Novel application of chemical cold packs for treatment of exercise-induced hyperthermia: a randomized controlled trial.

OBJECTIVE: Heat-related illness is a common disease with significant morbidity and mortality. Despite no proven efficacy, application of chemical cold packs (CCP) to the skin overlying the large vessels of the neck, groin, and axillae is a traditional recommended cooling modality. The study objective was to compare the cooling rates of CCP applied to these traditional areas vs the glabrous skin surfaces of the cheeks, palms, and soles in exercise-induced hyperthermia. METHODS: Ten healthy adult male volunteers walked on a treadmill in a heated room (40°±0.5°C) while wearing insulated military overgarments until their esophageal temperatures (Tes) reached 39.2°C. Each participant had three heat stress trials on separate days: no treatment followed by randomly ordered traditional (neck, groin, and axillae) cooling and glabrous skin cooling. RESULTS: With no treatment, Tes remained stable after the first 5 minutes of the heat trial (ΔTes=0.12°±0.07°C/10 min). Traditional cooling followed a linear decline (ΔTes=0.17°±0.04°C/10 min; P<.001). Glabrous cooling enhanced the treatment effect by a steeper decline (ΔTes=0.30°±0.06°C/10 min; P<.001), significantly different from traditional cooling by 2-way analysis of variance (P<.001). CONCLUSIONS: Application of CCP to glabrous skin surfaces was more effective for treating exercise-induced heat stress than the traditional CCP cooling intervention. This novel cooling technique may be beneficial as an adjunctive treatment for heat-related illness in the prehospital environment.

A prospective randomized blister prevention trial assessing paper tape in endurance distances (Pre-TAPED).

OBJECTIVE: Friction foot blisters are a common injury occurring in up to 39% of marathoners, the most common injury in adventure racing, and represent more than 70% of medical visits in multi-stage ultramarathons. The goal of the study was to determine whether paper tape could prevent foot blisters in ultramarathon runners. METHODS: This prospective randomized trial was undertaken during RacingThePlanet 155-mile (250-km), 7-day self-supported ultramarathons in China, Australia, Egypt, Chile, and Nepal in 2010 and 2011. Paper tape was applied prerace to one randomly selected foot, with the untreated foot acting as the own control. The study end point was development of a hot spot or blister on any location of either foot. RESULTS: One hundred thirty-six participants were enrolled with 90 (66%) having completed data for analysis. There were 36% women, with a mean age of 40 ± 9.4 years (range, 25-40 years) and pack weight of 11 ± 1.8 kg (range, 8-16 kg). All participants developed blisters, with 89% occurring by day 2 and 59% located on the toes. No protective effect was observed by the intervention (47 versus 35; 52% versus 39%; P = .22), with fewer blisters occurring around the tape on the experimental foot than under the tape (23 vs 31; 25.6% versus 34.4%), yet 84% of study participants when queried would choose paper tape for blister prevention in the future. CONCLUSIONS: Although paper tape was not found to be significantly protective against blisters, the intervention was well tolerated with high user satisfaction.

Chemical cold packs may provide insufficient enthalpy change for treatment of hyperthermia.

OBJECTIVE: Heat illness is a common ailment that, if left untreated, is associated with high morbidity and mortality. Chemical cold packs (CCPs) and ice packs are widely used in the pre-hospital setting and by those with limited resources, yet no controlled studies have compared the cooling of ice to that of CCPs. This study determined the theoretical cooling of CCPs on a benchtop model, comparing the results to similarly sized ice packs, and is the first known comparison of these hyperthermia treatments. METHODS: The CCPs used in Stanford University's Emergency Department were activated in an insulated volume of water (2 L), and temperature was recorded at 1-second intervals in a controlled environment (41°C at 20% humidity). The procedure was repeated with 1-quart ice packs. RESULTS: The CCPs resulted in a 5.25°C degree temperature drop, with a time constant (time to 63% of initial temperature--a common engineering characterization metric) of 1.72 minutes for the test volume. Ice packs resulted on average in a 19.8°C temperature change, with a time constant of 26.8 minutes. The CCPs provide less overall temperature change and were shorter lived. Application of 6 CCPs on a 50th percentile male (weight 86.6 kg, height 1.7 m), assuming ideal heat transfer, would result in less than 0.5°C temperature change. Similarly configured ice packs would result in a 2.5°C change. CONCLUSIONS: Experiments demonstrate that CCPs are inferior to similarly sized ice packs for thermal regulation, and lose their effectiveness more quickly. These findings support the consideration of ice packs as an alternative to chemical cold packs when cooling hyperthermic patients.

Fatal retroperitoneal hematoma after enoxaparin administration in a patient with paroxysmal atrial flutter.

PURPOSE: A case of fatal retroperitoneal hematoma that developed after enoxaparin administration in a woman with paroxysmal atrial flutter and chest pain is reported. SUMMARY: A 63-year-old, 74-kg, African-American woman arrived at the emergency department with a 24-hour history of severe, nonexertional, substernal chest pain that radiated down her left arm. An electrocardiograph with continuous telemetry showed new-onset paroxysmal atrial flutter without ST-segment elevation. She was treated with aspirin 325 mg, metoprolol 25 mg, and subcutaneous enoxaparin 80 mg (0.93 mg/kg) every 12 hours. On hospital day 2, she was given warfarin 5 mg daily and continued on enoxaparin. Approximately 36 hours after admission, she became acutely hypotensive and developed tachycardia. She was transferred to the medical intensive care unit and intubated for respiratory arrest. Soon after, she was found to be in asystole and, despite multiple rounds of standard advanced cardiac life support and infusion of blood products, the patient expired 3 hours after the initial emergency resuscitation code was called. A postmortem examination revealed a large, noncommunicating, retroperitoneal hematoma located posterior to the right kidney as the cause of death. CONCLUSION: A 63-year-old African-American woman with a 24-hour history of severe, nonexertional chest pain and new-onset paroxysmal atrial flutter without ST-segment elevation was treated with enoxaparin and subsequently died of a fatal spontaneous retroperitoneal hematoma.