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Comparison of patient-controlled sedation with either methohexitone or propofol
British Journal of Anaesthesia 1996; 77: 727–730
Comparison of patient-controlled sedation with either methohexitone or propofol
S. K. HAMID, N. MCCANN, L. MCARDLE AND A. J. ASBURY
Summary We studied 42 patients undergoing oral surgery under local anaesthesia with i.v. sedation, allocated randomly to receive either methohexitone (group M) or propofol (group P) for patientcontrolled sedation (PCS). Group M patients self-administered 2.5-mg (0.5 ml) bolus doses of methohexitone and group P, 5-mg (0.5 ml) doses of propofol, without a lockout. The 0.5-ml bolus dose was delivered over 7.2 s for both drugs. The procedure was completed satisfactorily in all patients. Patients in both groups achieved their desired levels of sedation. No patient lost verbal contact. Group M patients had higher heart rates during the procedure. The lowest S pO values recorded were 92% and 95% for group P and group M, respectively. Immediately after operation patients in group M reported that they felt more sleepy than those in group P (P : 0.01) but there were no differences at subsequent times. The results of the psychomotor tests were comparable for the two groups after operation, except for the “posting box task” at 15 min after operation when the mean decrement (compared with preoperative performance) was 93% for group P and 913% for group M (P : 0.05). More patients in group P complained of pain in their hand. We conclude that methohexitone is a suitable alternative drug to propofol for PCS. (Br. J. Anaesth. 1996; 77: 727–730) 2
Key words Anaesthetics i.v., methohexitone. Anaesthetics i.v., propofol. Sedation, patient-controlled. Surgery, oral.
Patient-controlled sedation (PCS) has been reported using either midazolam or propofol. However, they are not comparable in pharmacokinetics. Oversedation may be a problem with midazolam as it has a relatively slow onset and the patient may make additional demands for drug boluses before adequate time has elapsed for the earlier boluses to produce an effect. The use of methohexitone for PCS has not been described. It is cleared rapidly from the body and is cheaper than propofol.1 Studies of psychomotor function after induction doses of propofol or methohexitone suggest that there is faster recovery of psychomotor performance after
propofol.2–4 However, MacKenzie and Grant showed that propofol produces a slightly greater decrease in the critical flicker fusion threshold than methohexitone.5 A comparison of psychomotor performance after sedation with propofol or methohexitone has not been performed. Methohexitone may be a more suitable alternative than midazolam for day-case PCS. The objective of this prospective, randomized study was to compare PCS with either methohexitone or propofol.
Patients and methods Approval was obtained from the hospital Ethics Committee and we studied 42 unpremedicated patients, ASA I or II, aged 16 yr or more, undergoing oral surgery under local anaesthesia with i.v. sedation. Patients gave informed consent. Exclusion criteria included patients who were taking sedative medication, those who were pregnant and those who had previous adverse reactions to propofol or methohexitone. After a full explanation, patients were allocated randomly to receive PCS with either methohexitone (group M) or propofol (group P). Randomization was performed using sealed envelopes. Each drug was self-administered by the patient from a Graseby 3300 infusion pump. The bolus dose administered was 0.5 ml for both drugs. The concentrations of drugs used were 10 mg ml91 for propofol and 5 mg ml91 for methohexitone; hence group M patients received 2.5 mg of methohexitone and those in group P received 5 mg of propofol on demand. No lockout time was used but as the infusion rate was 250 ml h91, it took 7.2 s to infuse the 0.5-ml bolus. Demands made for drug during this period resulted in no drug being administered. Patients were instructed in the use of the infusion pump before sedation and were told that they could press the demand button as often as they liked to produce the level of sedation they desired but that the pump would not administer another dose for a S. K. HAMID, MB, CHB, FRCA, N. MCCANN*, BSC, MB, CHB, FRCA, A. J. ASBURY, MB, CHB, FRCA, PHD, MD, University Department of Anaesthesia, Western Infirmary, Dumbarton Road, Glasgow G11 6NT. L. W. MCARDLE, BDS, FDSRC(ENG), MSC, Glasgow Dental Hospital and School, Sauchiehall St, Glasgow G2 3JZ. Accepted for publication: July 19, 1996. *Address for correspondence: Department of Anaesthetics, University Hospital of Wales, Heath Park, Cardiff CF4 4XN.
