Clinical and hormonal response to general anaesthesia in patients affected by different degrees of mental retardation.

BACKGROUND: Poor or no clinical signs of psychological distress are usually observed in patients affected by severe or profound mental retardation (MR). The aim of this study was to use clinical and hormonal parameters in order to compare the amount of stress in patients affected by different degrees of MR undergoing general anaesthesia for dental care. METHODS: Nine patients affected by mild or moderate MR (group A: intellective quotient > 35) and 12 affected by severe or profound MR (group B: intellective quotient < 36), undergoing general anaesthesia for dental care, were studied. The reaction to venipuncture before anaesthesia induction and the recovery from anaesthesia were assessed by clinical scores. Cardiac rate and arterial pressure were recorded before and after venipuncture and after removing the endotracheal tube. Cortisol and prolactin, two hormones affected by stress, were determined in plasma the day prior to surgery (1), after anaesthesia induction (2), and after removing the endotracheal tube (3). RESULTS: During venipuncture, group B was significantly less reactive than group A (p < 0.05) and showed no arterial pressure increase while group A presented a significant increase of systolic pressure; conversely, the groups shared the same hormonal pattern at time 2 (cortisol did not change, prolactin increased significantly). Postoperatively A and B groups did not differ regarding cardiac rate and arterial pressure, while a wider range of postoperative scores was observed in group A in which a further prolactin increase was registered at time 3. CONCLUSIONS: Clinical evaluation can underestimate the stress to which patients affected by severe or profound MR are subjected during anaesthesia induction.