degrees F]) and forehead temperature in the pavillion (-0.14 degrees C [-0.25 degrees F]) was less than the allowed limit of +/-0.27 degrees C (+/-0.5 degrees F). Forehead temperature depended on the setting in which it was measured and showed greater variation than other temperatures. CONCLUSIONS: Compared with rectal temperature (the criterion standard), gastrointestinal temperature was the only measurement that accurately assessed core body temperature. Oral, axillary, aural, temporal, and field forehead temperatures were significantly different from rectal temperature and, therefore, are considered invalid for assessing hyperthermia in individuals exercising outdoors in the heat.     

Cold-Water Immersion for Hyperthermic Humans Wearing American Football Uniforms

Context

Current treatment recommendations for American football players with exertional heatstroke are to remove clothing and equipment and immerse the body in cold water. It is unknown if wearing a full American football uniform during cold-water immersion (CWI) impairs rectal temperature (T_rec) cooling or exacerbates hypothermic afterdrop.

Objective

To determine the time to cool T_rec from 39.5°C to 38.0°C while participants wore a full American football uniform or control uniform during CWI and to determine the uniform''s effect on T_rec recovery postimmersion.

Design

Crossover study.

Setting

Laboratory.

Patients or Other Participants

A total of 18 hydrated, physically active, unacclimated men (age = 22 ± 3 years, height = 178.8 ± 6.8 cm, mass = 82.3 ± 12.6 kg, body fat = 13% ± 4%, body surface area = 2.0 ± 0.2 m²).

Intervention(s)

Participants wore the control uniform (undergarments, shorts, crew socks, tennis shoes) or full uniform (control plus T-shirt; tennis shoes; jersey; game pants; padding over knees, thighs, and tailbone; helmet; and shoulder pads). They exercised (temperature approximately 40°C, relative humidity approximately 35%) until T_rec reached 39.5°C. They removed their T-shirts and shoes and were then immersed in water (approximately 10°C) while wearing each uniform configuration; time to cool T_rec to 38.0°C (in minutes) was recorded. We measured T_rec (°C) every 5 minutes for 30 minutes after immersion.

Main Outcome Measure(s)

Time to cool from 39.5°C to 38.0°C and T_rec.

Results

The T_rec cooled to 38.0°C in 6.19 ± 2.02 minutes in full uniform and 8.49 ± 4.78 minutes in control uniform (t₁₇ = −2.1, P = .03; effect size = 0.48) corresponding to cooling rates of 0.28°C·min⁻¹ ± 0.12°C·min⁻¹ in full uniform and 0.23°C·min⁻¹ ± 0.11°C·min⁻¹ in control uniform (t₁₇ = 1.6, P = .07, effect size = 0.44). The T_rec postimmersion recovery did not differ between conditions over time (F_1,17 = 0.6, P = .59).

Conclusions

We speculate that higher skin temperatures before CWI, less shivering, and greater conductive cooling explained the faster cooling in full uniform. Cooling rates were considered ideal when the full uniform was worn during CWI, and wearing the full uniform did not cause a greater postimmersion hypothermic afterdrop. Clinicians may immerse football athletes with hyperthermia wearing a full uniform without concern for negatively affecting body-core cooling.Key Words: heatstroke, rectal temperature, whole-body immersion

Key Points

• Body core-temperature cooling was excellent in participants wearing full American football uniforms during cold-water immersion.
• Wearing a full American football uniform after cold-water immersion did not result in excessive overcooling.
• Participants cooled faster in the full-uniform condition than in the control-uniform condition.
• Researchers should develop treatment protocols to improve outcomes and ensure the most efficient means of treating American football players with hyperthermia.