728 period of approximately 7 s. A maximum of 8 doses per minute could be administered, giving a maximum of 20 mg of methohexitone or 40 mg of propofol per minute. Before sedation and surgery, immediately after operation and at 15 and 30 min after the end of the procedure, patients were asked to rate their anxiety, pain and somnolence on a fourpoint scale (none, mild, moderate and severe). They were also asked to complete a Corah dental anxiety questionnaire before operation.6 Patients performed psychomotor tests before operation and again immediately on completion of the procedure and at 15 and 30 min. These tests consisted of a “posting box task” (PBX) which involved the patient putting 15 shaped bricks through appropriately shaped holes of a box as quickly as possible using one hand.7 The best time for two attempts for the PBX task was taken. The other test consisted of a choice reaction time (CRT) which was measured using a programme implemented on a hand-held Psion organizer.8 Before the CRT test itself, preliminary instructions scroll across the screen, prompted by key presses by the patient. The final message is “Are you ready?—press the Y key to go on”. After the patient presses the Y key, one of six letters (A–F) appears on the screen in random order and after a randomized time interval. The patient has to press the corresponding letter on the keyboard. This process is repeated 30 times. This test gave two results: a choice reaction time score (CRTS), that is the percentage of choices made correctly, and a mean choice reaction time (CRTM), that is the mean time taken to react. At the end of the test, the Psion displays the results which are stored and can be transferred subsequently to an IBM-compatible computer for manipulation by word-processing and spreadsheet programmes. When the patient was settled in the dental chair, monitoring (non-invasive arterial pressure, heart rate and pulse oximetry) was established and continued throughout the procedure. A 20-gauge cannula was inserted into a vein on the dorsum of the patient’s hand. For event timing, time 0 was taken as the time of administration of the first dose of drug. The patient’s deepest level of sedation was recorded using a modified published five-point scale.9 This was recorded every 1 min for the first 16 min, every 2 min for the next 15 min and every 5 min until the end of the dental procedure (table 1). Local anaesthetic infiltration (2% lignocaine with adrenaline 1:80 000) was performed by the dentist when the patient was ready. After completion of the dental procedure, the patient was transferred to a recovery area. Before discharge home, patients were questioned on nausea, pain in the hand, recall of intraoperative
British Journal of Anaesthesia events, if they had managed to achieve their desired level of sedation and if they would be prepared to have the same method of sedation again. Patients and the dentist were asked to evaluate the acceptability of the sedation technique using a fourpoint scale (poor, moderate, good or excellent). The dentist was also asked to evaluate patient cooperation during the procedure. Minitab for DOS release 7 was used for statistical analysis. The Mann–Whitney test was used for ordinal data, and chi-square test for nominal data. A probability (P) of less than 0.05 was considered to be statistically significant.
Results Forty patients were included in the data analysis; two patients were excluded, one in group M had a cannula resited during the procedure and the other patient in group P had to be given a general anaesthetic to reduce a dislocated jaw. There were 20 patients in each group. Fourteen patients in group M had third molar teeth extractions, two had extraction of other teeth, two had apicectomies, one had excision of a granuloma of the mouth and one had removal of a salivary calculus. Six patients in group P had third molar teeth extractions, eight had extraction of other teeth and six had apicectomies. The proposed dental procedure was completed satisfactorily in all patients (table 2). The lowest oxygen saturation value recorded was 92% for a group P patient and 95% for a group M patient. Group M patients had higher heart rates during the procedure. Mean arterial pressures remained within acceptable clinical limits and were similar in the two groups. The ratio of successful to unsuccessful demands was similar in both groups. No patient in either group lost verbal contact. Table 3 shows the deepest level of sedation achieved by the patients. All patients were discharged approximately 30 min after the end of the procedure. Immediately on arrival in the recovery area patients in group M reported that they felt drowsier than those in group P (P : 0.01). However, there were no Table 2 Summary data for patients and procedures (median (IQR)) Group
Methohexitone
Propofol
Age (yr) Sex (M:F) Weight (kg) Total dose (mg) Successful:unsuccessful PCS demand Start local anaesthetic (min) Procedure duration (min)
26 (12) 5:15 62 (23) 130 (127)
36 (20) 4:16 66 (20) 223 (126)
0.89 (0.4) 7.0 (4) 18 (29)
0.92 (0.2) 7.5 (4) 21 (25)
Table 3 Deepest level of sedation achieved by the patients in the intraoperative period Table 1 Sedation scoring used 1:Fully awake 2:Drowsy with eyes open and/or brisk response to command 3:Drowsy with eyes closed and/or slow response to command 4:Eyes closed but rousable with mild physical stimulus 5:Eyes closed and unrousable with mild physical stimulus
