872
Forum
only slightly prolonged. A previous study was unable to demonstrate an improvement in sedation when TDP was used, despite a similar method of assessment.8 The adequacy of sedation in our study was tested by a higher disturbance factor, in that children were moved from a distant children's ward to the noisy environment of the operating theatre. A quiet room was provided in the previous study in close proximity to the anaesthetic room and the disturbance to the children was less. This may explain why the previous workers failed to show any difference between the two sedative regimens. Another factor may be that lower doses of trimeprazine were given to both groups in the current study. It may be that TDP will provide useful analgesia during the recovery period. It has, however, been our standard practice to provide caudal analgesia to patients who have this type of surgery and we believed that although this may mask any potential analgesia benefits of TDP, it would be unethical to change our practice for this study.
Acknowledgments
The authors thank Mrs C. Evans, medical secretary and The Department of Medical illustration for preparing the manuscript, Mr K. D. Vellacott, FRCS, Consultant Surgeon, for his support and cooperation, Mr G. V. Brangham, MR Pharm S, Pharmacy Manager, Mr G. Titley, BA, ALA, Librarian, Royal Gwent Hospital and
the many ward and theatre staff whose hard work made this study possible. References 1. COPE RW, GLOVER WJ. Trimeprazine tartrate for premedication of children. Lancet 1959; 1: 858-60. 2. GUNNERBW. An evaluation of drugs used for oral premedication of children. Medical Journal of Australia 1960; 3 47-9. RGB, MANFORD MLM. Premedication of children 3. BRAMWELL with trimeprazine tartrate. British Journal of Anaesthesia 198 I; 5 3 821-5. 4. PETERS CG, BRUNTON JT. Comparative study of lorazepam and trimeprazine for oral premedication in paediatric anaesthesia. British Journal of Anaesthesia 1982; 54: 623-7. 5. BURTLESR, ASTIEY B. Lorazepam in children. A double-blind trial comparing lorazepam, diazepam, trimeprazine and placebo. British Journal of Anaesthesia 1983; 55: 275-9. 6. PADFIELD NL, TWOHIG MMcD, FRASER CL. Temazepam and trimeprazine compared with placebo as premedication in children. An investigation extended into the first 2 weeks at home. British Journal of Anaesthesia 1986; 58: 487-93. DJ, WALKER AKY. Premedication for children with 7. LAYFIELD oral trimeprazine and droperidol. Anaesthesia 1984; 39: 3 2 4 . C, BRAMWELL RGB. Oral premedication for children 8. BULLEN with a droperidol, trimeprazine and methadone mixture. Anaesthesia 1982; 37: 212-3. 9. ARMITAGE EN. Caudal block in children. Anaesthesia 1979; 34: 396. 10. DUNCAN BBA, ZAIMIF, NEWMAN GB, JENKINS JG, AVELING W. Effect of premedication on the induction dose of thiopentone in children. Anaesthesia 1984; 3 9 426-8.
Anaesthesia, 1990, Volume 45, pages 872-875
Anaesthesia for cardioversion A comparison between propofol, thiopentone and midazolam
A. Gupta, FFARCS, Senior Registrar, C. Lennmarken, MD, PhD, Associate Professor, M. Vegfors, MD, Senior Registrar, Department of Anaesthesiology, University Hospital, Linkoping, Sweden, H. TydCn, MD, PhD, Associate Professor, Department of Anaesthesiology, University Hospital, Uppsala, Sweden.
Summary This study compares the induction and recovery characteristics, haemodynamic changes and side efects of propofol, thiopentone and midazolam when used as the anaesthetic agents for cardioversion. Recovery after midazolam was signijicantly longer (p < 0.05) than with either thiopentone or propofol. There was no difference in the recovery times between thiopentone and propofol. There was a signijicant decrease in mean arterial pressure 2 minutes after induction with propofol and midazolam. Three patients each in the thiopentone and propofol groups needed assisted ventilation because of apnoea. and four patients each in the propofol and midazolam groups had low Spo, values ( < 95%). Flumazenil was used to reverse the effects of midazolam in eight patients andjive of these were still drowsy 4 hours after the procedure. This study indicates that thiopentone is the most satisfactory agent for anaesthesia for cardioversion.
