Acta Anaesthesiol Scand 1990: 34: 400-403
Randomized comparison of recovery after propofol-nitrous oxide versus thiopentoneisoflurane-nitrous oxide anaesthesia in patients undergoing ambulatory surgery K. KORTTILA, P. OSTMAN, E. FAURE, J. L. APFELBAUM, J. PRUNSKIS, M. EKDAWI and M. F. ROIZEN Department of Anesthesia and Critical Care, University of Chicago, Chicago, Illinois, USA
A randomized, prospective study was performed to compare recovery characteristics in 41 ASA physical status 1-11 patients scheduled for ambulatory surgery with either propofol or thiopentone-isoflurane anaesthesia. Particular attention was focused on the recovery time needed to meet discharge criteria. The propofol group received propofol 2 mg . kg-' for induction followed by propofol infusion (6-9 rng. kg-' . h - ' ) 1 min after intubation. The thiopentone-isoflurane group received thiopentone 4 mg . kg- for induction followed by isoflurane (0.5-276) I min after endotracheal intubation. Other drugs administered during or after anaesthesia were similar between the groups. The propofol group had significantly ( P < 0.05) faster clinical recovery than the isoflurane group with respect to times to response to commands, eye opening, orientation, ability to stand and void, tolerance to oral fluids, "home-readiness", and recovery of perceptual speed. Patients in the propofol group had significantly less (P10.05)emesis than the patients given isoflurane. We conclude that in patients undergoing ambulatory surgery propofol infusion is preferable to thiopentoneisoflurane anaesthesia, because it may allow faster discharge home.
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Received 20 September 1989, accepted f o r publication 24 January 1990
Key words: Anesthesia: outpatient; anesthetics, intravenous: propofol, thiopentone; anesthetics, volatile: isoflurane; anesthetic techniques: general; complications: nausea, vomiting; recovery: assessment.
Interest in intravenous (iv) anaesthesia has been revived by the introduction of propofol, the kinetics of which allow induction and maintenance of anaesthesia with rapid recovery of consciousness (1-4). Propofol has been compared favorably to other iv or inhalationa1 anaesthesia methods in operations of short duration (5);however, particular attention has not been focused on discharge times and "home-readiness". Using standard discharge criteria (6) and tests which have previously proved sensitive in evaluating residual effects of anesthetics (7), we designed this study to compare recovery in patients undergoing ambulatory surgery with propofol anaesthesia versus thiopentone-isoflurane anaesthesia.
PATIENTS AND METHODS The protocol was approved by the University of Chicago Clinical Investigation Committee and written informed consent was obtained from 41 unpremedicated patients (34 women, 7 men) with ASA physical status I or 11. The patients were scheduled for gynaecological laparoscopies, hysteroscopies, laser surgery, or other ambulatory surgical procedures. No patient had a history of allergy to medications
or evidence of hepatic, renal, haematologic, cardiovascular, respiratory, or metabolic disease. Patients entered the preanaesthesia care unit unpremedicated, and were randomly allocated to receive either propofol-nitrous oxide or thiopentone-isoflurane-nitrous oxide anaesthesia. Patients did not know which anaesthetic agent was to be administered. Intravascular access was established under local anaesthesia with an 18-gauge cannula in a vein on the dorsum of the hand or wrist. Infusion was started with dextrose 5% in water. Before induction, all patients received d-tubocurarine 3 mg, glycopyrrolate 0.2 mg, and fentanyl 1.5 pg. kg-' iv. Four minutes later, anaesthesia was induced with either propofol2 mg. kg-' or thiopentone 4 mg . kg-' iv over a period of 30 s. During induction, pain at the iv site was recorded. Oral tracheal intubation was performed 6 G 9 0 s after suxamethonium injection (1.5 mg. kg-'). Anaesthesia was maintained with either propofol infusion or isoflurane (0.5-2y0), both with nitrous oxide (N,O) 66% and oxygen started 60 s after intubation. The aim was to use the lowest isoflurane concentration possible to maintain haemodynamic variables within 30% of awake measurements. In the propofol group additional anaesthesia was provided with propofol boluses (0.25 mg. kg-') as needed to maintain blood pressure and heart rate within 30% ofawake measurements. Patients in the propofol group received 9 mg. kg-'. h - ' of propofol for the first 15 min and 6 mg. kg-'. h-' thereafter using a syringe infusion pump (Medfusion Systems Inc. Model # l O O l j . Vecuronium bromide was used for neuromuscular blockade in all patients. In order to allow the patients to show signs of light anaesthesia, 20-25y0 of the twitch response was maintained as assessed with a peripheral nerve stimulator (8).
