The effects of cyclopropane anesthesia without surgical operation on mental functions of normal man

Recovery characteristics following induction of anaesthesia with a combination of thiopentone and propofol

The purpose of this study was to determine the rate and quality of recovery when general anaesthesia was induced with a mixture of thiopentone and propofol, compared with thiopentone or propofol alone. Sixty ASA class I and II women scheduled for out-patient laparoscopic surgery underwent induction of anaesthesia with either (i) thiopentone, (ii) propofol, or (iii) a mixture of the two, in a randomized, double-blind fashion. Anaesthesia was then maintained using nitrous oxide, isoflurane and fentanyl. A psychometric test was administered before and after surgery, and the time taken to reach a series of recovery milestones was noted. Patients were discharged as soon as they were ambulant and had satisfactory control of pain and nausea with oral agents. They were telephoned at 24-48 hr later, and asked to rate their experience of a list of side effects on an ordinal scale. Patient groups were demographically comparable and underwent surgery of the same duration. Those receiving thiopentone were discharged after a mean time of 3 hr 25 +/- 58 min (SD). The corresponding figures for propofol and the thiopentone/propofol mixture were 2 hr 40 min (+/- 49) and 2 hr 48 min (+/- 68) respectively. The recovery time between thiopentone and the other two regimes was different (P < 0.05). All three groups experienced equally frequent and severe nausea, headache, tiredness and other side effects during the next 24 hr. It is concluded that induction with a mixture of thiopentone and propofol leads to a similar rate and quality of recovery to that of propofol above.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of H2-receptor antagonists and benzodiazepine sedation. A double-blind placebo-controlled investigation of the effects of cimetidine and ranitidine on recovery after intravenous midazolam

H2-receptor antagonists differentially inhibit cytochrome P450 and this may affect the rate at which benzodiazepines are metabolised. However, it is not known whether this delayed clearance results in prolonged psychomotor impairment. In a randomised double-blind trial 28 healthy volunteers received two single doses of midazolam (0.07 mg.kg-1) at an interval of one week during which they took cimetidine 400 mg, ranitidine 150 mg or placebo, each twice daily. Recovery from the benzodiazepine was monitored on each occasion over a 12 h period using a battery of psychometric tests. There was wide individual variation in performance; however, an overall measure of impairment indicated a significant difference at 2.5 h (p < 0.05), the cimetidine group having a high impairment score. This decrement appeared to be in cognitive and psychomotor functions and was not reflected in the subjective assessment.

Propofol in short gynaecological procedures. Comparison of recovery over 2 days after anaesthesia with propofol or thiopentone as sole anaesthetic agent

Recovery was assessed over 48 hours after anaesthesia with propofol or thiopentone as sole anaesthetic agent in 36 unpremedicated gynaecological patients. Immediate recovery, as measured by the Steward scale, was shown to be quicker for the patients given propofol. At one hour postoperatively the thiopentone group showed impaired visual-motor coordination on the aiming test (p less than 0.01) and dexterity task (p less than 0.05), and a slowing of reaction time (p less than 0.01). Patients given propofol showed only an increase in reaction time (p less than 0.05). By 2 hours the thiopentone group showed impairment only in the aiming task (p less than 0.05). No further significant impairment was detected at 4, 24 or 48 hours. However, patients reported symptoms throughout the 48 hours indicative of residual drug effects. There was a substantial practice effect with some tests which may have obscured impairment. It can be argued therefore that the better recovery profile after propofol is still evident at 24 hours.

Cognitive and functional competence after anaesthesia in patients aged over 60: controlled trial of general and regional anaesthesia for elective hip or knee replacement

OBJECTIVE

To determine the influence of general or regional anaesthesia on long term mental function in elderly patients.

DESIGN

Prospective study of patients randomly allocated to receive general or regional anaesthesia.

SETTING

The patients' homes and a large teaching hospital in Cardiff.

SUBJECTS

146 Patients aged 60 and over scheduled for elective hip or knee replacement.

MAIN OUTCOME MEASURES

Scores achieved in tests of cognitive function and functional competence.

