| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
From the Department of Anesthesiology, Veterans General Hospital-Taipei, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Address correspondence to: Dr. Shen-Kou Tsai, Department of Anesthesiology, National Yang-Ming University and Taiwan University, Veterans General Hospital-Taipei, 201, Sec. 2, Shi-Pai Rd, Pei-Tou 112, Taipei, Taiwan. Fax: 886-2-28751597; E-mail: sktsai{at}vghtpe.gov.tw
 |
Abstract |
|---|
 TOP Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
Methods: Forty ASA class I–II adolescents, were enrolled into either a desflurane (DES) group, or a fentanyl (FEN) group for scoliosis surgery. Bispectral index (BIS) was monitored continuously in all patients throughout the procedure; the relationship between the wake-up time and BIS value was evaluated.
Results: Patients in the DES group had a significantly shorter wake-up onset than patients in the FEN group (4.1 ± 0.6 vs 8.9 ± 2.1 min, P < 0.01). No recall occurred during the wake-up test in the DES group, while five patients had recall in the FEN group, including two patients who recalled a given colour. Extubation time was significantly shorter in the DES group than in the FEN group (7.2 ± 0.6 vs 16 ± 11.9 min, P < 0.01).
BIS values were significantly higher in the FEN group than in the DES group during anesthesia. (62 ± 4.5 vs 42 ± 5.3, P < 0.05) BIS after the wake-up test was similar in both groups (90 ± 2.9 vs 93.8 ± 2.5). There was a latency period (3.3 ± 1.2 min) between the maximal BIS value and wake-up time in the FEN group but not in the DES group.
Conclusions: DES provides a significantly shorter onset time during the wake-up test and a rapid emergence after scoliosis surgery. BIS monitoring during the wake-up test was more informative when anesthesia was maintained with DES compared to FEN infusion.
|
Introduction |
|---|
|
TOPAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
|
Methods |
|---|
|
TOPAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Anesthesia
After premedication with midazolam (0.08 mg•kg–1), anesthesia was induced with propofol (2 mg•kg–1, iv) and FEN (5 µg•kg–1, iv); atracurium was used to facilitate endotracheal intubation. The patients were divided randomly into two groups of 20. The randomization schedule was computer generated by a biostatistician (not otherwise involved in the study). The randomization schedule specified the group (I or II) to which each prospective patient would be allocated upon enrollment in the trial. An opaque envelope containing the patient number and group assignment was prepared, sealed, and numbered for each patient. In the DES group, anesthesia was maintained with DES (end-tidal 6–8%) and N2O (2 L•min–1) in O2 (1 L•min–1). In the FEN group, anesthesia was maintained with a FEN (3 g•kg–1•hr–1) continuous infusion and N2O (2 L•min–1) in O2 (1 L•min–1). Intraoperative monitors included pulse oximetry, electrocardiogram, non-invasive blood pressure, end-tidal anesthetic concentration and end-tidal capnography. Right radial arterial and jugular vein cannulation were performed and pressure was measured continuously. Rectal temperature was maintained at 37°C by using a warming blanket. The compound electromyogram of the adductor pollicis muscle was recorded using a Datex neuromuscular transmission monitor. Neuromuscular block was elicited by an intermittent iv bolus injection of atracurium to maintain one twitch of the train-of-four during anesthesia. Arterial oxygen saturation, mean arterial blood pressure (MAP), central venous pressure, respiratory rate and heart rate (HR) were also recorded simultaneously.
A disposable BisSensor (Aspect Medical Systems, Newton, MA, USA) was applied to the forehead of each patient before the induction of anesthesia and connected to a bispectral index (BIS) Model A-2000 monitor (Aspect Medical Systems, Newton, MA, USA). The BIS was monitored continuously in all patients throughout the procedure. T1 was defined as the time before starting the wake-up test; T2 was the time of maximal BIS value. T3 was the time when the patient followed the verbal command to move his/her fingers and toes. Mean blood pressure was maintained at 80 mmHg by the infusion of nitroglycerin as required.
Wake-up procedure
Thirty minutes before the wake-up test, the administration of atracurium was interrupted, allowing the train-of-four count to recover gradually. Small doses of a reversal agent (edrophonium and atropine) were given if the train-of-four count did not recover to four. When the wake-up test was begun, either DES or the FEN infusion was terminated. The patient was first asked to move his/her fingers and this was repeated every 15 sec until the patient responded. The patient was then instructed to move both his/her fingers and toes and, finally, was asked to remember a given colour.