Exertional heatstroke (EHS) is a medical emergency diagnosed when body core temperature (T_core) is greater than 40°C and central nervous system dysfunction is displayed.^1–3 The possibility of neurologic deterioration, organ failure, and death increases with increasing duration of T_core greater than 40°C.^4–7 Therefore, the immediate treatment priority is to initiate cold-water immersion (CWI) and lower T_core as rapidly as possible.^6,8,9American football athletes are susceptible to EHS, in part, due to the equipment-intensive nature of the sport. Recent prevalence trends have indicated a problem: 30 American football athletes died due to EHS between 2003 and 2011 compared with 22 in the 10 years before that time.¹⁰ Football athletes typically exercise outdoors starting in the late summer (eg, August in North America) in 1 of 3 uniform configurations: (1) a full uniform consisting of undergarments; shorts; crew socks; shoes; jersey; game pants; padding over the knees, thighs, and tailbone; helmet; and shoulder pads; (2) a partial uniform consisting of helmet, undergarments, shorts, crew socks, shoes, jersey, and shoulder peds; or (3) shorts, crew socks, shoes, and shirt.^11,12The National Athletic Trainers'' Association,⁸ American College of Sports Medicine,¹³ and expert consensus¹⁴ have recommended removing clothes and equipment before CWI if an American football athlete has EHS. These recommendations appear to be based on examinations of T_core cooling of participants immersed in cold water while wearing little clothing^15–20 or examinations of T_core of participants exercising in hot conditions while wearing full American football equipment.^11,21,22 To our knowledge, no researchers have addressed whether wearing a full American football uniform during CWI impedes T_core cooling. This issue requires clarification because removing athletic equipment before CWI may take several minutes depending on personnel, location, and the size and temperament of the athlete.²³ Any reduction in the delay in treatment, regardless of how small, would help clinicians more efficiently treat football athletes with EHS and ensure prompt CWI.Overcooling (ie, hypothermic afterdrop) is also a concern with CWI.^15,20,24,25 Hypothetically, wearing a full uniform after CWI could impair T_core rewarming in 2 ways. First, the full uniform would insulate the body,²⁶ thereby potentially sealing in the cold. Second, the cooled clothing and equipment would continue to reduce T_core via conduction. No data exist on the effect of T_core rewarming in players wearing a full uniform. Therefore, the primary purpose of our study was to examine the time required to reduce rectal temperatures (T_rec) of persons with hyperthermia cooled via CWI while wearing a full uniform or a control uniform. A secondary purpose was to determine how wearing a full uniform affects T_rec recovery after CWI. We hypothesized that participants wearing a full uniform would need longer to cool from 39.5°C to 38.0°C and would have lower T_rec postimmersion.     

Aural Canal,Esophageal, and Rectal Temperatures During Exertional Heat Stress and the Subsequent Recovery Period

Context:

The measurement of body temperature is crucial for the initial diagnosis of exertional heat injury and for monitoring purposes during a subsequent treatment strategy. However, little information is available about how different measurements of body temperature respond during and after exertional heat stress.

Objective:

To present the temporal responses of aural canal (T_ac), esophageal (T_es), and rectal (T_re) temperatures during 2 different scenarios (S1, S2) involving exertional heat stress and a subsequent recovery period.

Design:

Randomized controlled trial.

Setting:

University research laboratory.

Patients or Other Participants:

Twenty-four healthy volunteers, with 12 (5 men, 7 women) participating in S1 and 12 (7 men, 5 women) participating in S2.

Intervention(s):

The participants exercised in the heat (42°C, 30% relative humidity) until they reached a 39.5°C cut-off criterion, which was determined by T_re in S1 and by T_es in S2. As such, participants attained different levels of hyperthermia (as determined by T_re) at the end of exercise. Participants in S1 were subsequently immersed in cold water (2°C) until T_re reached 37.5°C, and participants in S2 recovered in a temperate environment (30°C, 30% relative humidity) for 60 minutes.

Main Outcome Measure(s):

We measured T_ac, T_es, and T_re throughout both scenarios.

Results:

The T_es (S1  =  40.19 ± 0.41°C, S2  =  39.50 ± 0.02°C) was higher at the end of exercise compared with both T_ac (S1  =  39.74 ± 0.42°C, S2  =  38.89 ± 0.32°C) and T_re (S1  =  39.41 ± 0.04°C, S2  =  38.74 ± 0.28°C) (for both comparisons in each scenario, P < .001). Conversely, T_es (S1  =  36.26 ± 0.74°C, S2  =  37.36 ± 0.34°C) and T_ac (S1  =  36.48 ± 1.07°C, S2  =  36.97 ± 0.38°C) were lower compared with T_re (S1  =  37.54 ± 0.04°C, S2  =  37.78 ± 0.31°C) at the end of both scenarios (for both comparisons in each scenario, P < .001).

Conclusions:

We found that T_ac, T_es, and T_re presented different temporal responses during and after both scenarios of exertional heat stress and a subsequent recovery period. Although these results may not have direct practical implications in the field monitoring and treatment of individuals with exertional heat injury, they do quantify the extent to which these body temperature measurements differ in such scenarios.     