RESULTS

72 Patients were allocated to receive general anaesthesia and 74 regional anaesthesia. Anaesthetic technique did not influence the duration of the operation, time to mobilisation postoperatively, requirements for analgesia after the operation, or duration of stay in hospital. Three months after the operation there was an improvement in the score for the recognition component (76 ms, 95% confidence interval 9 to 144) and the response component (82 ms, 5 to 158) of the choice reaction time in the group receiving general anaesthesia compared with the group receiving regional anaesthesia. This was the only significant difference between the two groups in the assessments of cognitive and functional competence. Eleven patients receiving regional anaesthesia and 12 receiving general anaesthesia reported that their memory and concentration were worse than before the operation, but this was not confirmed by testing.

CONCLUSION

Cognitive and functional competence in elderly patients was not detectably impaired after either general or regional anaesthesia when attention was paid to the known perioperative influences on mental function.

The effects of hypocapnic ventilation on mental function in elderly patients undergoing cataract surgery

Mental function was studied using the Rivermead Behavioural Memory Test and the Unprepared Simple Reaction Time test in 83 elderly patients for cataract surgery. Three groups of patients were studied: Group N (n = 40) whose lungs were ventilated to a mean PaCO2 of 4.9 kPa, Group H (n = 30) who were hyperventilated to a mean PaCO2 of 2.9 kPa, and Group L (n = 13) who received local anaesthesia for surgery. The psychometric tests were administered on the day before the operation, and 4 days and 4 weeks after the operation. Statistically significant changes in the performance of hyperventilated patients could not be demonstrated using these tests.

Sedation for fibreoptic bronchoscopy: comparison of alfentanil with papaveretum and diazepam

Sedation for fibreoptic bronchoscopy should produce optimal conditions for the operator, patient comfort and rapid recovery allowing early discharge home. We have compared a regimen producing 'light' sedation with a more traditional regimen producing 'deep' sedation. Seventy-six patients undergoing fibreoptic bronchoscopy under topical anaesthesia were randomized to receive either light sedation with the short acting opiate, alfentanil (median dose 1.1 mg, range 0.5-2.6 mg) or deep sedation with a combination of papaveretum (median dose 10 mg, range 5-15 mg) and diazepam (median dose 8 mg, range 0-20 mg). Both techniques gave equally good operating conditions, although patients given alfentanil coughed less than those given papaveretum and diazepam (U = 2.814 P less than 0.01). Patients recorded their degree of apprehension on a visual analogue scale prior to sedation and the actual degree of comfort experienced after recovery. There was no significant difference between apprehension or comfort between the groups. This was despite a higher degree of amnesia for an irrelevant object shown during the bronchoscopy in the deeply sedated group (chi 2 = 21.084 P less than 0.001). Patients given alfentanil performed significantly better in a modified Romberg test (chi 2 = 4.357 P less than 0.05) and a visualisation test (t = 3.035 P less than 0.01) two hours after the bronchoscopy. Alfentanil produced good operating conditions, patient comfort, less cough and a more rapid recovery, compared to the deep sedation regimen, and is an ideal sedative for fibreoptic bronchoscopy.

Propofol-induced anaesthesia. Double-blind comparison of recovery after anaesthesia induced by propofol or thiopentone

Postoperative psychomotor and cognitive recovery were assessed after anaesthesia induced by either propofol or thiopentone, and maintained with nitrous oxide and halothane in 40 unpremedicated dental patients. Performance was shown to be impaired one hour postoperatively for the whole sample in hand-eye coordination (p less than 0.001), reaction time (p less than 0.001) and digit span (p less than 0.05). There was evidence of impairment at 3 hours postoperatively in reaction time (p less than 0.05) and ataxia (p less than 0.01). Performance also deteriorated in the dexterity and aiming tasks. Patients reported significantly less clumsiness by 24 hours in blurred vision and shivering (p less than 0.05) and by 48 hours less coughing (p less than 0.05). However, there was no significant difference between groups. No evidence showed that recovery in the propofol group was faster, so it was concluded that induction with propofol offered no advantage when anaesthesia is maintained with nitrous oxide and halothane for the periods of time reported in this study.

