Respiratory and cardiovascular parameters during hyperventilation tested at patients with affective disorders

Abstract

Introduction. yperventilation is an important pathogenic factor in anxiety disorders as well as in affective disorder. It seems to provide symptoms by its metabolic and anxiogenic effects." Aim of study. The purpose of the study is to determine the relationship among respiratory, heart rate variability and psychological traits in healthy subject and affective disorder patients. Methods and materials. Respiratory and electrocardiographic characteristics were evaluated during voluntary hyperventilation test in 13 healthy subjects and 10 patients with affective disorders following the protocols: spontaneous breathing (Rest) -5 min followed by a voluntary hyperventilation at 20/min HV-3 min. Hyperventilation was performed at the controlled level of hypocapnia: end tidal CO2 (FETCO2) was maintained at 1 % below the individual spontaneous level. Respiratory plethysmograph Visuresp was used to record respiratory movements, Capnostream - to record PCO2 and PCO2 of exhaled air, ECG module - to record electrocardiographic trace. PID-5 and Nijmegen inventories were used to evaluate psychological traits. Results. The breath by breath analysis of respiration and R-R intervals of rest and hyperventilation periods were performed. At each breath, the tidal volume (VT), the breath (TTOT), the inspiratory (TI) and expiratory durations, the minute ventilation, VT/TI, TI/TTOT were quantified. The spectral analysis of the R-R intervals was applied to evaluate the heart rate variability characteristics –the normalized powers of high (HF) and low frequencies (LF) and LF/HF ratio. The multifactorial statistical analysis was performed to evaluate the importance of different psychological traits, respiratory and heart variability characteristics. A few significant correlations between psychological traits, respiratory and cardiovascular were found in healthy subjects. More correlations were found in the patients group during the rest period. Voluntary hyperventilation increased the number of significant correlations in the patient's group. One of the 7 facets which is included in PDB is anxiousness, and probably this explains the changes of the breathing pattern caused by influences of anxiogenic structures on the brain stem respiratory center. Conclusion. The high activity of anxiogenic structure in affective disorder patients provides respiratory and heart rate variability changes. Hypocapnia and respiratory alkalosis produced by voluntary hyperventilation seem to increase the activity of anxiogenic structures and provide more psychophysiological effects in affective disorder patients in contrast with the healthy subjects.