Sources for Altitude Illness Information for Trekkers in the Himalayas.

INTRODUCTION: Educational materials are important tools in the prevention of altitude illness among individuals traveling to high altitude destinations. Travelers obtain information about altitude illness from many different educational resources. Our objective was to determine which educational resources for altitude illness prevention were used by trekkers on the Everest Base Camp trek and Annapurna Circuit. We also sought to compare which resources were used by individuals from different geographic areas. METHODS: A survey was administered to trekkers attending an altitude illness information lecture at the Himalayan Rescue Association clinic. Trekkers provided their basic demographic information and educational resources they used while preparing for the trek. Comparisons were made between trekkers based on the resources they used, as well as their age and country of origin. RESULTS: Of 1075 surveys administered, 906 were completed. Internet sources were most commonly used by trekkers (49%), followed by friends or family (22%), and healthcare providers (18%). The age of participants using Internet sources was 36±12 y (mean±SD), lower than those who did not use Internet sources (39±14 y, P<0.01). Participants came from 8 geographic areas; Europe (55%), North America (24%), and Oceania (11%) made up the vast majority. Compared to the overall cohort, participants from Oceania demonstrated more Internet reliance at 65% (χ2(1, n=102)=9.7, P<0.01). CONCLUSIONS: In this group of trekkers in the Himalayas, the Internet was the most common source of information on altitude illness prevention and management. Trekkers using Internet sources were slightly younger than non-Internet users.

Prophylactic Acetaminophen or Ibuprofen Results in Equivalent Acute Mountain Sickness Incidence at High Altitude: A Prospective Randomized Trial.

OBJECTIVE: Recent trials have demonstrated the usefulness of ibuprofen in the prevention of acute mountain sickness (AMS), yet the proposed anti-inflammatory mechanism remains unconfirmed. Acetaminophen and ibuprofen were tested for AMS prevention. We hypothesized that a greater clinical effect would be seen from ibuprofen due to its anti-inflammatory effects compared with acetaminophen's mechanism of possible symptom reduction by predominantly mediating nociception in the brain. METHODS: A double-blind, randomized trial was conducted testing acetaminophen vs ibuprofen for the prevention of AMS. A total of 332 non-Nepali participants were recruited at Pheriche (4371 m) and Dingboche (4410 m) on the Everest Base Camp trek. The participants were randomized to either acetaminophen 1000 mg or ibuprofen 600 mg 3 times a day until they reached Lobuche (4940 m), where they were reassessed. The primary outcome was AMS incidence measured by the Lake Louise Questionnaire score. RESULTS: Data from 225 participants who met inclusion criteria were analyzed. Twenty-five participants (22.1%) in the acetaminophen group and 18 (16.1%) in the ibuprofen group developed AMS (P = .235). The combined AMS incidence was 19.1% (43 participants), 14 percentage points lower than the expected AMS incidence of untreated trekkers in prior studies at this location, suggesting that both interventions reduced the incidence of AMS. CONCLUSIONS: We found little evidence of any difference between acetaminophen and ibuprofen groups in AMS incidence. This suggests that AMS prevention may be multifactorial, affected by anti-inflammatory inhibition of the arachidonic-acid pathway as well as other analgesic mechanisms that mediate nociception. Additional study is needed.

Optic Nerve Sheath Diameter Increase on Ascent to High Altitude: Correlation With Acute Mountain Sickness.

OBJECTIVES: Elevated optic nerve sheath diameter on sonography is known to correlate with increased intracranial pressure and is observed in acute mountain sickness. This study aimed to determine whether optic nerve sheath diameter changes on ascent to high altitude are associated with acute mountain sickness incidence. METHODS: Eighty-six healthy adults enrolled at 1240 m (4100 ft), drove to 3545 m (11,700 ft) and then hiked to and slept at 3810 m (12,500 ft). Lake Louise Questionnaire scores and optic nerve sheath diameter measurements were taken before, the evening of, and the morning after ascent. RESULTS: The incidence of acute mountain sickness was 55.8%, with a mean Lake Louise Questionnaire score ± SD of 3.81 ± 2.5. The mean maximum optic nerve sheath diameter increased on ascent from 5.58 ± 0.79 to 6.13 ± 0.73 mm, a difference of 0.91 ± 0.55 mm (P = .09). Optic nerve sheath diameter increased at high altitude regardless of acute mountain sickness diagnosis; however, compared to baseline values, we observed a significant increase in diameter only in those with a diagnosis of acute mountain sickness (0.57 ± 0.77 versus 0.21 ± 0.76 mm; P = .04). This change from baseline, or Δ optic nerve sheath diameter, was associated with twice the odds of developing acute mountain sickness (95% confidence interval, 1.08-3.93). CONCLUSIONS: The mean optic nerve sheath diameter increased on ascent to high altitude compared to baseline values, but not to a statistically significant degree. The magnitude of the observed Δ optic nerve sheath diameter was positively associated with acute mountain sickness diagnosis. No such significant association was found between acute mountain sickness and diameter elevation above standard cutoff values, limiting the utility of sonography as a diagnostic tool.

Study Looking at End Expiratory Pressure for Altitude Illness Decrease (SLEEP-AID).

