Department of Anesthesiology, University of Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg, Germany*Corresponding author
Accepted for publication: September 25, 2000
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Abstract |
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Br J Anaesth 2001; 86: 2038
Keywords: anaesthesia, geriatric; age factors; anaesthesia, day-case
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Introduction |
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We investigated the effect of total intravenous anaesthesia (TIVA) with remifentanil and propofol and BAL with fentanyl and isoflurane on psychomotor recovery in patients aged 80 yr. Here we present a subgroup analysis of a clinical trial with pharmacoeconomic endpoints in which 124 patients (aged
65 yr) were enrolled. The results of this study have been accepted for publication elsewhere.3
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Subjects and methods |
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In order to avoid any effects of premedication on the postoperative psychomotor test results, none of the patients received sedative drugs as premedication. A peripheral intravenous cannula was placed for drug and fluid administration and standard monitoringcomprising pulse oximetry, automated arterial pressure cuff measurements and electrocardiogramwas applied. Subjects were monitored for systolic and diastolic arterial pressure, heart rate and haemoglobin oxygen saturation throughout surgery and the recovery period. Before induction of anaesthesia, all patients were preoxygenated for 2 min. In the TIVA group, anaesthesia was induced with propofol 1.5 mg kg1 and remifentanil 1 µg kg1 over a 3 min period. In the BAL group, subjects received etomidate 0.10.3 mg kg1 and fentanyl 1.5 µg kg1 for induction of anaesthesia. Approximately 3 min after starting anaesthesia, mivacurium 0.15 mg kg1 was administered in both groups to achieve muscle relaxation. After tracheal intubation, all patients were ventilated mechanically to normocapnia with oxygen-enriched air (FIO2=0.4) and a constant fresh gas flow of 3 litres min1. Anaesthesia was maintained by a continuous infusion of propofol 0.050.1 mg kg1 min1 and remifentanil 0.150.3 µg kg1 min1 in the TIVA group and with isoflurane 0.82.5 MAC and a bolus of fentanyl 0.1 mg at the beginning of surgery in the BAL group. Infusion rates and MAC were adjusted, if necessary, to achieve an adequate depth of anaesthesia and to provide haemodynamic stability. Hypotension and bradycardia were treated with sympathomimetic and anticholinergic drugs, respectively, following institutional guidelines.
At the end of surgery, anaesthesia was stopped and the patients lungs were ventilated manually with 100% oxygen. After adequate respiration had been resumed and the patients were able to open their eyes on command, the trachea was extubated and patients were transferred to the PACU, where monitoring of vital signs was continued.
The duration of surgery and anaesthesia was recorded. Recovery was assessed by recording the time to respond to verbal commands (open eyes) and extubation. The Aldrete score4 was recorded upon arrival in the PACU and every 15 min thereafter until the patients achieved a score of 9. The score includes five tasks that assess muscle activity, respiratory efficiency, changes in systolic arterial pressure from the preanaesthetic level, consciousness and skin colour. The maximum score is 10.
Recovery testing
Psychomotor and cognitive function tests used during the study included: simple visual reaction time, simple auditory reaction time, critical flicker fusion frequency (CFF) and short-term memory. These tests have been used in a similar way in previous studies and are considered suitable for detecting even minor impairment of psychomotor function.5 6 They are easy to use and are not time consuming, which is an important factor in psychomotor testing in the early postoperative period.
Simple reaction time
To evaluate the simple visual reaction time, the patient was instructed to press a button when a red light of about 3 cm diameter, placed approximately 80 cm from the eyes, was illuminated. In the test of simple auditory reaction time, the red light was replaced by an auditory stimulus, which could easily be heard by the patient, as verified before the start of the test. Each test was performed three times per session; mean results (expressed in seconds) were recorded.
CFF
In this test, the patient was shown a flickering red light, which was of the same diameter and placed at the same distance as the one used for the simple visual reaction time. Its flicker frequency was slowly increased and the patient was instructed to report as soon as the light appeared to be continuous. The test was performed three times per session; the mean results, expressed in hertz, were recorded.
Short-term memory test
In the short-term memory test, patients were asked to memorize five words, which were read to them twice and which they had to repeat once in order to exclude communication problems. After 2 min, in which patients had to fill in a concentration test in order to distract them from constantly repeating the given words, they were asked to recall those five words and the number of correctly recalled words was recorded. Different words were used in each session (Table 1).
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On the evening before anaesthesia, the patients were familiarized with this series of tests and the VAS and baseline values were obtained. The tests and the VAS were repeated 30 min, 120 min and 1 day after the end of surgery, and were always carried out by the same observer.
In addition to the assessment of each psychomotor test, we wanted to evaluate test compliance, defined as the ability and willingness to perform the complete series of tests at the given time points. Patients were always asked to perform the tests but the decision to do so was ultimately their own.
Statistical analysis
Patient characteristics were compared using the 2 test and Students t-test. Recovery times, atropine requirements, VAS results and between-group differences in the psychomotor recovery tests were analysed with two-way analysis of variance (ANOVA). Psychomotor recovery test results were further analysed with Students paired t-test for comparison between preoperative and postoperative values. Fishers exact probability test was used for comparison of test compliance. For all statistical tests, a two-sided P-value of <0.05 was considered statistically significant.
Statistical analysis was performed using SPSS version 6.0.1. Data are expressed as mean (SD) unless stated otherwise. For simple reaction time and CFF tests, postoperative results are presented as mean changes (SD), i.e. the difference between the mean baseline value and the mean postoperative value at the given time point.
