Acta Anaesthesiol Scand 1992: 36: 182-1 86
Propofol-fentanyl anesthesia compared to thiopental-halothane with special reference to recovery and vomiting after pediatric strabismus surgery* S. LARSSON, B. ASCEIRSSON and J. MACNUSSON Department of Anesthesiology, University Hospital, Lund, Sweden
Forty-four children, ASA physical status I or 11, aged 1.5-14 years and admitted for strabismus surgery, were studied. The study compared the postoperative condition after two different anesthesia methods. All children were premedicated with midazolam rectally, received glycopyrrolate i.v. and were then randomised to one of two anesthetic methods: I ) induction with thiopental, maintenance with halothane or 2) induction with propofol supplemented with fentanyl, maintenance with propofol infusion. In both groups, tracheal intubation was performed after vecuronium i.v. and the children were ventilated manually. Peroperatively, patients receiving propofol/fentanyl had more episodes of bradycardia ( P < 0.00 I ) . Times to spontaneous breathing and extubation were shorter in the propofol/fentanyl group ( P < 0.05) and there was also a lesser degree of sedation during the first 2 h postoperatively ( P < O . O I ) . Fewer children in the propofol/fentanyl group vomited postoperatively ( P < 0.05). The apprehension score was higher in the propofol/fentanyl group compared to the thiopental/halothane group ( P < 0.05). We conclude that children undergoing strabismus surgery anesthetized with propofol/fentanyl had more episodes of peroperative bradycardia, a lower incidence of postoperative vomiting and a shorter recovery time, and were more apprehensive during the initial postoperative period than children anesthetized with thiopental/halothane.
Received 2 Februaty, accepted f o r publication 9 August 1991
Key w o r h : Anesthesia; halothane; ophthalmologic; pediatric; propofol; recovery; thiopental; vomiting.
The incidence of nausea and vomiting after pediatric strabismus surgery may be as high as 60 to 85% (1-3). Prophylactic antiemetic therapy with droperidol (1, 2), dixyrazine (3), or metoclopramide (4)can reduce the incidence of vomiting to 16-59%, although there is a risk of delayed awakening (5, 6). Propofol is an i.v. anesthetic which in adults is associated with a smooth and comparatively short awakening period and a low incidence of postoperative vomiting (7, 8 ) . To investigate whether the use of propofol could also be beneficial in children undergoing strabismus surgery, we compared two groups of patients, one anesthetized with propofol, supplemented with fentanyl, and one anesthetized with halothane after thiopental induction, in a randomised open study. PATIENTS AND METHODS Forty-four childen in ASA I and 11, aged 1.5 to 14 years, admitted for strabismus surgery were studied. The children were otherwise healthy,
* Presented in part at the Annual Meeting of the American Society of Anesthesiologists, New Orleans, 1989.
and none was on long-term medication or had received sedatives during the days preceding surgery. The study was approved by the local human studies committee, and informed consent was obtained from the parents. The children were accompanied by a parent during the whole hospital stay. All patients were anesthetized by the same anesthesiologist (BA),and the postoperative data weregathered and interviews were performed by the same nurse anesthetist (SL).
Prernedication Both groups of children were premedicated with midazolam 0.3 mg/ kg given rectally 10 to 20 min before induction, to a maximum of 7.5 mg. All children were pretreated with an anesthetic cream (EMLA) to facilitate venous cannulation. Induction and maintenance When an antecuhital vein had been cannulated, the patients were given glycopyrrolate 7.5 pg/kg i.v., followed by an infusion of 2.5% glucose in 0.45% saline. The patients were then randomly assigned to one of the two following groups: Group I - induction with thiopental 4-6 mg/kg, maintained with halothane 0.5-1.5%, or Group 2 induction with propofol 2.5-3.5 rng/kg followed by fentanyl 2.0 pg/ kg, maintained with propofol infusion 5-10 mg/kg/h. In both groups vecuronium 100 pg/kg was given to facilitate tracheal intubation. After tracheal intubation, gastric contents were aspirated in all children. The patients were manually ventilated with nitrous oxide/oxygen, Fio, 0.354.40. Anesthetic depth was controlled and adjusted in a similar way in both groups by means of traditional clinical signs and symptoms.
