Pulse respiration quotient as a measure sensitive to changes in dynamic behavior of cardiorespiratory coupling such as body posture and breathing regime

Abstract

Objective: In this research we explored the (homeo)dynamic character of cardiorespiratory coupling (CRC) under the influence of different body posture and breathing regimes. Our tool for it was the pulse respiration quotient (PRQ), representing the number of heartbeat intervals per breathing cycle. We obtained non-integer PRQ values using our advanced Matlab® algorithm and applied it on the signals of 20 healthy subjects in four conditions: supine position with spontaneous breathing (Supin), standing with spontaneous breathing (Stand), supine position with slow (0.1 Hz) breathing (Supin01) and standing with slow (0.1 Hz) breathing (Stand01).Main results: Linear features of CRC (in PRQ signals) were dynamically very sensitive to posture and breathing rhythm perturbations. There are obvious increases in PRQ mean level and variability under the separated and joined influence of orthostasis and slow (0.1 Hz) breathing. This increase was most pronounced in Stand01 as the state of joint influences. Importantly, PRQ dynamic modification showed greater sensitivity to body posture and breathing regime changes than mean value and standard deviation of heart rhythm and breathing rhythm. In addition, as a consequence of prolonged supine position, we noticed the tendency to integer quantization of PRQ (especially after 14 min), in which the most common quantization number was 4:1 (demonstrated in other research reports as well). In orthostasis and slow breathing, quantization can also be observed, but shifted to other values. We postulate that these results manifest resonance effects induced by coupling patterns from sympathetic and parasympathetic adjustments (with the second as dominant factor).Significance: Our research confirms that cardiorespiratory coupling adaptability could be profoundly explored by precisely calculated PRQ parameter since cardiorespiratory regulation in healthy subjects is characterized by a high level of autonomic adaptability (responsiveness) to posture and breathing regime, although comparisons with pathological states has yet to be performed. We found Stand01 to be the most provoking state for the dynamic modification of PRQ (cardiorespiratory inducement). As such, Stand01 has the potential of using for PRQ tuning by conditioning the cardiorespiratory autonomic neural networks, e.g., in the cases where PRQ is disturbed by environmental (i.e., microgravity) or pathologic conditions.

Cardiorespiratory synchronization under the influence of strength endurance training

“…In this study, the analysis of the cardiorespiratory interaction indicators, obtained during the simultaneous registration of cardiac and respiratory activity data, was carried out. The specified changes confirm a number of known facts that allow to supplement the understanding of the physiological and pathophysiological aspects of the interaction of the cardiovascular and respiratory systems in the maintenance of hemodynamic homeostasis, as well as to identify diagnostically important features of cardiorespiratory relationships (Abreu et al, 2022;Braendholt et al, 2023;Pinsky et al, 2018;Parviainen et al, 2022;Matić et al, 2022). Taking into account the problem of diagnosing the state of athletes in the conditions of the training process, there is an expediency of using express valid non-invasive methods of instrumental diagnosis of the functional state of the body, which would allow directly during training and competitions to investigate the impact of psychophysical loads (Girin et al, 2021;Harford et al, 2019).…”

Changes in the autonomic cardiorespiratory activity in parturient women with severe and moderate features of preeclampsia

“…This robustness is critical as it helps protect the results from potential disruptions caused by movement artifacts and ectopic heartbeats. On the other hand, both linear features of PRQ fluctuations, such as mPRQ, and nonlinear features, like entropy, have demonstrated sensitivity to changes in the dynamic behavior of CRC, such as body posture and breathing patterns ( 22 ), as well as the ability to identify respiratory changes due to induced relaxation and potential parasympathetic activation ( 62 ). Therefore, this set of indices can likely identify subtle changes in CRC activity between the P and SP groups compared to the rest of the indices.…”

“…Existing research supports the notion that the exploration of adaptability in CRC can be significantly enhanced by precisely calculating diverse indices computed from PRQ time series. In healthy individuals, the regulation of cardiorespiratory functions exhibits a notable level of autonomic adaptability, particularly in response to posture and breathing patterns ( 22 ). According to the consulted literature, no studies are available that quantify the CRC changes by applying the PRQ and information theory methods in parturient preeclamptic women.…”

Induced Relaxation Enhances the Cardiorespiratory Dynamics in COVID-19 Survivors

“…Currently, studies related to PRQ primarily involve healthy individuals, and there is no data regarding COVID-19 survivors who experienced post-acute syndrome or performed slow-paced breathing. Matić et al reported increased mean PRQ and PRQ variability with orthostasis and slow-paced breathing as signs of cardiorespiratory coupling regulation and adaptability [ 62 ]. Our findings on the mean PRQ ( Figure 9 a) and SD-PRQ ( Figure 9 b) showed a significant difference in response to the change in breathing frequency with higher statistical significance than the mean and SD of PRV indices.…”