Similar Supine Heart Rate Variability Changes During 24-h Exposure to Normobaric vs. Hypobaric Hypoxia

Tanner, V.; Faiss, Raphaël; Saugy, Jonas; Bourdillon, Nicolas; Schmitt, Laurent; Millet, Grégoire P.

doi:10.3389/fnins.2021.777800

Cited by 3 publications

(5 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Interestingly, cTOI values were not different in HH2 compared to NN in our study, which may suggest that some minor phenotypic adaptations may have occurred in HH, as discussed elsewhere [ 67 ]. In addition, similar to previously published research [ 11 ], SpO 2 was higher in NH compared to HH1 (ΔSpO 2 NH vs HH1: 1.7±0.5%, Fig 4a ) in our study.…”

Section: Discussionsupporting

confidence: 93%

“…However, there is some evidence to suggest that this is not the case for all physiological variables. For example, cerebral oxygenation [ 10 ] and heart rate variability [ 11 ] are similar following exposure to both NH and HH. Unfortunately, as highlighted by Coppell and colleagues (2015) the current evidence base limits the conclusions which can be drawn due to various confounding factors such as the duration of exposure, temperature, humidity, and small sample sizes [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The effects of normobaric and hypobaric hypoxia on cognitive performance and physiological responses: A crossover study

et al. 2022

View full text Add to dashboard Cite

This partially randomised controlled, crossover study sought to investigate the effects of normobaric hypoxia (NH) and hypobaric hypoxia (HH) on cognitive performance, the physiological response at rest and after a 3-min step-test. Twenty healthy participants (10 females and 10 males, 27.6±6.2yrs, 73.6±13.7kg, 175.3±8.9cm) completed a cognitive performance test, followed by the modified Harvard-step protocol, in four environments: normobaric normoxia (NN; PiO2: 146.0±1.5mmHg), NH (PiO2: 100.9±1.3mmHg), HH at the first day of ascent (HH1: PiO2 = 105.6±0.4mmHg) and HH after an overnight stay (HH2: PiO2 = 106.0±0.5mmHg). At rest and/or exercise, SpO2, NIRS, and cardiovascular and perceptual data were collected. The cerebral tissue oxygenation index and the cognitive performance (throughput, accuracy, and reaction time) were not different between the hypoxic conditions (all p>0.05). In NH, SpO2 was higher compared to HH1 (ΔSpO2 NH vs HH1: 1.7±0.5%, p = 0.003) whilst heart rate (ΔHR NH vs HH2: 5.8±2.6 bpm, p = 0.03) and sympathetic activation (ΔSNSi NH vs HH2: 0.8±0.4, p = 0.03) were lower in NH compared to HH2. Heart rate (ΔHR HH1 vs HH2: 6.9±2.6 bpm, p = 0.01) and sympathetic action (ΔSNSi HH1 vs HH2: 0.9±0.4, p = 0.02) were both lower in HH1 compared to HH2. In conclusion, cognitive performance and cerebral oxygenation didn’t differ between the hypoxic conditions. SpO2 was only higher in NH compared to HH1. In HH2, heart rate and sympathetic activation were higher compared to both NH and HH1. These conclusions account for a PiO2 between 100–106 mmHg.

show abstract

Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

The effects of normobaric and hypobaric hypoxia on cognitive performance and physiological responses: A crossover study

et al. 2022

View full text Add to dashboard Cite

show abstract

“…However, a decrease in the time and frequency domain as well as an increase in the LF/HF ratio was found at comparable exposure duration at altitude as in our study. [32] Exposure to 4970 m led to an acute activation of the https://publications.ersnet.org on on June 27, 2024 by guest Copyright Downloaded from sympathetic nervous system in healthy volunteers, which persisted even after one week. In contrast, blood pressure returned to the baseline value at sea level after one week of exposure.…”

Section: Discussionmentioning

confidence: 96%

“…In contrast to the study by Mezaros et al, [20] a recent study in healthy volunteers showed that acute normobaric hypoxia leads to a decrease in HRV and parasympathetic tone and an increase in sympathetic activity. [31] In a study by Tanner et al, [32] the difference between a 24-hour exposure to normobaric and hypobaric hypoxia was investigated in 41 healthy subjects. No significant difference was found in HRV between hypobaric and normobaric hypoxia.…”

Section: Discussionmentioning

confidence: 99%

Heart rate variability in pulmonary vascular disease at altitude: a randomised trial