When the wake-up test was completed, patients were reanesthetized with a bolus of propofol and anesthesia maintained with either DES (end-tidal 6–8%) or a FEN infusion (3 µg•kg–1•hr–1) as before. Neuromuscular blockade was re-established. By the end of surgery, the anesthetics were discontinued and the patient’s lungs were ventilated with 100% oxygen with a fresh gas flow of 6 L•min–1. The time to the first spontaneous motion was recorded. Response to verbal command to open the eyes, and orientation to body parts (left vs right, mouth vs eyes, toes vs hands) were assessed in a uniform method at one-minute intervals. All patients were extubated before they were sent to the postanesthesia care unit.
On the day following surgery, the patients were interviewed to ascertain whether they remembered intraoperative events including pain, voice or the given colour during the wake-up test. All patients in both groups received iv morphine patient controlled analgesia (PCA) for postoperative pain control. The loading dose of iv PCA was morphine 0.05 mg•kg–1, with a continuous infusion of 0.015 mg•kg–1. The PCA dose was 0.02 mg•kg–1 with a lockout interval of ten minutes and a four-hour maximum dose of 10 mg morphine.
For statistical analysis, the wake-up time and the BIS values at T1 and T3 were compared within each group using a paired Student’s t test and between each group using an unpaired Student’s t test. Time to response (T3–T1) was analyzed by the Kaplan-Meier method. Values were considered significant when P < 0.05. Results are presented as mean ± SD. The power of the study was calculated.
|
Results |
|---|
|
TOPAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
.
|
) Onset of wake up was significantly shorter in the DES group than in the FEN group (4.1 ± 0.6 vs 8.9 ± 2.1 min, P < 0.01). There were significant increases in BIS, MAP, and HR from T1 to T3 in both groups. Changes in mean BIS value, MAP, and HR during the wake-up test are shown in Table II. Before the wake-up test, the BIS value was significantly higher in the FEN group than in the DES group during surgery, but the BIS value at the end of the wake-up test was similar in both groups (Table II). The time required to reach T3 was longer in FEN patients compared to DES patients. In addition, there was a latency period (T2 to T3) (3.3 ± 1.2 min) between the maximal BIS value and wake-up in the FEN group but not in the DES group (Table II and Figures 1–3).
|
|
|
|
During the postoperative follow-up, there was no recall during the wake-up test in the DES group compared to five patients who had recall in the FEN group (Table III).
|
).
|
|
Discussion |
|---|
|
TOPAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Our results also showed that no patient in the DES group but 25% patients in the FEN group had recall with two remembering the colour given during the test. The BIS value of these five patients was not different from that of the other FEN patients. The incidence of recall in our study is comparable to that reported by McCann et al.7 who observed that 17.5% of patients with FEN anesthesia had recall. This result suggests that DES may be superior to FEN during maintenance of anesthesia for the wake-up test during scoliosis surgery.
Bispectral analysis is a well known mathematical technique of signal processing that quantifies the degree of phase coupling between different frequency components within a signal. The BIS yields the best combination of sensitivity and specificity of any commercially available depth-of-anesthesia monitoring device,8,9 and has been reported to be an alternative technique for the wake-up test.7 Our data show that BIS values were lower during DES anesthesia than during FEN anesthesia. BIS values do not appear to be independent of the anesthetic agent administered,10–13 therefore, comparable BIS values achieved with different agents may not represent the same depth of anesthesia.11–14 The current BIS algorithm was derived from patients anesthetized with predominantly hypnotic drugs, such as propofol and inhaled anesthetics.14–18 Therefore, the BIS value for adequate anesthesia or wake up will vary among patients and among anesthetic regimens. The effect of narcotics on BIS level is not as clear as with other drugs. In our study, BIS values were high in the FEN group (> 60) during maintenance of anesthesia, but without recall of intraoperative events. This suggests that BIS values in opioid-based anesthesia may be different than with other techniques.17
The wake up from anesthesia has to ensure not only that the patient responds to verbal command but also that the patient is orientated to body parts (moving the toes). The recovery time from anesthesia for these two categories of response varies with different anesthetic agents. The slow response to orientation was responsible for the latency period between the maximal BIS value and patient awakening. Our results show that the final BIS value was greater than 90 when the patient woke up and that there was a latency period between the maximal BIS value and patient awakening in the FEN group but not in the DES group. Patients in the FEN group did not respond to the command to move their toes for few minutes when BIS values were greater than 90. This would imply that the maximal BIS value adequately reflects the time of awakening in DES patients but not in FEN patients. It has been shown previously that DES anesthesia is associated with a rapid emergence and faster response to verbal command and orientation.6
In conclusion, DES provides a significantly shorter wake-up time and a rapid emergence from anesthesia. BIS monitoring during the wake-up test was more informative when anesthesia was maintained with DES compared to FEN infusion.
