Aim of the study: to compare AG versus MAC using propofol & remifentanil in a day surgery setting evaluating intra and postoperative clinical conditions and emergence times.
Methods: Propofol and remifentanil, either for general anesthesia (AG) then conscious sedation (MAC), have been administered to 218 patients undergoing mainly plastic or proctologic surgery as day hospital. AG was induced with propofol 1.5-2 mg/kg followed by a continuous infusion of 10 mg/kg/h and remifentanil infused at 10 micrograms/kg/h; MAC was started with propofol 3 mg/kg/h and remifentanil 4-5 micrograms/kg/h; during the maintenance phase of both AG and MAC, infusion rates of both drugs were adjusted according to clinical needs. Diazepam (0.05-0.06 mg/kg) and/or midazolam (2-3 mg) were given as premedication or coinduction as necessary. All patients received field infiltration with local anesthetics (lidocaine or mepivacaine); patients under GA were artificially ventilated with O2/air through IOT or LMA. Surgical and anesthesiological data were collected on specially designed records, with special attention to time intervals between anesthesia (FA) and surgery (FC) end and eyes opening (EO), orientation (OR), return of spontaneous breathing (SR), extubation (EST), sitting (SED), walking (CAMM), dressing (VEST) and discharge (DIM); data were analyzed with parametric and non parametric analysis of variance.
Results: All emergence intervals were longer under AG than under MAC: the earlier in the range of 4-5 vs 0.5-1 min; for the late intervals; FA-SED 24 +/- 18 vs 15 +/- 8, FA-PIED 65 +/- 48 vs 34 +/- 17, FA-VEST 69 +/- 58 vs 33 +/- 17, FA-CAMM 68 +/- 42 vs 39 +/- 19. Discharge times (83 +/- 67 vs 73 +/- 60) were similar between the two groups. Drugs consumption under AG were roughly double than under MAC; total dose infused of propofol (mg/kg/min) 0.118 +/- 0.044 vs 0.06 +/- 0.036; total dose of remifentanil (microgram/kg/min): 0.106 +/- 0.049 vs 0.066 +/- 0.027. AG resulted in a higher % incidence of intraoperative hypotension and bradycardia: hypotension 61.7 vs 25.7 and bradycardia 30.3 vs 12.4. SaO2 decreased more commonly during MAC than AG (20.9% vs 10.1); intraoperative itching was referred in 20% of MAC patients. Conversions rate from MAC to AG was 2.8%. Psychomotor agitation was more frequent following AG (14%) than MAC (2%); nausea (1%), vomiting, shivering (12%), headache (2%), ortostatic hypotension (2%) were similar between the two groups. Diazepam and/or midazolam caused a significant prolongation of recovery intervals, for both AG and MAC with a mean delay of the order of 100-200%.
Conclusions: Propofol- remifentanil gave excellent conditions for a wide variety of day surgery procedures, offering good anesthesia with quick emergence; the addition of bdz, even at low doses, prolongs significantly discharge times.