Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2024 Update.

The Wilderness Medical Society (WMS) convened an expert panel in 2011 to develop a set of evidence-based guidelines for the recognition, prevention, and treatment of heat illness. The current panel retained 5 original members and welcomed 2 new members, all of whom collaborated remotely to provide an updated review of the classifications, pathophysiology, evidence-based guidelines for planning and preventive measures, and recommendations for field- and hospital-based therapeutic management of heat illness. These recommendations are graded based on the quality of supporting evidence and the balance between the benefits and risks or burdens for each modality. This is an updated version of the WMS clinical practice guidelines for the prevention and treatment of heat illness published in Wilderness & Environmental Medicine. 2019;30(4):S33-S46.

Intensive Cryotherapy in the Emergency Department (ICED): A Randomized Controlled Trial.

INTRODUCTION: Pain control is an essential component of musculoskeletal injury treatment in the emergency department (ED). We evaluated the most effective type of cryotherapy for analgesia of acute musculoskeletal injury and the impact on opioid utilization. METHODS: This was a prospective, randomized, single-blind controlled trial of adult ED patients who presented with acute musculoskeletal pain. Patients were randomized to either intensive targeted cryotherapy (crushed wetted ice in a plastic bag) or agitated chemical cold pack applied to the injury site for 20 minutes. All other diagnostic and therapeutic orders were at the discretion of the treating physician. Visual analog pain scores were measured at the time of cryotherapy application, at 20 minutes (time of cryotherapy removal), and at 60 minutes (40 minutes after removal). RESULTS: We enrolled 38 patients, 17 randomized to intensive targeted cryotherapy and 21 to chemical cold packs, with well-matched demographics. The intensive targeted cryotherapy group achieved significantly greater pain relief at 20 minutes (2.1 [95% confidence interval (CI), 1.3 - 2.9] vs 0.9 [95% CI, 0.3 - 1.5], P < 0.05) and at 60 minutes (2.7 [95% CI, 1.6 - 3.7] vs 1.2 [95% CI, 0.6 - 1.7], P < 0.05), number need to trial (NNT) = 3.2. Opioid administration in the ED was significantly lower in the intensive targeted cryotherapy group (1 [6%] vs 7 [33%], P < 0.05), NNT = 3.6. Those who received a discharge opiate prescription had significantly higher 60-minute pain scores (7.3 ± 2.2 vs 4.1 ± 2.7, P < 0.05). CONCLUSION: Intensive targeted cryotherapy provided more effective analgesia than chemical cold packs for acute musculoskeletal injuries in the ED and may contribute to lower opioid usage.

Prospective Observational Study of Weight-based Assessment of Sodium Supplements on Ultramarathon Performance (WASSUP).

BACKGROUND: Sodium supplements are ubiquitous in endurance running, but their impact on performance has been subjected to much debate. The objective of the study was to assess the effect of sodium supplementation as a weight-based predictor of race performance in ultramarathon runners. METHODS: Prospective observational study during an 80 km (50 mi) stage of a 6-stage 250 km (155 mi) ultramarathon in Chile, Patagonia, Namibia, and Mongolia. Finish line hydration status as measured by weight change, point-of-care serum sodium, and questionnaire provided sodium ingestion categories at 33rd percentile and 66th percentile both for weight-adjusted rate and total sodium consumption, then analyzed for significant relationships to race performance, dysnatremia, and hydration. RESULTS: Two hundred sixty-six participants were enrolled, with 217 (82%) with complete sodium supplement rate data, 174 (80%) with finish line sodium, and 161 (74%) with both pre-race weights and total sodium ingestion allowing weight-based analysis. Sodium intake ranged from 131-533 mg/h/kg (2-7.2 gm), with no statistically significant impact on pace, race time, or quintile rank. These outcomes did not change when sodium intake was analyzed as a continuous variable or by sub-group analysis of the 109 (68%) normonatremic runners. When controlled for weight-adjusted sodium intake, performance was poorly correlated with hydration (r = - 0.152, 95% CI - 0.348-0.057). Dehydrated runners outperformed those overhydrated, with 11% of top 25th percentile finishers dehydrated (versus 2.8% overhydrated), with 3.6 min/km faster pace and time 4.6 h faster finishing time. CONCLUSIONS: No association was found between sodium supplement intake and ultramarathon performance. Dehydrated runners were found to have the best performance. This reinforces the message to avoid overhydration.

