[Hemodynamic effects following bolus administration of different vasopressive agents for blood pressure stabilization during peridural anesthesia].

Vasopressors are often used to counteract hypotension induced by sympathetic blockade during epidural or spinal anaesthesia. This study contains data of invasive haemodynamic investigations following single-shot applications of different vasoconstrictor agents (Akrinor, etilefrine, ephedrin, norfenefrin, amezinium) during a combination of epidural block and controlled ventilation with oxygen and nitrous oxide. In a preceding dose finding study equipotent dosage of the substances used was confirmed. Usually bolus application of these vasopressors causes only a short-lasting circulatory stimulation, which does not cover the whole period of sympathetic blockade (exception: amezinium). Even small doses of drugs acting only upon alpha-receptors, may cause unwanted peripheral vasoconstriction and decrease of the already lowered cardiac output (example: norfenefrine). The rise of blood pressure after betamimetics may be delayed by an initial vascular beta 2 stimulation (example: etilefrine). In other sympathetic stimulants venoconstriction and therefore improvement of cardiac output by increase of preload takes place after an interval of some minutes to cardiac stimulation (example: ephedrin, Akrinor). Though the use of vasopressor agents during central blockade cannot be recommended in general, substances with alpha- as well as beta-stimulation should be preferred, if necessary. When using substances with short duration of action continuous infusion has to be taken into consideration.