Analysis of heart rate variability as an index of noncardiac surgical stress

Measurement of heart rate variability (HRV) is useful in assessing the function of the autonomic nervous system and in staging of clinical diseases. The purpose of this study is to assess a feasibility of HRV for evaluating surgical stress during the noncardiac perioperative period. Standard deviation of normal-to-normal RR intervals (SDNN) and HRV triangular index derived from 24-h Holter ECC were measured in 24 patients undergoing digestive surgery. Holter ECG was performed at 1 day before operation, the first day (postoperative day 1: POD1), and the 7th day (POD7) after operation. Indices of HRV were compared with factors influencing surgical stress, such as duration of the operation and amount of blood loss during the operation, and postoperative complications. The SDNN and HRV triangular index decreased significantly on POD1 and recovered on POD7 (P < 0.05). Heart rate variability indices correlated significantly to duration and blood loss of operation (both P < 0.05). In 7 patients with postoperative complications, HRV indices were statistically lower than those in patients without complications on POD1 (P < 0.05). Our results indicate that HRV may provide useful information with respect to surgical stress.