Predictive Capacity of Pulmonary Function Tests for Acute Mountain Sickness.

Small, Elan, Nicholas Juul, David Pomeranz, Patrick Burns, Caleb Phillips, Mary Cheffers, and Grant S. Lipman. Predictive capacity of pulmonary function tests for acute mountain sickness. High Alt Med Biol. 22: 193-200, 2021. Background: Pulmonary function as measured by spirometry has been investigated at altitude with heterogenous results, though data focused on spirometry and acute mountain sickness (AMS) are limited. The objective of this study was to investigate the capacity of pulmonary function tests (PFTs) to predict the development of AMS. Materials and Methods: This study was a blinded prospective observational study run during a randomized controlled trial comparing acetazolamide, budesonide, and placebo for AMS prevention on White Mountain, CA. Spirometry measurements of forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and peak expiratory flow were taken at a baseline altitude of 1,250 m, and the evening of and morning after ascent to 3,810 m. Measurements were assessed for correlation with AMS. Results: One hundred three participants were analyzed with well-matched baseline demographics and AMS incidence of 75 (73%) and severe AMS of 48 (47%). There were no statistically significant associations between changes in mean spirometry values on ascent to high altitude with incidence of AMS or severe AMS. Lake Louise Questionnaire scores were negatively correlated with FVC (r = -0.31) and FEV1 (r = -0.29) the night of ascent. Baseline PFT had a predictive accuracy of 65%-73% for AMS, with a receiver operating characteristic of 0.51-0.65. Conclusions: Spirometry did not demonstrate statistically significant changes on ascent to high altitude, nor were there significant associations with incidence of AMS or severe AMS. Low-altitude spirometry did not accurately predict development of AMS, and it should not be recommended for risk stratification.

Effect of Sodium Supplements and Climate on Dysnatremia During Ultramarathon Running.

OBJECTIVE: Analyze the effect of sodium supplementation, hydration, and climate on dysnatremia in ultramarathon runners. DESIGN: Prospective observational study. SETTING: The 2017 80 km (50 mile) stage of the 250 km (150 mile) 6-stage RacingThePlanet ultramarathon in 2017 Chilean, Patagonian, and 2018 Namibian, Mongolian, and Chilean deserts. PARTICIPANTS: All race entrants who could understand English were invited to participate, with 266 runners enrolled, mean age of 43 years (± 9), 61 (36%) females, average weight 74 kg (± 12.5), and average race time 14.5 (± 4.1) hours. Post-race sodium collected on 174 (74%) and 164 (62%) participants with both the blood sample and post-race questionnaire. INTERVENTION: Weight change and finish line serum sodium levels were gathered. MAIN OUTCOME MEASURES: Incidence of exercise-associated hyponatremia (EAH; <135 mmol·L-1) and hypernatremia (>145 mmol·L-1) by sodium ingestion and climate. RESULTS: Eleven (6.3%) runners developed EAH, and 30 (17.2%) developed hypernatremia. Those with EAH were 14 kg heavier at baseline, had significantly less training distances, and averaged 5 to 6 hours longer to cover 50 miles (80 km) than the other participants. Neither rate nor total ingested supplemental sodium was correlated with dysnatremia, without significant differences in drinking behaviors or type of supplement compared with normonatremic runners. Hypernatremic runners were more often dehydrated [8 (28%), -4.7 kg (± 9.8)] than EAH [4 (14%), -1.1 kg (± 3.8)] (P < 0.01), and EAH runners were more frequently overhydrated (6, 67%) than hypernatremia (1, 11%) (P < 0.01). In the 98 (56%) runners from hot races, there was EAH OR = 3.5 [95% confidence interval (CI), 0.9-25.9] and hypernatremia OR = 8.8 (95% CI, 2.9-39.5) compared with cold races. CONCLUSIONS: This was the first study to show that hot race climates are an independent risk factor for EAH and hypernatremia. Sodium supplementation did not prevent EAH nor cause hypernatremia. Longer training distances, lower body mass, and avoidance of overhydration were shown to be the most important factors to prevent EAH and avoidance of dehydration to prevent hypernatremia.

