Sleep and Periodic Breathing at High Altitude: Sherpa Natives Versus Sojourners

Lahiri, S.; Maret, K. H.; Sherpa, Mingma G.; PetersJr., Richard M.

doi:10.1007/978-1-4614-7525-5_8

Cited by 14 publications

(6 citation statements)

References 37 publications

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“…A phase difference between the apneic part of the PB cycle and the measured minimal SaO 2 has been noted. 38,41 Lahiri et al found the time lag between peak ventilation and peak SaO 2 (measured at the ear and indicating circulation time) during PB at an altitude of 5400 m to be 12 s compared to 6.8 to 9.4 s found during rest at sea level. 38,43 Therefore, the increased gain of the O 2 chemoreflex system and the increased circulation time observed at high altitude would make the ventilatory feedback loop unstable as predicted by the ventilatory control model described before.…”

Section: Mechanism Of Periodic Breathingmentioning

confidence: 95%

“…1,4,8,11,16,[34][35][36][37] Sustained PB with apnea was not seen in Sherpa natives who were long standing dwellers at high altitude. 38 Several studies of sleep at high altitude have noted that PB and apnea are commonly seen during nonREM sleep but not during REM sleep. 8,9,11,39 All these studies were performed at or below an altitude of 4300 m (barometric pressure ϳ450 mm Hg).…”

Section: Sleep State and Ventilation Under Hypobaric Hypoxic Conditionsmentioning

confidence: 99%

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Sleep and Breathing at High Altitude

Wickramasinghe

Anholm

1999

Sleep Breath

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Sleep at high altitude is characterized by poor subjective quality, increased awakenings, frequent brief arousals, marked nocturnal hypoxemia, and periodic breathing. A change in sleep architecture with an increase in light sleep and decreasing slow-wave and REM sleep have been demonstrated. Periodic breathing with central apnea is almost universally seen amongst sojourners to high altitude, although it is far less common in long-standing high altitude dwellers. Hypobaric hypoxia in concert with periodic breathing appears to be the principal cause of sleep disruption at altitude. Increased sleep fragmentation accounts for the poor sleep quality and may account for some of the worsened daytime performance at high altitude. Hypoxic sleep disruption contributes to the symptoms of acute mountain sickness. Hypoxemia at high altitude is most severe during sleep. Acetazolamide improves sleep, AMS symptoms, and hypoxemia at high altitude. Low doses of a short acting benzodiazepine (temazepam) may also be useful in improving sleep in high altitude.

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Section: Mechanism Of Periodic Breathingmentioning

confidence: 95%

Section: Sleep State and Ventilation Under Hypobaric Hypoxic Conditionsmentioning

confidence: 99%

Sleep and Breathing at High Altitude

Wickramasinghe

Anholm

1999

Sleep Breath

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“…None of them showed PB with apnea, in contrast to the acclimatized lowlanders, who showed sustained PB with apnea during sleep. Indeed, Sherpas exhibited only nominal decreases in arterial oxygen saturation during sleep (Lahiri et al, 1984). PB has been proposed to be a major cause of sleep-related arterial oxygen desaturation , whereas others have observed that PB during sleep at high altitude may improve average saturation levels (Salvaggio et al, 1998).…”

Section: Sleep Qualitymentioning

confidence: 99%

High Altitude Adaptation in Tibetans

Wu¹,

Kayser

2006

High Altitude Medicine & Biology

207

181

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Since the beginning of the Himalayan climbing era, the anecdotal extraordinary physical performance at high altitude of Sherpas and Tibetans has intrigued scientists interested in altitude adaptation. These ethnic groups may have been living at high altitude for longer than any other population, and the hypothesis of a possible evolutionary genetic adaptation to altitude makes sense. Reviewed here is the evidence as to whether Tibetans are indeed better adapted for life and work at high altitude as compared to other populations and, if so, whether this better adaptation might be inborn. Tibetans, compared to lowlanders, maintain higher arterial oxygen saturation at rest and during exercise and show less loss of aerobic performance with increasing altitude. Tibetans have greater hypoxic and hypercapnic ventilatory responsiveness, larger lungs, better lung function, and greater lung diffusing capacity than lowlanders. Blood hemoglobin concentration is lower in Tibetans than in lowlanders or Andeans living at similar altitudes. Tibetans develop only minimal hypoxic pulmonary hypertension and have higher levels of exhaled nitric oxide than lowlanders or Andeans. Tibetans' sleep quality at altitude is better and they desaturate less at night. Several of these findings are also found in Tibetans born at low altitude when exposed for the first time to high altitude once adult. In conclusion, Tibetans indeed seem better adapted to life and work at high altitude, and this superior adaptation may very well be inborn, even though its exact genetic basis remains to be elucidated.

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“…This case series found that the use of supplemental oxygen during ketamine dissociative anesthesia at high altitude was not required in healthy, acclim atized patients (ASA Physical Status Class 1 and 2). SaO 2 is known to fall in lowland residents during sleep at high altitude (Lahiri et al, 1984); however, under moderate ketamine anesthesia, the patient is arousable and the dissociated pain of the procedure provides a stimulus to breathe. During recovery when stimuli are preferably kept to a minimum to reduce nightmares, supplemental oxygen may be required for less acclim atized patients.…”

Section: Discussionmentioning

confidence: 99%

Ketamine Anesthesia at High Altitude

Bishop¹,

Litch

Stanton

2000

High Altitude Medicine & Biology

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There is a clinical need for a safe and effective anesthetic technique in high altitude and remote areas. This report presents a series of 11 consecutive cases documenting the use of ketamine anesthesia in a remote hospital at an altitude of 3,900 m, by primary-care physicians without specialist training in anesthesia. The method of administration is fully described. At a low dose of 2.0 mg/kg, ketamine produces a dissociative anesthesia that does not depress the hypoxic drive, or interfere with the pharyngeal or laryngeal reflexes. Although supplemental oxygen is useful in the recovery phase for less acclimatized individuals, it is usually not required as reductions in oxygen saturation can be raised by physical stimulation that encourages the patient to breathe faster and deeper. The common side effect of emergent nightmares was avoided using midazolam as premedication and a quiet recovery area. This study offers the first available evidence that ketamine with midazolam offers a safe and effective means of anaesthesia at very high altitude, without the need for specialist equipment or training, by careful clinicians experienced in basic airway management.

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Sleep and Periodic Breathing at High Altitude: Sherpa Natives Versus Sojourners

Cited by 14 publications

References 37 publications

Sleep and Breathing at High Altitude

Sleep and Breathing at High Altitude

High Altitude Adaptation in Tibetans

Ketamine Anesthesia at High Altitude

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