Comparison of Whole Spine Sagittal Alignment in Patients with Spinal Disease between EOS Imaging System versus Conventional Whole Spine X-ray

PurposeThe biplanar whole body imaging system (EOS) is a new tool for measuring the whole body sagittal alignment in a limited space. This tool may affect the sagittal balance of patients compared to conventional whole spine X-ray (WSX). This study aimed to investigate the difference in sagittal alignment between WSX and EOS.Materials and MethodsWe compared the spinal and pelvic sagittal parameters in 80 patients who underwent EOS and WSX within one month between July 2018 and September 2019. The patients were divided based on sagittally balanced and imbalanced groups according to pelvic tilt (PT) >20°, pelvic incidence-lumbar lordosis >10°, C7-sagittal vertical axis (SVA) >50 mm in WSX.ResultsIn the sagittally imbalanced group, compared to WSX, the pelvic parameters demonstrated compensation in EOS with smaller PT (27.4±11.6° vs. 24.9±10.9°, p=0.003) and greater sacral slope (SS), and the patients tended to stand more upright with smaller C7-SVA (58.4±17.0 mm vs. 48.9±57.3 mm, p=0.018), T1-pelvic angle (TPA), T5-T12, and T2-T12. However, in the sagittally balanced group, these differences were less pronounced only with smaller PT (10.8±6.9° vs. 9.4±4.7°, p=0.040), TPA and T2-T12 angle, but with similar SS and C7-SVA (p>0.05).ConclusionEOS showed a negative SVA shift and lesser PT compared to WSX, especially in patients with sagittal imbalance. When preparing a surgical plan, surgeons should consider these differences between EOS and WSX.     

Current Knowledge,Attitudes, and Practices of Certified Athletic Trainers Regarding Recognition and Treatment of Exertional Heat Stroke

Context:

Previous research has indicated that despite awareness of the current literature on the recommended prevention and care of exertional heat stroke (EHS), certified athletic trainers (ATs) acknowledge failure to follow those recommendations.

Objective:

To investigate the current knowledge, attitudes, and practices of ATs regarding the recognition and treatment of EHS.

Design:

Cross-sectional study.

Setting:

Online survey.

Patients or Other Participants:

We obtained a random sample of e-mail addresses for 1000 high school and collegiate ATs and contacted these individuals with invitations to participate. A total of 498 usable responses were received, for a 25% response rate.

Main Outcome Measure(s):

The survey instrument evaluated ATs'' knowledge and actual practice regarding EHS and included 29 closed-ended Likert scale questions (1  =  strongly disagree, 7  =  strongly agree), 2 closed-ended questions rated on a Likert scale (1  =  lowest value, 9  =  greatest value), 8 open-ended questions, and 7 demographic questions. We focused on the open-ended and demographic questions.

Results:

Although most ATs (77.1%) have read the current National Athletic Trainers'' Association position statement on heat illness, only 18.6% used rectal thermometers to assess core body temperature to recognize EHS, and 49.7% used cold-water immersion to treat EHS. Athletic trainers perceived rectal thermometers as the most valid temperature assessment device when compared with other assessment devices (P ≤ .05), but they used oral thermometers as the primary assessment tool (49.1%). They identified cold-water immersion as the best cooling method (P ≤ .05), even though they used other means to cool a majority of the time (50.3%).

Conclusions:

The ATs surveyed have sound knowledge of the correct means of EHS recognition and treatment. However, a significant portion of these ATs reported using temperature assessment devices that are invalid with athletes exercising in the heat. Furthermore, they reported using cooling treatment methods that have inferior cooling rates.     

Is Oral Temperature an Accurate Measurement of Deep Body Temperature? A Systematic Review

Context:

Oral temperature might not be a valid method to assess core body temperature. However, many clinicians, including athletic trainers, use it rather than criterion standard methods, such as rectal thermometry.

Objective:

To critically evaluate original research addressing the validity of using oral temperature as a measurement of core body temperature during periods of rest and changing core temperature.

Data Sources:

In July 2010, we searched the electronic databases PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature (CINAHL), SPORTDiscus, Academic Search Premier, and the Cochrane Library for the following concepts: core body temperature, oral, and thermometers. Controlled vocabulary was used, when available, as well as key words and variations of those key words. The search was limited to articles focusing on temperature readings and studies involving human participants.

Data Synthesis:

Original research was reviewed using the Physiotherapy Evidence Database (PEDro). Sixteen studies met the inclusion criteria and subsequently were evaluated by 2 independent reviewers. All 16 were included in the review because they met the minimal PEDro score of 4 points (of 10 possible points), with all but 2 scoring 5 points. A critical review of these studies indicated a disparity between oral and criterion standard temperature methods (eg, rectal and esophageal) specifically as the temperature increased. The difference was −0.50°C ± 0.31°C at rest and −0.58°C ± 0.75°C during a nonsteady state.

