Effects of one-lung ventilation on cardiac autonomic nervous activity as evaluated by power spectral analysis of heart rate variability

The purpose of this prospective study was to evaluate the effects of one-lu ng ventilation on the activity of the cardiac autonomic nervous system. Ten adult patients who underwent thoracotomy were endotracheally intubated wit h a double-lumen tube under general anesthesia using isoflurane. After indu ction of anesthesia, a continuous, 256-sec electrocardiogram (ECG) was obta ined during bilateral lung ventilation (control) followed by recordings dur ing one-lung ventilation of each side. Using the R-R interval tachograms ob tained for the 256-sec ECGs, low frequency (LF: 0.04-0.15 Hz) and high freq uency (HF: 0.15-0.40 Hz) bands of the spectral density of the heart rate va riability and the HF/LF ratio were analyzed using the fast Fourier transfor m algorithm. Log(HF), which indicates parasympathetic activity, increased d uring one-lung ventilation on each side, but did not differ between ventila ted sides. Log(LF), which represents sympathetic and parasympathetic activi ty, increased similarly to log(HF) on both sides. Log(HF/LF), the balance o f the sympathetic and parasympathetic activity, did not change during one-l ung ventilation. We suggest that one-lung ventilation alone does not substa ntially affect the cardiac autonomic nervous system.