Sedation score
Group M (n) Group P (n)
1
2
3
4
5
0 0
16 14
4 6
0 0
0 0
PCS with methohexitone or propofol
729
Table 4 Patient scoring of their drowsiness. Patient sedation score 1:not at all sleepy, 2:mildly sleepy, 3:moderately sleepy, 4:extremely sleepy. The sedation scores immediately after operation for the methohexitone group were significantly different (P < 0.01) from the propofol group Sedation score 1
2
3
4
0 5
11 13
5 2
4 0
15 min after operation Group M (n) Group P (n)
8 11
10 8
1 1
1 0
30 min after operation Group M (n) Group P (n)
14 7
6 3
0 0
0 0
Immediately after operation Group M (n) Group P (n)
Table 5 Median (IQR2) percentage changes in individual performance of the psychomotor tests compared with preoperative values *P:0.05 Time (min) 0
15
30
PBX Group M Group P
−20 (28) −18 (24)
−7 (14)* 0 (15)
4.5 (15) 0 (15)
CRTS Group M Group P
0 (3) 0 (1)
0 (0) 0 (0)
0 (0) 0 (3)
CRTM Group M Group P
26 (26) 28 (14)
2 (8) 3 (9)
4 (11) 8 (12)
significant differences at 15 or 30 min after operation. Table 4 shows how sedated patients said they felt immediately after, 15 min and 30 min after the procedure. Table 5 shows the results of psychomotor testing. Group M patients showed a greater decrement in the PBX task at 15 min than those in group P. However, there were no significant differences in performance times immediately after or 30 min after the procedure. CRTS and CRTM were not significantly different between the two groups at any time after operation. Two patients in group M had some fine tremorlike movements of their limbs of short duration but this did not upset the patient or dentist. Four patients in group M and nine patients in group P complained of pain in their hand but this was not statistically significant. Eleven patients in group M and 12 in group P had amnesia for certain intraoperative events. One patient in each group had amnesia for recovery room events. No patient complained of nausea or vomited. All patients said that they had managed to achieve their desired level of sedation. All patients thought their sedation was either good or excellent. Patient cooperation was rated as excellent in 19 patients and poor in one patient in group M and excellent in 15 and poor in one patient in group P.
Discussion Our study has shown that methohexitone compared favourably with propofol when used for patientcontrolled sedation. However, patients who received methohexitone reported that they felt more drowsy immediately after the procedure than those who received propofol. Fifteen minutes after surgery both groups felt less drowsy and there was no difference between the groups at this time or subsequently. More patients in the methohexitone group had wisdom teeth extractions. This could have resulted in an increased demand for sedation by this group. The methohexitone group performed the PBX more slowly than the propofol group 15 min after the procedure. Immediately and 30 min after the procedure there were no significant differences in performance times. However, this is a fairly insensitive test.10 There were no differences between the two groups in CRTM and CRTS at any time after operation. All patients were discharged home escorted 30 min after operation with written instructions. Studies comparing PCS with propofol or midazolam suggest faster recovery of psychomotor function in patients who received propofol.11 12 The amnesic effects of propofol and methohexitone appeared to be similar when used for sedation in this study, with the most marked effect being amnesia for intraoperative events. Amnesia is more likely to persist for recovery events with midazolam.12 Hence methohexitone and propofol would be more suitable agents for day-case patients requiring sedation. More patients in the propofol group complained of pain in the hand but this was not statistically significant. The lower incidence of pain in the hand than would have been expected for the methohexitone patients may have been because of the more dilute concentration (0.5%) of methohexitone used in this study. Patients were allowed to start and maintain their own sedation. The amount of drug administered was limited by the drug concentration and the time taken to infuse each dose. The infusion rate of the pump used in this study was 250 ml h91. If a pump capable of infusing at a faster rate had been used, then a faster onset time for sedation would have been achieved. However, this may have risked the patient being oversedated. No patient lost verbal contact and all patients were satisfied with their level of sedation. An initial bolus dose of drug was not administered because of individual patient requirements for depth of sedation. The anaesthetist who carried out the intraoperative sedation assessment and the dentist were not blinded and this may have resulted in some bias of the intraoperative results but the anaesthetist who carried out the postoperative assessments was blinded to the agent used. It must be stressed that although we were able to maintain verbal contact with all patients throughout the procedure, it is imperative that personnel skilled in airway management and resuscitation are present during sedation procedures. Equipment and drugs used for resuscitation must be at hand.
