195 The Canadian Journal of Hospital Pharmacy- Volume 48, No. 4, August 1995 208

:y, Pharmacoeconomics of Propofol Versus Thiopental 1e, on for Induction of Anaesthesia in Short Procedures .ve si­ Sandy H.L. Hsu and Stephen J. Shalansky tre r1is :al ABSTRACT RESUME of This study compared the costs and benefits of using On a compare, au cours de cette etude prospective avec >rk propofol/fentanyl versus thiopental/fentanyl for cohorte qui a ete menee conjointement a un sondage lCY induction of anaesthesia in short procedures. A aupres des memes patients, les couts et les avantages de lCY prospective, cohort trial was conducted in conjunction /'association propofol/fentanyl a ceux de /'association with a patient survey. The study population included a thiopentallfentanyl pour /'induction de l'anesthesie dans ng consecutive sample of American Society of Anaes­ les interventions de courte duree. La population de l 'etude de thesiologists. Class I or II patients who underwent comprenait un echantillon consecutifde patients de classe I ou II de !'American Society ofAnesthesiologists qui ont ity short operative procedures and who were given one of the studied anaesthetic regimens. Insofl.urane/N20 was subi une breve operation et reru l'un des deux regimes me used for maintenance of anaesthesia in all cases. anesthesiques al'etude. Le maintien de l 'anesthesie etait el­ Propofol patients showed a significantly shorter time assure dans tousles cas par l'isojlurane et le N20. On a cs. to eye opening (p=0.0025 ); orientation to date ofbirth, note une diminution du temps d'ouverture des yeux ew place, and day of week (p=0.0002); time to (p = 0, 0025 ), du temps d 'orientation; evocation de la date )0- consciousness (p=0.0019); and time in recovery room denaissance, des lieuxetdujourde lasemaine(p = 0,0002), cal (p=0.013); but not time to tolerating 50 mL of oral du temps de reprise de conscience (0 = 0,0019) et du fluid (p=0.06). Nausea and vomiting occurred in 41% temps en salle de reveil (p = 0,013), mais non du temps an of thiopental patients and 19% of propofol patients pourgarder50mLdeliquide (p = 0,06), chezlespatients we (difference 22%; 95% C.I., -1% to 44%). Based on qui ont reru du propofol comparativement a ceux qui ont os- survey results, propofol patients subjectively reported reru du thiopental. Ces demiers Ont eprouve des nausees et des vomissements dans 4 I % des cas, comparativement 1da fewer side effects upon returning home and were able to resume daily activities earlier than thiopental a 19 % chez ceux qui avaient re9u du propofol (difference )ur patients. With the current staffing and patient load at de 22 %, intervalle de confiance de 95 %, ecart - I % a im­ our institution, an estimated 4.8 hours ofnursing time 44 % ). Se/on Les resultats du sondage, l'evaluation •act per day would be made available ifpropofol were used subjective des patients qui ont reru du propofol montre 1ar­ in place of thiopental for induction of anaesthesia in qu 'ils ont eu moins d' effets secondaires a leur retour a la ~l's these procedures. Ifpropofol were usedforall daycare maison et qu 'ils etaient capables de reprendre leurs surgery patients in our institution, the annual acquisi­ activites quotidiennes plus rapidement que ceux qui avaient tion cost is projected to be $60,33 I .28 versus $8,079.68 re9u du thiopental. Avec le personnel actuel et le nombre for thiopental. In conclusion, the use of propofol for de patients par in.firmier( ere) a notre etablissement, nous induction of anaesthesia in short procedures is more pourrions consacrer 4,8 heures du plus en temps de soins expensive than thiopental but may yield qualitative parjour si le propofol etait utilise a la place du thiopental advantages including more rapid recovery, less nausea pour !'induction de l'anesthesie dans Les interventions de and vomiting, and less burden on recovery room courte duree. Le cout d'achat annuel du propofol pour nursing staff. toutes les chirurgies d'un jour dans notre etablissement s'eleverait a 60 331,28 $ comparativement a 8 079,68 $ Key Words: pharmacoeconomics, propofol, thiopental. pour le thiopental. Le recours au propofol serait certes plus cher que /'usage du thiopental, mais ii concederait des avantages qualitatifs comme un reveil plus rapide, moins de nausees et de vomissements et moins d 'heures affectees en salle de reveil pour le personnel infirmier. Mots cles : pharmacoeconomie, propofol, Can J Hosp Pharm 1995; 48:208-213 thiopental.

