Impact of acute hypobaric hypoxia on blood flow distribution in brain

Pagani, Marco; Salmaso, Dario; Sidiras, Georgios; Jonsson, Cathrine; Jacobsson, Hans; Larsson, Stig; Lind, Folke

doi:10.1111/j.1748-1716.2011.02264.x

Cited by 34 publications

(33 citation statements)

References 30 publications

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“…PAGANI et al [29] showed that the changes in regional cerebral blood flow (rCBF) in response to hypoxia are different in the gray and white matter. They found a greater degree of rCBF in the forebrain grey matter during acute hypoxia and speculated that this localised response might be ascribed to an acute compensatory mechanism involving regions with increased sensitivity to oxygen deficits, possibly because they would develop reversible neuronal impairment.…”

Section: Discussionmentioning

confidence: 99%

Exertional dyspnoea and cortical oxygenation in patients with COPD

et al. 2015

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This study was designed to investigate the association of perceived dyspnoea intensity with cortical oxygenation and cortical activation during exercise in patients with chronic obstructive pulmonary disease (COPD) and exertional hypoxaemia.Low-intensity exercise was performed at a constant work rate by patients with COPD and exertional hypoxaemia (n=11) or no hypoxaemia (n=16), and in control participants (n=11). Cortical oxyhaemoglobin (oxy-Hb) and deoxyhaemoglobin (deoxy-Hb) concentrations were measured by multichannel near-infrared spectroscopy. Increased deoxy-Hb is assumed to reflect impaired oxygenation, whereas decreased deoxy-Hb signifies cortical activation.Exercise decreased cortical deoxy-Hb in control and nonhypoxaemic patients. Deoxy-Hb was increased in hypoxaemic patients and oxygen supplementation improved cortical oxygenation. Decreased deoxy-Hb in the pre-motor cortex (PMA) was significantly correlated with exertional dyspnoea in control participants and patients with COPD without hypoxaemia. In contrast, increased cortical deoxy-Hb concentration was correlated with dyspnoea in patients with COPD and hypoxaemia. With the administration of oxygen supplementation, exertional dyspnoea was correlated with decreased deoxy-Hb in the PMA of COPD patients with hypoxaemia.During exercise, cortical oxygenation was impaired in patients with COPD and hypoxaemia compared with control and nonhypoxaemic patients; this difference was ameliorated with oxygen supplementation. Exertional dyspnoea was related to activation of the pre-motor cortex in COPD patients. @ERSpublications Exertional dyspnoea was related to activation of the pre-motor cortex in COPD patients

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Section: Discussionmentioning

confidence: 99%

Exertional dyspnoea and cortical oxygenation in patients with COPD

et al. 2015

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“…Distribution of blood flow to the head and brain is not uniform during exercise [62], [63]. Cerebral blood flow is heterogeneously distributed under hypoxia [64], [65]. Moreover, dynamic cerebral autoregulation may be impaired at rest [66] and during exercise [67] under moderate hypoxia, although hypocapnia is thought to counteract impaired dynamic cerebral autoregulation under hypoxia [68].…”

Section: Discussionmentioning

confidence: 99%

The Effects of Exercise Under Hypoxia on Cognitive Function

et al. 2013

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Increasing evidence suggests that cognitive function improves during a single bout of moderate exercise. In contrast, exercise under hypoxia may compromise the availability of oxygen. Given that brain function and tissue integrity are dependent on a continuous and sufficient oxygen supply, exercise under hypoxia may impair cognitive function. However, it remains unclear how exercise under hypoxia affects cognitive function. The purpose of this study was to examine the effects of exercise under different levels of hypoxia on cognitive function. Twelve participants performed a cognitive task at rest and during exercise at various fractions of inspired oxygen (FIO2: 0.209, 0.18, and 0.15). Exercise intensity corresponded to 60% of peak oxygen uptake under normoxia. The participants performed a Go/No-Go task requiring executive control. Cognitive function was evaluated using the speed of response (reaction time) and response accuracy. We monitored pulse oximetric saturation (SpO2) and cerebral oxygenation to assess oxygen availability. SpO2 and cerebral oxygenation progressively decreased during exercise as the FIO2 level decreased. Nevertheless, the reaction time in the Go-trial significantly decreased during moderate exercise. Hypoxia did not affect reaction time. Neither exercise nor difference in FIO2 level affected response accuracy. An additional experiment indicated that cognitive function was not altered without exercise. These results suggest that the improvement in cognitive function is attributable to exercise, and that hypoxia has no effects on cognitive function at least under the present experimental condition. Exercise-cognition interaction should be further investigated under various environmental and exercise conditions.

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“…During mild to moderate inspiratory hypoxia, cerebral blood flow increases to compensate for the reduced blood oxygenation, maintaining cerebral oxygen delivery and metabolic function (19). There has been some evidence of regional differences in the CBF response to hypoxia (20–22) which may indicate there are also different lactate responses regionally. Similarly, grey matter is considered more metabolically active and has greater CBF compared to white matter (19).…”

Section: Discussionmentioning

confidence: 99%

Temporal dynamics of lactate concentration in the human brain during acute inspiratory hypoxia

Harris

Roberton

Huckle

et al. 2012

Magnetic Resonance Imaging

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Purpose To demonstrate the feasibility of measuring the temporal dynamics of cerebral lactate concentration and examine these dynamics in human subjects using MRS during hypoxia. Methods A respiratory protocol consisting of 10 min baseline normoxia, 20 min inspiratory hypoxia and ending with 10 min normoxic recovery was used, throughout which lactate-edited MRS was performed. This was repeated four times in three subjects. A separate session was performed to measure blood lactate. Impulse response functions using end-tidal oxygen and blood lactate as system inputs and cerebral lactate as the system output were examined to describe the dynamics of the cerebral lactate response to a hypoxic challenge. Results The average lactate increase was 20%±15% during the last half of the hypoxic challenge. Significant changes in cerebral lactate concentration were observed after 400s. The average relative increase in blood lactate was 188%±95%. The temporal dynamics of cerebral lactate concentration was reproducibly demonstrated with 200s time bins of MRS data (coefficient of variation 0.063±0.035 between time bins in normoxia). The across subject coefficient of variation was 0.333. Conclusions The methods for measuring the dynamics of the cerebral lactate response developed here would be useful to further investigate the brain’s response to hypoxia.

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Impact of acute hypobaric hypoxia on blood flow distribution in brain

Abstract: These findings underscore the specific sensitivity of the frontal lobe to acute hypobaric hypoxia and of limbic and central structures to blood gas changes emphasizing the involvement of these brain areas in acute hypoxia.

Cited by 34 publications

References 30 publications

Exertional dyspnoea and cortical oxygenation in patients with COPD

Exertional dyspnoea and cortical oxygenation in patients with COPD

The Effects of Exercise Under Hypoxia on Cognitive Function

Temporal dynamics of lactate concentration in the human brain during acute inspiratory hypoxia

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