During the awake craniotomy, 60% of the patients experienced no complications, and they did not voice any complaints (fentanyl, 15; remifentanil, 15). The total incidence of intraoperative complications/complaints was not different between groups, 14 in the fentanyl and 16 in the remifentanil group (Table 3). More than one complication occurred in three patients in the fentanyl and five patients in the remifentanil group. Respiratory complications occurred in total of 9 (18%) patients. In the fentanyl group, five patients developed decreased respiratory rate and mild airway obstruction during or just after the insertion of headpins. One patient also had a short period of oxygen desaturation (<90%). The propofol infusion was decreased in all patients and three needed a short period of manual jaw thrust. One patient (fentanyl group) during a long tumor resection was restless and with deepening of sedation developed recurrent airway obstruction (snoring) and required the insertion of a nasal airway. In the remifentanil group, three patients developed decreases in respiratory rate, decrease in oxygen saturation (<90%), and short periods of airway obstruction during adjustments in the infusion rate for remifentanil. Remifentanil infusion rates were decreased, but two patients needed a brief period of jaw thrust and the third also needed a short application of oxygen and ventilation by mask.
Nonrespiratory complications/complaints occurred in 4 patients (16%) in the fentanyl group and 7 (28%) in the remifentanil group (Table 3). Changes in cardiovascular variables that required treatment occurred in three patients. One patient in the fentanyl group who had a long procedure and was very restless also had increases in arterial blood pressure requiring the administration of labetalol and metoprolol. In the remifentanil group, one patient became hypotensive with the sudden loss of 400 mL of blood. This was treated with administration of IV fluids. The other patient in the remifentanil group developed a sudden onset of hypotension, which was immediately followed by a seizure. Treatment of the seizure with propofol corrected the hypotension. Preoperative seizures had occurred in 9 (36%) patients in the fentanyl group and in 10 (40%) in the remifentanil group. Intraoperative seizures occurred during mapping and tumor resection in four patients, all in the remifentanil group. Three of these patients had a history of preoperative seizures
On arrival in the PACU the patients' median Glasgow Coma Score for the fentanyl group was 15 (range, 14–15) and for remifentanil 15 (range, 14–15). There were no differences in sedation and pain scores or in the hemodynamic or respiratory variables in the PACU (Table 2). During the first postoperative hour pain in the fentanyl group was treated with codeine (mean ± sd) 62 ± 7 mg (n = 18 patients), fentanyl 52 ± 18 μg (n = 11), and morphine 6 mg (n = 1). In the remifentanil Group 16 patients received codeine 60 ± 0 mg and 9 patients received fentanyl 52 ± 43 μg.
Postoperative complications did not differ between the two groups (Table 3). New neurological deficits were present in five patients; in the fentanyl group two patients developed a visual field defect, one patient had transient aphasia, and in the remifentanil group one patient developed a persistent mild hemiplegia that started in the operating room and another patient had transient episodes of arm weakness that were related to seizure activity.
Patient recall of the procedure and of intraoperative pain and anxiety and satisfaction results are shown in Figure 1. There were no differences between the two groups. Most patients gave the same responses to the questions at the three different interview times. Only 1 patient changed his satisfaction score from an initial 1-h score of complete satisfaction to partial at 4 h and 24 h. Two patients recalled having severe intraoperative pain, but their highest intraoperative pain scores were 2 and 4 and neither had voiced any complaints of pain. The duration of stay in hospital did not influence the satisfaction scores. Eleven (22%) patients (fentanyl, n = 6; remifentanil, n = 5) were discharged home on the day of surgery. The mean (± sd) cost of the total amount of propofol, fentanyl, and remifentanil administered to the patients in each groups was not different (fentanyl group $11.29 ± $12.92 [US] and remifentanil $9.25 ± $4.28 [US]).
In our study, we found that the use of both conscious sedation techniques, remifentanil plus propofol infusions and intermittent fentanyl with propofol infusion, were similar with respect to intraoperative management and in the incidence of intraoperative and postoperative complications. Overall, 93% of the patients were completely satisfied with their anesthetic management.
There is considerable variation in the anesthetic techniques of the “awake craniotomy” (4–13). They range from the “asleep-awake-asleep” techniques, with or without the use of an airway, to those of monitored anesthesia care or conscious sedation. Most institutions have developed their own methods for providing anesthesia for these procedures depending on the needs of their surgeons and their patient population. During the procedure frequent changes in the depth of sedation/anesthesia are needed to prevent complications such as excessive pain or respiratory depression. An alert and cooperative patient is essential for adequate functional testing. Propofol has been frequently used and more recently remifentanil has also been used (4,6,8,14). Johnson and Egan (4) published a case report of propofol and remifentanil infusion using computer simulation. The advantage of remifentanil was a rapid reversal of narcosis when intraoperative consciousness was required. Another case report by Hans et al. (6) described the use of a target-controlled administration of propofol and remifentanil, which allowed them to adjust drug administration according to painful stimulation and functional testing. Berkenstadt et al. (8) reported on the use of remifentanil with propofol in 25 patients. Although their patients had stable hemodynamic profiles, there was a more frequent incidence of respiratory depression in the first 10 patients. The incidence of respiratory complications improved over the course of the study probably the result of more careful adjustment of the drugs.