730
References 1. Briemer DD. Pharmacokinetics of methohexitone following intravenous infusion in humans. British Journal of Anaesthesia 1976; 48: 643–648. 2. MacKenzie N, Grant IS. Comparison of the new emulsion formulation of propofol with methohexitone and thiopentone for induction of anaesthesia in day cases. British Journal of Anaesthesia 1985; 57: 725–731. 3. Raeder JC, Misvaer G. Comparison of propofol induction with thiopentone or methohexitone in short outpatient general anaesthesia. Acta Anaesthesiologica Scandinavica 1988; 32: 607–613. 4. Kay B, Healey TEJ. Propofol (‘Diprivan’) for outpatient cystoscopy: efficacy and recovery compared with althesin and methohexitone. Postgraduate Medical Journal 1985; 61: 108–114. 5. MacKenzie N, Grant I. Comparison of propofol with methohexitone in the provision of anaesthesia for surgery under regional blockade. British Journal of Anaesthesia 1985; 57: 1167–1172. 6. Corah NL Development of a dental anxiety scale. Journal of Dental Research 1969; 48: 596.
British Journal of Anaesthesia 7. Craig J, Cooper GM, Sear JW. Recovery from day-case anaesthesia—comparison between methohexitone, althesin and etomidate. British Journal of Anaesthesia 1982; 54: 447–451. 8. Hickey S, Asbury AJ, Millar K. Psychomotor recovery after outpatient anaesthesia: Individual impairment may be masked by group analysis. British Journal of Anaesthesia 1991; 66: 345–352. 9. Wilson E, David A, MacKenzie N, Grant IS. Sedation during spinal anaesthesia: comparison of propofol and midazolam. British Journal of Anaesthesia 1990; 64: 48–52. 10. Hindmarch I, Bhatti JZ. Recovery of cognitive and psychomotor function following anaesthesia. A review. In: Hindmarch I, Jones JG, Moss E, eds. Aspects of Recovery from Anaesthesia. Chichester: Wiley, 1987; 113–165. 11. Cook LB, Lockwood GG, Moore CM, Whitwam JG. True patient-controlled sedation. Anaesthesia 1993; 48: 1039–1044. 12. Rudkin GE, Osborne GA, Finn BP, Jarvis DA, Vickers D. Intra-operative patient-controlled sedation. Comparison of patient-controlled propofol with patient-controlled midazolam. Anaesthesia 1992; 47: 376–381.
Comparison of patient-controlled sedation with either methohexitone or propofol
S. K. HAMID, N. MCCANN, L. MCARDLE AND A. J. ASBURY
Summary We studied 42 patients undergoing oral surgery under local anaesthesia with i.v. sedation, allocated randomly to receive either methohexitone (group M) or propofol (group P) for patientcontrolled sedation (PCS). Group M patients self-administered 2.5-mg (0.5 ml) bolus doses of methohexitone and group P, 5-mg (0.5 ml) doses of propofol, without a lockout. The 0.5-ml bolus dose was delivered over 7.2 s for both drugs. The procedure was completed satisfactorily in all patients. Patients in both groups achieved their desired levels of sedation. No patient lost verbal contact. Group M patients had higher heart rates during the procedure. The lowest S pO values recorded were 92% and 95% for group P and group M, respectively. Immediately after operation patients in group M reported that they felt more sleepy than those in group P (P : 0.01) but there were no differences at subsequent times. The results of the psychomotor tests were comparable for the two groups after operation, except for the “posting box task” at 15 min after operation when the mean decrement (compared with preoperative performance) was 93% for group P and 913% for group M (P : 0.05). More patients in group P complained of pain in their hand. We conclude that methohexitone is a suitable alternative drug to propofol for PCS. (Br. J. Anaesth. 1996; 77: 727–730) 2
Key words Anaesthetics i.v., methohexitone. Anaesthetics i.v., propofol. Sedation, patient-controlled. Surgery, oral.