Conclusions:

Evidence suggests that, regardless of whether the assessment is recorded at rest or during periods of changing core temperature, oral temperature is an unsuitable diagnostic tool for determining body temperature because many measures demonstrated differences greater than the predetermined validity threshold of 0.27°C (0.5°F). In addition, the differences were greatest at the highest rectal temperatures. Oral temperature cannot accurately reflect core body temperature, probably because it is influenced by factors such as ambient air temperature, probe placement, and ingestion of fluids. Any reliance on oral temperature in an emergency, such as exertional heat stroke, might grossly underestimate temperature and delay proper diagnosis and treatment.     

Movement Technique and Standing Balance After Graded Exercise-Induced Dehydration

ContextHypohydration has been shown to alter neuromuscular function. However, the longevity of these impairments remains unclear.ObjectiveTo examine the effects of graded exercise-induced dehydration on neuromuscular control 24 hours after exercise-induced hypohydration.DesignCrossover study.SettingLaboratory.Patients or Other ParticipantsA total of 23 men (age = 21 ± 2 years, height = 179.8 ± 6.4 cm, mass = 75.24 ± 7.93 kg, maximal oxygen uptake [VO₂max] = 51.7 ± 5.5 mL·kg⁻¹·min⁻¹, body fat = 14.2% ± 4.6%).Intervention(s)Participants completed 3 randomized exercise trials: euhydrated arrival plus fluid replacement (EUR), euhydrated arrival plus no fluid (EUD), and hypohydrated arrival plus no fluid (HYD) in hot conditions (ambient temperature = 35.2°C ± 0.6°C, relative humidity = 31.3% ± 2.5%). Each trial consisted of 180 minutes of exercise (six 30-minute cycles: 8 minutes at 40% VO₂max; 8 minutes, 60% VO₂max; 8 minutes, 40% VO₂max; 6 minutes, passive rest) followed by 60 minutes of passive recovery.Main Outcome Measure(s)We used the Landing Error Scoring System and Balance Error Scoring System (BESS) to measure movement technique and postural control at pre-exercise, postexercise and passive rest (POST_EX), and 24 hours postexercise (POST₂₄). Differences were assessed using separate mixed-design (trial × time) repeated-measures analyses of variance.ResultsThe magnitude of hypohydration at POST_EX was different among EUR, EUD, and HYD trials (0.2% ± 1%, 3.5% ± 1%, and 5% ± 0.9%, respectively; P < .05). We observed no differences in Landing Error Scoring System scores at pre-exercise (2.9 ± 1.6, 3.0 ± 2.1, 3.0 ± 2.0), POST_EX (3.3 ± 1.5, 3.0 ± 2.0, 3.1 ± 1.9), or POST₂₄ (3.3 ± 1.9, 3.2 ± 1.4, 3.3 ± 1.6) among the EUD, EUR, and HYD trials, respectively (P = .90). Hydration status did not affect BESS scores (P = .11), but BESS scores at POST_EX (10.4 ± 1.1) were greater than at POST₂₄ (7.7 ± 0.9; P = .03).ConclusionsWhereas exercise-induced dehydration up to 5% body mass did not impair movement technique or postural control 24 hours after a prolonged bout of exercise in a hot environment, postural control was impaired at 60 minutes after prolonged exercise in the heat. Consideration of the length of recovery time between bouts of exercise in hot environments is warranted.     

Effectiveness of Online Video Instruction on Time to Start Ambulation and Duration of Hospital Stay,Satisfaction and Functional Recovery in Patients Undergoing Total Hip Arthroplasty

BackgroundAt the end of 2014, we implemented an online video to inform patients of the entire process from admission to rehabilitation after total hip arthroplasty (THA). In this study, we investigated the effectiveness of online video instruction in THA patients.MethodsElectronic medical records of 184 patients undergoing THA in 2014 (pre-video group) and 182 patients in 2015 (post-video group) were reviewed. We compared 1) the time to start wheelchair ambulation, 2) walker or crutch ambulation, 3) the length of hospital stay, 4) postoperative satisfaction using visual analogue scale (0–10 points), and 5) modified Harris Hip Score (mHHS) at postoperative 6 weeks.ResultsIn the post-video group, the time to start wheelchair ambulation (1.8 ± 0.6 vs. 2.4 ± 3.2 days, P = 0.021) and walker/crutch ambulation were faster (2.9 ± 1.2 vs. 3.8 ± 1.0 days, P = 0.016), and the hospital stay was shorter (8.2 ± 4.7 vs. 9.9 ± 7.8 days, P = 0.001) compared to the pre-video group. The visual analogue scale for satisfaction (7.84 ± 1.62 vs. 7.68 ± 1.85 points) and mHHS (89.59 ± 9.47 vs. 89.58 ± 8.59) were similar.ConclusionOnline video instruction is an effective tool to expedite ambulation and reduce the hospital stay without compromising the clinical outcome and postoperative complications after THA.     