Key words. Anaesthetics, intravenous; thiopentone, propofol. Hypnotics, benzodiazepines; midazolam. Direct current countershock after its first introduction in 1962' is used commonly today for the conversion of abnormal cardiac rhythm to normal sinus rhythm. Many different anaesthetic techniques were described for this Accepted 28 March 1990.
purpose; the agent used most commonly is thiopentone. Muenster and his colleagues* reported a greater frequency of extrasystoles after thiopentone as compared to the number after diazepam, which then became an alternative
Forum
873
Table 1. Patient characteristics of the three groups studied. Values are expressed as mean (SD).
~
~~
Propofol
Thiopentone
Midazolam
(10)
(10)
(10)
64 (6)
66 (7) 911 74 (11) 9/ 1 9/10
70 (6) 812 76 (8) 10/0 8/10
~
Age; years Sex; M/F Weight; kg Rhythm; atrial fibrillation, atrial flutter Successful cardioversions
method for induction of anaesthesia in these patient^.^^ However, many side effects associated with the use of diazepam are reported including unpredictability of effect,6 high incidence of r e ~ a l land ~ , ~ventricular arrythmiasP Midazolam sedation is also used and is reported to be effective for cardioversion.'O,'' Midazolam, according to Kaplan,I2 is ideal for short procedures such as cardioversion. Propofol was recently used as an induction agent for cardioversion" and shown to have shorter recovery times compared to thiopentone. The aim of this study was to compare propofol, thiopentone and midazolam as induction agents for elective cardioversion and to investigate the recovery characteristics, haemodynamic changes and side effects associated with these drugs.
Methods
The study was approved by the Hospital Ethics Committee and verbal consent was taken from all patients before the study. Thirty unpremedicated patients (ASA groups 2-3), were randomly allocated to receive either propofol, midazolam or thiopentone in such a way that there were 10 patients in each group. Digoxin was discontinued 24 hours before the procedure and all patients were fasting for at least 6 hours. A Nellcor N-200 pulse oximeter was used continuously to display Spo, after the procedure was explained to the patient. Arterial blood pressure was measured every minute using an automatic device (EME Auto BP, Brighton, UK). An intravenous cannula inserted in the left arm was used for injecting drugs and taking blood samples as necessary. The patients' lungs were pre-oxygenated for 2-3 minutes before induction of anaesthesia until the Spo, reached 98%. All anaesthetics were given by the same anaesthetist; the observer had no information about the drug used. A stop-watch was started at the onset of induction of anaesthesia. Propofol and thiopentone were injected continuously over a I-minute period until loss of the eyelash reflex, and subsequent increments were given as needed to achieve this point. Midazolam 5 mg were injected over 1 minute, and subsequent 2-mg increments were given until loss of the eyelash reflex. The patients' lungs were artificially ventilated with 100% 0, via a facemask if Spo, was less than 95% or if the patient was apnoeic for more than 30 seconds at any time during the procedure. Cardioversion was attempted by the cardiologist using SBrW-DMS 600/3 (Albertslund, Denmark) apparatus, with the paddles placed at the right upper sternal border and apex of the heart. The intensity of the shock given depended on the type of rhythm, the success of previous attempted cardioversions, and the cardiologist who performed the procedure. The continued loss of eyelash reflex was used as a guide for the need of supplement anaesthetic if more than one attempt was needed to cardiovert the patient.
