Journal of Wilderness Medicine 1, 193-202 (1990) Successful use ofthe Gamow Hyperbaric Bag in the treatment ofaltitude illness at MountEverest SJ. KINGl* and R.R. GREENLEE2 1Departmentof Emergency Medicine, Parkview Episcopal Medical Center, 400 West 16th Street, Pueblo CO 81003, USA 2Department ofemergency Medicine, Latter-Day Saints Hospital, 55 North Redwood Road, Salt Lake City, UT 84116, USA Descent, the definitive treatment of altitude illness, can be simulated through the use of a new medical device, the Gamow Hyperbaric Bag (Gamow Bag). The Gamow Bag was field tested on Mount Everest during the 1988 Wyoming Centennial Everest Expedition (WCEE). We report six cases of acute mountain sickness which were managed in part with the Gamow Bag. All of the patients presented with dyspnea, weakness, and headache. They were treated with combinations of the Gamow Bag, oxygen, and descent. The patients were in the Gamow Bag from 1 to 10 h. After treatment, three of the patients had complete resolution of their symptoms and later ascended to or above the altitude where they first became ill. The other three patients were able to continue descent without incident. The Gamow Bag is a useful device in the treatment of altitude illness. Key words: Gamow Bag; altitude illness; high altitude pulmonary edema; hyperbaric bag Introduction A portable pressurized chamber, the Gamow Hyperbaric Bag (Gamow Bag), was devised in 1987. The Gamow Bag simulates a descent in altitude. In laboratory trials, it provides an effective decrease in altitude as measured by altimeters and was well tolerated by healthy subjects in the Rocky Mountains of Colorado. However, it has not yet been extensively field-tested under expedition conditions. In August 1988, a thirty-five member expedition, the Wyoming Centennial Everest Expedition (WCEE), approached Mount Everest overland after arriving by airplane in Lhasa, Tibet. Three Gamow Bags were carried as part of the medical supplies. A portion of the team traveled for five days by bus from 3680 m at Lhasa to the 5185 m Everest Base Camp. The remainder of the team required two weeks to reach the Base Camp. Over the ensuing two months, team members climbed between 5185 m and 7620 m. Four team members and two visiting trekkers suffered from extreme altitude illness during the stay. They were all placed in the Gamow Bag as a part of their treatment, with varying responses. These case reports detail their clinical courses. *To whom correspondence should be addressed at P.O. Box 1881, Pueblo, CO 81002, USA. 0953-9859/90 $03.00 +.12 1990 Chapman and Hall Ltd.
194 King and Greenlee Case reports Case 1 (RAPE andrace) JC, a 34-year-old male, traveled by bus from Xegar's altitude of 4270 m to Everest Base Camp at 5185 m without difficulty. He spent eight days at 4270 m, often hiking up to 4750 m, before ascent to Everest Base Camp. He did not use any medication during his travel. His past medical history included asthma. He had developed high altitude pulmonary edema in January 1988 at an altitude of 3050 m, necessitating treatment in an intensive care unit. His pulmonologist granted him medical clearance for the expedition. Upon arrival at Base Camp, he noted the onset of a headache, which gradually worsened. During his first day there, he developed an intermittent non-productive cough. The second day, he noticed shortness of breath while walking on level ground, accompanied by loss of assertiveness, apathy and malaise. On the third day, the headache became severe, the cough worsened, and he developed shortness of breath at rest. Examination revealed an overweight male with a persistent cough in no acute distress. His vital signs included blood pressure (BP) of 109/54 mmhg, pulse of 120 beats per min (bpm), and respiratory rate of 14 per min. Lung fields were clear with poor air flow. He had some difficulty with tandem gait and the nail beds were dusky. There was no peripheral edema. His forced vital capacity (FVC) averaged 2.70 I and his pulse oxygen saturation was 48%. The patient was treated in the Gamow Bag for 2 h. After 10 min in the Gamow Bag, oxygen saturation rose to 84% and pulse rate dropped to 99. Monitoring was continued after the victim was removed from the Gamow Bag. Within 15 min, he felt his headache returning. Oxygen saturation fell to 50% and pulse rate remained at 100. He was given dexamethasone 4 mg orally every 6 h and acetazolamide 250 mg every 8 h. The next day, he felt better despite no change in oxygen saturation and FVC. He was maintained on the above medications, and nifedipine 10 mg sublingually was added, accompanied by a rise in oxygen saturation. On the second day of treatment, he was given furosemide 60 mg IV, without a significant diuresis. His pulse was 112 and his BP was 122/74. That afternoon, he