| JOURNAL HOME | CME HOME | THIS MONTH | PAST ISSUES | ETOC | COLLECTIONS |
| AUTHORS | REVIEWERS | EDITORIAL BOARD | FEEDBACK | RSS | HELP |
| ||||||||||||||
| ||||||||||||||
|
|
|
|
||||||||||||
|
||||||||||||||
Department of Anesthesiology, CHUL du Centre Hospitalier Universitaire de Québec, Québec, Canada
Address correspondence to Bernard J. Dalens, Department of Anesthesiology, CHUL du Centre Hospitalier Universitaire de Québec, 2705, boul. Laurier - Local 2206, Sainte-Foy, Québec, Canada, G1V 4G2. Address e-mail to bdalens{at}videotron.ca.
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
All infants and children ranging in age from 6 mo to 8 yr scheduled for elective cerebral MRI were eligible for inclusion in the study protocol. Exclusion criteria included hemodynamically or respiratory unstable patients, severe mental retardation and physical disabilities, patients under treatment with sedatives or anticonvulsants, emergency indications, extremely distressed and uncooperative children, and parental refusal.
Patient demographics including age, gender, and weight were recorded. Past and current medical records were carefully checked for associated medical disorders as well as concomitant medication intake. The neurodevelopmental status and social abilities of the children were recorded.
All patients underwent inhaled induction of anesthesia with 6% sevoflurane in 100% oxygen. After the patient’s loss of consciousness, a peripheral venous catheter was inserted and 10 mL/kg of lactated Ringer’s solution was infused over 20 min followed by standard fluid maintenance therapy according to the patient’s weight. A laryngeal mask was inserted and maintenance of anesthesia was maintained with 3% sevoflurane (delivered concentration) in oxygen/air (Fio2 between 0.3 and 0.5 depending on Sao2 values). Ear plugs were inserted in all patients. Spontaneous breathing was allowed provided ETco2 remained below 50 mm Hg; if ETco2 had exceeded 50 mm Hg, the patient would have been excluded from the protocol and assisted ventilation would have been performed. No sedative, muscle relaxant or narcotic was administered during the procedure. At the end of the procedure, the patients randomly received saline, ketamine 0.25 mg/kg, or nalbuphine 0.1 mg/kg in a blinded fashion.
The vials used for the study were prepared by the pharmacy of our institution. All the vials were identical and contained the same volume of transparent and unidentifiable fluid. The patient’s anesthesiologist and the nursing staff were all unaware of the drug administered, and the administered drug was only revealed after completion of the protocol study. Sevoflurane administration was discontinued immediately after the study drug injection, the anesthetic circuit was set to 100% oxygen, and the laryngeal mask was removed precisely 60 s later.
The following variables were evaluated for all patients:
Recovery monitoring was performed for all patients during their stay in the PACU according to the standard protocol of our institution. No patient was returned to the ambulatory unit earlier than 30 min after completion of the procedure.
In the PACU, all patients were evaluated 5, 10, 15, and 30 min after the removal of the laryngeal mask for the following:
Any undesired or unexpected effects were reported on the postanesthetic recovery chart.
The same standard discharge criteria were used during the study protocol as for patients not included in the study protocol. The anesthesiologist who provided anesthesia signed the discharge form after controlling:
The sample size was determined assuming that the probability of sevoflurane agitation was 30% or more. We wanted to find a significant difference (P < 0.05) (
= 0.05, one-tailed) with a power of 80% (ß error = 0.2) to detect a difference of 25%. Twenty-five patients per group would have been sufficient but we expected some exclusions from the protocol (which did not happen) and increased this number to 30 (which allowed finding the same significant difference with a power of 90%). The random list was established by the department of Epidemiology and Human Statistics of our institution; allocation of each patient to one of the three groups was blind and did not take into account the results of previous allocations, thus resulting in an uneven number of patients in each group.
Continuous variables (age, weight, duration of anesthesia) were expressed as means and standard deviations. Comparisons among groups were made by using Kruskal-Wallis test (nonparametric analysis of variance) and Dunn’s multiple comparison test.
Discontinuous variables (nausea/vomiting, quality of early awakening after removal of the laryngeal mask, items of the Recovery Mental State and Emergence Agitation Scale) were compared using both Pearson 
2 test with Yates’s continuity correction, when applicable, and Fisher’s exact test. Differences were considered significant at P < 0.05.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
|
The three groups did not differ significantly in terms of age, weight, ASA physical status, or duration of anesthesia. In all patients enrolled in the study, the protocol was achieved with no intraoperative incident or secondary exclusion from the protocol. All patients breathed spontaneously with ETco2 below 50 mm Hg throughout the procedure. Physiological status and behavioral conditions after removal of the laryngeal mask performed 60 s after injection of saline, ketamine, or nalbuphine are displayed in Table 2. Differences among the three groups were not significant. No apnea was observed and the 5 patients who developed mild desaturation (1 in K-group and 2 in both S-group and N-group) were easily managed using assisted facemask ventilation in 100% oxygen for <1 min. No additional measures were necessary and all patients breathed spontaneously throughout the recovery phase.
|
In the PACU, only 1 patient experienced nausea without vomiting, at the tenth minute in the S-group. No other clinically relevant adverse effect was observed in any group.