Sandy H.L. Hsu, B. Sc. (Phann.), is a Pharmacist, Department of Pharmacy, Vancouver Hospital and Health Sciences Centre, Vancouver, BC. At the time of the study, Ms. Hsu was a Pharmacy Resident at Lions Gate Hospital. Stephen J. Shalansky, Pharm.D., is Intensive Care Pharmacist, Education and Residency Coordinator, Department of Pharmacy, Lions Gate Hospital, and Clinical Assistant Professor, University of British Columbia, Vancouver, BC. Acknowledgments: The authors would like to acknowledge Linne Storey, Head Nurse of PAR and Daycare Surgery at Lions Gate Hospital, and her whole nursing staff for patiently preparing the charts and monitoring the patients. Ruth Milner of U.B.C. Hospital Shaughnessy Site Research Centre for her statistical work. Dr. Francis C. Ping, Head of Anaesthesia at Lions Gate Hospital, for his help and suggestions. Dr. Bruce Carlton of the Pharmacy Department at B.C. Children's Hospital for his advice on our protocol. Address Correspondence lo: Stephen Shalansky, Pharrn.D., Department of Pharmacy, Lions Gate Hospital, 231 East 15th Street, North Vancouver, B.C. V7L 2L 7. 209 The Canadian Journal of Hospital Phannacy - Volume 48, No. 4, aout 1995 Th

Ta INTRODUCTION After the procedure, patients were marized to identify patients' sub­ Propofol' s rapid onset of action, short discharged to the post anaesthetic jective opinions regarding the agent duration of effect, and low incidence recovery unit (PAR) where nursing they received. Cost calculations were of side effects make it well suited for staff, who were unaware of the based on a propofol acquisition anaesthesia in short surgical pro­ anaesthetic agents used (anaesthetic cost of $8.88/200mg ampoule and cedures. While many studies have records were not available in PAR), $7 .88/2.5g vial ofthiopental. All costs demonstrated advantages of propofol recorded the patient's recovery time are in Canadian dollars. Annual cost for total anaesthesia, 1-11 propofol has from the end of surgery in terms of: projections assume 8726 patients per also been shown to reduce recovery time to spontaneous eye opening; year which was the number of daycare time and adverse effects when used orientation to date of birth, place, and operations done at our institution from strictly for induction.12-21 The high day of week; time when the patient April 1, 1992 to March 31, 1993. acquisition cost of propofol compared could tolerate 50 mL of clear oral to that of traditional anaesthetic agents fluid; time to consciousness defined RESULTS raises questions about its cost­ as achieving a Steward scale23 of 6, Fifty-two propofol and 22 thiopental effectiveness. Several authors have and total time spent in recovery. The patients were included over the three­ examined this issue;8-11 however, number of nausea and vomiting month study period. All patients these studies have all utilized regimens episodes experienced in PAR was also enrolled in the study were used in the in which propofol was used for both recorded. Patients were requested to data analysis. Patients received an induction and maintenance. We complete a questionnaire at approx­ average dose :!: SD of 2.29 :!: 0.45 designed this study to compare the imately 24 hours after their procedure mg/kg of propofol or 4.32 :!: 0.73 Ta costs and benefits of propofol and to document side effects experienced mg/kg of thiopental for induction, thiopental for induction ofanaesthesia at home including nausea, vomiting, and nitrous oxide in oxygen with in short procedures. Specifically we difficulty sleeping, headache, and isoflurane O to 4% for maintenance. looked at recovery times, incidence weakness. The survey also included Patients also received succinyl­ of nausea and vomiting, and nursing patients' estimates of when they were choline, vecuronium, and/or d-tubo­ hours per patient. Through a patient able to eat, resume leisure activities, curarine. Twenty-seven patients survey we also assessed side effects and return to work. Finally, the received 20 to 50 mg of lidocaine after discharge and the ability to questionnaire asked whether the prior to the propofol to reduce pain on resume daily activities. patient had undergone previous injection. surgery, whether they would choose The differences in patient age, METHODS the same anaesthetic if they required weight, sex, ASA grouping, fentanyl Propofol was compared to thiopental subsequent surgery, and asked for dose, and length of procedure are for induction of anaesthesia in short