Caudwell Xtreme Everest: An Overview

Grocott, Michael P.W.; Levett, Denny; Martin, Daniel; Wilson, Mark; Mackenney, A.; Dhillon, Sundeep; Montgomery, Hugh; Mythen, Michael G.; Mitchell, Kay

doi:10.1007/978-1-4899-7678-9_28

Cited by 2 publications

(3 citation statements)

References 34 publications

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“…The transportation of expensive and fragile equipment to high-altitude regions is a significant final hurdle because conventional carriage is impossible and there may exist difficulties with importation tax and customs. It is for these reasons that high-altitude field studies have normally included multiple experimental questions and their corollary publications, often yielding >10 papers from a single expedition (recent examples include: AltitudeOMICS [ 23 ]; Caudwell Xtreme Everest [ 10 ]). Such a research design is sometimes criticized for duplication or overlap of data, but is defensible providing that that any duplication of data is acknowledged and that publications are not intentionally partitioned, but rather best packaged to address their respective a priori hypotheses.…”

Section: Discussionmentioning

confidence: 99%

“…Expedition members flew to Lukla (2860m) over two days, after which they hiked as a group to the Pyramid Laboratory (5050m) over 9–10 days with obligatory rest / testing days at 3440m (day 4; 2 days) and 4371m (day 7; 2 days). These testing days were scheduled as part of a conservative acclimatization schedule [ 10 ] to mitigate acute mountain sickness and prevent the need for prophylactic acetazolamide, and were also necessary to complete a range of studies conducted during ascent. High-altitude medications (e.g., acetazolamide, dexamethasone) and oxygen were available at all times in case of an emergency.…”

Section: Methodsmentioning

confidence: 99%

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UBC-Nepal Expedition: An experimental overview of the 2016 University of British Columbia Scientific Expedition to Nepal Himalaya

et al. 2018

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The University of British Columbia Nepal Expedition took place over several months in the fall of 2016 and was comprised of an international team of 37 researchers. This paper describes the objectives, study characteristics, organization and management of this expedition, and presents novel blood gas data during acclimatization in both lowlanders and Sherpa. An overview and framework for the forthcoming publications is provided. The expedition conducted 17 major studies with two principal goals—to identify physiological differences in: 1) acclimatization; and 2) responses to sustained high-altitude exposure between lowland natives and people of Tibetan descent. We performed observational cohort studies of human responses to progressive hypobaric hypoxia (during ascent), and to sustained exposure to 5050 m over 3 weeks comparing lowlander adults (n = 30) with Sherpa adults (n = 24). Sherpa were tested both with (n = 12) and without (n = 12) descent to Kathmandu. Data collected from lowlander children (n = 30) in Canada were compared with those collected from Sherpa children (n = 57; 3400–3900m). Studies were conducted in Canada (344m) and the following locations in Nepal: Kathmandu (1400m), Namche Bazaar (3440m), Kunde Hospital (3480m), Pheriche (4371m) and the Ev-K2-CNR Research Pyramid Laboratory (5050m). The core studies focused on the mechanisms of cerebral blood flow regulation, the role of iron in cardiopulmonary regulation, pulmonary pressures, intra-ocular pressures, cardiac function, neuromuscular fatigue and function, blood volume regulation, autonomic control, and micro and macro vascular function. A total of 335 study sessions were conducted over three weeks at 5050m. In addition to an overview of this expedition and arterial blood gas data from Sherpa, suggestions for scientists aiming to perform field-based altitude research are also presented. Together, these findings will contribute to our understanding of human acclimatization and adaptation to the stress of residence at high-altitude.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

UBC-Nepal Expedition: An experimental overview of the 2016 University of British Columbia Scientific Expedition to Nepal Himalaya

et al. 2018

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“…Therefore, counterintuitively (1), hypoxemia should not be the priority when addressing SILI or managing ARDS. Indeed, a) High altitude evokes severe hypoxemia, hypocapnia, alkalosis, but low lactate (45) and normal microcirculation. b) Runners experience severe tachypnea, hyperpnea and acidosis, which are addressed only with rest and cooling.…”

Section: We Follow a Modified Strategy To Breakup Sili Allowing For E...mentioning

confidence: 99%

Does Interrupting Self-Induced Lung Injury and Respiratory Drive Expedite Early Spontaneous Breathing in the Setting of Early Severe Diffuse Acute Respiratory Distress Syndrome?

Petitjeans

Leroy²,

Pichot

et al. 2022

Critical Care Medicine

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In patients with acute respiratory distress syndrome (ARDS), a high inspiratory respiratory activity intensity ("drive") leads to a high transpulmonary inspiratory pressure (1), vascular leakage, tachypnea, a high tidal volume (hyperpnea), hypocapnia (2), and pendelluft (3), that is, self-inflicted lung injury (SILI). More severe lung injury leads to a higher drive (4) and vice versa. Therefore, endotracheal intubation ("intubation"), controlled mechanical ventilation and paralysis (i.e., controlled mandatory ventilation [CMV]) are required to interrupt SILI and protect the lung and diaphragm (1-3). Initially, deep sedation, in fact general anesthesia (GA), is needed. However, the respiratory muscles of ARDS patients are fully functional, at variance with exhaustion observed in decompensated chronic obstructive pulmonary disease. Thus, CO 2 excretion is not an issue and does require neither resting and paralyzing the muscles nor GA. Hence, our approach to treatment of early severe diffuse ARDS is at variance with present practice (5, 6) but rests on physiologically controlling the drive, allowing for early spontaneous breathing (SB) (7-9). Indeed, randomized controlled trials of neuromuscular blockade (5) are flawed (10), as there is no comparison with adequate SB. Furthermore, the duration of paralysis is undocumented: 12 hours (11), 24 hours, or 48 hours (5)? Similarly, the randomized controlled trials of prone positioning ("proning") ( 6) are not compared with upright positioning (12) despite a similar increase in Pao 2 /Fio 2 (P/F). Finally, is prolonged GA harmful or beneficial to the patients? Are these questions relevant? Indeed, the use of CMV + GA + paralysis + proning decreased mortality from ~45-52% (13) to 16% (6) (Milan: 15-20%, J. J. Marini, personal communication, 2020). However, mortality remained high in some critical care units (CCUs) at the beginning of the severe acute respiratory syndrome coronavirus 2 (coronavirus disease [COVID]) pandemic (mortality: 88% [14]; Lombardy excluding Milan: ∼80%). We will provide some thoughts below which we argue that CMV + GA + paralysis + proning is only a rescue therapy but is currently being used as first-line therapy. This style of practice does not address: a) the shortage of proning staff and anesthetics and the required high turnover, b) the core disease including early expiratory bronchiolar (11) or alveolar closure ("closure"; diffuse alveolar disease) that lowers the oxygen diffusion surface,

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Caudwell Xtreme Everest: An Overview

Cited by 2 publications

References 34 publications

UBC-Nepal Expedition: An experimental overview of the 2016 University of British Columbia Scientific Expedition to Nepal Himalaya

UBC-Nepal Expedition: An experimental overview of the 2016 University of British Columbia Scientific Expedition to Nepal Himalaya

Does Interrupting Self-Induced Lung Injury and Respiratory Drive Expedite Early Spontaneous Breathing in the Setting of Early Severe Diffuse Acute Respiratory Distress Syndrome?

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