183
PROPOFOL/FENTANYL VS THIOPENTAL/HALOTHANE Table I Scales used for postoperative estimations. Vomiting
Degree of sedation
Apprehension
Postoperative pain
Score
No vomiting or retching Retching Vomiting
Awake, lucid Awake but drowsy Asleep, easy to arouse Asleep, difficult to arouse Not arousable
Calm, resting Some, easily calmed Clearly restless
No pain Some, whining Clearly in pain
0 1
Five minutes prior to the calculated end of surgery, halothane administration was discontinued in Group 1, and anesthesia continued with nitrous oxideloxygen only. In Group 2, the nitrous oxide administration was discontinued 5 min before end of surgery, but the propofol infusion 5.0 mg/kg/h, was continued until the surgeon announced the end of surgery. In both groups, additional vecuronium, 25.0 pg/kg, was given when needed.
Monitoring During anesthesia the children were continuously monitored with ECG and pulse oximetry. The blood pressure was measured intermittently with a mercury manometer and a manually inflatable cuff. Ulnar nerve stimulation (TOF) was used to assess the degree of muscle relaxation. Emergence In both groups neostigmine 50 pg/kg and glycopyrrolate 10 pg/kg were used to reverse the effect of the vecuronium. Before leaving the operation theatre, acetaminophen I(tl5 mg/kg was administered rectally in all children to provide postoperative pain relief. The intravenous fluid was continued until the children were able to take clear liquids orally. Documentation Pain at the injection site during induction was classified according to the reactions of the patient as follows: 1) no pain; 2) mild, moving arm or grimacing, 3) moderate, moving arm, complaining vocally, 4) severe, crying or strong protest. Peroperative bradycardia was defined as a 20% or greater decrease in heart rate compared to the value during stable anesthesia before surgery. The times of the following events were recorded: end of surgery (surgeon’s announcement), return of spontaneous breathing, return of laryngeal and hypopharyngeal reflex (coughing, swallowing), extubation. Awakening time was measured as the time lapsed from the end of surgery until the patient reacted to a verbal stimulus, such as speaking the child’s name.
Table 2 Demoaraphic data.
Number of patients Sex ratio M / F Age, years Weight, kg No of muscles repaired Duration of surgery, min Duration of anesthesia, min Mean 2 s.d.
Propofol/ fentanyl
22 14/8 7.0k3.9 26.8 f 11.6 2.5f 1.0 56.5 f 26.1 96.3 ? 26.6
22 16/6 6.8 f 3.5 27.9 17.7 2.3 kO.6 52.6 2 15.4 82.4 f 16.5
The occurrence of vomiting, degree of sedation, apprehension, and pain were recorded after the first and second hour and then every other hour for the first 8 postoperative hours. For the score points used, see Table 1 . Administration of antiemetics (dixyrazine 0.25 mg/kg i.v.) or analgesics (acetaminophen 10-15 mg/kg rectally) during the first 24 h postoperatively was also registered. Refusal to drink postoperatively was noted. To obtain information about vomiting or other side-effects of the anesthetics, the children and their parents were interviewed during the first postoperative day. Statistics
Statistical analysis was performed with Fisher’s exact test, the Wilcoxon rank-sum test and Student’s t-test. Probability values less than 0.05 were considered to indicate statistical significance.
RESULTS The two groups were comparable in respect of age, weight, sex and type of operation as well as duration of anesthesia and surgery (Table 2). The incidence ofpain during the injection of the induction agent, was greater in the propofol/fentanyl group (6/22 patients, 27%) than in the thiopental/halothane group (2/22 patients, 9”/),but the difference was not statistically significant. The intensity of pain was estimated as mild or moderate, and no child had postoperative phlebitis. There were no differences between the two groups’ needs for antiemetics or analgesics during the first 24 postoperative hours. The intraoperative phase was smooth and uneventful, except for some episodes of bradycardia induced by the surgical manipulation of the eye muscles. These occurred more commonly Table 3 Episodes of bradycardia in connection with surgical manipulation of the eye.