any additional comments. listed in Table I along with 95% daycare procedures in a prospective, A minimum required sample size confidence intervals. When these cohort study. The study included a of 14 patients per group was estimated group comparability parameters were consecutive sample of patients to detect a 15% difference in time to included as independent variables in undergoing short procedures between eye opening (ex = 0.05, ~ = 0.20) multiple regression analysis, none September21 andDecember24, 1992. based on recovery results from were associated with outcome (i.e., all Patients were included in the study if previous studies where propofol and recovery times studied). The pro­ wi they were classified as ASA I or II (as thiopental were used for induc­ portion of patients in the two study ve per the American Society of tion.3,6,7,12,19,24 The group compar- groups undergoing each procedure is de Anaesthesiologists guidelines22); ability and length of recovery times also listed in Table I. fn underwent cystoscopy :!: pyelogram, calculated from the end of the Propofol patients showed a an laparoscopic tubal ligation, dilation procedure were analyzed statistically significantly shorter time to eye w: and curettage, or termination of using descriptive statistics and opening, orientation, time to con­ as pregnancy; were given propofol/ multiple regression analysis, where sciousness, and time spent in recovery th fentanyl or thiopental/fentanyl for appropriate. Each nausea and room, but not time to tolerating 50 ge induction of isoflurane/N20 main­ vomiting episode was estimated, mL of oral fluid (Table II). SU tained anaesthesia; and were older based on nursing experience, to Based on the average doses of than 19 years. Patients were excluded consume fl ve minutes of nursing time propofol and thiopental quoted above, 41 if they did not meet the criteria listed to account for patient monitoring, a mean patient weight of 68 kg 15 above. The choice of the anaesthetic clean up, and medication admini­ (Table I), and the annual daycare (d was at the discretion of the stration. Comments on the returned surgery patient load at our institution, 4:1 anaesthetist. patient questionnaires were sum- the annual drug acquisition cost for th The Canadian Journal of Hospital Pharmacy- Volume 48, No. 4, August 1995 210 195

Table I: Group Comparability lb­ room was 31.09 minutes (Table II). Given our institution's standard of ent Propofol Thiopental Difference ere n=52 n=22 (95%C.I.) one nurse to three patients, this would free 10.36 minutes of nursing time on Mean age, yrs (SD) 43.7 (15.94) 50.4 (18.94) 6.7 (-2.3 to 15.7) ,nd per patient. Therefore, nursing time Sex,% male 25.0 13.6 -11.4 (-29.9 to 7.2) sts would be reduced by 11.96 minutes to ost Mean weight, kg (SD) 67.63 (14.05) 67.97 (14.22) 0.34 (-6.72 to 7.40) attend to a patient recovering from propofol induction. At our institution, Jer ASA I/II 37/15 13/9 are this translates to an average of 4.8 )m Mean length of surgery, hours per day if all surgical daycare min (SD) 8.83 (6.019) 13.86 (8.061) 5.03 (1.28 to 8.77) patients were induced with propofol Mean fentanyl dose, versus thiopental. mcg/kg (SD) 1.12 (0.499) 0.87 (0.260) -0.25 (-0.42 to -0.08) Fifty percent (11/22) of thiopental ital Procedures: patients and 33% ( 17 /52) of propofol laporoscopic tubal ligation I (2%) 3 (14%) patients returned their questionnaires pregnancy termination 12 (23%) nts 2 (9%) (Table III). In the 24 hours following dilatation and curettage 19 (36%) 7 (32%) their procedure, a higher percentage the cystoscopy 3 (6%) 3 (14%) of thiopental patients reported side an cystoscopy and pyelogram 17(33%) 7 (32%) .45 effects and a higher percentage of .73 propofol patients were able to eat, Table II: Recovery Outcomes )fl, resume leisure activities, and return to work. It should be noted that a ith Propofol Thiopental ce. Mean SD Mean SD p higher percentage of thiopental yl­ (min) (min) patients indicated they were retired Jo­ and thus could not be assessed with (n = 52) (n = 22) nts respect to the timing of their return to Time to eye opening 7.00 4.30 10.91 4.83 0.0025 ine work. Side effects listed as "other" on Time to consciousness 8.25 4.64 13.32 6.03 0.0019 for propofol included neck- or backache (two patients), perspiring Time spent in recovery room 111.46 26.36 142.55 49.95 0.013 ge, (one patient), pain of injection (one r1yl (n = 52) (n = 13) patient), cramps (two patients), tongue are Time to orientation 