Psychomotor recovery in very old patients after total intravenous or balanced anaesthesia for cataract surgery

J. Kubitz*, J. Epple, A. Bach, J. Motsch, E. Martin and H. Schmidt

Department of Anesthesiology, University of Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg, Germany*Corresponding author

Accepted for publication: September 25, 2000


    Abstract
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Discussion
 References
 
We compared psychomotor recovery after total intravenous anaesthesia (TIVA) with remifentanil/propofol and balanced anaesthesia (BAL) with etomidate/fentanyl/isoflurane in 40 patients, ASA I–III, aged >=80 yr undergoing elective cataract surgery. Recovery times were recorded and psychomotor recovery was assessed according to simple reaction time, critical flicker fusion frequency (CFF) and short-term memory 30 min, 2 h and 1 day after surgery. Physical characteristics of patients in the two groups (19 in the TIVA group and 21 in the BAL group) were comparable. The TIVA group recovered significantly more quickly. Both groups showed a poorer psychomotor performance 30 min after surgery than at baseline assessment, but simple reaction time and short-term memory were close to baseline values 2 h after surgery. Only performance in the CFF test remained below baseline at this point. No deficits in psychomotor performance were noted on the first day after surgery. We conclude that there is only a minor deficit in psychomotor function in elderly patients 2 h after cataract surgery under general anaesthesia and that psychomotor function recovers completely by 24 h after surgery.

Br J Anaesth 2001; 86: 203–8

Keywords: anaesthesia, geriatric; age factors; anaesthesia, day-case


    Introduction
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Discussion
 References
 
Life expectancy has increased considerably over the last few decades and, accordingly, so has the proportion of elderly patients requiring surgery and anaesthesia. Simultaneously, an increasing number of surgical procedures is performed on an outpatient basis. In order to avoid delays in the postanaesthesia care unit (PACU) and in the time to discharge after outpatient anaesthesia, fast and predictable recovery of cognitive function is of major importance. It is particularly a matter of concern in aged patients, as the morphological and physiological changes in the brain related to ageing have to be taken into consideration. It is known that in elderly patients the required dose of certain anaesthetics is lower.1 2 However, little is known about how recovery of cognitive function is affected by anaesthesia in elderly patients.

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


    Subjects and methods
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Discussion
 References
 
Anaesthesia
Following institutional review board approval, 40 patients aged >=80 yr, ASA physical status I–III, undergoing elective cataract surgery under general anaesthesia were included in this single-blind study. All patients gave written informed consent. Prospective patients with a history of an allergic reaction to one of the drugs used in this study were ineligible for participation. A computer-generated randomization schedule was used to assign patients randomly to receive either TIVA with remifentanil and propofol or BAL with fentanyl and isoflurane.

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 monitoring—comprising pulse oximetry, automated arterial pressure cuff measurements and electrocardiogram—was 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 kg–1 and remifentanil 1 µg kg–1 over a 3 min period. In the BAL group, subjects received etomidate 0.1–0.3 mg kg–1 and fentanyl 1.5 µg kg–1 for induction of anaesthesia. Approximately 3 min after starting anaesthesia, mivacurium 0.15 mg kg–1 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 min–1. Anaesthesia was maintained by a continuous infusion of propofol 0.05–0.1 mg kg–1 min–1 and remifentanil 0.15–0.3 µg kg–1 min–1 in the TIVA group and with isoflurane 0.8–2.5 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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Table 1 Words used in the short-term memory test (translated from German)
 
In addition to these tests, a visual analogue scale (VAS) was used to evaluate the intensity of sedation. According to this scale, a score of 0 represented no sedation/totally awake and a score of 100 represented the deepest sedation imaginable. At each time point, patients were asked to move the pointer on the VAS to the place where they considered their sedation to be most accurately represented. The numerical equivalent was noted by the observer. Patients feeling too drowsy to perform this test were not given a value.

