Hypobaric hypoxia is not a direct dyspnogenic factor in healthy individuals at rest

Nakano, Takayuki; Iwazaki, Masayuki; Sasao, Gen; Nagai, Asuka; Ebihara, Akinori; Iwamoto, Tokuzen; Kuwahira, Ichiro

doi:10.1016/j.resp.2015.07.009

Cited by 14 publications

(43 citation statements)

References 18 publications

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“…Mice acutely breathing 17% O 2 had a mean PaO 2 of 77.5 ± 8 mmHg and a mean transcutaneous SpO 2 of 88.5 ± 3%. Breathing 11% O 2 resulted in a mean PaO 2 of 45 ± 4 mmHg and mean SpO 2 of 61.3 ± 2.5% ( n = 5) (Table 1), resulting in a similar PaO 2 as seen in humans breathing equivalent O 2 pressures (23, 24). After 3 wk of chronic 17% O 2 breathing, the value of venous hematocrit in KO mice was 51 ± 3%, compared with 60 ± 6% at 11% O 2 (normoxic control level, 44 ± 6%), ( P < 0.05 between groups; n = 6) (Fig.…”

Section: Resultsmentioning

confidence: 78%

Hypoxia treatment reverses neurodegenerative disease in a mouse model of Leigh syndrome

Ferrari

Jain

Goldberger

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

134

128

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SignificanceInherited or acquired defects in mitochondria lead to devastating disorders for which we have no effective general therapies. We recently reported that breathing normobaric 11% O2 prevents neurodegeneration in a mouse model of a pediatric mitochondrial disease, Leigh syndrome. Here we provide updated survival curves of mice treated with varying doses of oxygen and explore eventual causes of death. We explore alternative hypoxia regimens and report that neither intermittent nor moderate hypoxia regimens suffice to prevent neurological disease. Finally, we show that hypoxia can not only prevent, but also reverses the brain lesions in mice with advanced neuropathology. Our preclinical studies will help guide future clinical studies aimed at harnessing hypoxia as a safe and practical therapy.

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Section: Resultsmentioning

confidence: 78%

Hypoxia treatment reverses neurodegenerative disease in a mouse model of Leigh syndrome

Ferrari

Jain

Goldberger

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

134

128

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“…The change in barometric pressure in our study was not associated with shortness of breath, also not in participants with decreased lung function. This has previously been found in healthy adults (Nakano et al 2015). There are considerable effects of altitude in patients with cardiac or respiratory disease.…”

Section: Discussionsupporting

confidence: 66%

“…A study with recreational climbers indicated significant changes in pulse oximetry, peak flow, and heart rate when reaching a height of about 1000 m (Napoli et al 2009). However, no shortness of breath, also called dyspnea, could be observed during a state of hypobaric hypoxia at rest in healthy individuals (Nakano et al 2015).…”

Section: Introductionmentioning

confidence: 99%

The effect of atmospheric pressure on oxygen saturation and dyspnea: the Tromsø study

2020

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A drop in atmospheric pressure, as observed at high altitudes, leads to decreased oxygen saturation. The effect of regular changes in barometric pressure at sea level has never been studied in a general population. A cohort of adults aged 40 years were examined with pulse oximetry at two separate visits, and the local barometric pressure was available from the local weather station. The study aimed at determining the effect of atmospheric pressure on oxygen saturation also called SpO 2 , as well as on shortness of breath. Based on spirometry, the participants were divided into two groups, with normal and decreased lung function. Decreased lung function was defined as forced expiratory volume in 1 s (FEV 1 ) below lower limit or normal (LLN) or FEV 1 /FVC (FVC, forced vital capacity) below LLN, with GLI 2012 reference values. The statistical analysis included uni/multivariable linear and logistic regression. A total of 7439 participants of the Tromsø 7 cohort study were included. There was a significant association between barometric pressure and SpO 2 < 96%, and we found that a reduction of 166.67 hPa was needed to get a 1% reduction in SpO 2 . The change in atmospheric pressure was not significantly associated with shortness of breath, also not in subjects with reduced lung function.

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“…2012; Nakano et al . 2015). The sensation of dyspnoea may represent a conscious awareness of the outgoing respiratory motor command, in which areas of the brain that control ventilation send efferent commands to the ventilatory muscles, and a neurological copy of these commands is sent to the sensory cortex (Nishino, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Dyspnoea typically does not occur with hypoxaemia alone, particularly if P CO 2 is normal or near normal, although this response is variable. Generally, a secondary stimulus, such as activation of pulmonary afferent neurons and/or CO 2 chemoreceptors, is necessary for dyspnoea to be evoked by all but the most severe hypoxaemia (Moosavi et al 2003;Parshall et al 2012;Nakano et al 2015). The sensation of dyspnoea may represent a conscious awareness of the outgoing respiratory motor command, in which areas of the brain that control ventilation send efferent commands to the ventilatory muscles, and a neurological copy of these commands is sent to the sensory cortex (Nishino, 2011).…”

Section: Introductionmentioning

confidence: 99%

Silent hypoxaemia in COVID‐19 patients

Simonson

Baker

Banzett

et al. 2021

The Journal of Physiology

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The clinical presentation of COVID‐19 due to infection with SARS‐CoV‐2 is highly variable with the majority of patients having mild symptoms while others develop severe respiratory failure. The reason for this variability is unclear but is in critical need of investigation. Some COVID‐19 patients have been labelled with ‘happy hypoxia’, in which patient complaints of dyspnoea and observable signs of respiratory distress are reported to be absent. Based on ongoing debate, we highlight key respiratory and neurological components that could underlie variation in the presentation of silent hypoxaemia and define priorities for subsequent investigation.

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Hypobaric hypoxia is not a direct dyspnogenic factor in healthy individuals at rest

Cited by 14 publications

References 18 publications

Hypoxia treatment reverses neurodegenerative disease in a mouse model of Leigh syndrome

Hypoxia treatment reverses neurodegenerative disease in a mouse model of Leigh syndrome

The effect of atmospheric pressure on oxygen saturation and dyspnea: the Tromsø study

Silent hypoxaemia in COVID‐19 patients

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