Hemodynamic effects

Interestingly, these studies provided the important information that the hemodynamic effects of mediators depend on both the underlying cardiovascular conditions and the pharmacologic treatment (e.g. H2 blockade). 

Aim for a 10-15% reduction in mean arterial pressure (MAP) ° Nitroprusside—0.25-0.5 mcg/kg/min continuous IV infusion increase in increments of 0.25-0.5 mcg/kg/min until desired hemodynamic effect. Usual doses up to 2-3 mcg/kg/min. High-alert medication—read package insert before use... 

TABLE 3-10. Usual Hemodynamic Effects of Commonly Used Intravenous Agents for Treatment of Acute or Severe Heart Failure... 

Dosing recommendations for milrinone include a loading dose of 50 mcg/kg, followed by an infusion beginning at 0.5 mcg/kg per minute (range 0.23 mcg/kg per minute for patients with renal failure up to 0.75 mcg/kg per minute). A loading dose is not necessary if immediate hemodynamic effects are not required or if patients have low systolic blood pressures (less than 90 mm Hg). Decreases in blood pressure during an infusion may necessitate dose reductions as well. 

B. Arregui, B. Lopez, M.G. Salom, F. Valero, C. Navarro, and F.J. Fenoy, Acute renal hemodynamic effects of dimanganese decacarbonyl and cobalt protoporphyrin. Kidney Int. 65, 564-574 (2004). 

Although concern over attenuation of dobutamine s hemodynamic effects with prolonged administration has been raised, some effect is likely retained. Consequently, the dobutamine dose should be tapered rather than abruptly discontinued. 

Dopamine produces dose-dependent hemodynamic effects because of its relative affinity for cq-, /Jr, /J2-, and Dr (vascular dopaminergic) receptors. Positive inotropic effects mediated primarily by / -receptors become more prominent with doses of 2 to 5 mcg/kg/min. At doses between 5 to 10 mcg/kg/min, chronotropic and -mediated vasoconstricting effects become more prominent. Especially at higher doses, dopamine alters several parameters that increase myocardial oxygen demand and potentially decrease myocardial blood flow, worsening ischemia in some patients with coronary artery disease. 

Sodium nitroprusside is a mixed arterial-venous vasodilator that acts directly on vascular smooth muscle to increase cardiac index and decrease venous pressure. Despite its lack of direct inotropic activity, nitroprusside exerts hemodynamic effects that are qualitatively similar to those of dobutamine and milrinone. However, nitroprusside generally decreases PAOP, SVR, and blood pressure more than those agents do. 

The hallmark of the hemodynamic effect of sepsis is the hyperdynamic state characterized by high cardiac output and an abnormally low systemic vascular resistance. 

Tolerance to nitrates is defined as the reduction in hemodynamic effect or the requirement for higher doses to achieve a persistent effect with continuous use in the face of constant plasma concentrations [15]. Nitrate tolerance was first described for nitroglycerin in 1888 [36] it occurs with all organic nitrates, albeit to different extents. For reasons that are not understood, PETN appears to be the least susceptible to the development of tolerance. No, or much less, tolerance is observed with nitrite esters, such as amyl nitrite [37], molsidomine, and sodium nitroprusside. Earlier investigations suggested that a depletion of intracellular thiols is involved in tolerance development [17], but this has not been substantiated in later studies [38, 39]. As with organic nitrate bioactivation, the precise mechanism(s) involved in nitrate tolerance remain(s) unknown, but it is likely to be complex and multifactorial. Two principal... 

J. E., Peray, P.A., Desch, G., Sassine, A. and Eledjam, J.J. (1996) Comparative electrophysiologic and hemodynamic effects of several amide local anesthetic drugs in anesthetized dogs. Anesthesia and Analgesia, 82, 648—656. 

Introduction of chlorine or bromine into the 3- and/or 4- positions of the side chain yields more potent compounds in terms of hypotension in rats and dopamine p- hydroxylase inhibition (31. 32). The analog YP-279 (XXXV) is also hypotensive in rats but is said not to affect brain norepinephrine biosynthesis unlike fusaric acid or dibromofusaric acid (33-35). Fusaric acid amide (bupicomide, Sch 10595, XXXVI) is clinically effective at 300 to 1800 mg per day and is said to have hemodynamic effects similar to hydralazine (36. 37). The amide is... 

Because of their capability of lowering the blood pressure regardless of body position, of their overall excellent acceptance by the patients and because of their favorable hemodynamic effects, the diuretic agents remain the most important contribution to antihypertensive therapy. 

The inhibition of sympathetic tone to the venous system (capacitance vessels) results in increased pooling of blood in the venous vascular bed with consequent decreased venous return to the heart and decreased cardiac output. This phenomenon is more pronounced in upright positions because of the effect of gravity. The hemodynamic effects of ganglionic blockers include decreases in cardiac output, renal blood flow, cerebral blood flow and orthostatic hypotension(20,21). 

---