Introduction: The endogenous opioid beta-endorphin is a known indicator of stress and pain. Opioid anesthesia during operation may prevent postoperative beta-endorphin hypersecretion. We examine the effect on serum beta-endorphin of both preoperative stress and stress of operation under opioids in neonates, infants and preschool children. In order to eliminate the effect of hospitalization anxiety we compared with inpatients of similar age with non-surgical disease.
Material and methods: We included 74 surgical patients (25 neonates, 24 infants, 25 preschool children), and 44 non-surgical inpatients (14 neonates, 12 infants, 18 preschool children). Anesthesia comprised propofol and fentanyl. In presence of pain after extubation, supplementary morphine was administered. Sera were taken preoperatively and 2 h postoperatively in surgical patients, and once in non-surgical patients. Beta-endorphin was tested using ELISA (ng/ml).
Results: In all surgical patients beta-endorphin did not increase significantly after surgery. Neonates showed significantly elevated beta-endorphin preoperatively (mean+/-SD: 2.02+/-0.76) and postoperatively (2.07+/-0.90) compared to neonates with a non-surgical disease (1.05+/-0.34; p<0.005). In contrast, infants (preoperative values: 1.75+/-1.32, postoperative values: 2.00+/-1.83) did not differ from respective non-surgical inpatients (1.49+/-0.70). Before and after surgery, beta-endorphin was significantly elevated in preschool children (7.19+/-1.85, 6.42+/-1.31), as compared with neonates and infants (p<0.0005), and with preschool children with non-surgical disease (1.01+/-0.27; p<0.0005).
Conclusions: Fentanyl/propofol anesthesia, supplemented by postoperative morphine where necessary, protects from surgical stress and postoperative pain, as denoted by no postoperative increase of beta-endorphin in all age groups. Preschool children, who exhibit increased emotional perception, have explicitly high serum beta-endorphin before and after surgery. Preoperative preparation programs might be worthy in this age group. Neonates show a moderate but still significantly high response of beta-endorphin to stress, retained after operation. In contrast, infants tolerated stress better (not increased beta-endorphin pre- and post-operatively).