Advertisement

Controlled Hyperventilation After Training May Accelerate Altitude Acclimatization

Published:October 13, 2014DOI:https://doi.org/10.1016/j.wem.2014.04.009
      To the Editor:
      On January 28, 2014, a group of 26 trekkers (aged 29 to 65 years), under the supervision of the authors, ascended one of the world’s highest mountains (Mt. Kilimanjaro, 5895 m) in 48 hours (Figure 1). While doing so, the group appears to have broken new medical ground, utilizing a new method to largely prevent, and as needed, reverse, symptoms of acute mountain sickness (AMS).
      Figure thumbnail gr1
      Figure 1Map of the Marangu route showing ascent versus time.
      Seemingly an unlikely group of people for such a feat, the group consisted of nonathletes with little or no prior climbing experience, inhabitants of low altitudes, some with typically handicapping diagnoses such as multiple sclerosis, rheumatoid arthritis, and metastasized cancer. The team was predicted by mountaineering experts to fail owing to those demographics. It was assessed at the highest risk for exhaustion and altitude sickness due to very rapid ascent (>500 m per day), high final altitude (>4000 m), and unknown history of AMS (according to a recent literature review).
      • Bärtsch P.
      • Swenson E.R.
      Clinical practice: acute high-altitude illnesses.
      To offset these significant disadvantages, the group received special training, including mindset coaching, cold exposure, and breathing technique practice, as previously described and currently under investigation by the authors.
      • Kox M.
      • van Eijk L.T.
      • Zwaag J.
      • van den Wildenberg J.
      • Sweep F.C.
      • van der Hoeven J.G.
      • Pickkers P.
      Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans.
      The trekkers used breathing techniques (permanent controlled hyperventilation aimed at keeping oxygen saturation (Spo2) greater than 90% during the ascent both prophylactically and therapeutically. At regular intervals, all trekkers participated in 30-minute breathing sessions, filled out a safety checklist based on the Lake Louis Scoring System (LLSS [Figure 2]) with a “buddy,” and were examined by the medical doctor.
      • Luks A.M.
      • McIntosh S.E.
      • Grissom C.K.
      • et al.
      Wilderness Medical Society consensus guidelines for the prevention and treatment of acute altitude illness.
      Figure thumbnail gr2
      Figure 2The Acute Mountain Sickness Safety Checklist. AMS, acute mountain sickness; GI, gastrointestinal; F/W, fatigue/weakness; N&V, nausea and vomiting.
      The results were remarkable. First, the ascent is typically completed by 61% of trekkers and takes 4 to 7 days.
      • Davies A.J.
      • Kalson N.S.
      • Stokes S.
      • et al.
      Determinants of summiting success and acute mountain sickness on Mt Kilimanjaro (5895 m).
      Of our group, 92% completed the ascent (2 had to stop at 5681 m). Second, the group reached the summit (5895 m) in only 48 hours. Third, none of the trekkers had severe AMS following the LLSS nor reported symptoms of hypocapnia due to the hyperventilation. None had used any method of prevention other than the training and techniques described above.
      • Luks A.M.
      • McIntosh S.E.
      • Grissom C.K.
      • et al.
      Wilderness Medical Society consensus guidelines for the prevention and treatment of acute altitude illness.
      • Davies A.J.
      • Kalson N.S.
      • Stokes S.
      • et al.
      Determinants of summiting success and acute mountain sickness on Mt Kilimanjaro (5895 m).
      The LLSS remained 4 or less for 22 trekkers (mild AMS). Four had an LLSS of 5 or 6 (moderate AMS) at 1 check-up, and the LLSS decreased to 4 or less after a 30-minute breathing session. Two had clinical signs of physical/respiratory exhaustion at 5681 m, which resolved after 15 minutes of oxygenation (12 L/min) and descent; of whom one had transient mild hypothermia, and a third had suspected mild high-altitude pulmonary edema (LLSS 5, pulse 97 beats/min, Spo2 73%, respiratory rate 18 breaths/min, frothy sputum, but absence of crepitations on auscultation of the lungs) upon descent to a rest camp (3760 m), and it resolved within 3 hours after oral administration of nifedipine 30 mg.
      The technique used by the trekkers is named the Wim Hof method, after the inventor who has been inspired by Tummo meditation. First, by intense mindset coaching, one can gain more confidence in one’s physical potential and is continuously challenged to push physical boundaries and improve health control. Second, decreasing pCO2 by controlled hyperventilation can stimulate this process as it improves endurance and enhances perceived energy levels. Third, generation of body heat during gradual cold exposure using breathing techniques is one of the fundamental exercises of the method (Tummo). The method seems to have a direct biological effect on the autonomic nervous system, and warrants further investigation.
      • Kox M.
      • van Eijk L.T.
      • Zwaag J.
      • van den Wildenberg J.
      • Sweep F.C.
      • van der Hoeven J.G.
      • Pickkers P.
      Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans.
      The exact pathophysiology of AMS remains unclear. In the authors’ opinion, the severity and duration of hypobaric hypoxia play a key role. The remarkable results are most likely explained by the continuous controlled hyperventilation reducing hypoxia severity. However, the resultant state of respiratory alkalosis may cause symptoms such as dizziness and visual disturbances. The fact that none of the trekkers experienced such symptoms is most likely due to the long-term training.
      In comparison with previous studies,
      • Davies A.J.
      • Kalson N.S.
      • Stokes S.
      • et al.
      Determinants of summiting success and acute mountain sickness on Mt Kilimanjaro (5895 m).
      • Meyer J.
      Twice-daily assessment of trekkers on Kilimanjaro’s Machame route to evaluate the incidence and time-course of acute mountain sickness.
      this report may suggest that acclimatization, as well as AMS symptom relief, can be safely accelerated. Based on previous data, it was expected that the majority of our group would experience severe AMS. All 26 trekkers had symptoms of AMS to some extent, but even without prophylaxis, none had severe AMS. Even though we discourage (very) rapid ascent because of potentially lethal risks, we consider these outcomes of potentially great relevance for the prevention and treatment of AMS, as well as for rescue teams needing to ascend fast with little time for acclimatization. Further research is warranted to expand or revise our understanding of the physiology and treatment of these conditions.

      References

        • Bärtsch P.
        • Swenson E.R.
        Clinical practice: acute high-altitude illnesses.
        N Engl J Med. 2013; 368: 2294-2302
        • Kox M.
        • van Eijk L.T.
        • Zwaag J.
        • van den Wildenberg J.
        • Sweep F.C.
        • van der Hoeven J.G.
        • Pickkers P.
        Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans.
        Proc Natl Acad Sci USA. 2014; 111: 7379-7384
        • Luks A.M.
        • McIntosh S.E.
        • Grissom C.K.
        • et al.
        Wilderness Medical Society consensus guidelines for the prevention and treatment of acute altitude illness.
        Wilderness Environ Med. 2010; 21: 146-155
        • Davies A.J.
        • Kalson N.S.
        • Stokes S.
        • et al.
        Determinants of summiting success and acute mountain sickness on Mt Kilimanjaro (5895 m).
        Wilderness Environ Med. 2009; 20: 311-317
        • Meyer J.
        Twice-daily assessment of trekkers on Kilimanjaro’s Machame route to evaluate the incidence and time-course of acute mountain sickness.
        High Alt Med Biol. 2012; 13: 281-284