Anesth Analg 1999;88:742
© 1999 International Anesthesia Research Society
PEDIATRIC ANESTHESIA
Tracheal Extubation of Deeply Anesthetized Pediatric Patients: A Comparison of Isoflurane and Sevoflurane
Robert D. Valley, MD,
Justin T. Ramza, MD,
Pauletta Calhoun, RN,
Eugene B. Freid, MD, FCCM,
Ann G. Bailey, MD,
Vincent J. Kopp, MD, and
Linda S. Georges, MD
Department of Anesthesiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
Address correspondence to Robert D. Valley, MD, Department of Anesthesiology, University of North Carolina at Chapel Hill, CB# 7010 223 Burnett-Womack Building, Chapel Hill, NC 27599-7010.
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Abstract
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We studied the emergence characteristics of unpremedicated children tracheally extubated while deeply anesthetized ("deep extubation") with isoflurane or sevoflurane. Forty children were assigned to one of two groups, Group I or Group S. At the end of the operation, Group I patients were extubated while breathing 1.5 times the minimum alveolar anesthetic concentration (MAC) of isoflurane. Group S patients were tracheally extubated while breathing 1.5 times the MAC of sevoflurane. Recovery characteristics and complications were noted. Group S patients were arousable sooner than Group I patients (10.1 + 6.5 vs 16.3 + 9.9 min). Later arousal scores and times to discharge were the same. There were no serious complications in either group. Breath-holding was more common in Group I. We conclude that the overall incidence of airway problems and desaturation episodes was similar between groups. Emergency delirium was common in both groups (32% overall: 40% for Group I, 25% for Group S).
Implications: Deep extubation of children can be safely performed with either isoflurane or sevoflurane. After deep tracheal extubation, airway problems occur but are easily managed. Return to an arousable state occurred more quickly with sevoflurane, although time to meeting discharge criteria was not different between the two groups. Emergence delirium occurs frequently with either technique.
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Introduction
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Tracheal extubation of patients while deeply anesthetized (deep extubation) has the advantage of removing a potent stimulus to coughing and breath-holding before the return of upper airway reactivity (1,2). This technique may provide a smoother emergence from anesthesia and may reduce bleeding after airway procedures, reduce the chance of wound dehiscence, or lower the likelihood of bronchospasm. In 1991, Pounder et al. (3) reported that children undergoing tracheal extubation while deeply anesthetized with either isoflurane or halothane had significantly fewer episodes of hemoglobin desaturation than those who were tracheally extubated awake.
Leaving the patient with an unprotected airway is the primary reservation to extubating patients while deeply anesthetized. Techniques that reduce the time from tracheal extubation to return of protective airway reflexes would minimize the risk of aspiration or airway obstruction secondary to obtundation.
Because sevoflurane is easily tolerated for inhaled induction of anesthesia and has a relatively low blood-gas solubility partition coefficient, we hypothesized that sevoflurane may be more effective for deep extubation than isoflurane (4,5).
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Methods
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After obtaining institutional review board approval and written, informed consent, forty ASA physical status I or II children were enrolled. They ranged in age from 4 mo to 14 yr and were all scheduled for elective surgical procedures below the umbilicus. Children with a history of airway disease were excluded from the study. Children underwent either an IV induction with propofol or an inhaled induction with sevoflurane and nitrous oxide; all were tracheally intubated with the use of muscle relaxants. Maintenance anesthesia was determined by random assignment to either the isoflurane (I) or sevoflurane (S) group and consisted of the assigned potent inhaled anesthetic and nitrous oxide in oxygen. Exhaled anesthetics were monitored using side-stream sampling to an infrared analyzer (Datex Ultima; Datex-Engstrom, Inc., Tewksbury, MA). No systemic analgesics were administered. Oral airway use was at the discretion of the attending anesthesiologist. Each child was given an appropriate regional or local anesthetic block before awakening to provide effective postoperative analgesia. During the last 20 min of the operation, any residual neuromuscular blockade, as determined by train-of-four monitoring, was reversed with neostigmine, and the patient was allowed to breathe spontaneously. Nitrous oxide was discontinued, and the inhaled anesthetic (I or S) was adjusted to provide an age-appropriate end-tidal concentration of 1.5 minimum alveolar anesthetic concentration (MAC) (6,8). The patient was then turned on his/her side, and the oropharynx was gently suctioned. The endotracheal tube was removed, and oxygen was administered via a face mask. Once the extubated airway was determined to be adequate, the child was transported to the postanesthesia care unit (PACU) and observed until fully awake. They received 40% oxygen via a face mask or "blow by" oxygen until it was judged not necessary by the PACU nursing staff. Pulse oximetry monitoring was provided continuously from induction through recovery.
A research nurse, blinded to the assigned group, observed the induction, tracheal extubation, transport, and recovery. The use of airway adjuncts, the need for airway support and the occurrence of airway events (excessive secretions, breath-holding, coughing and laryngospasm) were noted during each time period. The number, severity, and duration of any desaturation episodes, as determined by a pulse oximetry reading <95%, were recorded. Arousal scores, as described in Table 1, were monitored until the patient was either discharged from the PACU or fully awake. Time from tracheal extubation to spontaneous eye opening, time to meeting standard discharge criteria, and the actual time to discharge from phase 1 PACU were noted. Any analgesic requirements and postoperative vomiting were noted. The incidence and duration of emergence delirium were also recorded. Emergence delirium was defined as disoriented behavior characterized by inconsolable agitation, similar to the definition used by Davis et al. (9).