was started on oxygen at 1 1 min- t via face mask. On ambient air, his oxygen saturation had been 55%, dropping to 40% with any exertion, but rose to 86% while he breathed 11 min- t oxygen. Early in the morning of the third day of treatment, the oxygen tank ran dry and the victim's oxygen saturation dropped to 40%. Although his coughing increased, there was no increase in his respiratory rate, and he did not exhibit signs of respiratory distress. He was placed back in the Gamow Bag, with a resulting rise of his oxygen saturation to 75% and improvement of clinical symptoms. At this point, the decision was made to evacuate the patient from Base Camp by means of a vehicle that had become available. He was transported breathing oxygen at 11 min-t. The patient's symptoms resolved completely upon his return to 4270 m. Case 2 (RAPE) CS, a 53-year-old male, spent 18 days at Base Camp before continuing the climb up the mountain. He spent his first night at 5530 m, his second night at 5820 m, and his third night at 6020 m before arriving at the 6390 m Advanced Base Camp (ABC). He intermittently used a benzodiazepine to sleep at night. On his third day at ABC, he noticed increasing insomnia and took acetazolamide to promote rest. Over the next two
Successful use of the Gamow Hyperbaric Bag 195 days, he noted a worsening productive cough, exertional dyspnea, nausea and a headache. When he approached the physician on his fifth day at ABC, the patient was found to have a persistent cough productive of frothy pink to brown sputum, peripheral cyanosis, resting dyspnea, and bilateral pulmonary rales which extended halfway up the posterior lung fields. His FVC was 2.421. Aided by another team member, he descended to 5820 m with difficulty while breathing oxygen. The next day he continued his descent, stopping at 5530 m to be treated in a Gamow Bag for 1 h. When he arrived in Base Camp that afternoon, he was slightly improved with decreased sputum production. He still complained of dyspnea at rest and a cough. His vital signs included BP of 140/103 mmhg and pulse of 96 bpm. Examination revealed mucosal cyanosis and rales halfway up the posterior lung fields. His FVC averaged 3.00 1, with pulse oxygen saturation 76%. Shortly after arrival at Base Camp, he was placed in a Gamow Bag and treated continuously for 9.5 h. Examination at the end of the treatment revealed no cough, resolution of cyanosis, and a few faint crackles to pulmonary auscultation. He maintained a BP of 128/73, pulse of 94 bpm, oxygen saturation of 83%, and an average FVC of 2.871. He had mild dyspnea on exertion, but not at rest. He was not treated with any further oxygen or medications. Two days after the Gamow Bag treatment, he had a BP of 140/107 mmhg, pulse of 80 bpm, oxygen saturation of 83%, FVC of 4.081, and resolution of all symptoms. CS remained at Base Camp for one week before making a five-day ascent to 6390 m. He insisted on climbing to 7070 m, and was able to do so without recurrence of high altitude pulmonary edema. He returned from the climb in good condition with the rest of his team mates. Case 3 (HACE) RP, a 47-year-old female, traveled by vehicle from 4000 m to 5090 m in 1 day. During the day, she had onset of a severe headache, unrelieved by analgesics. She ate and drank little that afternoon and evening. The headache worsened, and she experienced a restless, uncomfortable night. The next morning, she complained of dyspnea and refused to leave her sleeping bag. Her travel companions gave her acetazolamide and oxygen, which provided some decrease in the headache. Her companions then hiked up to the Everest Base Camp to seek help, leaving her with the Nepalese cook. When they returned to camp 4 h later, RP was not there. The cook stated that she had gone for a walk. She was found wandering aimlessly about one-half mile away. She was oriented to place and name, but had a very short attention span. Physical examination revealed a well developed, dyspneic woman, with a pulse of 85 bpm, oxygen saturation of 77%, and FVC of 2.46 1. She had peripheral edema. The woman was taken to Everest Base Camp and put into the Gamow Bag. After 15 min in the chamber, her headache decreased dramatically, and her dyspnea disappeared. While in the Gamow Bag, her oxygen saturation rose to 92% and her cognition markedly improved. 2 h later, immediately after treatment, she noted that her edema was gone. Six hours after treatment, RP awoke with another terrible headache. Oxygen did not change the intensity of the headache. She was given analgesics and again put into the Gamow Bag. She spent 6 h in the bag, sleeping most of the time. 2 h after completion of the second treatment, she had neither headache nor dyspnea, and very clear cognition. She descended by vehicle to 4000 m with her companions.