515 74 (10) 812 10/10
The following recovery times were noted: opening eyes on command; recalling 'date of birth' on questioning; ability to do simple calculations e.g. 100-7. All patients were interviewed 4 hours after the procedure and questioned about the side effects and awareness during the procedure. Results are presented as mean (SD). Data were analysed by the paired Student's t-test, p < 0.05 was considered to be significant. Results The mean age and weight of the patients were comparable (Table 1). There were more females in the propofol group compared to the others. Propofol (2.2 (0.3) mg/kg) and midazolam (0.24 (0.03) mg/kg) were associated with a significant decrease in mean arterial blood pressure 2 minutes after induction of anaesthesia. In contrast, thiopentone (5.2 (1.0) mg/kg) did not cause a significant decrease in mean arterial blood pressure (Fig. 1). The mean blood pressure continued to be significantly lower in the propofol group during the entire period of the study. The 'time to loss of eyelash reflex' was similar in the propofol and thiopentone groups but significantly longer in the midazolam group (Table 2). Recovery characteristics were similar in the thiopentone and propofol groups and there was no significant difference in the three recovery times. However, patients in the midazolam group took much longer to recover (Table 3), and it was decided to wake them 15-30 minutes after induction by giving flumazenil (0.3-0.5 mg). The response to flumazenil occurred within 2-3 minutes but was short-lasting. Five of 10 patients were asleep at the time of interview 4 hours later. I50 r
130 E
5 t
120
t
110
n t u
100
-0
n c
90
I"
00 70
60
0
I
2
Time (minutes) Fig. 1. Mean blood pressure, expressed as mean (SD), during cardioversion in the three groups studied. W, propofol; M, thiopentone; 0, midazolam. *p < 0.05; **p < 0.05.
874
Forum Table 2. Doses, ventilation and time to loss of eyelash reflex in the three groups studied. Values are expressed as mean (SD).
Total dose; mg Total dose; mg/kg Time to loss of eyelash reflex; seconds Assisted ventilation Apnoea > 30 seconds
Propofol (10)
Thiopentone
Midazolam
(10)
(10)
164 (25) 2.2 (0.3)
380 (85) 5.2 (1.0)
18.1 (3.2) 0.24 (0.03)
100 (16)
99 (14)
339 (73)*
3 4
Sao, < 95%
3 1
4
*p < 0.05.
Table 3. Recovery characteristics in the three groups studied. Values are expressed as mean
W).
Opening eyes on command; seconds Recalling date of birth; seconds Doing simple calculations; seconds
Propofol
Thiopentone
Midazolam
(10)
(10)
(10)
639 (182) 689 (172) 719 (186)
616 (253) 656 (270) 673 (266)
> 9008 >900; > 900,
*p
Forum
only slightly prolonged. A previous study was unable to demonstrate an improvement in sedation when TDP was used, despite a similar method of assessment.8 The adequacy of sedation in our study was tested by a higher disturbance factor, in that children were moved from a distant children's ward to the noisy environment of the operating theatre. A quiet room was provided in the previous study in close proximity to the anaesthetic room and the disturbance to the children was less. This may explain why the previous workers failed to show any difference between the two sedative regimens. Another factor may be that lower doses of trimeprazine were given to both groups in the current study. It may be that TDP will provide useful analgesia during the recovery period. It has, however, been our standard practice to provide caudal analgesia to patients who have this type of surgery and we believed that although this may mask any potential analgesia benefits of TDP, it would be unethical to change our practice for this study.
Acknowledgments
The authors thank Mrs C. Evans, medical secretary and The Department of Medical illustration for preparing the manuscript, Mr K. D. Vellacott, FRCS, Consultant Surgeon, for his support and cooperation, Mr G. V. Brangham, MR Pharm S, Pharmacy Manager, Mr G. Titley, BA, ALA, Librarian, Royal Gwent Hospital and
the many ward and theatre staff whose hard work made this study possible. References 1. COPE RW, GLOVER WJ. Trimeprazine tartrate for premedication of children. Lancet 1959; 1: 858-60. 2. GUNNERBW. An evaluation of drugs used for oral premedication of children. Medical Journal of Australia 1960; 3 47-9. RGB, MANFORD MLM. Premedication of children 3. BRAMWELL with trimeprazine tartrate. British Journal of Anaesthesia 198 I; 5 3 821-5. 4. PETERS CG, BRUNTON JT. Comparative study of lorazepam and trimeprazine for oral premedication in paediatric anaesthesia. British Journal of Anaesthesia 1982; 54: 623-7. 5. BURTLESR, ASTIEY B. Lorazepam in children. A double-blind trial comparing lorazepam, diazepam, trimeprazine and placebo. British Journal of Anaesthesia 1983; 55: 275-9. 6. PADFIELD NL, TWOHIG MMcD, FRASER CL. Temazepam and trimeprazine compared with placebo as premedication in children. An investigation extended into the first 2 weeks at home. British Journal of Anaesthesia 1986; 58: 487-93. DJ, WALKER AKY. Premedication for children with 7. LAYFIELD oral trimeprazine and droperidol. Anaesthesia 1984; 39: 3 2 4 . C, BRAMWELL RGB. Oral premedication for children 8. BULLEN with a droperidol, trimeprazine and methadone mixture. Anaesthesia 1982; 37: 212-3. 9. ARMITAGE EN. Caudal block in children. Anaesthesia 1979; 34: 396. 10. DUNCAN BBA, ZAIMIF, NEWMAN GB, JENKINS JG, AVELING W. Effect of premedication on the induction dose of thiopentone in children. Anaesthesia 1984; 3 9 426-8.