40 1
RECOVERY AFTER PROPOFOL AND ISOFLURANE ANAESTHESIA Blood pressure was measured (Dynamap, model #1846P) once per minute for the first 10 rnin and every 5 min thereafter. ECG was monitored continuously. All patients were mechanically ventilated and end-tidal carbon dioxide concentration and oxygen saturation were continuously measured to ascertain normal ventilation and oxygenation in all patients. At the end of surgery, glycopyrrolate 0.4 mg and neostigmine 2.0 mg were given for reversal of the neuromuscular blockade. Nitrous oxide administration was stopped after completion of surgery, and both isoflurane administration and propofol infusion were stopped approximately 5 rnin before discontinuation of nitrous oxide. Fentanyl 50 pg iv acetaminophen 650 mg PO was given when needed for postoperative pain and droperidol 0.6 mg iv was used for prolonged nausea for vomiting. All recovery characteristics were assessed by a research nurse who was blinded to the treatment group. Duration of anaesthesia is reported as the time from the start of propofol or thiopentone injection until the tracheal tube was removed. Early recovery, ix., the time between discontinuation of N,O to the time when the patient was awake and oriented with protected reflexes, was assessed by extubation time, responsiveness to commands, spontaneous eye opening, and orientation to time and place. “Home-readiness”, defined as the time from discountinuation of N,O until the patient met criteria for discharge home, was evaluated by a trained nurse who was not aware of the anaesthetics given. Postanaesthesia recovery score (PARS) according to Aldrete & Kroulik (9), which is based on the patient’s activity, respiration, blood pressure, consciousness and colour, was assessed at 15-min intervals after discontinuation of nitrous oxide until the patient had a score of 10 points. The patient’s ability to sit, stand, tolerate fluids orally, and perform three psychomotor tests (perceptual speed, Maddox wing, tapping board) was evaluated by a research nurse at 30-min intervals after cessation of propofol or after the end-tidal (Puritan Bennett, Airway Gas Monitor, Model #254) isoflurane concentration was 0.20/. Emesis (nausea, retching, and vomiting) was evaluated every 15 rnin in the PACU. Patients were considered ready for discharge when they had tolerated oral fluids, walked to the bathroom and voided, had no excessive pain and no or only minimal emesis (6). Statistical analysis for continuous data was performed using Student’s t-test and analysis of variance followed by Scheffe’s F-test. The chi-square test with continuity correction was used for nonparametric proportions.
RESULTS Treatment groups were demographically similar in age, weight, and ASA class (Table 1). Four patients in the propofol group and two in the thiopentoneisoflurane group required a second dose (25% of the first dose) to induce hypnosis. At the time of induction, two patients receiving propofol and one patient receiving thiopentone complained of pain at the iv site. Twenty-four hours postoperatively, three patients given propofol and five patients given thiopentone complained of pain at the iv site. No significant differences were found in the total amount of fentanyl, droperidol or acetaminophen used between propofol and isoflurane groups. The propofol group required significantly (P
Randomized comparison of recovery after propofol-nitrous oxide versus thiopentoneisoflurane-nitrous oxide anaesthesia in patients undergoing ambulatory surgery K. KORTTILA, P. OSTMAN, E. FAURE, J. L. APFELBAUM, J. PRUNSKIS, M. EKDAWI and M. F. ROIZEN Department of Anesthesia and Critical Care, University of Chicago, Chicago, Illinois, USA
A randomized, prospective study was performed to compare recovery characteristics in 41 ASA physical status 1-11 patients scheduled for ambulatory surgery with either propofol or thiopentone-isoflurane anaesthesia. Particular attention was focused on the recovery time needed to meet discharge criteria. The propofol group received propofol 2 mg . kg-' for induction followed by propofol infusion (6-9 rng. kg-' . h - ' ) 1 min after intubation. The thiopentone-isoflurane group received thiopentone 4 mg . kg- for induction followed by isoflurane (0.5-276) I min after endotracheal intubation. Other drugs administered during or after anaesthesia were similar between the groups. The propofol group had significantly ( P < 0.05) faster clinical recovery than the isoflurane group with respect to times to response to commands, eye opening, orientation, ability to stand and void, tolerance to oral fluids, "home-readiness", and recovery of perceptual speed. Patients in the propofol group had significantly less (P10.05)emesis than the patients given isoflurane. We conclude that in patients undergoing ambulatory surgery propofol infusion is preferable to thiopentoneisoflurane anaesthesia, because it may allow faster discharge home.
'
Received 20 September 1989, accepted f o r publication 24 January 1990
Key words: Anesthesia: outpatient; anesthetics, intravenous: propofol, thiopentone; anesthetics, volatile: isoflurane; anesthetic techniques: general; complications: nausea, vomiting; recovery: assessment.
Interest in intravenous (iv) anaesthesia has been revived by the introduction of propofol, the kinetics of which allow induction and maintenance of anaesthesia with rapid recovery of consciousness (1-4). Propofol has been compared favorably to other iv or inhalationa1 anaesthesia methods in operations of short duration (5);however, particular attention has not been focused on discharge times and "home-readiness". Using standard discharge criteria (6) and tests which have previously proved sensitive in evaluating residual effects of anesthetics (7), we designed this study to compare recovery in patients undergoing ambulatory surgery with propofol anaesthesia versus thiopentone-isoflurane anaesthesia.