|
Footnotes |
|---|
|
References |
|---|
|
TOPAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
2 Sudhir KG, Smith RM, Hall JE, Hansen DD. Intraoperative awakening for early recognition of possible neurologic sequelae during Harrington-rod spinal fusion. Anesth Analg 1976; 55: 526–8.
3 Patel SS, Goa KL. Desflurane. A review of its pharmacodynamic and phamacokinetic properties and its efficacy in general anaesthesia. Drugs 1995; 50: 742–67.[Medline]
4 Dexter F, Tinker JH. Comparisons between desflurane and isoflurane or propofol on time to following commands and time to discharge. Anesthesiology 1995; 83: 77–82.[Medline]
5 Lee C, Kwan WF, Tsai SK, Chen BJ, Cheng M. A clinical assessment of desflurane anaesthesia and comparison with isoflurane. Can J Anaesth 1993; 40: 487–94.
6 Tsai SK, Lee C, Kwan WF, Chen BJ. Recovery of cognitive functions after anaesthesia with desflurane or isoflurane and nitrous oxide. Br J Anaesth 1992; 69: 255–8.
7 McCann ME, Brustowicz RM, Bacsik J, Sullivan L, Auble SG, Laussen PC. The bispectral index and explicit recall during the intraoperative wake-up test for scoliosis surgery. Anesth Analg 2002; 94: 1474–8.
8 Schneider G, Sebel PS. Monitoring depth of anaesthesia. Eur J Anaesthesiol 1997; 14(Suppl. 15): 21–8.
9 Drummond JC. Monitoring depth of anesthesia. With emphasis on the application of the bispectral index and the middle latency auditory evoked response to the prevention of recall. Anesthesiology 2000; 93: 876–82.[Medline]
10 Gajraj RJ, Doi M, Mantzaridis H, Kenny GN. Analysis of the EEG bispectrum, auditory evoked potentials and the EEG power spectrum during repeated transitions from consciousness to unconsciousness. Br J Anaesth 1998; 80: 46–52.
11 Iselin-Chaves IA, Flaishon R, Sebel PS, et al. The effect of the interaction of propofol and alfentanil on recall, lossof consciousness, and the bispectral index. Anesth Analg 1998; 87: 949–55.
12 Sebel PS, Lang E, Rampil IJ, et al. A multicenter study of bispectral electroencephalogram analysis for monitoring anesthetic effect. Anesth Analg 1997; 84: 891–9.[Abstract]
13 Mi WD, Sakai T, Takahashi S, Matsuki A. Haemodynamic and electroencephalograph responses to intubation during induction with propofol or propofol/fentanyl. Can J Anaesth 1998; 45: 19–22.
14 Iselin-Chaves IA, Flaishon R, Sebel PS, et al. The effect of the interaction of propofol and alfentanil on recall, loss of consciousness, and the bispectral index. Anesth Analg 1998; 87: 949–55.
15 Lysakowski C, Dumont L, Pellegrini M, Clergue F, Tassonyi E. Effects of fentanyl, alfentanil, remifentanil and sufentanil on loss of consciousness and bispectral index during propofol induction of anaesthesia. Br J Anaesth 2001; 86: 523–7.
16 Mychaskiw G 2nd, Horowitz M, Sachdev V, Heath BJ. Explicit intraoperative recall at a bispectral index of 47. Anesth Analg 2001; 92: 808–9.
17 Barr G, Anderson RE, Samuelsson S, Owall A, Jakobsson JG. Fentanyl and midazolam anaesthesia for coronary bypass surgery: a clinical study of bispectral electroencephalogram analysis, drug concentrations and recall. Br J Anaesth 2000; 84: 749–52.
18 Glass PS, Bloom M, Kearse L, Rosow C, Sebel P, Manberg P. Bispectral analysis measures sedation and memory effects of propofol, midazolam, isoflurane, and alfentanil in healthy volunteers. Anesthesiology 1997; 86: 836–47.[Medline]
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
