The Pulse-Respiration Quotient: A Powerful but Untapped Parameter for Modern Studies About Human Physiology and Pathophysiology

Scholkmann, Felix; Wolf, Ursula

doi:10.3389/fphys.2019.00371

Cited by 39 publications

(47 citation statements)

References 119 publications

(163 reference statements)

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“…The PRQ is a parameter to attain the overall current state of human physiology. 43 PRQ represents the state of the ANS and is a measure of cardiorespiratory coordination. PRQ is time-and sex-dependent, and changes during human development, physical activity, and body posture with specific patterns during sleep.…”

Section: Absolute Values Of Cardiorespiratory Parametersmentioning

confidence: 99%

Frontal cerebral oxygenation asymmetry: intersubject variability and dependence on systemic physiology, season, and time of day

2020

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Significance: Our study reveals that frontal cerebral oxygenation asymmetry (FCOA), i.e. a difference in the oxygenation between the right and left prefrontal cortex (PFC), is a real phenomenon in healthy human subjects at rest. Aim: To investigate FCOA, we performed a study with 134 healthy right-handed subjects with the systemic physiology augmented functional near infrared spectroscopy (SPA-fNIRS) approach. Approach: Subjects were measured 2 to 4 times on different days resulting in an unprecedented number of 518 single measurements of the absolute values of tissue oxygen saturation (StO 2) and total hemoglobin concentration ([tHb]) of the right and left PFC. Measurements were performed with frequency-domain functional near-infrared spectroscopy. In addition, the cardiorespiratory parameters were measured simultaneously. Results: We found that (i) subjects showed an FCOA (higher StO 2 on the right PFC), but not for tHb; (ii) intrasubject variability was excellent for both StO 2 and tHb, and fair for FCOA; (iii) StO 2 correlated significantly with blood CO 2 concentration, [tHb] with heart rate, respiration rate (RR), and the pulse-respiration quotient (PRQ), and FCOA with RR and PRQ; (iv) FCOA and StO 2 were dependent on season and time of day, respectively; (v) FCOA was negatively correlated with the room temperature; and (vi) StO 2 and tHb were not correlated with the subjects mood but with their chronotype, whereas FCOA was not dependent on the chronotype. Conclusion: Our study demonstrates that FCOA is real, and it provides unique insights into this remarkable phenomenon.

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Section: Absolute Values Of Cardiorespiratory Parametersmentioning

confidence: 99%

Frontal cerebral oxygenation asymmetry: intersubject variability and dependence on systemic physiology, season, and time of day

2020

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“…Two intrinsic oscillatory processes accompany each moment of a living human being: cardiac activity and respiration. Both oscillations are locally triggered but regulated in a complex way as best represented by a nonlinear dynamical system based on two weakly coupled oscillators that are coupled by several structural and functional types of cardiorespiratory interactions, leading to emergent cardiorespiratory coupling phenomena (Benarroch 2018, Dick et al 2014, Elstad et al 2018, Krause et al 2017, Lotrič and Stefanovska 2000, Moser et al 2008, Schulz et al 2013, Valenza et al 2016. Such a cardiorespiratory coupling phenomenon is that the heart rate (HR) and the respiration rate (RR) have a specific frequency relationship.…”

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confidence: 99%

“…Such a cardiorespiratory coupling phenomenon is that the heart rate (HR) and the respiration rate (RR) have a specific frequency relationship. As recently reviewed by our group (Scholkmann and Wolf 2019), this relationship is given by dividing the heart rate (HR) by the respiration rate (RR), resulting in the pulse-respiration quotient (PRQ = HR/RR). The PRQ in humans is of physiological relevance and depends mainly on the age, sex and individual physiological constitution of the subject, as well as on the time-of measurement (linked to the chronobiological state), physical activity, psychophysical and cognitive activity, and body posture (Scholkmann and Wolf 2019).…”

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“…68 that (ii) the PRQ is not normally distributed but seems to follow a lognormal distribution (Scholkmann and Wolf 2019). Furthermore, there are reports indicating that the PRQ tends to favour integer values (a quantization) due to an in-phase cardiorespiratory coupling effect (termed cardiorespiratory coordination) with preferred values of the harmonic ratios n/m with n = 3-6 and m = 1 while n and m represent the numerator and denominator of the equation PRQ = HR/RR = n/m (Bettermann et al 2000, Bettermann et al 2001, Bettermann et al 2002, Scholkmann and Wolf 2019. The relationship between the HR and RR is thus not random but is an emergent property as a result of complex cardiorespiratory interactions.…”

