BRADYCARDIA DURING ANESTHESIA IN INFANTS - AN EPIDEMIOLOGIC-STUDY

Background: The frequency and morbidity of bradycardia during anesthes ia in infants are not well documented. This study sought to determine the frequency of bradycardia during anesthesia in infants (0 to 1 yr) compared to that in older children, describe causes and morbidity, and identify factors that influence its frequency. Methods: Computerized information abstracted from 7,979 anesthetic records of patients ages 0-4 yr undergoing noncardiac surgery were examined for the presence or absence of intraoperative bradycardia. To study bradycardia in infant s, 4,645 anesthetics in patients aged 0-1 yr were considered. Those wi th bradycardia to heart rates less than 100 beats/min were examined fo r causes, morbidity, and treatment of the bradycardia. For analysis of influencing factors, the frequency of bradycardia in infants was rela ted to age, sex, race, ASA physical status, surgical site (body cavity ), complexity (major or minor) and duration, type of primary anestheti st, type of supervising anesthesiologist, and anesthetic agents. Logis tic regression was used to estimate the significance (P<0.05) and odds ratios for each. Results: The frequency of bradycardia was 1.27% in t he Ist yr of life, but only 0.65% in the third and 0.16% in the 4th yr , a significant difference. Causes of bradycardia in infants included disease or surgery in 35%, the dose of inhalation agent in 35%, and hy poxemia in 22%. Morbidity included hypotension in 30%, asystole or ven tricular fibrillation in 10%, and death in 8%. Treatment involved epin ephrine in 30% and chest compression in 25%. Associated factors includ ed an ASA physical status of 3-5 (vs. 1 or 2) and longer (us. shorter) surgery. Bradycardia was less than half as likely when the supervisin g anesthesiologist was a member of the Pediatric Anesthesia service as with other anesthesiologists (P<0.001). Conclusions: Bradycardia is m ore frequent In infants undergoing anesthesia compared to older childr en and is associated with substantial morbidity. It is more likely in sicker infants undergoing prolonged surgery and less likely when a ped iatric anesthesiologist is present.