A body bag can save your life: a novel method of cold water immersion for heat stroke treatment.

Non-exertional heat stroke is a life-threatening condition characterized by passive exposure to high ambient heat, a core body temperature of 40°C (104°F) or greater, and central nervous system dysfunction. Rapid cooling is imperative to minimize mortality and morbidity. Although evaporative and convective measures are often used for cooling heat stroke patients, cold water immersion produces the fastest cooling. However, logistical difficulties make cold water immersion challenging to implement in the emergency department. To our knowledge, there is no documented case utilizing a body bag (ie, human remains pouch) as a cold water immersion tank for rapid resuscitation of heat stroke. During a regional heat wave an elderly woman was found unconscious in a parking lot with an oral temperature of 40°C (104°F) and altered mental status. She was cooled to 38.4°C (101.1°F) in 10 minutes by immersion in an ice- and water-filled body bag. The patient rapidly regained normal mentation and was discharged home from the ED. This case highlights a novel method for efficient and convenient cold water immersion for heat stroke treatment in the emergency department.

A Randomized Controlled Trial of the Lowest Effective Dose of Acetazolamide for Acute Mountain Sickness Prevention.

BACKGROUND: Acetazolamide is the most common medication used for acute mountain sickness prevention, with speculation that a reduced dose may be as efficacious as standard dosing with fewer side effects. METHODS: This double-blind, randomized, controlled noninferiority trial compared acetazolamide 62.5 mg twice daily to the standard dose acetazolamide 125 mg twice daily starting the evening prior to ascent from 1240 m (4100 ft) to 3810 m (12,570 ft) over 4 hours. The primary outcome was acute mountain sickness incidence (ie, headache, Lake Louise Questionnaire ≥3, and another symptom). RESULTS: A total of 106 participants were analyzed, with 51 (48%) randomized to 125 mg and 55 (52%) to 62.5 mg, with a combined acute mountain sickness incidence of 53 (50%) and mean severity of 3 (± 2.1). The 62.5-mg group failed to fall within the prespecified 26% noninferiority margin for acute mountain sickness incidence (62.5 mg = 30 [55%] vs 125 mg = 23 [45%], 95% confidence interval [CI] -11% to 30%). Participants in the 62.5-mg group had a higher risk of acute mountain sickness (odds ratio = 1.5, 95% CI 0.7-3.2) and moderate acute mountain sickness (odds ratio = 1.8, 95% CI 0.6-5.9), with a number needed to harm (NNH) of 9, with a number needed to treat (NNT) in the 125-mg group of 4.8. Increased acute mountain sickness incidence and symptom severity corresponded to lower weight-based and body mass index dosing, with similar side effects between groups. CONCLUSION: Acetazolamide 62.5 mg twice daily failed to demonstrate equal effectiveness to 125 mg twice daily for prevention of acute mountain sickness. With increased risk and no demonstrable symptomatic or physiologic benefits, acetazolamide 62.5 mg twice daily should not be recommended for acute mountain sickness prevention.

Precipitous Delivery Masquerading as Biliary Colic in the Setting of Depo-Provera® Failure.

Precipitous delivery in the emergency department is a high-acuity, low-occurrence event that requires rapid recognition and interdepartment cooperation to prevent fetal and maternal morbidity and mortality. Prompt recognition of the peripartum state can be delayed by reported usage of long-acting contraception and concurrent distracting complaints. In this case report, a young female presented to the emergency department with epigastric abdominal pain in the setting of recent workup for biliary colic and multiple doses of long-acting, depot contraceptive agents. Early utilization of bedside ultrasound confirmed a full-term, intrauterine pregnancy as well as an impacted gallbladder stone, followed by a precipitous footling breech presentation that required an emergent cesarean section.