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 {chi}2 test and Student’s 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 Student’s paired t-test for comparison between preoperative and postoperative values. Fisher’s 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.


    Results
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Discussion
 References
 
Forty ASA class II–III patients were enrolled in this study. The two study groups were similar with respect to physical characteristics and duration of surgery (Table 2). However, immediate recovery, as assessed by times to awakening and to meeting the Aldrete recovery criteria4 (score >=9), differed between the two groups, with significantly shorter times being observed in the TIVA group (Table 2). One subject in the TIVA group had a myocardial infarction on the day after surgery and was excluded from the analysis at this time point. The patient was transferred to the cardiac intensive care unit, where coronary arteriography showed three-vessel disease.


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Table 2 Physical characteristics and recovery times (mean (SD)). ns, not statistically significantly different
 
In the TIVA group, atropine was administered for treatment of bradycardia in 18 of the 19 patients, whereas only 12 of the 21 patients in the BAL group received atropine. The mean dose of atropine differed significantly (P=0.003) between the two groups (0.55 mg in the TIVA group and 0.25 mg in the BAL group).

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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Table 3 Test compliance (number of patients who participated in psychomotor testing at the given time points); *significant difference between the TIVA and BAL groups (P<0.01)
 
The results of the VAS are presented in Figure 1. In the TIVA group, 18 of 19 patients completed the VAS 30 min after the end of surgery, whereas only 14 of 21 in the BAL group did so. Patients in the TIVA group had significantly lower sedation scores than patients in the BAL group at this time point. In both groups, patients felt significantly more tired at the time points 30 min and 120 min postoperatively compared to the preoperative value, but on the first postoperative day sedation scores did not differ from baseline values.



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Fig 1 Visual analogue sedation scores (mean ± SD). *P<0.01; TIVA versus BAL.

 
The results of the simple reaction time tests, the CFF and short-term memory test are shown in Table 4. Thirty minutes after the end of anaesthesia, both visual and auditory reaction times were significantly longer than baseline in both groups, but there were no differences from baseline 2 h and 1 day after the end of anaesthesia. A significant between-group difference was observed in the mean change in auditory reaction time 30 min after surgery (P=0.04). At this time point, auditory reaction time was significantly shorter in the TIVA group. However, there were no between-group differences in mean change in reaction time at any of the other time points.


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Table 4 Results of psychomotor tests. For each test, data are expressed as mean changes (SD); n=number of patients. *Significantly different from pre-operative value (P<0.05); #significantly different from pre-operative value (P<0.01)
 
The results of the CFF showed a minor psychomotor impairment in both groups for 2 h following surgery. In both groups, the CFF remained significantly lower than baseline 30 min and 120 min after the end of anaesthesia, but did not differ significantly from baseline on the first postoperative day. At no time point were differences between the groups in mean changes of CFF noted.

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.


    Discussion
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Discussion
 References
 
In this study we investigated psychomotor recovery in the early post-operative period in very elderly patients undergoing cataract surgery under general anaesthesia. Cataract surgery, a minimally invasive procedure, serves as a model to focus on the effects of general anaesthesia on recovery of psychomotor function in that other factors that might have an effect after major surgery, such as blood loss, hypercapnia, hypoxaemia and postoperative pain, are eliminated or reduced to a minimum. Carbon dioxide partial pressure and oxygen saturation were not noted, but with the ventilation pattern used in this study we assumed that they remained within the physiological range and did not differ among the study groups. The decision as to whether surgery was performed under local or general anaesthesia in a patient eligible for randomization depended on the patient’s and surgeon’s preferences.

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 etomidate–vecuronium–isoflurane 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 propofol–alfentanil 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.


    Acknowledgements
 
This study was supported by a grant from Glaxo Wellcome GmbH & Co., Hamburg, Germany.


