Changes in Heart Rate and Autonomic Nervous Activity after Orthopedic Surgery in Elderly Japanese Patients.

Evidence regarding nursing support for delirium prevention is currently insufficient. An evaluation of changes in autonomic nervous activity over time after surgery would elucidate the features of autonomic nervous activity in patients with delirium. These results could provide a basis for effective nursing intervention and timing for preventing the onset of delirium. Here, we aimed to obtain basic data on effective nursing interventions for preventing the onset of postoperative delirium. Heart rate variability was recorded during the morning and nighttime on the day before surgery until 3 days postoperatively in elderly patients who underwent orthopedic surgery to investigate the manner in which heart rate and autonomic nervous activity changed over time. Data were collected over 11 months from July 2013 to November 2014. Surgical stress led to the maintenance of heart rate at a significantly higher value from the day of the surgery until postoperative day 3 compared to that before surgery. Moreover, the autonomic nervous activity remained unchanged during the morning, and it was significantly lower during the night from postoperative day 1 until postoperative day 3 than before the surgery. These results suggest that there is a decrease in parasympathetic nervous activity during the nighttime postoperatively.