Positive end expiratory pressure as a method for preventing acute mountain sickness

Abstract

In order to study the use of positive end expiratory pressure (PEEP) to prevent acute mountain sickness (AMS), 22 subjects were exposed randomly to 8-h hypobaric hypoxia in a hypobaric chamber (4500 m, 589 hPa, 22 degrees C) once being administered 5-cm H2O PEEP and once without. The prevention of AMS by PEEP was evaluated by scoring AMS according to the Lake Louise system (self-report questionnaire and clinical assessment) throughout the experiment with O2 saturation (SO2) and heart rate measurements being made. Arterial blood analyses (partial pressures of arterial O2 and CO2, PaO2, PaCO2, and pH) were made at the end of the exposure. Results showed decreased AMS scores with PEEP at the end of the 8-h hypoxia [1.50 (SEM 1.32) vs 3.23 (SEM 2.07), P < 0.01 for self-report plus clinical assessment scores] with a lower prevalence (23% vs 55%, P < 0.01). The SO2, PaO2, PaCO2 and HCO3- did not change significantly. However, a smaller increase in arterial pH [7.47 (SEM 0.02) vs 7.50 (SEM 0.02), P < 0.05] was observed with PEEP, attesting a lesser alkalosis. Moreover, heart rate increased with PEEP (P < 0.05). In conclusion, this study would suggest that a 5-cm H2O PEEP may help decrease AMS scores at the end of an 8-h exposure to hypoxia in a hypobaric chamber. Such a method could be used to prevent AMS in such experimental conditions without adverse effects.

Prevention of acute mountain sickness by low positive end-expiratory pressure in field conditions

“…This observation may be related to an increase in alveolar ventilation, as reported by Savourey et al (7) in their study using the same system under laboratory conditions. The absence of a significant change in heart rate and in arterial blood pressure attests that the PEEP-5 system does not modify the cardiac variables, as also reported by Savourey et al (4,7,8). In the same way, the PEEP-5 system in our experiment did not affect microhematocrit after the ascent of Mount Blanc.…”

“…The PEEP prototype has been described earlier (4), and it was calibrated before each experiment. Briefly, it consisted of a bi-directional valve (patent 96402315-4-2309 Etat français) that applied a PEEP of 5-cm H 2 O and was attached to a Hans Rudolf face mask with a low dead space (Hans Rudolph Inc, Kansas City, MI, USA).…”

“…These pharmacological drugs have adverse side effects (3). Recently, Savourey et al (4) have shown that a nonpharmacological method, represented by low positive end-expiratory pressure (PEEP), is efficient in preventing acute mountain sickness in a hypobaric chamber without adverse effects. However, the efficacy of this PEEP system has yet to be evaluated at a high altitude under field conditions, which are very different from laboratory conditions.…”

Continuous Positive Airway Pressure Treatment for Acute Mountain Sickness at 4240 m in the Nepal Himalaya

“…The findings from this research are in agreement with previous findings that CPAP, PEEP, Auto-PEEP/ pursed lip breathing, and EPAP used at high altitude, rapidly increases the oxygen saturation (Schoene et al, 1985;Savourey et al, 1998;Davis et al, 1999;Launay et al, 2004;Tannheimer et al, 2009;Agostoni et al, 2010). The low number of subjects limits the robustness of the findings but it is clear that CPAP provides potential for treating this common disorder in an area where treatment availability is limited.…”

“…Other investigations into positive airway pressure at high altitude have found that, in awake subjects, positive end expiratory pressure (PEEP) applied via face mask increased Spo 2 and decreased AMS symptoms (Schoene et al, 1985) or decreased AMS but did not significantly improve Spo 2 (Savourey et al, 1998;Launay et al, 2004). Continuous positive airway pressure (CPAP) was used after ascent to 3205 m on Mount Cook in New Zealand; it improved Spo 2 and reduced symptoms of high altitude pulmonary edema (Davis et al, 1999).…”