Reversal of sedation and respiratory depression after anaesthesia by the combined use of physostigmine and naloxone in neurosurgical patients

Effect of aminophylline or physostigmine on recovery from nitrous oxide-enflurane anaesthesia

If facilities for recovery are limited, shortening the recovery time from general anaesthesia is important. A comparative study on the effect of 3 mg.kg-1 aminophylline or 0.04 mg.kg-1 physostigmine on duration and quality of the recovery time from nitrous oxide-enflurane anaesthesia is presented. Three groups of 35 patients were observed, placebo being included for comparison in this double-blind study. Without treatment, recovery from nitrous oxide-enflurane inhalation anaesthesia lasted 18.8 +/- 5.80 min. Aminophylline considerably shortened the recovery time (12.06 +/- 3.52 min), whereas physostigmine did not (18.97 +/- 9.18 min). In the physostigmine group, however, a remarkably calm recovery and early return of protective reflexes was observed. Although aminophylline shortens the recovery time, due to earlier incidence of pain and other disturbances, it cannot be recommended for general improvement of recovery, whereas physostigmine clearly improves the quality of recovery from nitrous oxide-enflurane anaesthesia.

Reversal of postoperative somnolence using a two-rate infusion of physostigmine

In order to antagonize immediate postoperative somnolence, 24 surgical patients were given a two-rate infusion of physostigmine, aiming at a constant plasma concentration in the range of 1 to 10 ng/ml. Plasma concentrations of physostigmine were determined during infusion and after infusion and the effects of physostigmine on analgesia and postoperative sedation, and its side effects were monitored throughout. On the 1st postoperative day some of the patients (n = 8) were given 5 mg physostigmine orally, after which plasma concentrations as well as effects were measured. Steady-state concentrations were generally lower than predicted. Clearance varied between 10 and 85 ml/min x kg with a mean of 40.8 +/- 21.0 ml/min x kg. Oral bioavailability was 25.3 +/- 11.1%. Physostigmine administered as an intravenous infusion antagonized immediate postoperative somnolence in 21 out of 24 patients. Effects were poorly correlated with the established steady-state concentration of physostigmine. The patients' experience of postoperative pain relief was mostly satisfactory and the side effects of physostigmine infusion were generally limited. The effects of physostigmine in the immediate postoperative period seemed dependent on the dose as well as on the time which had elapsed since administration of anticholinergic drugs. After oral physostigmine administration the following morning, the majority of patients experienced side effects such as nausea and abdominal pain. In conclusion, physostigmine given as infusion antagonizes postoperative somnolence. However, the arousal effect was considered not better than that resulting from a bolus dose of the drug, although the infusion regimen allowed a prolonged clinical effect duration.

Early extubation after coronary artery surgery in efficiently rewarmed patients: a postoperative comparison of opioid anesthesia versus inhalational anesthesia and thoracic epidural analgesia

Twenty-eight patients were studied after uncomplicated aortocoronary bypass surgery with hypothermic cardiopulmonary bypass (CPB). In all patients residual hypothermia was effectively treated by the use of extended rewarming during CPB and postoperatively by an external heat source. This treatment almost eliminated postoperative shivering, and it resulted in the lowering of oxygen uptake, carbon dioxide production, and required ventilatory volumes to stable levels where spontaneous breathing could be used safely. The patients were divided into two groups. In group I (n = 12), intraoperative anesthesia was based on an intravenous (IV) opioid (phenoperidine), which caused persistent respiratory depression and made mechanical ventilation necessary for a mean postoperative time period of 10.7 +/- 3.8 hours even with the rewarming. In group II (n = 16), thoracic epidural analgesia and intraoperative general anesthesia with enflurane were used. In this group, postoperative metabolic and ventilatory requirements were stable and low, finger skin temperature was normalized earlier, systemic vascular resistance was lower, and stroke index was higher. Emergence from anesthesia was uneventful and was achieved early postoperatively in Group II. The patients had good pain relief and were mentally alert. Adequate spontaneous breathing was resumed quickly and endotracheal extubation was performed within the first two postoperative hours (1.6 +/- 0.5 hours). No complications or increased morbidity occurred, and no patient needed to be reintubated in Group II.

Cerebral blood flow, cerebral metabolic rate of oxygen and relative CO2 reactivity during neurolept anaesthesia in patients subjected to craniotomy for supratentorial cerebral tumours

In 10 patients subjected to craniotomy for supratentorial cerebral tumours in neurolept anaesthesia, cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were measured twice peroperatively by a modification of the Kety & Schmidt technique, using 133Xe. The relative CO2 reactivity was assessed indirectly as the % change of the arteriovenous oxygen difference (AVDO2) per mm change in PaCO2. The patients were premedicated with diazepam 10-15 mg perorally. For induction, thiopentone 4-6 mg/kg, droperidol 0.2 mg/kg and fentanyl 5 micrograms/kg were used, and for maintenance N2O 67% and fentanyl 4 micrograms/kg/h. During the first flow measurement the median and range of CBF was 30 ml/100 g/min (range 17-45), of AVDO2 8.0 vol % (range 4.1-9.5), and of CMRO2 2.28 ml O2/100 g/min (range 1.57-2.84). During the second CBF study, AVDO2 increased to 9.3 vol % (range 3.4-11) (P less than 0.05), and CMRO2 increased to 2.51 ml O2/100 g/min (range 1.88-3.00) P less than 0.05, while CBF was unchanged. The CO2 reactivity was present in all studies, median 1.8%/mmHg (range 0.5-15.1). The correlation coefficients between jugular venous oxygen tension/saturation, respectively, and CBF were high at tensions/saturations exceeding 4.0 kPa and 55%, indicating that hyperperfusion is easily unveiled by venous samples from the jugular vein during this anaesthesia.

Endogenous opiates: 1986

This is the ninth installment of our annual review of research involving the endogenous opiate peptides. It is restricted to the non-analgesic and behavioral studies of the opiate peptides published in 1986. The specific topics this year include stress; tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic processes; mental illness; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; activity; sex, pregnancy, and development; and some other behaviors.