Articles: general-anesthesia.
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J. Auton. Nerv. Syst. · Feb 1981
Role of baroreceptor reflexes in the hemodynamic and heart rate responses to althesin, ketamine and thiopentone anesthesia.
The effects of i.v. infusions of althesin, ketamine and thiopentone were studied in instrumental rabbits, in doses that produced similar levels of light anesthesia. The main hemodynamic differences were in the rises in mean arterial pressure (MAP) and in total peripheral resistance (TPR) which were in the order of ketamine greater than thiopentone greater than althesin. These rises in MAP and TPR did not occur in sino-aortic denervated rabbits suggesting that in normal rabbits these depended on the integrity of the arterial baroreceptors and /or chemoreceptors. ⋯ All drugs depressed the following curve parameters: (i) HP range, i.e. the difference in HP plateaux from maximal tachycardia to maximal bradycardia; and (ii) the reflex gain (sensitivity). The order of depression was ketamine greater than thiopentone greater than althesin, i.e. the same as the order in which they evoked pressor effects. The results suggest that the 3 anesthetics produce differing depression of afferent mechanisms related to baroreceptor reflexes and that this accounts for both the differences in pressor effects (through disinhibition of constrictor tone) and in depression of the vagal and sympathetic components of the baroreceptor--heart rate reflex.
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Anasth Intensivther Notfallmed · Feb 1981
Clinical Trial Controlled Clinical Trial[Mechanics of breathing during anaesthesia with controlled ventilation by means of the engström ecs 2000 respirator (author's transl)].
Compliance, resistance, gas flow, blood gas tension and intrapulmonary shunt volume were measured in 20 anaesthetized patients ventilated by the volume-controlled Engström respirator ECS 2000. All patients had neurosurgical or vascular procedures. ⋯ Ventilation with the large tidal volume was characterized by better compliance and oxygenation indicating that the mechanics of breathing and the intrapulmonary gas exchange benefit from larger tidal volumes. Due to the special features of the Engström respirator as regards air flow and pressure steady ventilation with a low tidal volume of 6 ml/kg bodyweight does not result in a significant decrease in compliance and an increase in shunt volume as is the case with other types of respirators.
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Anesth Analg (Paris) · Jan 1981
[Intervention among patients with right bundle branch block and left anterior hemiblock. Operatory risk (author's transl)].
In order to assess the risk of advanced heart block during anesthesia in patients with right bundle branch block and left anterior hemiblock, 35 consecutive patients were monitored throughout the pre-, intra- and postoperative period. As conventional ECG monitoring may only detect advanced atrioventricular block, patients were monitored according to the Holter method which can easily detect even minor changes of atrioventricular conduction namely slight increased PR interval or dropped P wave. All patients were asymptomatic, in normal sinus rhythm without second degree AV block. ⋯ They immediately regressed at the termination of the sinus bradycardia either spontaneously or following atropine injection, strongly suggesting the responsability of increased vagal tone. Thus general or epidural anesthesia did not compromise infranodal conduction in any of the observed patients. These data indicate that anesthesia can be safely used without prophylactic preoperative insertion of pacemakers in patients with asymptomatic chronic right bundle branch block and left anterior hemi-block.