Herzig,

Ulrich,

Schneider

et al. 2024

ERJ Open Res

View full text Add to dashboard Cite

BackgroundHypoxia is a trigger for sympathetic activation and autonomic cardiovascular dysfunction. Pulmonary vascular disease (PVD) is associated with hypoxemia, which increases with altitude. The aim was to investigate how exposure of patients with PVD to hypobaric hypoxia at altitude affects autonomic cardiovascular regulation.MethodsIn a randomised cross-over study, patients with PVD were studied for one day and one night at an altitude of 2500 m (hypobaric hypoxia) and low altitude at 470 m in random order. Outcomes were heart rate variability (HRV) in the time domain and in the frequency domain (low/high frequency, LF/HF) and heart rate (HR) during day and night, and baroreflex sensitivity (BRS).ResultsIn 25 patients with PVD (72% pulmonary arterial hypertension, 28% distal chronic thromboembolic pulmonary hypertension; mean±sdage 60.7±13.6 years), exposure to altitude resulted in significant increases in awake HR by 9.4 bpm (95%CI 6.3 to 12.4, p<0.001) and nocturnal HR by 9.0 bpm (95%CI 6.6 to 11.4, p<0.001) and significant changes in awake and particularly nocturnal HRV indicating decreasing parasympathetic and increasing sympathetic activity (change in daytime LF/HF 1.7 (95%CI 0.6 to 2.8), p=0.004; nocturnal LF/HF 1.9 (95%CI 0.3 to 3.4), p=0.022), and a significant decrease in BRS (−2.4 mmHg−1(95%CI - 4.3 to −0.4, p=0.024)).InterpretationExposure of PVD patients to altitude resulted in a significant change in HRV indicating an increase in sympathetic activity and a decrease in BRS. The relative change in HRV at altitude was more pronounced during sleep.

show abstract

“…Lower tidal volume is reported in HH 37 , 41 – 44 . Heart rate variability is reported to be higher in HH 44 or equivalent 46 . Blood pressure is reported to be higher in NH 41 , and also equivalent between NH and HH 37 , 45 .…”

Section: Introductionmentioning

confidence: 97%

Comparing neuronal oscillations during visual spatial attention orienting between normobaric and hypobaric hypoxia

Hutcheon,

Vakorin,

Nunes

et al. 2023

Sci Rep

View full text Add to dashboard Cite

Normobaric hypoxia (NH) and hypobaric hypoxia (HH) are both used to train aircraft pilots to recognize symptoms of hypoxia. NH (low oxygen concentration) training is often preferred because it is more cost effective, simpler, and safer than HH. It is unclear, however, whether NH is neurophysiologically equivalent to HH (high altitude). Previous studies have shown that neural oscillations, particularly those in the alpha band (8–12 Hz), are impacted by hypoxia. Attention tasks have been shown to reliably modulate alpha oscillations, although the neurophysiological impacts of hypoxia during cognitive processing remains poorly understood. To address this we investigated induced and evoked power alongside physiological data while participants performed an attention task during control (normobaric normoxia or NN), NH (fraction of inspired oxygen = 12.8%, partial pressure of inspired oxygen = 87.2 mmHg), and HH (3962 m, partial pressure of inspired oxygen = 87.2 mmHg) conditions inside a hypobaric chamber. No significant differences between NH and HH were found in oxygen saturation, end tidal gases, breathing rate, middle cerebral artery velocity and blood pressure. Induced alpha power was significantly decreased in NH and HH when compared to NN. Participants in the HH condition showed significantly increased induced lower-beta power and evoked higher-beta power, compared with the NH and NN conditions, indicating that NH and HH differ in their impact on neurophysiological activity supporting cognition. NH and HH were found not to be neurophysiologically equivalent as electroencephalography was able to differentiate NH from HH.

show abstract

Similar Supine Heart Rate Variability Changes During 24-h Exposure to Normobaric vs. Hypobaric Hypoxia

Cited by 3 publications

References 72 publications

The effects of normobaric and hypobaric hypoxia on cognitive performance and physiological responses: A crossover study

The effects of normobaric and hypobaric hypoxia on cognitive performance and physiological responses: A crossover study

Heart rate variability in pulmonary vascular disease at altitude: a randomised trial

Comparing neuronal oscillations during visual spatial attention orienting between normobaric and hypobaric hypoxia

Contact Info

Product

Resources

About