Patient-controlled sedation (PCS) has been reported using either midazolam or propofol. However, they are not comparable in pharmacokinetics. Oversedation may be a problem with midazolam as it has a relatively slow onset and the patient may make additional demands for drug boluses before adequate time has elapsed for the earlier boluses to produce an effect. The use of methohexitone for PCS has not been described. It is cleared rapidly from the body and is cheaper than propofol.1 Studies of psychomotor function after induction doses of propofol or methohexitone suggest that there is faster recovery of psychomotor performance after
propofol.2–4 However, MacKenzie and Grant showed that propofol produces a slightly greater decrease in the critical flicker fusion threshold than methohexitone.5 A comparison of psychomotor performance after sedation with propofol or methohexitone has not been performed. Methohexitone may be a more suitable alternative than midazolam for day-case PCS. The objective of this prospective, randomized study was to compare PCS with either methohexitone or propofol.
Patients and methods Approval was obtained from the hospital Ethics Committee and we studied 42 unpremedicated patients, ASA I or II, aged 16 yr or more, undergoing oral surgery under local anaesthesia with i.v. sedation. Patients gave informed consent. Exclusion criteria included patients who were taking sedative medication, those who were pregnant and those who had previous adverse reactions to propofol or methohexitone. After a full explanation, patients were allocated randomly to receive PCS with either methohexitone (group M) or propofol (group P). Randomization was performed using sealed envelopes. Each drug was self-administered by the patient from a Graseby 3300 infusion pump. The bolus dose administered was 0.5 ml for both drugs. The concentrations of drugs used were 10 mg ml91 for propofol and 5 mg ml91 for methohexitone; hence group M patients received 2.5 mg of methohexitone and those in group P received 5 mg of propofol on demand. No lockout time was used but as the infusion rate was 250 ml h91, it took 7.2 s to infuse the 0.5-ml bolus. Demands made for drug during this period resulted in no drug being administered. Patients were instructed in the use of the infusion pump before sedation and were told that they could press the demand button as often as they liked to produce the level of sedation they desired but that the pump would not administer another dose for a S. K. HAMID, MB, CHB, FRCA, N. MCCANN*, BSC, MB, CHB, FRCA, A. J. ASBURY, MB, CHB, FRCA, PHD, MD, University Department of Anaesthesia, Western Infirmary, Dumbarton Road, Glasgow G11 6NT. L. W. MCARDLE, BDS, FDSRC(ENG), MSC, Glasgow Dental Hospital and School, Sauchiehall St, Glasgow G2 3JZ. Accepted for publication: July 19, 1996. *Address for correspondence: Department of Anaesthetics, University Hospital of Wales, Heath Park, Cardiff CF4 4XN.
728 period of approximately 7 s. A maximum of 8 doses per minute could be administered, giving a maximum of 20 mg of methohexitone or 40 mg of propofol per minute. Before sedation and surgery, immediately after operation and at 15 and 30 min after the end of the procedure, patients were asked to rate their anxiety, pain and somnolence on a fourpoint scale (none, mild, moderate and severe). They were also asked to complete a Corah dental anxiety questionnaire before operation.6 Patients performed psychomotor tests before operation and again immediately on completion of the procedure and at 15 and 30 min. These tests consisted of a “posting box task” (PBX) which involved the patient putting 15 shaped bricks through appropriately shaped holes of a box as quickly as possible using one hand.7 The best time for two attempts for the PBX task was taken. The other test consisted of a choice reaction time (CRT) which was measured using a programme implemented on a hand-held Psion organizer.8 Before the CRT test itself, preliminary instructions scroll across the screen, prompted by key presses by the patient. The final message is “Are you ready?—press the Y key to go on”. After the patient presses the Y key, one of six letters (A–F) appears on the screen in random order and after a randomized time interval. The patient has to press the corresponding letter on the keyboard. This process is repeated 30 times. This test gave two results: a choice reaction time score (CRTS), that is the percentage of choices made correctly, and a mean choice reaction time (CRTM), that is the mean time taken to react. At the end of the test, the Psion displays the results which are stored and can be transferred subsequently to an IBM-compatible computer for manipulation by word-processing and spreadsheet programmes. When the patient was settled in the dental chair, monitoring (non-invasive arterial pressure, heart rate and pulse oximetry) was established and continued throughout the procedure. A 20-gauge cannula was inserted into a vein on the dorsum of the patient’s hand. For event timing, time 0 was taken as the time of administration of the first dose of drug. The patient’s deepest level of sedation was recorded using a modified published five-point scale.9 This was recorded every 1 min for the first 16 min, every 2 min for the next 15 min and every 5 min until the end of the dental procedure (table 1). Local anaesthetic infiltration (2% lignocaine with adrenaline 1:80 000) was performed by the dentist when the patient was ready. After completion of the dental procedure, the patient was transferred to a recovery area. Before discharge home, patients were questioned on nausea, pain in the hand, recall of intraoperative
British Journal of Anaesthesia events, if they had managed to achieve their desired level of sedation and if they would be prepared to have the same method of sedation again. Patients and the dentist were asked to evaluate the acceptability of the sedation technique using a fourpoint scale (poor, moderate, good or excellent). The dentist was also asked to evaluate patient cooperation during the procedure. Minitab for DOS release 7 was used for statistical analysis. The Mann–Whitney test was used for ordinal data, and chi-square test for nominal data. A probability (P) of less than 0.05 was considered to be statistically significant.
