Best practice & research. Clinical anaesthesiology
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Best Pract Res Clin Anaesthesiol · Jun 2008
ReviewEndocrine effects of vasopressin in critically ill patients.
Vasopressin, also called antidiuretic hormone, is a 9 amino-acid peptide, synthesized from a precursor containing neurophysin II, by neurones from the supra-optic and peri-ventricular nuclei, and then stored in the posterior hypophysis. Vasopressin regulates plasmatic osmolality and volaemia via V2 receptors at the levels of the kidney, and vascular smooth muscle tone via V1a arterial receptors. ⋯ Interestingly, during critical illness, exogenous administration of vasopressin showed little effects on the circulating levels of these various hormones, except an increase in prolactin. The absence of endocrine effects of vasopressin during critical illness is unclear and may relate to an already maximal hormonal stimulation or to down-regulation of vasopressin receptors.
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This review article summarizes the structure, signalling pathways, and tissue distribution of the vasopressin receptors, V1 vascular, V2 renal, V3 pituitary, and oxytocin receptors, as well as the P2 class of purinoceptors. The physiological effects of vasopressin on its receptors are described. The future direction with regard to the role of the V1a receptor in circulatory shock states is discussed; further studies with V1a receptor agonists are warranted to further develop treatment strategies to reduce mortality in life threatening diseases like septic shock.
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Best Pract Res Clin Anaesthesiol · Jun 2008
ReviewArginine vasopressin as a rescue vasopressor to treat epidural anaesthesia-induced arterial hypotension.
Epidural anaesthesia is a well-established and recognized technique in anaesthetic practice. Its benefits are multiple and range from positive effects on the respiratory and cardiocirculatory system, a reduced need for analgesics and decreased costs to earlier hospital discharge. Disadvantages like sympathetic blockade followed by hypotension, bradycardia, and cardiac arrest, however, must be taken into consideration. ⋯ In case reports and a small clinical study, administration of AVP or one of its analogues could rapidly reverse hypotension and restore cardiovascular stability. Because no major controlled clinical trial has yet evaluated the effects of AVP on morbidity, AVP can so far not be recommended as a first-line drug to treat cardiovascular instability during epidural anaesthesia. In refractory cases, however, the use of AVP as a rescue vasopressor may be beneficial.
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Best Pract Res Clin Anaesthesiol · Jun 2008
ReviewRole of vasopressinergic V1 receptor agonists in the treatment of perioperative catecholamine-refractory arterial hypotension.
Three pathways are critically involved in blood pressure regulation during anaesthesia, i.e. the sympathetic nervous system, the renin angiotensin system (RAS), and the vasopressinergic system. The fact that anaesthetic agents typically blunt the regulatory role of the adrenergic system emphasises the importance of the remaining compensatory mechanisms. In patients chronically treated with RAS antagonists, such as angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists, however, this mechanism is also blunted, possibly resulting in absolute dependency of blood pressure regulation on the vasopressinergic system. ⋯ In the absence of catecholamine resistance and RAS blockade, administration of V1 agonists may contribute to a dose-dependent reduction in regional splanchnic vasoconstriction. Likewise, bolus infusion may result in coronary vasospasm and is thus not recommended for routine clinical use. Future large-scale randomized, controlled clinical trials are warranted to evaluate the role of V1 agonists in the treatment of perioperative hypotension in more detail.