196 King and Greenlee Case 4 (HAPE) RS, a 41-year-old male, previously healthy and on no medications, arrived at Everest Base Camp after a 3 day journey from Lhasa, an ascent of 1550 m. He noted onset of headache and nausea approximately 2 h after arrival. He was treated by the expedition's medic with an anti-emetic and 500 mg of acetazolamide. He slept reasonably well that night, but upon awakening, noted continued headache and nausea. The next day, he suffered several episodes of emesis, again treated with an anti-emetic. During the evening, he developed a persistent non-productive cough. He was given acetaminophen with codeine as a cough suppressant. Overnight, he experienced periodic breathing and upon awakening noticed moderate dyspnea with minimal exertion. On the third day, he was brought to our Base Camp for medical evaluation. Examination revealed a tired looking, slightly pale man. Vital signs were: BP 148/107 mmhg, pulse 82 bpm, respiratory rate 22, and FVC 4.0 1. Fine inspiratory rales in the posterior lung fields were noted; lips and nail beds were slightly cyanotic. The patient was placed in the Gamow Bag for a total of 165 min. He was also given two doses of nifedipine 10 mg. His symptoms resolved within 10 min after the bag was brought to pressure. After the first 2 h, he was taken out of the bag for 20 min at his request. After 15 min he felt his symptoms returning and asked to be put back into the bag. Thirty minutes later, the patient was again removed from the bag at his request, so that he could travel by jeep to return home. Case 5 (HAPE) BS, a previously healthy 59-year-old male, traveled from Base Camp to ABC over 7 days, an ascent of 1210 m. Upon his arrival in ABC, he complained of diminished appetite and had two episodes of emesis. The next day, he ascended to 6700 m with a light load. The second day after his arrival, he carried a moderately heavy load to 6600 m. On the morning of the third day, he complained of a non-productive cough but denied shortness of breath. Examination at that time revealed clear lung fields and no signs of cyanosis. Repeat examination that evening revealed rales and dusky nail beds. Although the patient was extremely stoic in nature, he admitted to shortness of breath at rest, worsened by laying down. Vital signs were BP 124/98 mmhg, pulse 110 bpm, respiratory rate 36 per min, and FVC of 1.18 1. Since darkness made descent impractical, he was placed in the Gamow Bag for 150 min. His symptoms resolved within 10 min. His appetite returned, so he was taken out to eat dinner. He elected to spend the night with oxygen (21 min-i), rather than in the bag. During the night, he experienced orthopnea but was not placed back in the bag because he did not want to disturb others. In the morning, he began to descend to Base Camp accompanied by a physician equipped with a Gamow Bag and oxygen. During the descent, he experienced chest pain which was relieved by rest and exacerbated by cold wind. The patient spent the night at 5800 m and again experienced orthopnea, but refused supplemental oxygen and the Gamow Bag. Upon arrival at Base Camp, his exam revealed bibasilar crackles, but arterial oxygen saturation and FVC had returned to near normal. After several days rest, he re-ascended to ABC without difficulty and did not experience further trouble. Case 6 (HAPE) AS, a previously healthy 30-year-old female, had stayed for approximately 4 days at
Successful use of the Gamow Hyperbaric Bag 197 the North Col, elevation 7070 m. On the fourth day she noticed a constant nonproductive cough. She rested in her tent most of the day; when she tried to ambulate, she had marked dyspnea with minimal exertion. Late in the afternoon, she descended with considerable difficulty to ABC (6390 m). Her symptoms at that point improved considerably, but she was still short of breath while talking. Examination revealed a breathless woman. Vital signs were pulse 105 bpm, respiratory rate 36 per min, PVC 2.28 I and BP not obtained due to extreme cold. Respiratory exam revealed faint bibasilar crackles. Lighting was not adequate to exclude the presence of cyanosis. She was placed in the Gamow Bag for 1 h. Supplemental oxygen was used at 2 I min-i, and she exhaled through