In our study we also found that the combination of remifentanil and propofol was effective in maintaining the appropriate level of sedation and control of pain as well as hemodynamic stability. The results for remifentanil did not differ from the use of fentanyl and propofol. The failure to find a difference between the two groups in our study may have been attributable to the small sample size studied. Our sample size was calculated on the basis of our hypothesis of a 10% reduction for intraoperative pain with remifentanil using α of 0.05 and power of 0.8. To show no difference that is significant with adequate power, 600 patients would be required for each group. In our study we also did not vigorously regulate the doses of the anesthetics given to each patient. It was left up to the anesthesiologist as to which drug was administered for pain and anxiety. The mean dose of propofol used in the fentanyl group was larger than that used in the remifentanil group in our study, but this result was skewed by one patient who required an excessively large dose for restlessness. The overall cost of anesthetics used in each group was not different; however, we did not calculate the cost of the portion of drug from each vial that was wasted.
There is reluctance to perform awake craniotomy procedures for fear of complications. There is limited information in the literature with respect to the incidence of complications during an awake craniotomy for tumor surgery. Respiratory complications are feared the most, especially when there is an unprotected airway. Sarang and Dinsmore (11) reported an incidence of 7% airway obstruction in a group of 46 patients with sedation and a nasopharyngeal airway. The airway obstruction was treated with jaw thrust or manual support. In our study, airway complications occurred in 18% (9 patients). All these events were easily treated and there was no difference between the two groups. Respiratory complications can be anticipated during an awake craniotomy when the airway is not secured. It is difficult to always predict the correct dose of a drug in an awake and anxious patient. These periods of respiratory depression are usually very brief, because of the short-acting drugs used, and are easily treatable by decreasing the drug administration and/or by a short chin lift or jaw thrust. However, whatever technique of awake craniotomy is used, it is essential for the anesthesiologist to have a plan of action and the necessary equipment to deal with all airway complications.
The incidence of nonrespiratory complications/complaints was frequent (22%), but we were looking for all complications including voiced complaints, as we were also interested in the satisfaction experience of our patients. Most of these complications were short in duration and easily treated, such as two patients who complained of being cold and were given warming blankets. New onset of seizures is a common presentation for a patient with a brain tumor and thus seizures may occur at any time. Seizures that occur while rigid head fixation is used can be frightening. Most intraoperative seizures occur during mapping or tumor resection and are of short duration. They can be quickly treated with small doses of propofol. In our study, all the patients with intraoperative seizures were in the remifentanil group; however, because the numbers are small it is not possible to determine whether the presence of remifentanil played a role. There were no incidences of intraoperative nausea or vomiting. The restless or disinhibited patient is of great concern and treatment may lead to further complications, such as airway obstruction with increased sedation. In our study one patient required insertion of a nasal airway, but the induction of general anesthesia was not required in any patient. In a previous report from our institution in 241 patients there was only one conversion to general anesthesia after a generalized seizure (16). In a series of 150 patients, Nikas et al. (3) reported that the majority of patients did not have any anesthetic complications, and those that did experience complications were easily treatable. Only one patient required conversion to general anesthesia. The incidence of neurological deficits in our study was 10%, but it was not our intent to evaluate the role of the awake craniotomy in preventing neurological injury.
We also assessed the overall satisfaction of the patients' experience and their recall during both of these anesthetic techniques. We found that most patients were completely satisfied with their experience at all times of questioning. There was no difference between the two groups. Patients who stated that they had complete recall for intraoperative events were completely satisfied with their experience. The incidence of severe pain during the procedure and the recall of pain postoperatively were infrequent; 56% of the patients recalled mild pain and 22% recalled no pain at all times of interviewing. A reason for the high satisfaction rate may be that our patients were preselected by their surgeons for this procedure and were also well prepared for it by the surgeon and anesthesiologist. Our findings on the subjective experience of patients were similar to those of Danks et al. (1). They interviewed their patients 2 or 3 days postoperatively and included a psychiatric assessment at 1 month. Initially, about one half of their patients did not recall intraoperative pain and were satisfied with their experience. At 1 month all patients were comfortable with the experience.
The awake craniotomy for tumor surgery has become well established, although the anesthetic management will continue to differ at each institution. Complications, especially respiratory, will occur in some patients, but treatment can be readily accomplished. Continuous vigilance is absolutely necessary. The use of remifentanil infusion in conjunction with propofol is a good alternative to fentanyl and propofol for conscious sedation for the awake craniotomy, and these techniques are both well accepted by patients.
The authors wish to thank the Toronto Western Hospital neurosurgeons for their cooperation with this study and Dr. Hossam El-Beheiry for his assistance in statistical analysis.
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© 2006 International Anesthesia Research Society
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