Drug‐induced cardiomyopathy: Characterization of a rat model by [18F]FDG/PET and [99mTc]MIBI/SPECT

BackgroundDrug‐induced cardiomyopathy is a significant medical problem. Clinical diagnosis of myocardial injury is based on initial electrocardiogram, levels of circulating biomarkers, and perfusion imaging with single photon emission computed tomography (SPECT). Positron emission tomography (PET) is an alternative imaging modality that provides better resolution and sensitivity than SPECT, improves diagnostic accuracy, and allows therapeutic monitoring. The objective of this study was to assess the detection of drug‐induced cardiomyopathy by PET using 2‐deoxy‐2‐[¹⁸F]fluoro‐D‐glucose (FDG) and compare it with the conventional SPECT technique with [^99mTc]‐Sestamibi (MIBI).MethodsCardiomyopathy was induced in Sprague Dawley rats using high‐dose isoproterenol. Nuclear [¹⁸F]FDG/PET and [^99mTc]MIBI/SPECT were performed before and after isoproterenol administration. [¹⁸F]FDG (0.1 mCi, 200‐400 µL) and [^99mTc]MIBI (2 mCi, 200‐600 µL) were administered via the tail vein and imaging was performed 1 hour postinjection. Isoproterenol‐induced injury was confirmed by the plasma level of cardiac troponin and triphenyltetrazolium chloride (TTC) staining.ResultsIsoproterenol administration resulted in an increase in circulating cardiac troponin I and showed histologic damage in the myocardium. Visually, preisoproterenol and postisoproterenol images showed alterations in cardiac accumulation of [¹⁸F]FDG, but not of [^99mTc]MIBI. Image analysis revealed that myocardial uptake of [¹⁸F]FDG reduced by 60% after isoproterenol treatment, whereas that of [^99mTc]MIBI decreased by 45%.ConclusionWe conclude that [¹⁸F]FDG is a more sensitive radiotracer than [^99mTc]MIBI for imaging of drug‐induced cardiomyopathy. We theorize that isoproterenol‐induced cardiomyopathy impacts cellular metabolism more than perfusion, which results in more substantial changes in [¹⁸F]FDG uptake than in [^99mTc]MIBI accumulation in cardiac tissue.     

Necessity of Removing American Football Uniforms From Humans With Hyperthermia Before Cold-Water Immersion

Context The National Athletic Trainers'' Association and the American College of Sports Medicine have recommended removing American football uniforms from athletes with exertional heat stroke before cold-water immersion (CWI) based on the assumption that the uniform impedes rectal temperature (T_rec) cooling. Few experimental data exist to verify or disprove this assumption and the recommendations.Objectives To compare CWI durations, T_rec cooling rates, thermal sensation, intensity of environmental symptoms, and onset of shivering when hyperthermic participants wore football uniforms during CWI or removed the uniforms immediately before CWI.Design Crossover study.Setting Laboratory.Intervention(s) On 2 days, participants exercised in the heat (approximately 40°C, approximately 40% relative humidity) while wearing a full American football uniform (shoes; crew socks; undergarments; shorts; game pants; undershirt; shoulder pads; jersey; helmet; and padding over the thighs, knees, hips, and tailbone [PADS]) until T_rec reached 39.5°C. Next, participants immersed themselves in water that was approximately 10°C while wearing either undergarments, shorts, and crew socks (NO_pads) or PADS without shoes until T_rec reached 38°C.Results Participants had similar exercise times (NO_pads = 40.8 ± 4.9 minutes, PADS = 43.2 ± 4.1 minutes; t₁₇ = 2.0, P = .10), hypohydration levels (NO_pads = 1.5% ± 0.3%, PADS = 1.6% ± 0.4%; t₁₇ = 1.3, P = .22), and thermal-sensation ratings (NO_pads = 7.2 ± 0.3, PADS = 7.1 ± 0.5; P > .05) before CWI. The CWI duration (median [interquartile range]; NO_pads = 6.0 [5.4] minutes, PADS = 7.3 [9.8] minutes; z = 2.3, P = .01) and T_rec cooling rates (NO_pads = 0.28°C/min ± 0.14°C/min, PADS = 0.21°C/min ± 0.11°C/min; t₁₇ = 2.2, P = .02) differed between uniform conditions.Conclusions Whereas participants cooled faster in NO_pads, we still considered the PADS cooling rate to be acceptable (ie, >0.16°C/min). Therefore, if clinicians experience difficulty removing PADS or CWI treatment is delayed, they may immerse fully equipped hyperthermic football players in CWI and maintain acceptable T_rec cooling rates. Otherwise, PADS should be removed preimmersion to ensure faster body core temperature cooling.Key Words: clothing, equipment, exertional heat stroke, rectal temperature