9.30 6.01 14.5 6.91 0.0002 quivering ( one patient), and dizziness 5% (one patient), while those listed for (n = 43) (n = 14) ~se thiopental included sore throat ( one Time to tolerating 50 mL of oral fluid 53.79 26.61 76.07 ere 30.49 0.06 patient), neck- or backache (two ;in patients), chest pain ( one patient), and me tiredness (two patients). .e., all daycare patients to be induced episodes in the propofol group. Anti­ ro- with propofol would be $60,331.28 emetics (dimenhydrinate or prochlor­ DISCUSSION 1dy versus $8,079.68 for thiopental. This perazine) were used in five thiopental Propofol has been used for induction e is does not take into account wastage and seven propofol patients. and maintenance of anaesthesia in a from discarding partly used vials or An estimate of nursing time large number of trials investigating a ampoules. Quantification of wastage required to attend to patients its impact on recovery and side effect 1 1 :ye was not possible; however, it was recovering from propofol induction profile. · 1 Most of these studies have 1 1 )fi­ assumed to be small since anaes­ versus thiopental induction was shown shorter recovery times · 1 and 3 11 ery thetists involved in the cases studied calculated. Using an estimate of five fewer side effects · compared to 50 generally save part vials for minutes of nursing time to attend to traditional anaesthetics. Investigators subsequent cases. each nausea and vomiting episode, have also compared propofol to of Nausea and vomiting occurred in nurses spent 2.7 minutes for this traditional induction agents when ve, 41 % (9/22) of thiopental patients and activity in each thiopental patient and inhalation anaesthetics are used for 12 21 25 26 kg 19% (10/52) of propofol patients 1.1 minutes for each propofol patient, maintenace. · • , While the are (difference 22%; 95% C.I., -1% to representing a difference of 1.6 majority of these trials have on, 44%). This included 12 episodes in minutes per patient. The mean demonstrated a reduced recovery 12 21 for the thiopental group versus 11 difference in time spent in the recovery period, • the observations 211 The Canadian Journal of Hospital Pharmacy - Volume 48, No. 4, aout 1995 TheC

Table III: Response to Patient Survey was similar between the two study the c! groups (Table I). Our results also was Propofol Thiopental (%) (%) suggest that the use of propofol is theti n=S2 n =22 associated with less nausea and invol vomiting than thiopental. invo] Response 17 (33) 11 (50) It is difficult to draw conclusions was Nausea 3 (18) 4 (36) about the cost advantages of propofol exch as its benefits do not correspond to a excll Vomiting 2 (12) 2 (18) direct dollar value. The reduced selec Difficulty sleeping l (6) l (9) nursing time to attend to propofol thes, Headache 6 (35) 3 (27) patients cannot be projected to a cost­ thio Weakness 3 (18) 4 (36) savings since staffing levels are pyel Other 9 (53) 6 (55) predetermined and cannot fluctuate forg Able to eat: in small increments to adjust for this right away 2 (12) 0 reduced workload. In order to take of l same day 13 (76) 7 (64) advantage of the potential 4.8 hours proc next day l (6) 2 (18) grm more than 24 hours 0 l (9) perdayofnursingtimemadeavailable survey incomplete l (6) l (9) with the exclusive use of propofol for 45(}1 Resume leisure activities: induction in the studied procedures, triec right away l (6) 0 significant changes in the PAR assc same day 13 (76) 5 (45) staffing system would have to be sele next day 3 (18) l (9) implemented. Without such changes, thro more than 24 hours 0 l (9) this advantage would be limited to of! survey incomplete 0 l (9) increasing the amount of nursing time The Return to work: con same day 0 0 available per patient. It may increase next day 6 (35) l (9) the capacity of the PAR; however, the wer more than 24 hours 4 (24) 3 (27) number of operations performed per diff retired 2 (12) 4 (36) day also depends on the number of l survey incomplete 5 (29) 3 (27) surgeons and the operating room Wa! Previous surgery: capacity. for yes 15 (88) 9 (82) The results of the patient survey par no 2 (12) l (9) survey incomplete 0 l (9) show that a higher percentage of thi< Would you choose the same anaesthetic? propofol patients indicated that they 50 yes 14 (82) 6 (55) would choose the same anaesthetic if 14/ no 3 (18) 4 (36) they had another surgery. The ser survey incomplete 0 l (9) decreased incidence of nausea and res vomiting in this group probably sta