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High Altitude Pulmonary Edema and Exercise at 4, 400 Meters on Mount McKinley: Effect of Expiratory Positive Airway Pressure
Section snippets
Subjects
Subjects were volunteers from climbers on Mt McKinley in the months of May and June, 1983. They gave informed consent as approved by the Human Subjects Review Committees of the Universities of Washington and Alaska. The healthy subjects consisted of 12 men and one woman (23 to 41 years). The 13 subjects (29. 7±5. 9 years) had successfully ascended to 4, 400 m or higher without symptoms of altitude illness and had resting arterial oxygen saturations (SaO2 percent) of 85 ± 3 percent. The four
RESULTS
No subjects suffered any adverse effects from the EPAP mask.
Resting SaO2 percent was significantly lower in HAPE subjects than normal subjects at all levels of EPAP (p<0. 005). Climbers with HAPE increased their resting SaO2 percent at 0, 5, and 10 cm H2O EPAP, respectively (Fig 1A). The SaO2 percent was significantly higher in normal subjects on EPAP 10 cm H2O than on EPAP 0 cm H2O at rest (p<0. 01). The SaO2 percent decreased significantly in normal subjects from rest to 600 kpm/min at each
DISCUSSION
The results of this study demonstrate that in a small number of climbers with HAPE at the same altitude at rest, increasing levels of EPAP increased oxygen saturation without increasing ventilation and changed the pattern of breathing to a higher tidal volume and lower frequency. In healthy subjects at 4, 400 m, the use of EPAP with 5 and 10 cm H2O pressure, at rest and modest workloads, increases SaO2 percent, probably because of an increased ventilation. It also raises HR. This study is the
ACKNOWLEDGMENT
This project would not have been possible without our camp managers, Brian and Diane Okonek; the enthusiastic and helpful cooperation of the climbing rangers of the US National Park Service; the skilled assistance of pilots Jim Okonek of K-2 Aviation and Doug Geeting and Lowell Thomas, Jr, of Talkeetna Air Taxi, both of Talkeetna, Alaska; the invaluable technical skills of Karl H. Maret, MD; and the literature search of Matthew Hegewald.
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This study was supported by PHs NHLBI Clinical Investiator Grant HL00906 and an E. L. Trudeau Scholar Award of the American Lung Association (R.B.S.).