[Hemodynamic effects following bolus administration of different vasopressive agents for blood pressure stabilization...

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.