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Results |
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There was a significant difference between groups with respect to the ability to complete the testing session 30 min after surgery. Eighteen of the 19 patients in the TIVA group completed the whole series of tests at that time, whereas only 11 of 21 patients in the BAL group did so. However, 120 min after surgery and on the day after surgery, test compliance between the groups was comparable (Table 3). Common reasons for omitting psychomotor testing were feeling sleepy or drowsy, nausea, vomiting or simply not being in the mood to do the test series for unknown reasons. The latter was the main reason why more patients in the TIVA group did not perform the psychomotor tests 120 min and 1 day after surgery, although they were considered capable of doing so by the observer.
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In both groups, performance in the short-term memory test was slightly, but not significantly, decreased 30 min and 2 h after the end of anaesthesia as compared with baseline. On the first day after surgery, the mean number of correctly recalled words was identical to baseline values for both groups.
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Discussion |
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Recovery from anaesthesia in aged patients was quicker after TIVA with remifentanil and propofol than after BAL with fentanyl and isoflurane, which is related to the different pharmacokinetic characteristics of the two opioids. In this study, the time to extubation after remifentanil/propofol anaesthesia was similar to that in younger adults observed in previous studies.79 Suttner and colleagues8 and Hogue and colleagues9 reported a time to extubation of 6 min and 7 min, respectively, in adult patients. However, Hogue and colleagues9 reported a time to first Aldrete score 9 of 20 min and 23 min depending on the remifentanil dose in adults
18 yr undergoing inpatient surgery. The shorter time taken to reach an Aldrete score of
9 in this study might be explained by the smaller requirements for anaesthetic drugs during cataract surgery. Recovery after fentanyl/isoflurane anaesthesia in the elderly subjects studied was prolonged and time to extubation and to eye opening was approximately 7 min longer than in non-geriatric adults who were extubated and able to open their eyes 7 and 9 min, respectively, after the end of anaesthesia (compared with 14 and 16 min in the present study).10 Suttner and colleagues,8 however, reported in ordinary adults a time to extubation similar to the one in this report.
With respect to the early post-operative period, we found that psychomotor recovery in very old patients was significantly impaired after both anaesthetic techniques 30 min after the end of anaesthesia, but 2 h post-operatively psychomotor function was close to the baseline value. Only sedation scores and performance in the CFF test differed significantly from baseline 120 min post-operatively, but the simple reaction times and short-term memory test were the same as preoperative values. The fact that a greater proportion of patients in the TIVA group felt able to complete the VAS 30 min after the end of surgery suggests that the difference in sedation between the groups was even greater than found in this study. The CFF has been considered to be one of the most sensitive tests for detecting psychomotor dysfunction caused by psychoactive drugs;5 our results suggest that a very slight impairment of psychomotor function remains 2 h postoperatively. No psychomotor deficit was found on the day after surgery.
There were fewer between-group differences than expected considering the very different pharmacokinetic characteristics of the two opioids used in this study. The more frequent administration and higher dose of atropine (which has been suspected of causing cognitive deficits11) in the TIVA group may be partly responsible. The lower test compliance observed in the BAL group seems to be related both to the comparatively high incidence of postoperative nausea and vomiting in this group, as described by Green and Jonsson,12 and the prolonged sedative effects of fentanyl. Considering the test compliance and simple auditory reaction time results 30 min after the end of surgery, TIVA with remifentanil and propofol seems to have advantages over BAL with fentanyl and isoflurane in relation to recovery of postoperative psychomotor function.
Data on psychomotor recovery in aged patients in the early postoperative period after general anaesthesia are comparatively scarce. This is one of the first studies to investigate it and therefore the comparability of the psychomotor test results presented here with those of previous studies is limited. Our findings are similar to those of Moffat and Cullen,13 who reported that cognitive mental function in patients aged >60 yr is close to preoperative values 2 h after general anaesthesia with propofol or etomidatevecuroniumisoflurane for day-case cataract surgery. However, early or short-term postoperative cognitive function was found to be impaired after major surgery in elderly patients.14 15 In a study by Keita and colleagues,16 cognitive function in elderly patients undergoing elective orthopaedic surgery under propofolalfentanil anaesthesia did not return to preoperative values within the first 2 h after surgery whereas younger patients showed the same test performance as they did before surgery at that time. In a multicentre study in which 1218 patients scheduled for major non-cardiac surgery were enrolled, Moller and colleagues17 demonstrated postoperative cognitive dysfunction in 25.8% of patients 1 week after surgery and in 9.9% of patients 3 months after surgery. Williams-Russo and colleagues18 found no differences in neuropsychological test performance between general and regional anaesthesia 1 week and 6 months after orthopaedic surgery, but that 5% of patients had impaired cognitive function 6 months after surgery. It is likely, therefore, that the reason why patients in the present study did not show impaired postoperative psychomotor function 1 day after surgery is related to the minimally invasive character and short duration of cataract surgery, which has been found to be related to early postoperative cognitive dysfunction.17
Within the confines of the psychomotor test battery used in this study, we conclude that there is only a minor postoperative deficit in psychomotor function in elderly patients 2 h after the end of general anaesthesia with remifentanil and propofol or fentanyl and isoflurane given for cataract surgery, and that there is no psychomotor dysfunction 1 day after the end of anaesthesia. Our results suggest that psychomotor function recovers more quickly after TIVA with remifentanil and propofol than after BAL with fentanyl and isoflurane.
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Acknowledgements |
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References |
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