Effects of anaesthesia on some aspects of mental functioning of surgical patients

Plastic surgery patients undergoing either local (LA) or general (GA) anaesthesia of at least forty-five minutes' duration and a non-patient control group were used to examine the extent and duration of deterioration in mental functioning following GA and the factors influencing such deterioration. Mental functioning was assessed by a battery of six tests administered one week before anaesthesia, four days after anaesthesia and six weeks after anaesthesia. Mental performance of GA patients but not of LA patients was significantly impaired on the fourth postoperative day. Six weeks after anaesthesia GA patients were still performing significantly below controls. There was marked variation in the pattern of recovery, some GA patients failing to regain their pre-operative level of performance after six weeks. Severity of deterioration following general anaesthesia was significantly correlated with habitual caffeine consumption.

Carbon dioxide homeostasis and recovery after general anaesthesia

The influence of different levels of carbon dioxide during general anaesthesia on postoperative recovery was studied. Sixty female patients were divided into two age groups. Thirty patients were over 60 years old and 30 patients were under 46 years old. Artificial ventilation with added carbon dioxide during general anaesthesia with thiopentone, nitrous oxide-oxygen, alcuronium and fentanyl was used. According to the arterial CO2 tension, patients were allocated to subgroups: hypercarbic, PaCO2 7.3 kPa, normocarbic, PaCO2 5.3 kPa and two different levels of hypocarbia: older patients PaCO2 3.7 kPa and younger patients PaCO2 2.9 kPa. As criteria for recovery, a battery of recovery tests and postoperative questionnaires were used. Regardless of age, patients subjected to hypercarbic ventilation scored better in the recovery tests than patients subjected to normo- or hypocarbia. Normocarbic ventilation also gave better results than hypocarbic ventilation. The level of hypocarbia used in the older patients and that used in the younger patients, though different, resulted in nearly the same deterioration of scoring in the recovery tests. This deterioration was seen in some patients up to 48 h postoperatively. No subjective differences were elicited from the questionnaires after various types of ventilation.

Anaesthesia for short-stay varicose vein surgery

The study was undertaken in order to elucidate the suitability of four different types of general anaesthesia and of epidural block in short-stay varicose vein surgery. Special consideration was given to recovery after anaesthesia. The series consisted of 230 female patients subjected to varicose vein surgery of one lower extremity. The patients' recovery after surgery was observed through tests measuring visual-motor coordination and through questionnaires. The general anaesthesias used were halothane-nitrous oxide-oxygen anaesthesia with spontaneous respiration (Ha), relaxant-dominated combined anaesthesia (Re), analgesic-dominated combined anaesthesia (An), and analgesic-dominated combined anaesthesia with hyperventilation (Hy). Of the general anaesthesias, halothane nitrous-oxide inhalation anaesthesia gave the fastest recovery, although there were no major differences between it and analgesic-dominated combined anaesthesia. In contrast, immediate recovery was prolonged after hyperventilation and after relaxant-dominated anaesthesia. Epidural blockade provided a good alternative to general anaesthesia.

Effects of diazepam and scopolamine on storage, retrieval and organizational processes in memory

The effects of intramuscular injections of diazepam (0.3 mg/kg) and scopolamine (8 mug/kg) on memory processes and subjective moods were studied in 36 volunteers. Subjects (Ss) were tested in groups of four in a double blind procedure with treatments distributed according to a Latin square design. Lists of words were presented to Ss who were then tested with an immediate free recall test prior to drug administration. Following injection delayed free recall and recognition tests were given. Subsequently two sets of lists were presented separately and tested in the same fashion. Two of the lists in the last set were composed of words falling into distinct categories. Memory was additionally analyzed by testing immediate recall of digit sequences and employing a visual recognition test. Subjective moods were evaluated with a rating questionnaire. Both diazepam and scopolamine impaired memory functions although the action of the latter drug was more pronounced and prolonged. The deficit appeared to be in the storage process leaving retrieval processes unaffected. Scopolamine in addition interfered with organizational processes. Subjectively, scopolamine also produced a larger sedative effect than diazepam.