Frink et al. (10) reported a 60% reduction in early recovery time (the time to following commands) in patients awakening from sevoflurane versus isoflurane anesthesia. Based on a more conservative estimate of a 40% difference in emergence times, it was determined that at least 17 patients would be required in each group to demonstrate a significant difference at the 0.05 level with a power of 0.8 and a standard deviation equal to the difference of the means. It was decided to enter 20 patients in each group.
Unless otherwise noted, all data are reported as the mean ± SD. Parametric data were analyzed by using the unpaired Student’s t-test. Nominal data were analyzed by using 
2 or Fisher’s exact test. A P value <0.05 was considered significant.
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Results
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Demographic data for the two study groups are presented in Table 2. There were no significant differences between groups for age, weight, gender, type of surgery, duration of anesthesia, or type of regional or local block performed.
The trachea of all patients were successfully extubated in the operating room (OR). No patient required reintubation. Recovery times are shown in Table 3. Early arousal scores were significantly higher in Group S. Time to eye opening, time to meeting standard discharge criteria, and actual time to discharge are also listed in Table 3. There were no differences between groups for any of these variables.
Problems with the airway and the use of oral airways at extubation in the OR, during transport, and in the PACU are noted in Table 4. There were no significant differences between groups except for the overall incidence of breath-holding, which occurred in five patients in Group I and in no patients in Group S. The total number of desaturation episodes and the number of patients that had periods of desaturation were similar in both groups (Table 4). All desaturation episodes were short-lived and required no intervention other than supplemental oxygen administration, airway support, or comforting the child.
There were five episodes of emesis in Group I and three episodes in Group S. Emergence delirium occurred in 40% (n = 8) of Group I and 25% (n = 5) of Group S. Although the mean duration of emergence delirium in Group I was twice that of Group S (14.3 ± 9.5 vs 7.6 ± 6.4 min, respectively), this did not reach statistical significance.
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Discussion
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In this study, we compared the recovery characteristics of children tracheally extubated while deeply anesthetized with either isoflurane or sevoflurane. We have demonstrated that both anesthetics can be used safely for this purpose. Children whose tracheas were extubated while breathing sevoflurane reached an arousable state more quickly than those who were breathing isoflurane. Based on the different blood-gas partition coefficients for sevoflurane (0.65) versus isoflurane (1.4), a more rapid emergence would be expected (5). This difference did not extend far into the recovery period, and time to discharge readiness was essentially the same for both groups. These findings might be explained by a greater effect of differences in the blood-gas partition coefficients on anesthetic elimination during the early recovery period, when the alveolar-blood gradient would be greatest. The effect of blood-tissue gradients on elimination may be relatively greater during the later stages of recovery. The brain-blood partition coefficients for isoflurane (1.6) and sevoflurane (1.7) are nearly identical. Thus, any difference in recovery times would be expected to be greatest during measures of early recovery.
The incidence of breath-holding was significantly higher in Group I. Although not statistically significant, coughing was more common in Group S. This is in contrast to the study of Doi et al. (11), who found that sevoflurane, compared with isoflurane, halothane, and enflurane, did not elicit any cough reflex. There was no difference between groups in the incidence of laryngospasm and the number of desaturation episodes. Similar results were reported for isoflurane by Pounder et al. (3), who found a 4% incidence of laryngospasm with isoflurane compared with a 5% incidence in this study. The overall incidence of adverse airway episodes was similar with either inhaled anesthetic (13 episodes with isoflurane, 10 episodes with sevoflurane). The reported increase in airway irritability seen with isoflurane may be less of a problem on emergence than on induction (12,13). Similar findings have been reported with desflurane (9,14).
Many studies have noted an increased incidence of postoperative agitation in children after general anesthesia with sevoflurane compared with halothane (15–18). Postoperative agitation has been described in as many as 50% of children anesthetized with sevoflurane (15). Although excitement on emergence from isoflurane anesthesia in adult patients has been reported to be as high as 12%, there are no published reports on the incidence of emergence delirium with isoflurane anesthesia in children (19). In our study, emergence delirium was relatively common, occurring in 32% of patients from a study group with good postoperative pain control but without premedication or intraoperative narcotic administration. Emergence delirium occurred as frequently in the isoflurane group (8 of 20) as in the sevoflurane group (5 of 20). The average duration of emergence delirium episodes in Group S was nearly half that in Group I, although this did not reach statistical significance.
In summary, we found that deep extubation of children could be safely performed with 1.5 MAC sevoflurane or isoflurane. Children tracheally extubated while breathing sevoflurane reached an arousable state more quickly than those who had received isoflurane and were less likely to have breath-holding episodes. Time to discharge readiness was the same. Airway complications and episodes of arterial desaturation occurred with equal frequency with either anesthetic and were all easily managed. The incidence of emergence delirium was the same after deep extubation with sevoflurane or isoflurane.
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Accepted for publication December 23, 1998.
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Abstract
Introduction