Pain Is Inevitable But Suffering Is Optional: Relationship of Pain Coping Strategies to Performance in Multistage Ultramarathon Runners.

INTRODUCTION: Ultramarathon runners commonly endure musculoskeletal pain during endurance events. However, the effect of pain coping skills on performance has not been examined. METHODS: A prospective observational study during three 250 km (155 mi), 6 stage ultramarathons was conducted. Finish line surveys were completed after each of the four 40 km (25 mi) and one 80 km (50 mi) stages of racing. Variables gathered included pain intensity, pain coping strategy use, pain interference, finishing position (quintile), and successful race completion. RESULTS: A total of 204 participants (age 41.4±10.3 y; 73% male) reported average pain intensity of 3.9 (±2.0 SD) and worst pain intensity of 5.3 (±2.3) on a 0 to 10 scale. They used greater adaptive pain coping strategies (3.0±1.3) relative to maladaptive strategies (1.3±1.1). Worst pain and pain interference increased over each stage of the race for all runners (P<0.001), with worst pain being significantly different by finishing status (P=0.02). Although all runners endured increased pain and interference, the nonfinishers (28 [14%]) had significantly greater differences in changes in pain intensity (P<0.01) and pain interference (P<0.001). Maladaptive pain coping strategies were more common in nonfinishers; with each 1-point increase (0-6 scale), there was a 3 times increase in odds of not finishing the race. CONCLUSIONS: Although increased pain intensity and pain interference was found in all multistage ultramarathon runners, successful event completion was significantly associated with less maladaptive pain coping. Training in coping with pain may be a beneficial part of ultramarathon preparation.

Wilderness Medical Society Clinical Practice Guidelines for the Management of Exercise-Associated Hyponatremia: 2019 Update.

Exercise-associated hyponatremia (EAH) is defined by a serum or plasma sodium concentration below the normal reference range of 135 mmol·L-1 that occurs during or up to 24 h after prolonged physical activity. It is reported to occur in individual physical activities or during organized endurance events conducted in environments in which medical care is limited and often not available, and patient evacuation to definitive care is often greatly delayed. Rapid recognition and appropriate treatment are essential in the severe form to increase the likelihood of a positive outcome. To mitigate the risk of EAH mismanagement, care providers in the prehospital and in hospital settings must differentiate from other causes that present with similar signs and symptoms. EAH most commonly has overlapping signs and symptoms with heat exhaustion and exertional heat stroke. Failure in this regard is a recognized cause of worsened morbidity and mortality. In an effort to produce best practice guidelines for EAH management, the Wilderness Medical Society convened an expert panel in May 2018. The panel was charged with updating the WMS Practice Guidelines for Treatment of Exercise-Associated Hyponatremia published in 2014 using evidence-based guidelines for the prevention, recognition, and treatment of EAH. Recommendations are made based on presenting with symptomatic EAH, particularly when point-of-care blood sodium testing is unavailable in the field. These recommendations are graded on the basis of the quality of supporting evidence and balanced between the benefits and risks/burdens for each parameter according to the methodology stipulated by the American College of Chest Physicians.

Wilderness Medical Society Clinical Practice Guidelines for Diabetes Management.

The Wilderness Medical Society convened an expert panel in 2018 to develop a set of evidence-based guidelines for the treatment of type 1 and 2 diabetes, as well as the recognition, prevention, and treatment of complications of diabetes in wilderness athletes. We present a review of the classifications, pathophysiology, and evidence-based guidelines for planning and preventive measures, as well as best practice recommendations for both routine and urgent therapeutic management of diabetes and glycemic complications. These recommendations are graded based on the quality of supporting evidence and balance between the benefits and risks or burdens for each recommendation.