Anaesthesia, 1990, Volume 45, pages 872-875
Anaesthesia for cardioversion A comparison between propofol, thiopentone and midazolam
A. Gupta, FFARCS, Senior Registrar, C. Lennmarken, MD, PhD, Associate Professor, M. Vegfors, MD, Senior Registrar, Department of Anaesthesiology, University Hospital, Linkoping, Sweden, H. TydCn, MD, PhD, Associate Professor, Department of Anaesthesiology, University Hospital, Uppsala, Sweden.
Summary This study compares the induction and recovery characteristics, haemodynamic changes and side efects of propofol, thiopentone and midazolam when used as the anaesthetic agents for cardioversion. Recovery after midazolam was signijicantly longer (p < 0.05) than with either thiopentone or propofol. There was no difference in the recovery times between thiopentone and propofol. There was a signijicant decrease in mean arterial pressure 2 minutes after induction with propofol and midazolam. Three patients each in the thiopentone and propofol groups needed assisted ventilation because of apnoea. and four patients each in the propofol and midazolam groups had low Spo, values ( < 95%). Flumazenil was used to reverse the effects of midazolam in eight patients andjive of these were still drowsy 4 hours after the procedure. This study indicates that thiopentone is the most satisfactory agent for anaesthesia for cardioversion.
Key words. Anaesthetics, intravenous; thiopentone, propofol. Hypnotics, benzodiazepines; midazolam. Direct current countershock after its first introduction in 1962' is used commonly today for the conversion of abnormal cardiac rhythm to normal sinus rhythm. Many different anaesthetic techniques were described for this Accepted 28 March 1990.
purpose; the agent used most commonly is thiopentone. Muenster and his colleagues* reported a greater frequency of extrasystoles after thiopentone as compared to the number after diazepam, which then became an alternative
Forum
873
Table 1. Patient characteristics of the three groups studied. Values are expressed as mean (SD).
~
~~
Propofol
Thiopentone
Midazolam
(10)
(10)
(10)
64 (6)
66 (7) 911 74 (11) 9/ 1 9/10
70 (6) 812 76 (8) 10/0 8/10
~
Age; years Sex; M/F Weight; kg Rhythm; atrial fibrillation, atrial flutter Successful cardioversions
method for induction of anaesthesia in these patient^.^^ However, many side effects associated with the use of diazepam are reported including unpredictability of effect,6 high incidence of r e ~ a l land ~ , ~ventricular arrythmiasP Midazolam sedation is also used and is reported to be effective for cardioversion.'O,'' Midazolam, according to Kaplan,I2 is ideal for short procedures such as cardioversion. Propofol was recently used as an induction agent for cardioversion" and shown to have shorter recovery times compared to thiopentone. The aim of this study was to compare propofol, thiopentone and midazolam as induction agents for elective cardioversion and to investigate the recovery characteristics, haemodynamic changes and side effects associated with these drugs.