a lithium hydroxide (LiOH) carbon dioxide scrubber. She felt considerably better in the bag, but was not able to keep warm. The oxygen cylinder apparently kept the bag interior cool. She therefore asked to come out of the bag and spent the rest of the night breathing oxygen. In the morning, she was able to descend to Base Camp without assistance. After several days rest at Base Camp, she returned to the North Col without difficulty and did not experience further difficulties. Methods These reports document effectiveness of the Gamow Bag, its optimum use, and indications and limitations in a mountaineering setting. There were 35 members of the Wyoming Centennial Everest Expedition and everyone provided informed consent to allow us to use the Gamow Bag when rapid descent was not possible. Use was monitored by expedition physicians at all times. Each member of the expedition was advised to take acetazolamide prophylactically. Subjects were placed in one of five categories: (1) Acute Mountain Sickness, (2) High Altitude Pulmonary Edema, (3) High Altitude Cerebral Edema, (4) Combinations of the above, or (5) Asymptomatic. A numerical scoring, based on the presence and severity of signs and symptoms, was used in an attempt to objectively quantify the severity of each illness (Table 1). Daily inquiries were made by the physicians regarding medical complaints of the expedition members. Persons with symptoms of altitude illness were scored on a diurnal basis. Members of the expedition were asked at frequent intervals to perform a forced vital capacity maneuver in an attempt to recognize early cases of HAPE. A hand-held Boehringer spirometer, calibrated by the Department of Pulmonary Medicine at LDS Hospital in Salt Lake City, Utah, was used. At the same time, altitude, use of medications, history of periodic breathing, and degree of physical exertion were recorded. When the Gamow Bag was used, the length of time in the bag, altitude, bag pressure, apparent altitude in the bag, PVC immediately before and after, and use of supplemental oxygen were recorded. Additionally, PVC measurements were recorded 2 and 6 h after bag use and twice daily for the next two days, providing the climber had access to a spirometer. Oxygen saturation was measured using an Ohmeda Biox 3740 pulse oximeter. The Gamow Hyperbaric Bag was invented by Dr Igor Gamow of the University of Colorado in Boulder and carries Food and Drug Administration approval for the treatment of acute altitude illness. It is a portable, air-tight, cylindrical bag of coated nylon into which a person can be placed. The Gamow Bags used by WCEE measure 7 ft long with a 21 in diameter, and have a 42 in entry/exit zipper along the length
198 Table 1. Scoring system for high altitude illnesses.'" King and Greenlee Acute Mountain Sickness (AMS)* (1) General impairment of condition (2) Anorexia (3) Nausea/vomiting (4) Ataxia (5) Insomnia (6) Headache High Altitude Pulmonary Edema (HAPE) (1) Cough (2) Dyspnea (3) Cyanosis (4) Lung sounds (5) Respiratory rate High Altitude Cerebral Edema (HACE) (1) Headache (2) Stupor/confusion (3) Papilledema (4) Ataxia (5) Hallucinations *Symptoms and signs were scored on a scale of 0 (no symptoms) to 4 (severe symptoms) in each of the following categories. of the bag. Air is pumped into the Gamow Bag with a hand pump, foot pump, or air compressor to a pressure of 2 psi or 103 torr. Bleed-off valves release air once the pressure in the bag reaches 2 psi; attachment of a manometer ensures that the valves are functioning properly. In its simplest form including the foot pump, the Gamow Bag weighs about 3.2 k. Studies with the bag have shown that if the air flow-through rate is maintained at 421 min-i, the carbon dioxide level in the bagis maintained below the 1% level [1]. This requires 15 pump strokes per min when using the bellows type foot pump. Since the fraction of oxygen in the atmosphere is 21%, a flow rate of 421 min-i results in the delivery of 8.8 1 of oxygen per min. Oxygen consumption at rest is approximately 0.510 2 min-i; therefore, more than enough oxygen is delivered to the Gamow Bag. The simulated descent created by the Gamow Bag increases as the initial altitude increases. At an altitude of 5400 m, the simulated altitude in the Gamow Bag is 3505 m, a decrease of 1895 m (Table 2). Discussion Descriptions of altitude sickness date as far back as 1590 [2]. Currently, there are four recognized major high altitude illnesses: (1) Acute Mountain Sickness (AMS), (2) High Altitude Pulmonary Edema (HAPE), (3) High Altitude Cerebral Edema (HACE), and