PATIENTS AND METHODS The protocol was approved by the University of Chicago Clinical Investigation Committee and written informed consent was obtained from 41 unpremedicated patients (34 women, 7 men) with ASA physical status I or 11. The patients were scheduled for gynaecological laparoscopies, hysteroscopies, laser surgery, or other ambulatory surgical procedures. No patient had a history of allergy to medications
or evidence of hepatic, renal, haematologic, cardiovascular, respiratory, or metabolic disease. Patients entered the preanaesthesia care unit unpremedicated, and were randomly allocated to receive either propofol-nitrous oxide or thiopentone-isoflurane-nitrous oxide anaesthesia. Patients did not know which anaesthetic agent was to be administered. Intravascular access was established under local anaesthesia with an 18-gauge cannula in a vein on the dorsum of the hand or wrist. Infusion was started with dextrose 5% in water. Before induction, all patients received d-tubocurarine 3 mg, glycopyrrolate 0.2 mg, and fentanyl 1.5 pg. kg-' iv. Four minutes later, anaesthesia was induced with either propofol2 mg. kg-' or thiopentone 4 mg . kg-' iv over a period of 30 s. During induction, pain at the iv site was recorded. Oral tracheal intubation was performed 6 G 9 0 s after suxamethonium injection (1.5 mg. kg-'). Anaesthesia was maintained with either propofol infusion or isoflurane (0.5-2y0), both with nitrous oxide (N,O) 66% and oxygen started 60 s after intubation. The aim was to use the lowest isoflurane concentration possible to maintain haemodynamic variables within 30% of awake measurements. In the propofol group additional anaesthesia was provided with propofol boluses (0.25 mg. kg-') as needed to maintain blood pressure and heart rate within 30% ofawake measurements. Patients in the propofol group received 9 mg. kg-'. h - ' of propofol for the first 15 min and 6 mg. kg-'. h-' thereafter using a syringe infusion pump (Medfusion Systems Inc. Model # l O O l j . Vecuronium bromide was used for neuromuscular blockade in all patients. In order to allow the patients to show signs of light anaesthesia, 20-25y0 of the twitch response was maintained as assessed with a peripheral nerve stimulator (8).
40 1
RECOVERY AFTER PROPOFOL AND ISOFLURANE ANAESTHESIA Blood pressure was measured (Dynamap, model #1846P) once per minute for the first 10 rnin and every 5 min thereafter. ECG was monitored continuously. All patients were mechanically ventilated and end-tidal carbon dioxide concentration and oxygen saturation were continuously measured to ascertain normal ventilation and oxygenation in all patients. At the end of surgery, glycopyrrolate 0.4 mg and neostigmine 2.0 mg were given for reversal of the neuromuscular blockade. Nitrous oxide administration was stopped after completion of surgery, and both isoflurane administration and propofol infusion were stopped approximately 5 rnin before discontinuation of nitrous oxide. Fentanyl 50 pg iv acetaminophen 650 mg PO was given when needed for postoperative pain and droperidol 0.6 mg iv was used for prolonged nausea for vomiting. All recovery characteristics were assessed by a research nurse who was blinded to the treatment group. Duration of anaesthesia is reported as the time from the start of propofol or thiopentone injection until the tracheal tube was removed. Early recovery, ix., the time between discontinuation of N,O to the time when the patient was awake and oriented with protected reflexes, was assessed by extubation time, responsiveness to commands, spontaneous eye opening, and orientation to time and place. “Home-readiness”, defined as the time from discountinuation of N,O until the patient met criteria for discharge home, was evaluated by a trained nurse who was not aware of the anaesthetics given. Postanaesthesia recovery score (PARS) according to Aldrete & Kroulik (9), which is based on the patient’s activity, respiration, blood pressure, consciousness and colour, was assessed at 15-min intervals after discontinuation of nitrous oxide until the patient had a score of 10 points. The patient’s ability to sit, stand, tolerate fluids orally, and perform three psychomotor tests (perceptual speed, Maddox wing, tapping board) was evaluated by a research nurse at 30-min intervals after cessation of propofol or after the end-tidal (Puritan Bennett, Airway Gas Monitor, Model #254) isoflurane concentration was 0.20/. Emesis (nausea, retching, and vomiting) was evaluated every 15 rnin in the PACU. Patients were considered ready for discharge when they had tolerated oral fluids, walked to the bathroom and voided, had no excessive pain and no or only minimal emesis (6). Statistical analysis for continuous data was performed using Student’s t-test and analysis of variance followed by Scheffe’s F-test. The chi-square test with continuity correction was used for nonparametric proportions.
RESULTS Treatment groups were demographically similar in age, weight, and ASA class (Table 1). Four patients in the propofol group and two in the thiopentoneisoflurane group required a second dose (25% of the first dose) to induce hypnosis. At the time of induction, two patients receiving propofol and one patient receiving thiopentone complained of pain at the iv site. Twenty-four hours postoperatively, three patients given propofol and five patients given thiopentone complained of pain at the iv site. No significant differences were found in the total amount of fentanyl, droperidol or acetaminophen used between propofol and isoflurane groups. The propofol group required significantly (P
