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Rapid emergence does not explain agitation following sevoflurane anaesthesia in infants and children: a comparison with propofol.Cohen IT, Finkel JC, Hannallah RS, Hummer KA, Patel KM. Paediatric Anaesthesia 2003;13:63-67
Reviewed by: Hoshang J. Khambatta, MD
Rapid emergence following the use of a highly insoluble volatile anesthetic agent, such as sevoflurane, is associated with emergence agitation in children. The authors studied 53 children who were undergoing ambulatory surgery. These children were randomized to receive either sevoflurane as a maintenance anesthetic or propofol, which is also associated with rapid, but calmer, emergence. The children were aged 2 - 36 months. No premedication was used. The two groups were matched for age, weight, sex, duration of surgery, and type of surgery. Induction of anesthesia was with 60% nitrous oxide, 40% oxygen, and 8% sevoflurane in all patients. Following induction, in the sevoflurane group the children were maintained on the same amount of oxygen and nitrous oxide, but received a maintenance dose of 1.5 to 2.5% sevoflurane. In the propofol group, following induction, sevoflurane was discontinued and the children received i.v. propofol, initially at a rate of 200 ug/kg/min, and maintained on nitrous oxide, oxygen, and propofol. (Maintenance dose of propofol is not mentioned by the authors.) Intra operative analgesia was administered by either a caudal block with bupivicaine 0.25%, or with 2 ug/kg of fentanyl i.v. according to surgical procedure. The two groups were matched for analgesics as well. Muscle relaxants were used when tracheal intubation was necessary. At the end of surgery, patients were transferred to the post anesthesia care unit. An observer blinded to the anesthetic technique recorded degree of agitation on a 3 point scale. 1 = calm, 2 = agitated but consolable, 3 = agitated and unconsolable. Pain was noted using the Objective Pain Scale. Recovery, using the Steward Recovery Score. When compared for agitation, the patients who received sevoflurane had a significantly higher incidence of severe agitation than those who received propofol, 23% to 4%. There was no relationship to agitation with the type of intra operative analgesic. The patients who received sevoflurane also had a higher incidence of pain, 23% versus 7%, and there was no significant difference in the incidence of vomiting.
Comments: The true nature of the phenomenon of emergence agitation is not properly understood. The incidence of severe agitation and pain was higher in the sevoflurane group, though the use of intra operative analgesics was similar. The authors felt that perhaps the increased pain reflected the effect of severe agitation on measuring pain on a pain behavior scale. They also suggest variable rate of neurological recovery, resulting in a dissociative state. There are reports that intra operative use of ketorolac also reduced the incidence of emergence agitation. In a recent report (Anesth Analg 2003;97:364-7), the authors studied children undergoing MRI who received sevoflurane anesthesia. Hence there was no question of surgical pain cofounding the study. The patients were divided in two groups. Sevoflurane was administered to both groups, but in the second group, 10 minutes prior to the end of anesthesia, the children received 1 ug/kg of i.v. fentanyl. There was a 56% incidence of agitation in the only sevoflurane group, where as in the second, fentanyl group, the incidence of agitation dropped to 12%. The time to discharge from the hospital was the same in both groups, indicating that the use of narcotics at the end of a procedure in an outpatient setting had no adverse effect on discharge time. The authors, though, do not offer an explanation for emergence agitation. The above and other studies suggest that even in the absence of a surgical maneuver, which could otherwise be blamed for pain and agitation, the additional use of a narcotic or an agent such as ketorolac, at the end of the procedure, does decrease the incidence of emergence agitation. It is very likely that the surgical pain being responsible may prove to be a red herring, and is also very likely that a central neurological mode is responsible instead. Nevertheless, analgesics were not able to completely abolish emergence agitation. For the present, analgesics administered shortly before the end of surgery appears to be the best treatment modality, awaiting a definitive etiology for emergence agitation.
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