~~
Thiopental/ halothane
2 3 4
ns ns ns ns ns ns
Number of patients Number of episodes Number of episodes requiring treatment
Thiopental/ halothane
Propofol/ fentanvl
4/22 6
15/22* 24
1
4
Bradycardia was defined as a 20% or greater decrease in heart rate compared to the value during stable anesthesia before surgery. * P
Propofol-fentanyl anesthesia compared to thiopental-halothane with special reference to recovery and vomiting after pediatric strabismus surgery* S. LARSSON, B. ASCEIRSSON and J. MACNUSSON Department of Anesthesiology, University Hospital, Lund, Sweden
Forty-four children, ASA physical status I or 11, aged 1.5-14 years and admitted for strabismus surgery, were studied. The study compared the postoperative condition after two different anesthesia methods. All children were premedicated with midazolam rectally, received glycopyrrolate i.v. and were then randomised to one of two anesthetic methods: I ) induction with thiopental, maintenance with halothane or 2) induction with propofol supplemented with fentanyl, maintenance with propofol infusion. In both groups, tracheal intubation was performed after vecuronium i.v. and the children were ventilated manually. Peroperatively, patients receiving propofol/fentanyl had more episodes of bradycardia ( P < 0.00 I ) . Times to spontaneous breathing and extubation were shorter in the propofol/fentanyl group ( P < 0.05) and there was also a lesser degree of sedation during the first 2 h postoperatively ( P < O . O I ) . Fewer children in the propofol/fentanyl group vomited postoperatively ( P < 0.05). The apprehension score was higher in the propofol/fentanyl group compared to the thiopental/halothane group ( P < 0.05). We conclude that children undergoing strabismus surgery anesthetized with propofol/fentanyl had more episodes of peroperative bradycardia, a lower incidence of postoperative vomiting and a shorter recovery time, and were more apprehensive during the initial postoperative period than children anesthetized with thiopental/halothane.
Received 2 Februaty, accepted f o r publication 9 August 1991
Key w o r h : Anesthesia; halothane; ophthalmologic; pediatric; propofol; recovery; thiopental; vomiting.
The incidence of nausea and vomiting after pediatric strabismus surgery may be as high as 60 to 85% (1-3). Prophylactic antiemetic therapy with droperidol (1, 2), dixyrazine (3), or metoclopramide (4)can reduce the incidence of vomiting to 16-59%, although there is a risk of delayed awakening (5, 6). Propofol is an i.v. anesthetic which in adults is associated with a smooth and comparatively short awakening period and a low incidence of postoperative vomiting (7, 8 ) . To investigate whether the use of propofol could also be beneficial in children undergoing strabismus surgery, we compared two groups of patients, one anesthetized with propofol, supplemented with fentanyl, and one anesthetized with halothane after thiopental induction, in a randomised open study. PATIENTS AND METHODS Forty-four childen in ASA I and 11, aged 1.5 to 14 years, admitted for strabismus surgery were studied. The children were otherwise healthy,
* Presented in part at the Annual Meeting of the American Society of Anesthesiologists, New Orleans, 1989.
and none was on long-term medication or had received sedatives during the days preceding surgery. The study was approved by the local human studies committee, and informed consent was obtained from the parents. The children were accompanied by a parent during the whole hospital stay. All patients were anesthetized by the same anesthesiologist (BA),and the postoperative data weregathered and interviews were performed by the same nurse anesthetist (SL).
Prernedication Both groups of children were premedicated with midazolam 0.3 mg/ kg given rectally 10 to 20 min before induction, to a maximum of 7.5 mg. All children were pretreated with an anesthetic cream (EMLA) to facilitate venous cannulation. Induction and maintenance When an antecuhital vein had been cannulated, the patients were given glycopyrrolate 7.5 pg/kg i.v., followed by an infusion of 2.5% glucose in 0.45% saline. The patients were then randomly assigned to one of the two following groups: Group I - induction with thiopental 4-6 mg/kg, maintained with halothane 0.5-1.5%, or Group 2 induction with propofol 2.5-3.5 rng/kg followed by fentanyl 2.0 pg/ kg, maintained with propofol infusion 5-10 mg/kg/h. In both groups vecuronium 100 pg/kg was given to facilitate tracheal intubation. After tracheal intubation, gastric contents were aspirated in all children. The patients were manually ventilated with nitrous oxide/oxygen, Fio, 0.354.40. Anesthetic depth was controlled and adjusted in a similar way in both groups by means of traditional clinical signs and symptoms.