Successful use ofthe Gamow Hyperbaric Bag 199 Table 2. Altitude changes within the pressurized Gamow Bag. Ambient conditions m ft Inside Gamow Bag * m ft (m) Change (ft) 3900 4800 5400 6600 7800 8700 12796 15749 17717 21655 25592 28545 2299 3028 3505 4436 5335 5986 7543 9935 11500 14555 17504 19640 1601 5253 1772 5814 1895 6217 2164 7100 2465 8088 2714 8905 *Gamow Bag pressurized to 2 psi (103 torr) Adapted with permission from Igor Gamow. (4) High Altitude Retinal Hemorrhage (HARH). Definitive treatment of severe cases consists of rapid descent to lower altitude [3]. Weather, avalanche conditions, illness, and injuries often make immediate descent impossible. This unavoidable delay can lead to disastrous and, in some cases, fatal consequences. Consequently, climbers and scientists have long sought alternative treatments, most of which have been only partially successful [4]. The occurrence of AMS seems to be very closely linked with rate of ascent; if the ascent is too rapid, virtually 100% of individuals will be affected [5]. AMS consists of a group of symptoms such as weakness, nausea, vomiting, headaches, sleep disturbances, and confusion. Signs such as ataxia, hallucinations, and difficulty performing simple calculations may also be present. AMS is generally best treated with preventive measures. Acclimatization, safe ascent rates, and acetazolamide have been shown to be effective prophylactic measures [6]. HAPE consists of symptoms such as marked dyspnea, and a cough commonly productive of pink frothy sputum. Observed signs include cyanosis, rales, tachycardia, and tachypnea. HAPE is ultimately treated with descent. When descent is not possible, alternative treatments such as oxygen supplementation, steroids, calcium channel inhibitors and diuretics have been used. HAPE often occurs among persons who travel to altitudes above 4200 m for recreation, sport, and mountaineering. These areas are usually remote, with few or no medical facilities available. The incidence of HAPE varies considerably and depends on age, rate of ascent, elevation attained, place of residence, past history of altitude illness, level of physical exertion, and pre-existing conditions [2]. One study carried out in Peru showed an overall HAPE incidence of 0.6% [7]. Another study in India showed incidences which ranged from 0.3% to as high as 13%, depending on rate of ascent and age [8]. Observation of other climbers before and after ascent revealed that 15% had rales, suggesting the presence of pulmonary edema [5]. HACE seems to be relatively rare in comparison to the other altitude illnesses. Its most prominent feature is severe headache. This may be accompanied by level of consciousness changes, confusion, hallucinations, ataxia, coma, and death. In addition to descent, treatment with dexamethasone has been reported to be effective [9]. The incidence of HARH has been carefully studied and found to occur in about 50% of individuals at altitudes of 5335 m or greater [10]. Most affected individuals are
tv o Table 3. Observed patient changes before and after Gamow Bag treatment. RAPE AMS RACE Ambient Altitude FVC FVC Sa0 2 Sa O 2 Rours Score Score Score Altitude in bag before after before after in bag Case 1 6.0 7.5 5.0 5180 3270 2.70 2.57 48 65 4.5* Case 2 11.5 8.0-5180 3270 2.42 4.23+ 48 83+ 9.5 Case 3 5.0 11.5 9.5++ 5180 3270 2.46 2.52 77-8.0 Case 4 8.5 9.5-5180 3400 4.03 4.65 70 87 2.5 Case 5 10.0 - - 6390 4200 1.18 2.99 - - 2.5 Case 6 5.0+ v - - 6390* 4200 2.28 2.44 61 65 1.0 *This patient had two treatments separated by 24h, for a totai4.5h. +These values did not change for several days after treatment. ++HACE score imcomplete due to language barrier. This patient had two treatments separated by 6 h. Patient had normal oxygen saturation and FVC upon descent to 5180 m. 'Lack of lighting did not permit accurate assessment of cyanosis. 'Patient descended from 7070m to 6390m before assessment and treatment. ~ ~. ~ c;') ~ ~ l1:l