Key Points

• Body core temperature decreased faster when participants wore undergarments, shorts, and crew socks than when they wore the full American football uniform (PADS) without shoes during cold-water immersion (CWI).
• If CWI is delayed or clinicians have difficulty removing PADS, they can immerse hyperthermic football players in PADS and maintain acceptable core temperature cooling rates.
• The PADS should be removed before CWI if that can be done properly, easily, and within 30 minutes of athlete collapse.

American football players (AFPs) may be at higher risk of developing exertional heat stroke (EHS) in part because of the equipment-intensive uniform worn during the sport.¹ These athletes compete and often practice while wearing a full uniform consisting of shoes; crew socks; undergarments; shorts; game pants; undershirt; shoulder pads; jersey; helmet; and padding over the thighs, knees, hips, and tailbone (PADS).^2,3 The increased metabolic demand and physiologic strain of exercising while wearing PADS, combined with a decreased evaporative surface area to dissipate heat, can result in substantial heat storage^2–5 and may contribute to the development of exertional heat illness. In fact, the rate of exertional heat illness in secondary school AFPs is 11 times higher than that in all other sports combined.⁶ If EHS develops and body core temperature stays above the critical threshold for cell damage (approximately 40.5°C) longer than 30 minutes, the risk of morbidity and mortality increases.^7,8 Therefore, it is paramount to develop efficient protocols for treating AFPs with hyperthermia.The criterion standard treatment for EHS is cold-water immersion (CWI) because of its superior cooling rates (ie, >0.16°C/min)^7,9 and high survival rates when implemented shortly after the onset of symptoms.^7,10–12 However, the most efficient CWI protocol for treating AFPs with hyperthermia is less clear. Experts,¹³ the American College of Sports Medicine (ACSM),¹⁴ and the National Athletic Trainers'' Association (NATA)¹⁵ have recommended removing PADS before CWI if an AFP wearing PADS develops EHS. The reasoning for this recommendation was not articulated clearly, but it was not based on experimental evidence examining the influence of PADS on body core temperature cooling.¹³Removing AFP uniforms may take several minutes¹⁶; whether this should be done depends on several extrinsic factors (eg, the size and temperament of the athlete, proximity to cooling tubs). Understanding the necessity of PADS removal in EHS scenarios would provide insight into the most efficient means of treating AFPs with hyperthermia. Clinically, this would provide useful guidance for the lay responder if trained medical staff are not present to quickly and skillfully remove the uniform, diagnose EHS, and implement CWI.Miller et al¹⁷ tested the hypothesis that participants with hyperthermia would cool slowly when wearing PADS during CWI, as implied by the ACSM¹⁴ and NATA¹⁵ position statements. Unexpectedly, participants cooled faster when they wore PADS than when they wore minimal clothing (ie, undergarments, shorts, crew socks). The authors speculated that this result was due to participants exercising to a thermal threshold (ie, 39.5°C) while wearing different amounts of equipment. Therefore, greater heat storage and higher skin temperatures may have occurred when they were fully equipped.^2,4,18 To test the expert recommendations,^13–15 participants would need to exercise to some hyperthermic threshold while fully equipped on 2 days, remove the equipment on 1 day, then undergo CWI. To our knowledge, no scientists have made this comparison and validated the ACSM¹⁴ and NATA¹⁵ recommendations. Therefore, the purpose of our study was 2-fold. First, we compared the time required to reduce the rectal temperature (T_rec) of individuals with hyperthermia cooled via CWI while wearing PADS or minimal clothing (undergarments, shorts, and crew socks [NO_pads]). However, unlike the Miller et al¹⁷ experiment, participants exercised in PADS on both days and then removed PADS immediately before CWI on 1 day. Second, given that CWI can elicit a cold-shock response or be intolerable to conscious patients,¹⁹ we sought to determine if wearing PADS during CWI affected thermal sensations of participants,²⁰ the intensity of environmental symptoms,¹⁸ or the onset of shivering. We hypothesized that participants wearing PADS during CWI would need longer to cool from 39.5°C to 38°C, feel warmer during CWI as indicated by higher thermal-sensation ratings, report more severe environmental symptoms, and exhibit a delayed shivering response.     

