Photoplethysmographic Waveform and Pulse Rate Variability Analysis in Hyperbaric Environments

Heart Rate Variability to Automatically Identify Hyperbaric States Considering Respiratory Component

This study's primary objective was to identify individuals whose physiological responses deviated from the rest of the study population by automatically monitoring atmospheric pressure levels to which they are exposed and using parameters derived from their heart rate variability (HRV). To achieve this, 28 volunteers were placed in a dry hyperbaric chamber, where they experienced varying pressures from 1 to 5 atmospheres, with five sequential stops lasting five minutes each at different atmospheric pressures. The HRV was dissected into two components: the respiratory component, which is linked to respiration; and the residual component, which is influenced by factors beyond respiration. Nine parameters were assessed, including the respiratory rate, four classic HRV temporal parameters, and four frequency parameters. A k-nearest neighbors classifier based on cosine distance successfully identified the atmospheric pressures to which the subjects were exposed to. The classifier achieved an 88.5% accuracy rate in distinguishing between the 5 atm and 3 atm stages using only four features: respiratory rate, heart rate, and two frequency parameters associated with the subjects' sympathetic responses. Furthermore, the study identified 6 out of 28 subjects as having atypical responses across all pressure levels when compared to the majority. Interestingly, two of these subjects stood out in terms of gender and having less prior diving experience, but they still exhibited normal responses to immersion. This suggests the potential for establishing distinct safety protocols for divers based on their previous experience and gender.

HIGH-INTENSITY TRAINING ON PULSE AND DICROTIC WAVEFORM IN CHRONIC DISEASES

ABSTRACT Introduction: The formation and propagation of pulse waves are mainly accomplished by coordinating the heart and the vascular system. The contraction and relaxation of the heart are the sources of pulse waves. The aorta vibrates regularly as the heart contracts. This vibration propagates forward along the elastic blood vessel to form a pulse wave. The pulse wave contains very rich physiological and pathological information about the cardiovascular system. If there is a problem with the heart's structure, it can cause abnormal pulse waveforms. Objective: This article analyzes pulse waveform changes and blood flow during high-intensity interval training. It combines the test results to guide the exercise rehabilitation treatment of patients with chronic diseases. Methods: Pulse waves were collected from subjects under different exercise loads and the characteristics of pulse wave parameters under intermittent exercise were studied. Results: An athlete's pulse wave response is different in the case of high-intensity intermittent exercise. There are differences in the cardiovascular response of patients with different body weights. Conclusion: High-intensity interval training can improve the cardiovascular function of patients with chronic diseases and affect their pulse waveform. Level of evidence II; Therapeutic studies - investigation of treatment results.