contributed to this. It should be noted thr, regarding adverse effects have not Our study is the first to investigate that the majority of patients in both pa been as consistent. the cost-benefit of propofol versus groups had undergone previous COi All of the published trials which thiopental when used strictly for surgery allowing an informed VO have investigated propofol's cost­ induction of anaesthesia in short assessment of their anaesthetic SU effectiveness compare regimens procedures. Propofol patients showed experience. The patient survey results dif utilizing propofol for both induction significantly shorter recovery than also indicate that propofol patients pa and maintenance to more traditional thiopental patients. We believe the were able to resume leisure activities int regimens involving an injectable induction agent was primarily and return to work sooner than fa, induction agent and inhalation responsible for the differences in the thiopental patients which would la1 anaesthetics for maintenance. 8-11 measured recovery times based on presumably hasten their return to Fi1 While most of these studies showed the results of multiple regression normal productivity. The fact that pr, benefits through a varied reduction analysis which indicated that age, sex, more thiopental patients were retired th, in recovery time and adverse weight, ASA class, length of surgery may have influenced this result. sh effects, 8,9, 11 one author concluded that and fentanyl dose did not influence Our results should be interpreted in the routine use of propofol for day­ recovery times. The proportion of with caution for several reasons. First, surgery patients was not justified.10 patients undergoing each procedure this was not a randomized trial and pr ------~------, i:

995 The Canadian Journal of Hospital Pharmacy - Volume 48, No. 4, August 1995 212

1dy the choice of anaesthetic agents used and may not represent a typical case 8. Sung YF, Reiss N, Tillette T. The lso was at the discretion of the anaes­ load in all institutions which utilize differential cost of anesthesia and , is recovery with propofol-nitrous oxide thetist. Of the five anaesthetists propofol for induction of anaesthesia. anesthesia versus thiopental sodium­ md involved in the cases studied, one was At many institutions, longerand more isoflurane-nitrous oxide anesthesia. J involved in a single case (thiopental diverse cases are being treated as Clin Anesth 1991; 3:391-4. )nS was used), one used thiopental outpatient procedures. The doses of 9. Killian A, Hamilton P, Tierney M. fol exclusively, and two used propofol propofol and thiopental used in this Propofol versus thiopental-isoflurane in outpatient surgical procedures. Can J oa exclusively. Only one anaesthetist study were comparable to previous Hosp Pharm 1992; 45:139-44. :ed selected between the two agents for studies.12-21,25 10. Cade L, Morley PT, Ross AW. Is fol these procedures. He tended to use The results of this study suggest propofol cost-effective for day-surgery >St- thiopental for cystoscopy and that there may be advantages patients. Anaesth Intensive Care 1991; 1re pyelograms, while propofol was used associated with the use of propofol in 19-201-4. 11. Marais ML, Maher MW, Wetchler BV, ate for gynecological procedures. Despite place of thiopental for induction of et al. Reduced demands on recovery for this tendency, the overall proportion anaesthesia in short procedures, but room resources with propofol tke of urological versus gynecological these results should be validated with (Diprivan) compared to thiopental­ urs procedures was similar between the a randomized, blinded, prospective isoflurane. Anesthesia/ Rev 1989; ble groups (39% versus 61 % forpropofol, study. Whether these advantages 16:29-40. 12. Gold MI, Abraham EC, Herrington C. for 45% versus 55% for thiopental). We justify the added expense of propofol A controlled investigation of propofol, ·es, tried to account for potential bias should be an institution-specific thiopentone and methohexitone. Can J \R associated with the anaesthetists' decision including consideration of Anaesth 1987; 34:478-81. be selection of the induction agent the quality of the patients' experience 13. MacKenzie N, Grant IS. Comparison of es, through multiple regression analysis and the amount of nursing care the new emulsion formulation of to propofol with methohexitone and of group comparability parameters. required in the recovery room. Iii thiopentone for induction of anaesthesia me The results indicate that none of the in day cases. Br J Anaesth 1985; lSe comparability parameters studied REFERENCES 57:725-31. :he were associated with the measured 1. Cork RC, Scipone P, Vonesh MJ, et al. 14. Rally G, Verichelen L. Comparison of Jer differences in recovery times. Propofol infusion vs. thiopentaV propofol and thlopentone for induction isoflurane for outpatient anesthesia. of anaesthesia in premedicated patients. of Another point worthy of comment Anesthesiology 1988; 69(suppl Anaesthesia 1985; 40:945-8. )ill was the incomplete documentation 3A):A563. 