Factors influencing intraoperative bradycardia in adult patients

In order to elucidate the prominent factors involved in intraoperative bradycardia in adult patients, we retrospectively investigated the association between the potential risk factors and intraoperative bradycardia, using multiple logistic regression.

The perioperative records for 499 adult patients who had undergone any of six elective surgeries were retrospectively examined. The potential factors included patient characteristics, the use of perioperative drugs for anesthesia, and the types of operational procedures. Heart rates were extracted at five points perioperatively. The frequencies and total doses of atropine injections to treat bradycardia were examined. Simple and multiple logistic regressions were used to analyze the relative risk factors for a intraoperative bradycardia.

The multiple logistic regression analysis revealed that the absence of atropine premedication was the most prominent risk factor for bradycardia (odds ratio; 1.86-5.51) from arrival in the operating room until the end of the operation. Other prominent factors, whose effects were only temporary, were as follows. Males had a higher risk of bradycardia than females upon arrival in the operating room. Surgical procedures with an epidural or subarachnoid blockade tended to have a higher risk for bradycardia after the operation. Propofol induction had a greater risk for bradycardia than thiopental after the end of the operation. Endotracheal intubation had a lower risk for bradycardia than no endotracheal intubation after induction. Vecuronium tended to induce bradycardia after operation.

The most prominent factor affecting heart rate was atropine premedication. It was noteworthy that a single preoperative administration of atropine affected heart rate throughout the operation.