Day of Ascent Dosing of Acetazolamide for Prevention of Acute Mountain Sickness.

Background: Acetazolamide is the most common medication used for prevention of acute mountain sickness (AMS), usually administered the day or night before ascent. The objective of this study was to evaluate the efficacy of day of ascent dosing of acetazolamide for AMS prevention. Methods: Double-blind, randomized, controlled noninferiority trial of acetazolamide 125 mg twice daily beginning either the night before or the morning of ascent. Healthy low altitude adults ascended from 1240 m (4100 ft) to 3810 m (12,570 ft) during summer 2018 on White Mountain, California. Primary outcome was incidence of AMS with the two different dosing patterns, assessed by the 1993 Lake Louise Questionnaire (LLQ) of ≥3 with headache and a minimum of 1 for other symptom. Results: One hundred four participants completed the study, with 54 (52%) randomized to night before acetazolamide and 50 (48%) to day of ascent dosing, without differences in baseline characteristics. There was 9% greater incidence of AMS in the day of ascent acetazolamide group (48.0% vs. 39%, 95% confidence interval [CI] -11.8 to 30, p = 0.46, number needed to treat [NNT] = 5.6 vs. 3.7), with the CI just surpassing the predetermined 26% noninferiority margin. There was a lower incidence of severe AMS (1993 LLQ >5) in the day of ascent group (n = 5, 10%, NNT = 2.3) compared with night before dosing (n = 12, 22%, NNT = 3.1) (95% CI -28 to 3.6), and lower average symptom severity in the day of ascent group (3 vs. 3.5, 95% CI -0.5 to 1.4). Conclusions: Day of ascent acetazolamide demonstrated higher rates of AMS compared with traditional dosing by a small margin. With similar rates of severe AMS and overall symptom severity, the potential for improved convenience and compliance may support day of ascent use.

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2019 Update.

The Wilderness Medical Society convened an expert panel in 2011 to develop a set of evidence-based guidelines for the recognition, prevention, and treatment of heat illness. We present a review of the classifications, pathophysiology, and evidence-based guidelines for planning and preventive measures, as well as best practice recommendations for both field- and hospital-based therapeutic management of heat illness. These recommendations are graded based on the quality of supporting evidence and balance the benefits and risks or burdens for each modality. This is an updated version of the original Wilderness Medical Society Practice Guidelines for the Treatment and Prevention of Heat-Related Illness published in 2013.

Interstitial Pulmonary Edema Assessed by Lung Ultrasound on Ascent to High Altitude and Slight Association with Acute Mountain Sickness: A Prospective Observational Study.

Background: Acute mountain sickness (AMS) is a common disease that may have a pulmonary component, as suggested by interstitial pulmonary edema quantified by the B-line score (BLS) on ultrasound (US). This subclinical pulmonary edema has been shown to increase with ascent to high altitude and AMS severity, but has not been prospectively associated with AMS incidence in a large prospective study. Materials and Methods: This prospective observational study was part of a randomized controlled trial enrolling healthy adults over four weekends ascending White Mountain, California. Subjects were assessed by lung US and the Lake Louise Questionnaire at 4110 ft (1240 m), upon ascent to 12,500 ft (3810 m), and the next morning at 12,500 ft (3810 m). Results: Three hundred five USs in total were completed on 103 participants, with 73% total incidence of AMS. The mean (±standard deviation) BLS increased from baseline (1.15 ± 1.80) to high altitude (2.56 ± 2.86), a difference of 1.37 (±2.48) (p = 0.04). Overall BLS was found, on average, to be higher among those diagnosed with AMS than without (2.97 vs. 2.0, p = 0.04, 95% confidence interval [CI] -∞ to -0.04). The change in BLS (ΔBLS) from low altitude baseline was significantly associated with AMS (0.88 vs. 1.72, r2 = 0.023, 95% CI -∞ to -0.01, p = 0.048). Conclusions: Interstitial subclinical pulmonary edema by lung US was found to have a small but significant association with AMS.