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confidence: 99%

“…For example, a tendency of resting-state PRQ to be closer to 4 during the course of an influenza disease has been documented (Müller 1972). A state of PRQ ≈ 4 has been termed "PRQ normalization", associated with an optimal functioning of the cardiovascular system a balanced state of the autonomic nervous system, being relevant for and being correlated with a healthy physiological state of a human (Hildebrandt 1997, Scholkmann andWolf 2019). The significance of PRQ ≈ 4 is highlighted by the fact that the resting-state PRQ is also around 4.5 for all mammals and thus is not following an algometric scaling law as the HR or RR (Schmidt-Nielsen 1984, Stahl 1967.…”

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The Resting-State Pulse-Respiration Quotient of Humans: Lognormally Distributed and Centered Around a Value of Four

Scholkmann

Zohdi²,

Wolf³

2019

Physiol Res

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The pulse-respiration quotient (heart rate divided by the respiration rate, PRQ = HR/RR) is a parameter capturing the complex state of cardiorespiratory interactions. We analysed 482 single PRQ values obtained from measurement on 134 healthy adult subjects (49 men, 85 women, age: 24.7 ± 3.4, range: 20-46 years) during rest. We found that the distribution of PRQ values (i) has a global maximum at around a value of 4 (median: 4.19) and (ii) follows a lognormal distribution function.A multimodality of the distribution, associated with several PRQ attractor states was not detected by our group-level based analysis. In summary, our analysis shows that in healthy humans the resting-state PRQ is around 4 and lognormally distributed.This finding supports claims about the special role of the 4 to 1 cardiorespiratory coupling in particular and the PRQ in general for physiological and medical views and applications. To the best of our knowledge, our study is the largest conducted so far in healthy adult humans about reference values of the PRQ during a resting-state at day.

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Changes in Cerebral Oxygenation and Systemic Physiology During a Verbal Fluency Task: Differences Between Men and Women

Zohdi

Scholkmann

Wolf

2022

Advances in Experimental Medicine and Biology

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Background: Sex differences in behavioural performance of a cognitive task have been repeatedly reported in the literature. Whether such differences are also relevant for evoked cerebral haemodynamic and oxygenation responses as well as systemic physiological changes is a topic of ongoing investigations. Aim: We investigated whether changes in cerebral oxygenation and systemic physiological activity are sex-dependent during a verbal fluency task (VFT). Subjects and methods: VFT performance and changes in cerebral oxygenation and systemic physiology were investigated in 32 healthy right-handed adults (17 females, 15 males, age: 25.5 ± 4.3 years). The total duration of the VFT was 9 min. During this phase, subjects were also exposed to blue light (peak wavelength: 450 nm, illuminance: 120 lux). Before and after the VFT, subjects were in darkness. In this study, we used the systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS) approach. Absolute concentration changes of oxyhaemoglobin ([O2Hb]), deoxyhaemoglobin ([HHb]), total haemoglobin ([tHb]), as well as tissue oxygen saturation (StO2) were measured bilaterally over the prefrontal cortex (PFC) and visual cortex (VC). Systemic physiological parameters were also recorded in parallel (e.g., end-tidal CO2, heart rate, respiration rate, skin conductance). Results: We found that: (i) Females were better VFT performers in comparison to males. (ii) Changes in [O2Hb] and [HHb] in the VC were higher for males compared to females during the VFT under blue light exposure. (iii) Lower and higher StO2 changes were detected for males compared to females in the PFC and VC, respectively. (iv) Sex-dependent changes were also evident for end-tidal CO2, heart rate, respiration rate, and pulserespiration quotient. Conclusions: Our study showed that sex differences are not only observed in task performance but also in the magnitudes of changes in cerebral and physiological parameters. The findings of the current study emphasise that sex differences in brain activation and systemic physiological activity need to be considered when interpreting functional neuroimaging data. These findings offer a broad range of implications for educational purposes and facilitate a better understanding of the effects of sex on behavioural performance as well as human physiology.

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The Pulse-Respiration Quotient: A Powerful but Untapped Parameter for Modern Studies About Human Physiology and Pathophysiology

Cited by 39 publications

References 119 publications

Frontal cerebral oxygenation asymmetry: intersubject variability and dependence on systemic physiology, season, and time of day

Frontal cerebral oxygenation asymmetry: intersubject variability and dependence on systemic physiology, season, and time of day

The Resting-State Pulse-Respiration Quotient of Humans: Lognormally Distributed and Centered Around a Value of Four

Changes in Cerebral Oxygenation and Systemic Physiology During a Verbal Fluency Task: Differences Between Men and Women

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