Clinical and metabolic responses to different kinds of premedication in ASA III patients.

Clinical and metabolic responses to atropine plus pethidine and to scopolamine plus morphine premedication were studied in 45 ASA physical status III patients undergoing gynaecological procedures. Atropine 0.5 mg plus pethidine 50 mg intramuscularly (Group 1), scopolamine 0.24 mg plus morphine 8 mg (Group 2), or intramuscular placebo (Group 3) premedication were given in random, double-blind fashion. Scopolamine-morphine premedication caused a significant decrease in energy expenditure (EE) and oxygen consumption (VO2) (from 1229 +/- 193 to 1184 +/- 221 kcal/24 h, P = 0.004 and from 105 +/- 11 to 102 +/- 12 ml/min/m2, P = 0.006, respectively) simultaneously with a decrease in rate-pressure product (RPP) (P = 0.0001) and an increase in pressure-rate quotient (PRQ) (P = 0.034). Atropine-pethidine premedication induced a decrease in RPP but not in EE or VO2. In the placebo group both RPP and VO2 first increased and then slowly returned to the levels measured prior to premedication. The RPP was significantly lower in Group 2 than in Groups 1 and 3 at both 30 and 60 min. The degrees of subjective tiredness and anxiolysis were significantly greater in Groups 1 and 2 (showing good sedative and anxiolytic effect) than in Group 3. These results show that in ASA III patients, atropine-pethidine premedication does not decrease the sympathoadrenal reaction to the degree its anxiolytic and sedative effect would suggest. This may indicate neuroendocrine stress induced by atropine-pethidine.