Results Forty patients were included in the data analysis; two patients were excluded, one in group M had a cannula resited during the procedure and the other patient in group P had to be given a general anaesthetic to reduce a dislocated jaw. There were 20 patients in each group. Fourteen patients in group M had third molar teeth extractions, two had extraction of other teeth, two had apicectomies, one had excision of a granuloma of the mouth and one had removal of a salivary calculus. Six patients in group P had third molar teeth extractions, eight had extraction of other teeth and six had apicectomies. The proposed dental procedure was completed satisfactorily in all patients (table 2). The lowest oxygen saturation value recorded was 92% for a group P patient and 95% for a group M patient. Group M patients had higher heart rates during the procedure. Mean arterial pressures remained within acceptable clinical limits and were similar in the two groups. The ratio of successful to unsuccessful demands was similar in both groups. No patient in either group lost verbal contact. Table 3 shows the deepest level of sedation achieved by the patients. All patients were discharged approximately 30 min after the end of the procedure. Immediately on arrival in the recovery area patients in group M reported that they felt drowsier than those in group P (P : 0.01). However, there were no Table 2 Summary data for patients and procedures (median (IQR)) Group
Methohexitone
Propofol
Age (yr) Sex (M:F) Weight (kg) Total dose (mg) Successful:unsuccessful PCS demand Start local anaesthetic (min) Procedure duration (min)
26 (12) 5:15 62 (23) 130 (127)
36 (20) 4:16 66 (20) 223 (126)
0.89 (0.4) 7.0 (4) 18 (29)
0.92 (0.2) 7.5 (4) 21 (25)
Table 3 Deepest level of sedation achieved by the patients in the intraoperative period Table 1 Sedation scoring used 1:Fully awake 2:Drowsy with eyes open and/or brisk response to command 3:Drowsy with eyes closed and/or slow response to command 4:Eyes closed but rousable with mild physical stimulus 5:Eyes closed and unrousable with mild physical stimulus
Sedation score
Group M (n) Group P (n)
1
2
3
4
5
0 0
16 14
4 6
0 0
0 0
PCS with methohexitone or propofol
729
Table 4 Patient scoring of their drowsiness. Patient sedation score 1:not at all sleepy, 2:mildly sleepy, 3:moderately sleepy, 4:extremely sleepy. The sedation scores immediately after operation for the methohexitone group were significantly different (P < 0.01) from the propofol group Sedation score 1
2
3
4
0 5
11 13
5 2
4 0
15 min after operation Group M (n) Group P (n)
8 11
10 8
1 1
1 0
30 min after operation Group M (n) Group P (n)
14 7
6 3
0 0
0 0
Immediately after operation Group M (n) Group P (n)
Table 5 Median (IQR2) percentage changes in individual performance of the psychomotor tests compared with preoperative values *P:0.05 Time (min) 0
15
30
PBX Group M Group P
−20 (28) −18 (24)
−7 (14)* 0 (15)
4.5 (15) 0 (15)
CRTS Group M Group P
0 (3) 0 (1)
0 (0) 0 (0)
0 (0) 0 (3)
CRTM Group M Group P
26 (26) 28 (14)
2 (8) 3 (9)
4 (11) 8 (12)
significant differences at 15 or 30 min after operation. Table 4 shows how sedated patients said they felt immediately after, 15 min and 30 min after the procedure. Table 5 shows the results of psychomotor testing. Group M patients showed a greater decrement in the PBX task at 15 min than those in group P. However, there were no significant differences in performance times immediately after or 30 min after the procedure. CRTS and CRTM were not significantly different between the two groups at any time after operation. Two patients in group M had some fine tremorlike movements of their limbs of short duration but this did not upset the patient or dentist. Four patients in group M and nine patients in group P complained of pain in their hand but this was not statistically significant. Eleven patients in group M and 12 in group P had amnesia for certain intraoperative events. One patient in each group had amnesia for recovery room events. No patient complained of nausea or vomited. All patients said that they had managed to achieve their desired level of sedation. All patients thought their sedation was either good or excellent. Patient cooperation was rated as excellent in 19 patients and poor in one patient in group M and excellent in 15 and poor in one patient in group P.