Lipman, Grant S., Nicholas C. Kanaan, Caleb Phillips, Dave Pomeranz, Patrick Cain, Kristin Fontes, Becky Higbee, Carolyn Meyer, Michael Shaheen, Sean Wentworth, and Diane Walsh. Study Looking at End Expiratory Pressure for Altitude Illness Decrease (SLEEP-AID). High Alt Med Biol 16:154-161, 2015.--Acute mountain sickness (AMS) affects 25%-70% of the tens of millions of high altitude travelers annually, with hypoxia and nocturnal desaturations as major contributing factors. This is the first double blind randomized placebo controlled trial to assess expiratory positive airway pressure (EPAP) for AMS prevention and nocturnal hypoxic events. Healthy adult participants trekking in the Khumbu region of the Himalayas were randomized to a single-use EPAP nasal strip, or a visually identical sham device (placebo) prior to first night sleeping between 4371-4530 m (14,340-14,800 ft). The primary outcome was AMS incidence, measured by Lake Louise Questionnaire (LLQ), with secondary outcomes of AMS severity (by LLQ) and physiologic sleep indices measured by continuous sleep monitor. Intent-to-treat analysis included 219 participants with comparable demographic characteristics, of which 115 received EPAP and 104 placebo. There was no decrease in AMS with EPAP intervention (14% EPAP vs. 17% placebo; p=0.65; risk difference (-)3.15%, 95% CI (-)12.85%-6.56%). While overall AMS severity was not different between groups, EPAP reported decreased incidence of headache (64% vs. 76%; p<0.05, OR 0.51, 95% CI 0.27-0.95) and dizziness (81% vs. 98%; p<0.03, OR 0.29, 95% CI 0.09-0.78). During sleep, EPAP resulted in significant improvements in average peripheral oxygenation (Spo(2)) (80% versus 78%; p<0.01, mean difference=2, 95% CI 0.58-3.63) and a reduced percentage of time below 80% Spo(2) (31% vs. 46%; p<0.03, median difference=16, 95% CI 2.22-28.18). This lightweight and inexpensive EPAP device did not prevent acute mountain sickness, but did reduce the subgroup incidence of headache and dizziness while improving average nighttime peripheral oxygenation.

Search and rescue in the Intermountain West states.

BACKGROUND: Minimal data exist regarding the activity, membership, training, and medical oversight of search and rescue (SAR) teams. OBJECTIVE: Our objective was to describe these characteristics in the Intermountain West SAR organizations. METHODS: A contact list was generated and electronic surveys were sent to SAR officials in each Intermountain West county. Results were descriptively analyzed. RESULTS: Of the contacted jurisdictions, 56% (156) responded to the survey. The annual average call volume was 29 missions (range, 5 to 152). Multiple levels of medical training were represented on SAR teams, ranging from first aid/cardiopulmonary resuscitation providers to the physician level, and 79% of teams provided some medical training to their membership. Of the SAR medical professionals, 23% had formal wilderness medical training. Local emergency medical services provided 60% of the medical care on SAR missions rather than SAR personnel. Formal physician medical oversight was present in 41% of the SAR teams. These physicians participated in a range of SAR activities including medical protocol drafting (including expanded scope of practice), medical trainings, mission participation, medical consultation, and prescribing medications for field use. The majority (69%) of those physicians were trained in emergency medicine, and 45% of the active medical directors had protocols allowing for an expanded scope of practice due to the remote nature of SAR medical care. CONCLUSIONS: Intermountain West SAR teams vary in their activity, composition, training, and level of medical oversight. This study confirms that opportunities exist for physician integration with SAR teams in the studied states and likely throughout the United States.

Ibuprofen prevents altitude illness: a randomized controlled trial for prevention of altitude illness with nonsteroidal anti-inflammatories.

STUDY OBJECTIVE: Acute mountain sickness occurs in more than 25% of the tens of millions of people who travel to high altitude each year. Previous studies on chemoprophylaxis with nonsteroidal anti-inflammatory drugs are limited in their ability to determine efficacy. We compare ibuprofen versus placebo in the prevention of acute mountain sickness incidence and severity on ascent from low to high altitude. METHODS: Healthy adult volunteers living at low altitude were randomized to ibuprofen 600 mg or placebo 3 times daily, starting 6 hours before ascent from 1,240 m (4,100 ft) to 3,810 m (12,570 ft) during July and August 2010 in the White Mountains of California. The main outcome measures were acute mountain sickness incidence and severity, measured by the Lake Louise Questionnaire acute mountain sickness score with a diagnosis of ≥ 3 with headache and 1 other symptom. RESULTS: Eighty-six participants completed the study; 44 (51%) received ibuprofen and 42 (49%) placebo. There were no differences in demographic characteristics between the 2 groups. Fewer participants in the ibuprofen group (43%) developed acute mountain sickness compared with those receiving placebo (69%) (odds ratio 0.3, 95% confidence interval 0.1 to 0.8; number needed to treat 3.9, 95% confidence interval 2 to 33). The acute mountain sickness severity was higher in the placebo group (4.4 [SD 2.6]) than individuals receiving ibuprofen (3.2 [SD 2.4]) (mean difference 0.9%; 95% confidence interval 0.3% to 3.0%). CONCLUSION: Compared with placebo, ibuprofen was effective in reducing the incidence of acute mountain sickness.