183
PROPOFOL/FENTANYL VS THIOPENTAL/HALOTHANE Table I Scales used for postoperative estimations. Vomiting
Degree of sedation
Apprehension
Postoperative pain
Score
No vomiting or retching Retching Vomiting
Awake, lucid Awake but drowsy Asleep, easy to arouse Asleep, difficult to arouse Not arousable
Calm, resting Some, easily calmed Clearly restless
No pain Some, whining Clearly in pain
0 1
Five minutes prior to the calculated end of surgery, halothane administration was discontinued in Group 1, and anesthesia continued with nitrous oxideloxygen only. In Group 2, the nitrous oxide administration was discontinued 5 min before end of surgery, but the propofol infusion 5.0 mg/kg/h, was continued until the surgeon announced the end of surgery. In both groups, additional vecuronium, 25.0 pg/kg, was given when needed.
Monitoring During anesthesia the children were continuously monitored with ECG and pulse oximetry. The blood pressure was measured intermittently with a mercury manometer and a manually inflatable cuff. Ulnar nerve stimulation (TOF) was used to assess the degree of muscle relaxation. Emergence In both groups neostigmine 50 pg/kg and glycopyrrolate 10 pg/kg were used to reverse the effect of the vecuronium. Before leaving the operation theatre, acetaminophen I(tl5 mg/kg was administered rectally in all children to provide postoperative pain relief. The intravenous fluid was continued until the children were able to take clear liquids orally. Documentation Pain at the injection site during induction was classified according to the reactions of the patient as follows: 1) no pain; 2) mild, moving arm or grimacing, 3) moderate, moving arm, complaining vocally, 4) severe, crying or strong protest. Peroperative bradycardia was defined as a 20% or greater decrease in heart rate compared to the value during stable anesthesia before surgery. The times of the following events were recorded: end of surgery (surgeon’s announcement), return of spontaneous breathing, return of laryngeal and hypopharyngeal reflex (coughing, swallowing), extubation. Awakening time was measured as the time lapsed from the end of surgery until the patient reacted to a verbal stimulus, such as speaking the child’s name.
Table 2 Demoaraphic data.
Number of patients Sex ratio M / F Age, years Weight, kg No of muscles repaired Duration of surgery, min Duration of anesthesia, min Mean 2 s.d.
Propofol/ fentanyl
22 14/8 7.0k3.9 26.8 f 11.6 2.5f 1.0 56.5 f 26.1 96.3 ? 26.6
22 16/6 6.8 f 3.5 27.9 17.7 2.3 kO.6 52.6 2 15.4 82.4 f 16.5
The occurrence of vomiting, degree of sedation, apprehension, and pain were recorded after the first and second hour and then every other hour for the first 8 postoperative hours. For the score points used, see Table 1 . Administration of antiemetics (dixyrazine 0.25 mg/kg i.v.) or analgesics (acetaminophen 10-15 mg/kg rectally) during the first 24 h postoperatively was also registered. Refusal to drink postoperatively was noted. To obtain information about vomiting or other side-effects of the anesthetics, the children and their parents were interviewed during the first postoperative day. Statistics
Statistical analysis was performed with Fisher’s exact test, the Wilcoxon rank-sum test and Student’s t-test. Probability values less than 0.05 were considered to indicate statistical significance.
RESULTS The two groups were comparable in respect of age, weight, sex and type of operation as well as duration of anesthesia and surgery (Table 2). The incidence ofpain during the injection of the induction agent, was greater in the propofol/fentanyl group (6/22 patients, 27%) than in the thiopental/halothane group (2/22 patients, 9”/),but the difference was not statistically significant. The intensity of pain was estimated as mild or moderate, and no child had postoperative phlebitis. There were no differences between the two groups’ needs for antiemetics or analgesics during the first 24 postoperative hours. The intraoperative phase was smooth and uneventful, except for some episodes of bradycardia induced by the surgical manipulation of the eye muscles. These occurred more commonly Table 3 Episodes of bradycardia in connection with surgical manipulation of the eye.
~~
Thiopental/ halothane
2 3 4
ns ns ns ns ns ns
Number of patients Number of episodes Number of episodes requiring treatment
Thiopental/ halothane
Propofol/ fentanvl
4/22 6
15/22* 24
1
4
Bradycardia was defined as a 20% or greater decrease in heart rate compared to the value during stable anesthesia before surgery. * P