Methods
The study was approved by the Hospital Ethics Committee and verbal consent was taken from all patients before the study. Thirty unpremedicated patients (ASA groups 2-3), were randomly allocated to receive either propofol, midazolam or thiopentone in such a way that there were 10 patients in each group. Digoxin was discontinued 24 hours before the procedure and all patients were fasting for at least 6 hours. A Nellcor N-200 pulse oximeter was used continuously to display Spo, after the procedure was explained to the patient. Arterial blood pressure was measured every minute using an automatic device (EME Auto BP, Brighton, UK). An intravenous cannula inserted in the left arm was used for injecting drugs and taking blood samples as necessary. The patients' lungs were pre-oxygenated for 2-3 minutes before induction of anaesthesia until the Spo, reached 98%. All anaesthetics were given by the same anaesthetist; the observer had no information about the drug used. A stop-watch was started at the onset of induction of anaesthesia. Propofol and thiopentone were injected continuously over a I-minute period until loss of the eyelash reflex, and subsequent increments were given as needed to achieve this point. Midazolam 5 mg were injected over 1 minute, and subsequent 2-mg increments were given until loss of the eyelash reflex. The patients' lungs were artificially ventilated with 100% 0, via a facemask if Spo, was less than 95% or if the patient was apnoeic for more than 30 seconds at any time during the procedure. Cardioversion was attempted by the cardiologist using SBrW-DMS 600/3 (Albertslund, Denmark) apparatus, with the paddles placed at the right upper sternal border and apex of the heart. The intensity of the shock given depended on the type of rhythm, the success of previous attempted cardioversions, and the cardiologist who performed the procedure. The continued loss of eyelash reflex was used as a guide for the need of supplement anaesthetic if more than one attempt was needed to cardiovert the patient.
515 74 (10) 812 10/10
The following recovery times were noted: opening eyes on command; recalling 'date of birth' on questioning; ability to do simple calculations e.g. 100-7. All patients were interviewed 4 hours after the procedure and questioned about the side effects and awareness during the procedure. Results are presented as mean (SD). Data were analysed by the paired Student's t-test, p < 0.05 was considered to be significant. Results The mean age and weight of the patients were comparable (Table 1). There were more females in the propofol group compared to the others. Propofol (2.2 (0.3) mg/kg) and midazolam (0.24 (0.03) mg/kg) were associated with a significant decrease in mean arterial blood pressure 2 minutes after induction of anaesthesia. In contrast, thiopentone (5.2 (1.0) mg/kg) did not cause a significant decrease in mean arterial blood pressure (Fig. 1). The mean blood pressure continued to be significantly lower in the propofol group during the entire period of the study. The 'time to loss of eyelash reflex' was similar in the propofol and thiopentone groups but significantly longer in the midazolam group (Table 2). Recovery characteristics were similar in the thiopentone and propofol groups and there was no significant difference in the three recovery times. However, patients in the midazolam group took much longer to recover (Table 3), and it was decided to wake them 15-30 minutes after induction by giving flumazenil (0.3-0.5 mg). The response to flumazenil occurred within 2-3 minutes but was short-lasting. Five of 10 patients were asleep at the time of interview 4 hours later. I50 r
130 E
5 t
120
t
110
n t u
100
-0
n c
90
I"
00 70
60
0
I
2
Time (minutes) Fig. 1. Mean blood pressure, expressed as mean (SD), during cardioversion in the three groups studied. W, propofol; M, thiopentone; 0, midazolam. *p < 0.05; **p < 0.05.
874
Forum Table 2. Doses, ventilation and time to loss of eyelash reflex in the three groups studied. Values are expressed as mean (SD).
Total dose; mg Total dose; mg/kg Time to loss of eyelash reflex; seconds Assisted ventilation Apnoea > 30 seconds
Propofol (10)
Thiopentone
Midazolam
(10)
(10)
164 (25) 2.2 (0.3)
380 (85) 5.2 (1.0)
18.1 (3.2) 0.24 (0.03)
100 (16)
99 (14)
339 (73)*
3 4
Sao, < 95%
3 1
4
*p < 0.05.
Table 3. Recovery characteristics in the three groups studied. Values are expressed as mean
W).
Opening eyes on command; seconds Recalling date of birth; seconds Doing simple calculations; seconds
Propofol
Thiopentone
Midazolam
(10)
(10)
(10)
639 (182) 689 (172) 719 (186)
616 (253) 656 (270) 673 (266)
> 9008 >900; > 900,
*p
