Cerebral blood flow, oxygen metabolism, and lactate during hypoxia in patients with obstructive sleep apnea

Jensen, Mette L.; Vestergaard, Mark Bitsch; Tønnesen, Philip; Larsson, Henrik; Jennum, Poul

doi:10.1093/sleep/zsy001

Cited by 25 publications

(26 citation statements)

References 46 publications

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“…A more in-depth discussion of the methods and data processing was reported previously. 16,23,32 MRS MRS was used to measure the NAA, lactate, and glx concentrations in the occipital lobe using a water-suppressed point-resolved spectroscopy pulse sequence (TR, 3000 or 5000 ms; TE, 36 ms; voxel size, 30 Â 35 Â 30 mm 3 ). Example of placement of MRS voxel is demonstrated in Figure 2 erroneous.…”

Section: Cmromentioning

confidence: 99%

Higher physiological vulnerability to hypoxic exposure with advancing age in the human brain

Vestergaard

Jensen

Arngrim

et al. 2018

J Cereb Blood Flow Metab

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The aging brain is associated with atrophy along with functional and metabolic changes. In this study, we examined age-related changes in resting brain functions and the vulnerability of brain physiology to hypoxic exposure in humans in vivo. Brain functions were examined in 81 healthy humans (aged 18–62 years) by acquisitions of gray and white matter volumes, cerebral blood flow, cerebral oxygen consumption, and concentrations of lactate, N-acetylaspartate, and glutamate+glutamine using magnetic resonance imaging and spectroscopy. We observed impaired cerebral blood flow reactivity in response to inhalation of hypoxic air (p = 0.029) with advancing age along with decreased cerebral oxygen consumption (p = 0.036), and increased lactate concentration (p = 0.009), indicating tissue hypoxia and impaired metabolism. Diminished resilience to hypoxia and consequently increased vulnerability to metabolic stress could be a key part of declining brain health with age. Furthermore, we observed increased resting cerebral lactate concentration with advancing age (p = 0.007), which might reflect inhibited brain clearance of waste products.

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Section: Cmromentioning

confidence: 99%

Higher physiological vulnerability to hypoxic exposure with advancing age in the human brain

Vestergaard

Jensen

Arngrim

et al. 2018

J Cereb Blood Flow Metab

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“…However, the OSA patients and controls studied by Jensen et al. () were 52 years of age, thus implicating a greater role for the differences in the duration of hypoxic challenges to explain the conflicting results.…”

Section: Discussionmentioning

confidence: 94%

“…More recently, using phase‐contrast magnetic resonance imaging, Jensen et al. () also reported OSA patients had a lower CBF response to hypoxia. Our finding of similar CBF hypoxic responses between OSA patients and controls at baseline contrasts with these studies.…”

Section: Discussionmentioning

confidence: 96%

“…() and Jensen et al. () used 20 and 35 min steady‐state hypoxic exposures, respectively, while Reichmuth et al. () used a 15 min graded hypoxic protocol.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, establishment of less reversible age-related vascular remodelling may outweigh IH-induced deficits, but this needs further study. However, the OSA patients and controls studied by Jensen et al (2018) were 52 years of age, thus implicating a greater role for the differences in the duration of hypoxic challenges to explain the conflicting results.…”

Section: Cbf and Map Responses To Hypoxiamentioning

confidence: 99%

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Vascular responses to hypoxia are not impaired in obstructive sleep apnoea patients free of overt cardiovascular disease

Beaudin

Hanly

Raneri

et al. 2019

Experimental Physiology

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New Findings What is the central question of this study?Does treatment of obstructive sleep apnoea (OSA) with nocturnal oxygen or continuous positive airway pressure (CPAP) improve hypoxic vascular responses, which are reportedly impaired in OSA? What is the main finding and its importance?Cerebrovascular and cardiovascular hypoxic responses were not impaired in OSA patients free of overt cardiovascular disease and known risk factors, and were not altered by nocturnal oxygen or CPAP treatment. We conclude that this OSA patient phenotype has normal vascular responses to hypoxia and is unlikely to obtain long term cardiovascular benefits from nocturnal oxygen or CPAP therapy. Abstract Cerebral blood flow (CBF) and cardiovascular responses to hypoxia are reportedly impaired in obstructive sleep apnoea (OSA) patients and corrected by continuous positive airway pressure (CPAP), beneficial effects that are ascribed to correction of OSA‐related intermittent hypoxia (IH). However, CPAP corrects both IH and ancillary OSA features (i.e. intermittent hypercapnia, sympathetic activation, blood pressure surges, negative intrathoracic pressure swings and sleep fragmentation). Whether correction of these ancillary OSA features contribute to CPAP's beneficial effects on vascular hypoxic responses is unknown. Nocturnal oxygen corrects OSA‐induced IH, but apnoeas and ancillary features persist. Thus, we examined the effects of nocturnal oxygen and CPAP on cerebrovascular and cardiovascular hypoxic responses in untreated OSA patients. Responses were assessed in 52 OSA patients free of overt cardiovascular disease and known risk factors at baseline, after 2 weeks of nocturnal oxygen (n = 26) or no treatment (n = 26), and after ∼4 weeks of CPAP treatment (n = 40). Twenty‐two age‐matched controls were assessed at baseline and follow‐up visits. Resting, isocapnic euoxia mean blood pressure was decreased following nocturnal oxygen (−3.6 ± 6.0 mmHg; P = 0.006) and CPAP (−4.5 ± 7.5 mmHg; P < 0.001) while cerebrovascular conductance was increased with CPAP (P = 0.001). However, these changes were not different from controls. Unexpectedly, OSA patients and controls had similar hypoxic vascular responses at baseline that were not changed by either nocturnal oxygen or CPAP. We conclude that OSA patients free of overt cardiovascular disease and known risk factors did not have impaired cerebrovascular or cardiovascular responses to hypoxia and are unlikely to obtain long term cardiovascular benefits from nocturnal oxygen or CPAP therapy.

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Sleep-disordered breathing and cerebral small vessel disease—acute and 6 months after ischemic stroke

et al. 2021

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Cerebral blood flow, oxygen metabolism, and lactate during hypoxia in patients with obstructive sleep apnea

Abstract: Patients with OSA exhibit reduced CBF in response to hypoxia. CPAP treatment normalized these patterns.

Cited by 25 publications

References 46 publications

Higher physiological vulnerability to hypoxic exposure with advancing age in the human brain

Higher physiological vulnerability to hypoxic exposure with advancing age in the human brain

Vascular responses to hypoxia are not impaired in obstructive sleep apnoea patients free of overt cardiovascular disease

Sleep-disordered breathing and cerebral small vessel disease—acute and 6 months after ischemic stroke

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