Endocrine reactions during standardized surgical stress: the effects of age and methods of anaesthesia

The aims of the study were to assess: (1) possible age-related differences in the endocrine stress response to standardized surgical trauma (inguinal hernias); and (2) the potential effects of anaesthetic methods (general versus spinal anaesthesia). A group of relatively healthy people suffering from inguinal hernias was selected from the surgical waiting list. The group was subdivided into younger people (mean age 36.4, range 23-45 years, n = 15) and older people (mean age 66.5, range 56-75 years, n = 17). Approximately half the subjects in each age group were given general anaesthesia for their operations and the remainder spinal blockade. Blood samples, heart rate and blood pressure were taken before, during, and following the operation. During resting conditions systolic blood pressure was higher in the elderly, 156.0 mm Hg versus 137.7, P less than 0.01. No differences were noticed in serum prolactin and cortisol during basal conditions. Although serum prolactin increased in both groups during surgery, it was significantly higher in the younger age group as compared with the older. There was an inverse correlation between serum prolactin and age during surgery but not under resting conditions. Age-related differences in the serum prolactin response were significantly attenuated during spinal blockade. No group differences were found in serum cortisol. Age-related differences in the serum prolactin stress response are due to a combination of central nervous system and peripheral changes. The increased morbidity and mortality and mortality risks observed in older surgical patients may partly be due to a hampered stress response.