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 ofone-lung ventilation on the activity of the cardiac autonomic nervous system.Ten adult patients who underwent thoracotomy were endotracheally intubatedwith a double-lumen tube under general anesthesia using isoflurane. Afterinduction of anesthesia, a continuous, 256-sec electrocardiogram (ECG) wasobtained during bilateral lung ventilation (control) followed by recordingsduring one-lung ventilation of each side. Using the R–R intervaltachograms obtained for the 256-sec ECGs, low frequency (LF: 0.04–0.15Hz) and high frequency (HF: 0.15–0.40 Hz) bands of the spectral densityof the heart rate variability and the HF/LF ratio were analyzed using the fastFourier transform algorithm. Log(HF), which indicates parasympatheticactivity, increased during one-lung ventilation on each side, but did notdiffer between ventilated sides. Log(LF), which represents sympathetic andparasympathetic activity, increased similarly to log(HF) on both sides.Log(HF/LF), the balance of the sympathetic and parasympathetic activity, didnot change during one-lung ventilation. We suggest that one-lung ventilationalone does not substantially affect the cardiac autonomic nervous system.