Heart Rate Nonlinear Dynamics During Sudden Hypoxia at 8230 m Simulated Altitude

Vigo, Daniel Eduardo; Lloret, Santiago Pérez; Videla, Alejandro J.; Chada, Daniel Pérez; Hünicken, Horacio M.; Mercuri, Jorge; Romero, R.; Siri, Leonardo C. Nicola; Cardinali, Daniel P.

doi:10.1016/j.wem.2009.12.022

Cited by 35 publications

(61 citation statements)

References 28 publications

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“…The results of this study revealed that hypoxia reduces linear HRV, but it increases non-linear HRV. This pattern is similar to heavy exercise or high risk ischemic heart diseases (10). It has been shown that serum iron profile significantly increases with biphasic pattern in altitudes exposure in the hypobaric chamber (at 8,000 feet) for 8.5 hours (11).…”

Section: Introductionsupporting

confidence: 52%

Serum and Stimulated Saliva C-reactive Protein Changes in Altitude Chamber

Mirzaii‐Dizgah

Khademi

2017

Ann Mil Health Sci Res

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Objectives: The object of the research was to examine stimulated saliva and serum C-reactive protein (hs-CRP) prior and following the experience of hypobaric hypoxia process (EHHP) in an altitude chamber in aviators.Methods: A total of 40 healthy aircrew (age: 31.8 ± 6.0 years; BMI: 25.6 ± 2.7 Kg/cm 2 ) experienced hypobaric chamber. Hs-CRP levels were assayed in stimulated whole saliva and serum before and after intervention by the ELISA method and were statistically analyzed by the paired student's t test.Results: Mean serum hs-CRP concentration was significantly increased following intervention (before: 1.78 ± 0.33 µg/mL versus after: 2.58 ± 0.45 µg/mL) (p = 0.02). Stimulated saliva hs-CRP level was also significantly higher following EHHP (1.71 ± 0.17 ng/mL) compared to before experiencing it (0.79 ± 0.12 ng/mL, P = 0.007). Conclusions:It seems that the salivary and serum levels of hs-CRP rise following the experience of hypobaric hypoxia process.

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Section: Introductionsupporting

confidence: 52%

Serum and Stimulated Saliva C-reactive Protein Changes in Altitude Chamber

Mirzaii‐Dizgah

Khademi

2017

Ann Mil Health Sci Res

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“…Heart rate variability is also responsive to the changes in the ANS associated with external stimuli such as real or simulated altitude (21). For example, an initially sharp increase in sympathetic activity is observed upon arrival at altitude (7,28), which gradually declines through the acclimatization process (14,23). The reduction in HRV is largely due to a reduction in the parasympathetic drive at the sinus node during hypoxia, the mechanism behind which has been well described by Roche et al (20).…”

mentioning

confidence: 92%

The effect of short-term intermittent hypoxic exposure on heart rate variability in a sedentary population

Lizamore¹,

Kathiravel²,

Elliott³

et al. 2016

Acta Physiologica Hungarica

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While the effects of instantaneous, single-bout exposure to hypoxia have been well researched, little is known about the autonomic response during, or as an adaptation to, repeated intermittent hypoxic exposure (IHE) in a sedentary population. Resting heart rate variability (HRV) and exercise capacity was assessed in 16 participants (8 receiving IHE, [Hyp] and 8 receiving a placebo treatment [C]) before and after a 4-week IHE intervention. Heart rate variability was also measured during an IHE session in the last week of the intervention. Post-intervention, the root mean squared successive difference (rMSSD) increased substantially in Hyp (71.6 ± 52.5%, mean change ± 90% confidence limits) compared to C suggesting an increase in vagal outflow. However, aside from a likely decrease in submaximal exercise heart rate in the Hyp group (-5.0 ± 6.4%) there was little evidence of improved exercise capacity. During the week 4 IHE measurement, HRV decreased during the hypoxic exposure (reduced R-R interval: -7.5 ± 3.2%; and rMSSD: -24.7 ± 17.3%) suggesting a decrease in the relative contribution of vagal activity. In summary, while 4 weeks of IHE is unlikely to improve maximal exercise capacity, it may be a useful means of increasing HRV in people unable to exercise.Keywords: autonomic nervous system, sedentary lifestyle, interval hypoxia, simulated altitude, physical fitness, health Heart rate variability (HRV) is the analysis of the variation in the beat to beat intervals in the heart rhythm, which reflects the autonomic nervous system (ANS) innervation on the sinus node (25). Heart rate variability is also responsive to the changes in the ANS associated with external stimuli such as real or simulated altitude (21). For example, an initially sharp increase in sympathetic activity is observed upon arrival at altitude (7, 28), which gradually declines through the acclimatization process (14, 23). The reduction in HRV is largely due to a reduction in the parasympathetic drive at the sinus node during hypoxia, the mechanism behind which has been well described by Roche et al. (20). The recovery of HRV to baseline levels upon return to normoxic ambient air depends on the length and severity of the initial exposure. That is, after 12 hours of continuous hypoxic exposure, a pronounced (dampened) effect on HRV is still evident an hour after returning to normoxic ambient air (7), but after a brief hypoxic exposure of 15 min, recovery is almost immediate (20).