Successful use ofthe Gamow Hyperbaric Bag 201 asymptomatic. Generally, there are no long term sequelae, and treatment is not required. The Gamow Bag did not delay or prevent evacuation. Vehicles would infrequently and unpredictably become available for the transport down to 5185 m; a distance of 30 km was needed for a descent of 1000 m below that point, making a hiking descent impractical. The Gamow Bag proved useful in quickly treating the symptoms of altitude illness. All subjects reported prompt resolution of symptoms while in the Gamow Bag. Furthermore, the Gamow Bag treatment effectively returned arterial oxygen saturation to a higher level in people with RAPE. Because the variables of dexamethasone, acetazolamide, nifedipine and descent affected the data, it is impossible to attribute all improvement to the pressurization, but it is our impression that the Gamow Bag provided quick relief of symptoms due to the simulated descent. Case 1 demonstrated a blunted response to hypoxia and had a predisposition to RAPE. In this case, the bag served as a supportive measure until evacuation became possible. Case 2 had descended over 1000 m in 2 days with little improvement in symptoms, but showed dramatic improvement after 9.5 h in the Gamow Bag, whereas descent largely cleared the symptoms experienced by Case 6. In some instances a remarkable improvement in FVC was seen with even relatively short treatment periods, perhaps indicating reversal of the disease process (Table 3). The two cases where FVC measurements did not improve occurred with case 1 who displayed a large component of RACE, and with case 6 who had already descended 700 m before 1 h of treatment. It appears that mild cases of altitude illness respond relatively quickly, while more severe cases may require extended treatment periods. This may represent a limitation of use, since pumping for extended periods of time at high altitude is quite exhausting, unless a large number of rescuers are available. It is also possible that an increased intrabag pcoz of 1% could increase respiratory drive, thereby increasing SaCO z ' Unfortunately, we were unable to measure PCOz' Conclusion The Gamow Bag appears to be an extremely useful device for treatment of altitude illness when descent is not possible or immediately advisable. Further studies are needed to show when the use of the Gamow Bag may totally obviate the need for descent. Acknowledgements We wish to thank Ohmeda, Protocol Systems, Boehringer Laboratories and Dr Igor Gamow for the generous use of their equipment. References 1. Kasic, J.F., Smith, H.M. and Gamow, R.I. A self-contained life support system designed for use with a portable hyperbaric chamber. Biomed Sci lnstrum 1989; 25, 79-81. 2. Houston, C.S., ed. High altitude physiology study-collected papers. Alberta: Arctic Institute of North America, 1980.
202 King and Greenlee 3. West, 1.B. and Lahiri, S. High altitude and man. Maryland clinical physiology series. Bethesda: American Physiological Society, 1984. 4. Schoene, R.B. High-altitude pulmonary edema: pathophysiology and clinical review. Ann Emerg Med 1987; 9, 987-92. 5. Houston, C.S. Going high. New York: American Alpine Club, 1980. 6. Hackett, P.H., Rennie, D. and Levine, H.D. The incidence, importance, and prophylaxis of acute mountain sickness. Lancet 1976; 2(7996), 1149-55. 7. Hultgren, H.N. and Marticorena, E.A. High altitude pulmonary edema-epidemiologic observations in Peru. Chest 1978; 16, 142. 8. Menon, N.D. High altitude pulmonary edema. N Engl J Med 1965; 273, 66-73. 9. Houston, C.S. and Dickinson, J. Cerebral form of high altitude illness. Lancet 1975; 2(7938),758-61. 10. Frayser, R., Houston, C.S., Bryan, A.C., Rennie, I.D. and Gray, G. Retinal Hemorrhage at High Altitude. N Engl J Med 1970; 282, 1183-4. WENATCHEE EMERGENCY PHYSICIANS Wenatchee, Washington Currently recruiting full time Emergency Physicians challenging practice outstanding lifestyle attractive compensation partnership after 1 year FOR FURTHER INFORMATION CONTACT: Mike Parnell, M.D., F.A.C.E.P. Wenatchee Emergency Physicians P.O. Box 4600 Wenatchee, WA 98807 (509) 662-1511 (Ext. 2210) KSlatcIJeeEmergencyPhysicians,PC.