Anaesthesia
-
Randomized Controlled Trial Clinical Trial
Enhancement of pressor response to ephedrine following clonidine medication.
We studied pressor responses and changes in plasma catecholamine concentrations following two consecutive doses of ephedrine 0.1 mg.kg-1 with (n = 20) and without (n = 20) clonidine 5 micrograms.kg-1 premedication in patients presenting for a variety of major surgical procedures under general anaesthesia. Arterial blood pressure and heart rate were measured at 1 min intervals for 10 min, and plasma catecholamines were measured before and 3 min after each dose of ephedrine. ⋯ Plasma catecholamine concentrations tended to be lower in the clonidine group throughout the study. The augmented pressor response to ephedrine in clonidine-treated patients can be attributed to enhanced cardiovascular response rather than clonidine-induced accumulation and subsequent increased release of catecholamine.
-
We have investigated the relationship between changes in the middle latency auditory evoked potentials during alternating periods of consciousness and unconsciousness produced by propofol infusion combined with spinal anaesthesia for total knee replacement. Eleven patients completed the study, of whom two had recollection of events after the onset of the anaesthetic. ⋯ During successive transitions from unconsciousness to consciousness, awake latencies were slightly higher than those of baseline awake, whereas anaesthetised latencies were similar to the ones obtained during the first period of unconsciousness. The consistent changes demonstrated, suggest that the auditory evoked potentials could represent a reliable indicator of potential awareness during anaesthesia.
-
Case Reports
Respiratory arrest in a parturient following intrathecal injection of sufentanil and bupivacaine.
A 19-year-old obstetric patient had a respiratory arrest shortly after receiving intrathecal sufentanil and bupivacaine as part of a combined epidural/spinal technique for pain relief in labour.
-
The effects of two calcium channel blockers (verapamil and nicardipine) on indirectly elicited muscle twitch and possible interactions between these drugs and non-depolarising muscle relaxants (vecuronium, atracurium, pancuronium) were investigated using isolated rat phrenic nerve-hemidiaphragm preparations. Both verapamil 10(-5) M and nicardipine 10(-6) M caused significant depression of twitch amplitude. ⋯ Nicardipine potentiated atracurium-induced neuromuscular block but had no effect on pancuronium- and vecuronium-induced twitch depression. Neostigmine 10(-6) M did not produce any significant changes in the maximal recovery of twitch depression induced with calcium channel blockers and muscle relaxants combinations; also, neostigmine had no effect on maximal recovery time of twitch depression.