Mt Whitney Zone Forums Reference Altitude Research Study at Whitney Portal

Dale R. Wagner, Ph.D.
Assist. Prof. Dept. of Health, Physical Education, & Recreation
Utah State University, Logan, UT

Mt. Whitney: Determinants of Summit Success

Introduction
Mt. Whitney (4419 m) is the highest point in the contiguous 48 states of the United States. There are numerous routes of varying difficulty to reach the summit with no technical climbing or mountaineering skill required for an ascent of the easiest route. The trailhead (2550 m) can be accessed by a paved road. Due to its distinction of being the "highest", ease of access, and a non-technical climbing route, Mt. Whitney sees many attempts by both novice and experienced mountaineers alike. In fact, there are so many attempts during the summer months that the Inyo National Forest Service has placed a permit restriction of 150 people/day on the normal route to protect the wilderness environment. Furthermore, the mountain is located within a half-day drive of many highly-populated California costal cities. Thus, many of the attempts are made by unacclimatized, sea-level residents.

Acute mountain sickness (AMS) is a self-limiting syndrome characterized by a headache with other symptoms such as gastrointestinal distress, lassitude, dizziness, and sleep difficulty that commonly occurs in unacclimatized individuals that ascend too rapidly above 2500 m. (1). Despite the fact that AMS can progress to the deadly condition of high altitude cerebral edema (HACE), mountaineers sometimes ignore these symptoms to reach a summit. Recently, we found that 33% of the summiteers of Mt. Whitney met the criteria for AMS (2). Although this study was valuable in that it quantified the prevalence of AMS on the summit and identified variables that were significant risk factors for developing this condition, it was limited in that only summiteers were studied. Many people that attempt Mt. Whitney turn back before reaching the summit for a variety of reasons including suffering from symptoms associated with altitude illness. It is likely that the incidence of AMS on the mountain is higher than the 33% reported from summiteers.

Although Mt. Whitney is one of the most sought after summits in the United States, the success rate has never been calculated. Furthermore, no studies have been done to identify the variables that significantly contribute to a successful summit on this peak. Thus, the purpose of this study is to estimate the summit rate and identify determinants of success on Mt. Whitney by interviewing climbers after they have descended and are preparing to exit from the Whitney Portal trailhead. Furthermore, we aim to add to the body of knowledge about altitude illness by estimating the total incidence of AMS on the mountain, rather than just what was observed on the summit, and identify significant risk factors.

Methods

Location and participants
We will collect data at the Whitney Portal trailhead (2550 m). Researchers will be positioned near the trailhead sign and pack weighing scale, and we will solicit volunteers who have descended from the mountain. The data collection period will span approximately 15 days (July 28 -- August 13). During this time, we hope to collect data on 1,000 to 2,000 participants. This number is based on the number of people on the mountain approaching the 150/day permit limit. Additionally, based on our previous research study (2), we anticipate a high percentage (80-90%) of the mountaineers will volunteer to participate in the study. Participants will be given an informed consent form (Appendix A) and will be encouraged to ask questions about the study. The study will be approved by the institutional review boards of the participating institutions. The Inyo National Forest Service will issue a special use permit for data collection at the Whitney Portal trailhead.

Data collection
Data will be gathered via a self-report questionnaire (Appendix B). The questionnaire contains four sections: 1) demographic characteristics to include age, gender, height, weight, and smoking status, 2) acclimatization, previous altitude experience, and training history to include altitude of residence, number of ascents and amount of time above 3000 m (10,000') in the two weeks prior to this ascent, lifetime maximum altitude achieved prior to this ascent, previous history of altitude illness, and the number of hours/week spent training in the month prior to this ascent, and 3) characteristics related to the ascent to include route of ascent, if the summit was reached and if so, what was the ascent time, reason for not reaching the summit and approximate altitude that was reached, type and amount of medication used (none, analgesics, acetazolamide, or Ginko biloba) and if it was taken as a prophylactic or after symptoms developed, and 4) AMS data to include the headache score and total AMS score from the Lake Louise Self-Assessment Questionnaire (LLSQ) (Appendix C). In addition to this self-report data, heart rate and oxygen saturation (%SaO2) at the trailhead will be measured with a finger pulse oximeter (SportStat, Nonin Medical, Plymouth, MN). Pulse oximetry data will be obtained from the right index finger in approximately 30 sec. with the subject in a standing position after completing the self-report questionnaire (approximately 10 minutes). These variables were selected for inclusion in this study based on our previous research on Mt. Whitney (2) and a recent similar study that looked at the determinants of success and AMS on Mt. Aconcagua, the highest point in the Western Hemisphere (3).
AMS will be assessed by the LLSQ developed by Roach et al. (1). This commonly used assessment includes five symptoms: headache, gastrointestinal distress, fatigue and/or weakness, dizziness or lightheadedness, and difficulty sleeping. Each symptom is scored zero (not present) through three (severe or incapacitating) for a combined minimal score of zero and a maximal score of 15. Our criteria for AMS will be 1) a headache, 2) at least one other symptom, and 3) a total score of 3 or more. This is the preferred assessment method and criteria for evaluating AMS (4,5).

Statistical Analysis
Basic descriptive statistics, including measures of central tendency, variance, and frequency, will be computed for all variables measured on the study sample. Multiple logistic regression analysis will be used to identify the factors that significantly predict summit success on Mt. Whitney as well as those that are potential protective and risk factors of AMS.

References

1. Roach RC, Bartsch P, Hackett PH, Oelz O. (Lake Louise AMS Scoring Consensus Committee). The Lake Louise acute mountain sickness scoring system. In: Sutton JR, Houston CS, Coates G, eds. Hypoxia and Molecular Medicine. Burlington, VT: Queen City Printers; 1993:272-274.
2. Wagner DR, Fargo JD, Parker D, Tatsugawa K, Young TA. Variables contributing to acute mountain sickness (AMS) on the summit of Mt. Whitney. Wilderness Environ Med In press.
3. Pesce C, Leal C, Pinto H, Gonzalez G, Maggiorini M, Schneider M, Bartsch P. Determinants of acute mountain sickness and success on Mount Aconcagua (6962 m). High Alt Med Biol 2005;6:158-166.