Medical Conditions and Driving: A Review of the Literature (1960 – 2000)

Section 15: The Effects of Anesthesia and Surgery

15.1 General Anesthesia

15.2 Outpatient surgery

15.3 Major Surgery

A summary of the current fitness-to-drive guidelines (Anesthesia and Surgery) for medical practitioners from Australia (1998) and Canada (2000) is presented in Table 39.

15.1 General Anesthesia

General anesthesia involves depression of the central nervous system. In the late 1950s and early 1960s, it was believed that the drugs used to produce anesthesia continued to exert effects on cognitive function for a period of time following anesthesia (Bedford, 1955). Since then, a number of researchers have investigated the effects of anesthesia on cognition by comparing cognitive performance in patients having either general or regional anesthesia (See Table 37). There is, however, considerable variability among the studies in age of sample, type of surgical procedures (cataract, total hip/knee replacement), the tests used to assess cognitive functioning, type of pre-medication and sedation used, and time of assessment. In general, however, the results have failed to find differences in cognitive functioning in the post-operative period between patients receiving either a general or regional anesthetic.

Despite the lack of significant differences in cognitive performance in patients receiving either a general or regional anesthetic, there is considerable evidence that declines in cognitive functioning occur in the post-operative period. A number of factors have been proposed to account for the changes in cognition following surgery. Factors include physiological effects of the anesthetic such as hyperventilation, hypotension, and/or hypoxia, and changes in the role of catecholamines or cholinergic transmission within the central nervous system (See Dodds and Allison, 1998 for a complete review). Regardless of the causal agent, there is considerable evidence that declines in cognitive functioning occur following surgery (See Table 38 for a summary of the findings).

Research suggests that the elderly population is particularly at risk. Ritchie, Polge, deRoquefeuil, Djakovic, and Ledesert (1997) recently reviewed the literature in order to describe post-operative cognitive impairment in elderly individuals. Results of the review indicate that significant cognitive impairment was a common finding in elderly persons 1 to 3 days post-surgery.

Table 37 Summary of Studies Examining Differences in Cognitive Impairment between Patients Receiving Either a General or Regional Anesthetic

Study	n	Surgery	Age (Range/Mean)	Results
Hole et al. (1980)	60	Total Knee Replacement.	56-84 years Mean = 71	↓ Mental function in 7/31 general anesthetic group. No change in epidural group.
Riis et al. (1983)	30	Total Hip Replacement.	> 60 years	↓ Learning and retention scores day 2 post-operatively, normal on day 7 post-op for both general and regional anaesthetic groups.
Jones et al. (1990)	146	Total Hip Replacement. Total Knee Replacement.	> 60 years	No change on tests of choice reaction time and critical flicker fusion threshold between individuals receiving general or regional anaesthesia.
Campbell et al. (1993)	169	Cataracts.	65-98 years	↓ at 24 hrs in verbal recall, verbal learning, psychomotor speed, and tactile naming in both general and regional anaesthesia groups. General anaesthesia group decrease was greater but results not significant. Recovery in both groups by 2 weeks post-operatively.
Williams-Russo et al. (1995)	262	Total Knee Replacement.	> 40 years Mean = 69	Generalized decline at 1 week followed by a return to baseline or improvement by 6 months in both general and regional anaesthesia groups.

Table 38 Summary of Studies of Effects of General Anesthesia on Cognitive Functioning Post-Operatively

(from Dodds, C., & Allison, J. (1998). Postoperative cognitive deficit in the elderly surgical patient, British Journal of Anaesthesiology, 81, 449-462, ©The Board of Management and Trustees of the British Journal of Anaesthesia. Reproduced by permission of Oxford University Press/British Journal of Anaesthesiology)

Study	n	Surgery	Age (Range /Mean)	Results
Hole et al. (1980)	60	Total Knee Replacement.	56-84 years. Mean = 71.	↓ mental function in 7/31 General Anaesthesia group. No change in epidural group.
Kaarhunen et al. (1982)	60F	Cataract Surgery.	> 65 years.	↓ in Wechsler Memory Scale and Luria tests at 1 week post-op.
Riis et al. (1983)	30	Total Hip Replacement.	> 60 years.	↓ in learning and retention scores day 2 post-op,normal on day 7 post-op for both general and regional anaesthetic groups.
Bigler et al. (1985)	40	Acute Hip Replacement.	> 60 years. Mean = 78.9.	Abbreviated Mental Test at one week.
Smith et al. (1986)	85	Orthopedic. Gynecological. General.	Young (50). Old (69).	↓ memory (all ages). ↓ orientation & concentration in older patients.
Chung et al. (1987)	44	Transurethral Prostatectomy.	60-93 years. Mean = 72 years.	↓ at 6 hours on recall, attention, calculation (MMSE). No differences at day 5 post-op.
Ghoneim et al. (1988)	105	Hysterectomy. Prostate. Joint.	25-86 years.	↓ Paired Associate Learning post-operatively. Marked improvement at 3 months post-op.
Hughes et al. (1988)	30	Total Hip Replacement.	50-80 years.	No change in recall. ↓ repeat recall and repeat recognition.
Ashborn et al. (1989)	40	Transurethral Prostatectomy.	60-80 years. Mean = 68.8 years.	No change in verbal memory. ↓ Paired Associate Learning day 4 ↓ visual memory and delayed visual recall.
Chung et al. (1990)	40	Cholecystectomy.	25-83 years. < 60 (39.7 percent). > 60 (67 percent).	↓ Digit Symbol Test day 1 (all patients). ↓ Trail Making Test Day 1 (Older patients).

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