oxide, vasopressin may be an effective alternative in catecholamine-resistant
shock since it inhibits NO synthase. It also improves renal perfusion by
vasodilating the afferent renal arterioles. However, large trials have failed to
demonstrate improved outcomes with vasopressin when compared to
norepineprine (ref). Major complications with the use of vasopressin include
cardiac arrest, as well as myocardial, mesenteric and digital ischemia. Dosing is
extrapolated from adult experience but generally will not exceed 0.005
units/kg/minute.
Milrinone is a phosphodiesterase III inhibitor that combines inotropic
activity with afterload reduction. It can improve left ventricvular relaxation (i.e.
lusitropy) and compliance, thereby improving stroke volume and CO. Indeed,
milrinone is able to maintain a favorable myocardial oxygen supply to demand
ratio. Milrinone also has vasodilatory effects that act to decrease systemic
vascular resistance. Milrinone may be an ideal medication in the management of
patients with LCOS and increased systemic vascular resistance (e.g. certain
septic shock states). Doses generally range from 0.3-0.7 μg/kg/minute.
Vasodilatory agents can be used for afterload reduction. Sodium
nitroprusside is a systemic arterial and venodilator that has a rapid onset of
action (2 minutes) and a very short half-life (3 minutes). These factors make it an
easy medication to administer and titrate to effect. Doses can range from 0.5
ug/kg/minute to 5 μg/kg/minute. However, toxicity, due to the accumulation of the
metabolic by-product, thiocyanate, can occur with doses >10 μg/kg/minute or if it
is used for >72 hours as a continuous infusion. Thiocyanate should therefore be
marcin
(Marcin)
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