    References
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Discussion
 References
 
1 Christensen JH, Andreasen F, Jansen JA. Thiopentone sensitivity in young and elderly women. Br J Anaesth 1983; 55: 33–9[Abstract]

2 Jakobs JR, Revers JG, Marry J, White WD, Bai SA, Smith LR. Aging increases pharmacodynamic sensitivity to the hypnotic effects of midazolam. Anesth Analg 1995; 80: 143–8[Abstract]

3 Epple J, Kubitz J, Schmidt H, Motsch J, Böttiger BW, Martin E, Bach A. Comparative analysis of costs of total intravenous anaesthesia with propofol and remifentanil versus balanced anaesthesia with isoflurane and fentanyl. Eur J Anaesth, in press

4 Aldrete JA, Kroulik D. A postanesthetic recovery score. Anesth Analg 1970; 49: 924–33[Medline]

5 Hindmarch I. Psychomotor function and psychoactive drugs. Br J Clin Pharmacol 1980; 10: 189–209[ISI][Medline]

6 Cashman JN, Power SJ. An evaluation of tests of psychomotor function in assessing recovery following a brief anesthetic. Acta Anaesthesiol Scand 1980; 33: 693–7

7 Rowbotham DJ, Peacock JE, Jones RM, et al. Comparison of remifentanil in combination with isoflurane or propofol for short stay surgical procedures. Br J Anaesth 1998; 80: 752–5[Abstract/Free Full Text]

8 Suttner S, Boldt J, Schmidt C, Piper S, Kumle B. Cost analysis of target-controlled infusion-based anesthesia compared with standard anesthesia regimens. Anesth Analg 1998; 88: 77–82[Abstract/Free Full Text]

9 Hogue CW Jr, Bowdle TA, O’Leary C et al. A multicenter evaluation of total intravenous anesthesia with remifentanil and propofol for elective inpatient surgery. Anesth Analg 1996; 83: 279–85[Abstract]

10 Philip BK, Kallar SK, Bogetz MS, Scheller MS, Wetchler BV. Multicenter comparison of maintenance and recovery with sevoflurane or isoflurane for adult ambulatory anesthesia. Anesth Analg 1996; 83: 314–9[Abstract]

11 Simpson KH, Smith RJ, Davies LF. Comparison of the effects of atropine and glycopyrrolate on cognitive function following general anaesthesia. Br J Anaesth 1987; 59: 966–9[Abstract]

12 Green G, Jonsson L. Nausea: the most important factor determining length of stay after ambulatory anesthesia. A comparative study of isoflurane and/or propofol techniques. Acta Anaesthesiol Scand 1993; 37: 742–6[ISI][Medline]

13 Moffat A, Cullen PM. Comparison of two standard techniques of general anaesthesia for day-case cataract surgery. Br J Anaesth 1995; 74: 145–8[Abstract/Free Full Text]

14 Dijkstra JB, Houx PJ, Jolles J. Cognition after major surgery in the elderly: test performance and complaints. Br J Anaesth 1999; 82: 867–74[Abstract/Free Full Text]

15 O’Keffe ST, Chonchubhair AN. Postoperative delirium in the elderly. Br J Anaesth 1994; 73: 673–87[ISI][Medline]

16 Keita H, Gilles P, Giraud O et al. Aging prolongs recovery of psychomotor functions at emergence from propofol-alfentanil anaesthesia. Can J Anaesth 1998; 45: 1211–14[Abstract]

17 Moller JT, Cluitmans P, Rasmussen LS et al. Long-term postoperative cognitive dysfunction in the elderly ISPOCD1 study. ISPOCD1 investigators. International Study of Post-Operative Cognitive Dysfunction. Lancet 1998; 351: 857–61[ISI][Medline]

18 Williams-Russo P, Urquhart BL, Sharrock NE, Charlson ME. Cognitive effects after epidural vs. general anesthesia in older adults. A randomized trial. J Am Med Assoc 1995; 274: 44–50[Abstract]





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