Roundtable on Preseason Heat Safety in Secondary School Athletics: Prehospital Care of Patients With Exertional Heat Stroke

ObjectiveFirst, we will update recommendations for the prehospital management and care of patients with exertional heat stroke (EHS) in the secondary school setting. Second, we provide action items to aid clinicians in developing best-practice documents and policies for EHS. Third, we supply practical strategies clinicians can use to implement best practice for EHS in the secondary school setting.Data SourcesAn interdisciplinary working group of scientists, physicians, and athletic trainers evaluated the current literature regarding the prehospital care of EHS patients in secondary schools and developed this narrative review. When published research was nonexistent, expert opinion and experience guided the development of recommendations for implementing life-saving strategies. The group evaluated and further refined the action-oriented recommendations using the Delphi method.ConclusionsExertional heat stroke continues to be a leading cause of sudden death in young athletes and the physically active. This may be partly due to the numerous barriers and misconceptions about the best practice for diagnosing and treating patients with EHS. Exertional heat stroke is survivable if it is recognized early and appropriate measures are taken before patients are transported to hospitals for advanced medical care. Specifically, best practice for EHS evaluation and treatment includes early recognition of athletes with potential EHS, a rectal temperature measurement to confirm EHS, and cold-water immersion before transport to a hospital. With planning, communication, and persistence, clinicians can adopt these best-practice recommendations to aid in the recognition and treatment of patients with EHS in the secondary school setting.     

Clinical Characteristics and Treatment Outcomes of Patients with Hepatitis C Virus and Human Immunodeficiency Virus Coinfection: Experience at a Single Center in Korea

BackgroundBecause of the very low incidence of human immunodeficiency virus (HIV) coinfection in Korea, data on hepatitis C virus (HCV)/HIV coinfection are limited. This study aimed to investigate the clinical characteristics and treatment outcomes of patients with HCV/HIV coinfection in Korea.MethodsWe performed a retrospective cohort study of all HCV-monoinfected and HCV/HIV-coinfected patients treated with antivirals at National Medical Center in Seoul, Korea, between January 2009 and March 2020.ResultsWe enrolled 220 HCV-monoinfected and 23 HCV/HIV-coinfected patients treated with antivirals. The HCV/HIV-coinfected patients were younger (HCV vs. HCV/HIV: 57.3 ± 11.3 vs. 40.7 ± 10.1 years, P < 0.001) and had a higher proportion of men (HCV vs. HCV/HIV: 54.5% [n = 120] vs. 91.3% [n = 21], P < 0.001) than the HCV-monoinfected patients. Genotype 1b and 2 were most common in both HCV monoinfection and HCV/HIV coinfection groups. HCV-monoinfected patients had a higher incidence of genotype 1b and 2 than HCV/HIV-coinfected patients (HCV vs. HCV/HIV: 95.4% [n = 210] vs. 73.9% [n = 17], P < 0.001), while the HCV/HIV-coinfected patients had genotype 1a (HCV vs. HCV/HIV: 1.8% [n = 4] vs. 21.7% [n = 5], P < 0.001). The fibrosis-4 index was significantly lower in the HCV/HIV-coinfected patients than in the HCV-monoinfected patients (HCV vs. HCV/HIV: 3.81 ± 3.38 vs. 1.66 ± 1.10, P < 0.001). Among the direct-acting antivirals (DAA)-treated patients, the sustained viral response (SVR) rate did not differ significantly between both groups (HCV vs. HCV/HIV: 94.9% [93/99] vs. 90.9% [10/11], P = 0.480).ConclusionIn Korea, the HCV/HIV-coinfected patients who received antiviral treatment were younger, had higher proportion of men and incidence of genotype 1a, and had less advanced fibrosis than the HCV-monoinfected patients. In actual clinical settings, HCV/HIV-coinfected patients show excellent SVR to DAA treatment, similar to HCV-monoinfected patients.     

Induction chemotherapy plus nimotuzumab followed by concurrent chemoradiotherapy for advanced nasopharyngeal carcinoma

