'Respiratory' oscillations of cardiovascular parameters during voluntary apnea

The aim of this study was to ascertain the persistence of heart rate and blood pressure oscillations at the onset of voluntary apnea in humans. In 24 young subjects (10 males, 14 females, mean age 20.4 years) RR intervals, systolic blood pressure (SBP) and diastolic blood pressure (DBP) during controlled breathing (CB) of atmospheric air followed by voluntary apnea on FRC level were recorded continuously. The cosine functions were then fitted by nonlinear regression analysis to heart rate, SBP and DBP oscillations during CB and at the onset of apnea. During apnea, the changes of base of RR intervals indicate primary tachycardic reaction followed by a decrease in heart rate. The base of the blood pressure oscillations was higher (hypertensive reaction) in apnea. At least one cosine-like wave oscillation was present at the onset of apnea in heart rate, SBP and DBP and the second wave was present in all assessed parameters at least in 70% of recordings. There were no significant gender differences neither in the duration of breath holding nor in the RR and SBP oscillations parameters.