15. Raeder JC, Misvaer G. Comparison of for two of our recovery time 2. Gold MI, Sacks DJ, Grosnoff DB, et al. propofol induction with thiopentone or ·ey parameters: orien_tation ( 13/22 Comparison of propofol with thiopental methohexitone in short outpatient of thiopental) and time to tolerating and isoflurane for induction and general anaesthesia. Acta Anaesthesia/ maintenance of general anesthesia. J Scand 1988; 32:607-13. 1ey 50 mL of oral fluid (43/52 propofol, Clin Anesth 1989; 1 :272-6. 16. Heath PJ, Kennedy DJ, Ogg TW, et al. ; if 14/22 thiopental). This could indicate 3. Korttila K, Nuotto EJ, Lichtor JL, et al. Which intravenous induction agent for he serious bias. However, even if these Clinical recovery and psychomotor day surgery? Anaesthesia 1988; 43:365- nd results are ignored, there is still a function after brief anesthesia with 8. ,Iy statistically significant difference for propofol or thiopental. Anesthesiology 17. Edelist G. A comparison ofpropofol :ed 1992; 76:676-81. and thiopentone as induction agents in three commonly measured recovery 4. Sanders LD, Clyburn PA, Rosen M, et outpatient surgery. Can J Anaesth 1987; )th parameters. As well, the 95% al. Propofol in short gynaecological 34:110-6. us confidence interval for nausea and procedures. Anaesthesia 1991; 46:451- 18. O'Toole DP, Milligan KR, Howe JP, et ed vomiting included zero, which 5. al. A comparison of propofol and tic suggests the possibility of no 5. Kashtan H, Edelist G, Mallon J, et al. methohexitone as induction agents for Its Comparative evaluation of propofol and day case isoflurane anaesthesia. difference between the groups for this thiopentone for total intravenous Anaesthesia 1987; 42:373-6. 1ts parameter. On the other hand, the anaesthesia. Can J Anaesth 1990; 19. Valtonen M, Kanta J, Rosenbert P. les interval was very much skewed in 37:170-6. Comparison of propofol and an favour of propofol and there was a 6. Boysen K, Sanchez R, Krintel JJ, et al. thiopentone for induction of anaesthesia 1ld large absolute difference (22% ). Induction and recovery characteristics for elective Caesarean section. Anaesthesia 1989; 44:758-62. to of propofol, thlopental and etomidate. Finally, the nature of the patient survey Acta Anaesthesia/ Scand 1989; 33:689- 20. Morison DH, Dunn GL. A comparative lat precluded statistical analysis and; 92. study of Diprivan and thiopental as ed therefore, no definite conclusions 7. DeGrood PMRM, Harbers BM, induction agents in dental patients should be drawn from this vanEgmond J, et al. Anaesthesia for (abstract). Anesth Analg 1987; 66:S123. ed information. laparoscopy: a comparison of five 21. Chittleborough MC, Osborne GA, st, techniques including propofol, Rudkin GE, et al. Double-blind One should keep in mind that the etomidate, thiopentone and isoflurane. comparison of patient recovery after nd procedures studied were very brief Anaesthesia 1987; 42:815-23. induction with propofol or thiopentone 213 The Canadian Journal of Hospital Phannacy - Volume 48, No. 4, aout 1995 Th

for day-case relaxant general room. Can Anaesth Soc J 1975; thiopentone as induction agents in anaesthesia. Anaesth Intensive Care 22:111-2. obstetric anaesthesia. Anaesthesia 1989; 1992; 20:169-73. 24. Dunn GL, Morison DH. Diprivan 44:753-7. 22. Schneider AJL. Assessment of risk (propofol) and thiopental as induction 26. Sanders LD, Isaac PA, Yeomans WA, et al. factors and surgical outcome. Surg Clin agents in dental outpatients. Semin Propofol-induced anaesthesia: double-blind North Am 1983; 63:1113-26. Anesth 1988; 7:(Suppl 1)26-8. comparison of recovery after anaesthesia 23. Steward DJ. A simplified scoring 25. Moore J, Bill KM, Flynn RJ, et al. A induced by propofol or thiopentone. system for the post-operative recovery comparison between propofol and Anaesthesia 1989; 44:200-4.

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