Alertness and spontaneous behavior of the patients according to the Recovery Mental State are displayed in Figure 1. The number of patients quietly alert did not differ significantly in the 3 groups at 5, 10 and 15 min but was significantly increased in the N-group and K-group as compared with the S-group at 30 min. More patients were drowsy in the K-group and S-group at 5, 10, and 15 min, but the difference was not statistically significant. There were more agitated children in the S-group as compared to the K-group or to the N-Group, at all times: the difference was only significant at 15 and 30 min using the Recovery Mental State Scale but was significant at all times using the Emergence Agitation Scale. More patients from the K-group developed agitation as compared with the N-group but the difference reached significance only at 15 min.
|
Assessment of patients according to the Emergence Agitation Scale is displayed in Figure 2. More patients were obtunded in the K-group and N-group at 5 and 10 min (P < 0.05) but not at 15 and 30 min. Thirty minutes after discontinuation of anesthesia, significantly more patients were awake, quiet, and responsive in both the K-group and N-group as compared with the S-group. Significantly more crying and thrashing children (score of 4 or 5) were observed in the S-group as compared with the 2 other groups, at all times, especially at 30 min (one third of the patients). In the K-group, the number of patients who were crying or thrashing was significantly less than in the S-group (0 versus 18%, 10 versus 25%, 15 versus 29%, and 12 versus 36%, respectively, at 5, 10, 15, and 30 min). In the N-group, only 1 patient was crying at 15 and 30 min, a result significantly better than that observed in the S-group (all times) and in the K-group at 10, 15, and 30 min.
|
In the same day unit, nausea and vomiting were reported in 2, 3, and 2 children of the S-group, K-group, and N-group, respectively (difference not significant). All patients from the K-group and N-groups were discharged from hospital in <3 h (1.7 ± 0.50 and 1.5 ± 0.52, respectively, versus 2.2 ± 1.32 in the S-group) after leaving the PACU. Five patients from the S-group had to stay longer (3 to 6 h), mostly as a result of agitation (4/5).
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
2–agonists such as clonidine (12) or dexmedetomidine (13–15), and other sedatives (16–19). Other techniques of anesthesia have also been explored (20), usually using deep general anesthesia with tracheal intubation. Because cerebral MRI is a rather lengthy procedure (typically 45 to 60 minutes in duration), the administration of large doses of sedatives at induction of anesthesia is necessary to maintain a pharmacodynamic effect at the end of the procedure. These large doses usually require that the airway and ventilation of the patient be controlled: consequently, an otherwise noninvasive pain-free examination such as an MRI requires deep general anesthesia and tracheal intubation with their attendant drawbacks in terms of potential morbidity and costs. Both ketamine (21,22) and nalbuphine (23,24) can provide mild to moderate safe sedation when administered in small doses. We tested the hypothesis that administering these sedative drugs just before discontinuing the anesthesia would not delay patient awakening and would significantly decrease the incidence of emergence agitation. The duration of anesthesia was the same in the three groups of patients and emergence conditions when sevoflurane administration was discontinued were similar in all groups. Episodes of coughing and desaturation were unusual and mild, and could be resolved in <2 minutes in the 3 groups. Brief facemask-assisted ventilation with oxygen was sufficient to overcome the transient breathing difficulty. Patients given ketamine or nalbuphine were more sedated during the first 15 minutes, but at 30 minutes more than 50% of children were awake and quiet in the K-group and N-group versus fewer than 30% in the S-group. All patients could be discharged from the PACU 30 minutes after discontinuation of anesthesia.
One third of patients presented with emergence agitation in the S-group, a result comparable to other clinical studies (3,4). Patients from the K-group experienced significantly fewer episodes of delirium than those in the S-group, and this complication was almost completely absent in the N-group.
Evaluation using the Emergence Agitation Scale (4) confirmed that fewer patients were crying or thrashing in the K-group and still fewer in the N-group. Irrespective of the level of sedation at early evaluation times in these two groups, more patients were also awake, quiet, and alert 30 minutes after discontinuation of anesthesia, and none required either additional sedation or prolonged stay in the PACU.
A limitation of the study is that as nalbuphine is an opioid agonist/antagonist, nausea and vomiting could represent a significant adverse effect after hospital discharge even though the three groups did not differ in this regard during the evaluation time.
In conclusion, the IV administration of either 0.25 mg/kg of ketamine or 0.1 mg/kg of nalbuphine in sevoflurane-anesthetized children at the end of a MRI examination did not delay awakening and removal of the laryngeal mask. Immediate and delayed postanesthetic conditions were improved with significantly fewer episodes of agitation in the K-group and virtually none in the N-group versus more than 30% in patients given saline. The stay in the PACU was not prolonged in those patients who received either ketamine or nalbuphine. There were significantly more patients awake, quiet, and alert at the time of discharge from the PACU in both the K-group and the N-group as compared with the S-group. Because of its excellent efficacy in preventing emergence agitation with no additional adverse effects, IV nalbuphine at the end of the procedure at a dose of 0.1 mg/kg seems to offer the highest benefit/risk ratio when sevoflurane has been used as the sole anesthetic.
The authors thank Dr. Russel A. Rarity, MA FRCA, Consultant Anaesthetist, Department of Anaesthetics, Timaru Hospital, Private Bag 911, Timaru (New Zealand) for his assistance in the editing of the manuscript.
|
Footnotes |
|---|
Accepted for publication December 1, 2005.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  A.-M. Machata, H. Willschke, B. Kabon, S. C. Kettner, and P. Marhofer Propofol-based sedation regimen for infants and children undergoing ambulatory magnetic resonance imaging Br. J. Anaesth., August 1, 2008; 101(2): 239 - 243. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