IntroductionThis study investigated the best mode for the application of nimotuzumab (Nimo) in combination with chemoradiotherapy to treat nasopharyngeal carcinoma (NPC).Material and methodsData were prospectively collected from 168 patients with NPC from September 2009 to February 2014. One hundred twelve patients received 2–3 cycles of induction chemotherapy (IC) followed by concurrent chemoradiotherapy (CCRT), and 56 patients with well-matched propensity scores received IC + CCRT + Nimo. Patients were divided into 3 subgroups according to the application schedule of Nimo: group A, IC + CCRT; group B: IC (combined with Nimo) + CCRT; and group C: IC + CCRT (combined with Nimo). The 5-year overall survival (OS) and progression-free survival (PFS) and adverse events were investigated.ResultsWith a median follow-up of 61.4 months (range: 1.7–96.5 months), the 5-year OS and PFS for group A vs. groups B + C were 74.8 ±4.1% versus 87.0 ±4.6% (p = 0.043) and 72.7 ±4.3% vs. 83.1 ± 5.1% (p = 0.243), respectively. The 5-year OS of group B was significantly improved over that of group A (93.0 ±4.8% vs. 74.8 ±4.1%, p = 0.038); however, there was no benefit to the 5-year PFS (89.3 ±5.9% vs. 72.7 ±4.3%, p = 0.144). The 5-year OS and PFS for group C were 80.4 ±7.9% and 76.4 ±8.5%, respectively, and there was no statistically significant difference from group A (p = 0.257 and p = 0.611, respectively). No significant increase in toxicities was observed with the addition of Nimo.ConclusionsNimo administered with chemoradiotherapy is effective for NPC. Nimo concurrent with IC followed by CCRT could be the optimal mode of sequential treatment.     

Influence of central obesity in estimating maximal oxygen uptake

OBJECTIVE:To assess the influence of central obesity on the magnitude of the error of estimate of maximal oxygen uptake in maximal cycling exercise testing.METHOD:A total of 1,715 adults (68% men) between 18-91 years of age underwent cardiopulmonary exercise testing using a progressive protocol to volitional fatigue. Subjects were stratified by central obesity into three quartile ranges: Q1, Q2-3 and Q4. Maximal oxygen uptake [mL.(kg.min)^-1] was estimated by the attained maximal workload and body weight using gender- and population-specific equations. The error of estimate [mL.(kg.min)^-1] and percent error between measured and estimated maximal oxygen uptake values were compared among obesity quartile ranges.RESULTS:The error of estimate and percent error differed (mean ± SD) for men (Q1=1.3±3.7 and 2.0±10.4; Q2-3=0.5±3.1 and -0.5±13.0; and Q4=-0.3±2.8 and -4.5±15.8 (p<0.05)) and for women (Q1=1.6±3.3 and 3.6±10.2; Q2-3=0.4±2.7 and -0.4±11.8; and Q4=-0.9±2.3 and -10.0±22.7 (p<0.05)).CONCLUSION:Central obesity directly influences the magnitude of the error of estimate of maximal oxygen uptake and should be considered when direct expired gas analysis is unavailable.     

Reliability and Validity of a Clinical Assessment Tool for Measuring Scapular Motion in All 3 Anatomical Planes

ContextA single clinical assessment device that can be used to objectively measure scapular motion in each anatomical plane is not currently available. The development of a novel electric goniometer would allow scapular motion in all 3 anatomical planes to be quantified.ObjectiveTo investigate the reliability and validity of an electric goniometer for measuring scapular motion in each anatomical plane during upper extremity elevation.DesignCross-sectional study.SettingLaboratory.Patients or Other ParticipantsSixty participants (29 women, 31 men; age = 30 ± 14 years, height = 1.73 ± 0.10 m, mass = 75.32 ± 16.90 kg) recruited from the general population.Intervention(s)An electric goniometer was used to record clinical measurements of scapular position at rest and total arc of motion (excursion) during active upper extremity elevation in 2 testing sessions separated by several days. Measurements were recorded independently by 2 examiners. In 1 session, scapular motion was recorded simultaneously using a 14-camera, 3-dimensional optical motion-capture system.Main Outcome Measure(s)Reliability analysis included examination of clinical measurements for scapular position at rest and excursion during each condition. Both the intrarater reliability between testing sessions and the interrater reliability recorded in the same session were assessed using intraclass correlation coefficients (ICCs [2,3]). The criterion validity was examined by comparing the mean excursion values of each condition recorded using the electric goniometer and the 3-dimensional optical motion-capture system. Validity was assessed by evaluating the average difference and root mean square error.ResultsThe between-sessions intrarater reliability was moderate to good (ICC [2,3] range = 0.628–0.874). The within-session interrater reliability was moderate to excellent (ICC [2,3] range = 0.545–0.912). The average difference between total excursion values recorded using the electric goniometer and the 3-dimensional optical motion-capture system ranged from −7° to 4°, and the root mean square error ranged from 7° to 10°.ConclusionsThe reliability of scapular measurements was best when a standard operating procedure was used. The electric goniometer provided an accurate measurement of scapular excursions in all 3 anatomical planes during upper extremity elevation.