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“…However, the majority of the published data relate to short-term HRV recordings (1–5 min) obtained conducted in hypoxic chambers during ‘simulated’ rather than genuine terrestrial HA (Vigo et al, 2010; Prabhakaran and Tripathi, 2011; Mairer et al, 2013; Zhang et al, 2014). The hypoxic period examined has been generally brief (minutes to <8 h) with a tendency to assess at a single HA (Saito et al, 2005; Sutherland et al, 2017) leading to an under appreciation of the influence of acclimatization on HRV.…”

Section: Introductionmentioning

confidence: 99%

High Altitude Affects Nocturnal Non-linear Heart Rate Variability: PATCH-HA Study

Boos

Bye²,

Sevier

et al. 2018

Front. Physiol.

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Background: High altitude (HA) exposure can lead to changes in resting heart rate variability (HRV), which may be linked to acute mountain sickness (AMS) development. Compared with traditional HRV measures, non-linear HRV appears to offer incremental and prognostic data, yet its utility and relationship to AMS have been barely examined at HA. This study sought to examine this relationship at terrestrial HA.Methods: Sixteen healthy British military servicemen were studied at baseline (800 m, first night) and over eight consecutive nights, at a sleeping altitude of up to 3600 m. A disposable cardiac patch monitor was used, to record the nocturnal cardiac inter-beat interval data, over 1 h (0200–0300 h), for offline HRV assessment. Non-linear HRV measures included Sample entropy (SampEn), the short (α1, 4–12 beats) and long-term (α2, 13–64 beats) detrend fluctuation analysis slope and the correlation dimension (D2). The maximal rating of perceived exertion (RPE), during daily exercise, was assessed using the Borg 6–20 RPE scale.Results: All subjects completed the HA exposure. The average age of included subjects was 31.4 ± 8.1 years. HA led to a significant fall in SpO2 and increase in heart rate, LLS and RPE. There were no significant changes in the ECG-derived respiratory rate or in any of the time domain measures of HRV during sleep. The only notable changes in frequency domain measures of HRV were an increase in LF and fall in HFnu power at the highest altitude. Conversely, SampEn, SD1/SD2 and D2 all fell, whereas α1 and α2 increased (p < 0.05). RPE inversely correlated with SD1/SD2 (r = -0.31; p = 0.002), SampEn (r = -0.22; p = 0.03), HFnu (r = -0.27; p = 0.007) and positively correlated with LF (r = 0.24; p = 0.02), LF/HF (r = 0.24; p = 0.02), α1 (r = 0.32; p = 0.002) and α2 (r = 0.21; p = 0.04). AMS occurred in 7/16 subjects (43.8%) and was very mild in 85.7% of cases. HRV failed to predict AMS.Conclusion: Non-linear HRV is more sensitive to the effects of HA than time and frequency domain indices. HA leads to a compensatory decrease in nocturnal HRV and complexity, which is influenced by the RPE measured at the end of the previous day. HRV failed to predict AMS development.

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Heart Rate Nonlinear Dynamics During Sudden Hypoxia at 8230 m Simulated Altitude

Abstract: The observed pattern of diminished linear HRV and increased nonlinear HRV is similar to that seen in subjects undergoing heavy exercise or in patients with ischemic heart disease at high risk for ventricular fibrillation.

Cited by 35 publications

References 28 publications

Serum and Stimulated Saliva C-reactive Protein Changes in Altitude Chamber

Serum and Stimulated Saliva C-reactive Protein Changes in Altitude Chamber

The effect of short-term intermittent hypoxic exposure on heart rate variability in a sedentary population

High Altitude Affects Nocturnal Non-linear Heart Rate Variability: PATCH-HA Study

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