Discussion Our study has shown that methohexitone compared favourably with propofol when used for patientcontrolled sedation. However, patients who received methohexitone reported that they felt more drowsy immediately after the procedure than those who received propofol. Fifteen minutes after surgery both groups felt less drowsy and there was no difference between the groups at this time or subsequently. More patients in the methohexitone group had wisdom teeth extractions. This could have resulted in an increased demand for sedation by this group. The methohexitone group performed the PBX more slowly than the propofol group 15 min after the procedure. Immediately and 30 min after the procedure there were no significant differences in performance times. However, this is a fairly insensitive test.10 There were no differences between the two groups in CRTM and CRTS at any time after operation. All patients were discharged home escorted 30 min after operation with written instructions. Studies comparing PCS with propofol or midazolam suggest faster recovery of psychomotor function in patients who received propofol.11 12 The amnesic effects of propofol and methohexitone appeared to be similar when used for sedation in this study, with the most marked effect being amnesia for intraoperative events. Amnesia is more likely to persist for recovery events with midazolam.12 Hence methohexitone and propofol would be more suitable agents for day-case patients requiring sedation. More patients in the propofol group complained of pain in the hand but this was not statistically significant. The lower incidence of pain in the hand than would have been expected for the methohexitone patients may have been because of the more dilute concentration (0.5%) of methohexitone used in this study. Patients were allowed to start and maintain their own sedation. The amount of drug administered was limited by the drug concentration and the time taken to infuse each dose. The infusion rate of the pump used in this study was 250 ml h91. If a pump capable of infusing at a faster rate had been used, then a faster onset time for sedation would have been achieved. However, this may have risked the patient being oversedated. No patient lost verbal contact and all patients were satisfied with their level of sedation. An initial bolus dose of drug was not administered because of individual patient requirements for depth of sedation. The anaesthetist who carried out the intraoperative sedation assessment and the dentist were not blinded and this may have resulted in some bias of the intraoperative results but the anaesthetist who carried out the postoperative assessments was blinded to the agent used. It must be stressed that although we were able to maintain verbal contact with all patients throughout the procedure, it is imperative that personnel skilled in airway management and resuscitation are present during sedation procedures. Equipment and drugs used for resuscitation must be at hand.
730
References 1. Briemer DD. Pharmacokinetics of methohexitone following intravenous infusion in humans. British Journal of Anaesthesia 1976; 48: 643–648. 2. MacKenzie N, Grant IS. Comparison of the new emulsion formulation of propofol with methohexitone and thiopentone for induction of anaesthesia in day cases. British Journal of Anaesthesia 1985; 57: 725–731. 3. Raeder JC, Misvaer G. Comparison of propofol induction with thiopentone or methohexitone in short outpatient general anaesthesia. Acta Anaesthesiologica Scandinavica 1988; 32: 607–613. 4. Kay B, Healey TEJ. Propofol (‘Diprivan’) for outpatient cystoscopy: efficacy and recovery compared with althesin and methohexitone. Postgraduate Medical Journal 1985; 61: 108–114. 5. MacKenzie N, Grant I. Comparison of propofol with methohexitone in the provision of anaesthesia for surgery under regional blockade. British Journal of Anaesthesia 1985; 57: 1167–1172. 6. Corah NL Development of a dental anxiety scale. Journal of Dental Research 1969; 48: 596.
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