Inotropes and vasodilators

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Cite this article as:
Anders, M. Inotropes and vasodilators, Don't Forget the Bubbles, 2013. Available at:
http://doi.org/10.31440/DFTB.3934

Vasodilators:

Decreasing the pressures against which the heart works (systemic and pulmonary afterload); decreasing the work of the heart hence myocardial O2 demand.

Usual indications for vasodilator therapy are: systemic vasodilation (LV afterload reduction), pulmonary vasodilatation (RV afterload reduction), systemic hypertension, improving coronary blood flow.

Beware that infants, in response to low CO, increase afterload to maintain BP.

The use of vasodilators leads to increase in vascular capacitance and may require volume replacement. Avoid or use judiciously with lesions where there is obstruction to blood flow or fixed stroke volume.


Sodium-nitroprusside (SNP) via release of endogenous NO

Dosemcg/kg/min Clinical effect
0.2-6 Direct smooth muscle cell relaxationarterial > venous vasodilation
Side effects: severe hypotension (titrate slowly), worsening V/Q mismatch, cyanide and thiocyanate intoxication, methaemoglobinemia, tachyphylaxis

Glyceryl-trinitrate (GTN) via release of endogenous NO

Dosemcg/kg/min Clinical effect
1-10 Direct smooth muscle cell relaxationvenous > arterial vasodilationimproved coronary perfusion
Side effects: severe hypotension (titrate slowly)

Phenoxybenzamine via irreversible alpha-blockage

Dosemcg/kg/min Clinical effect
Load: 1 mg/kg over 1hr Vasodilation
TDS or BD:0.5mg/kg
Side effects: severe hypotension

Hydralazine via direct vasodilation by decreasing intracellular Ca++

Dosemcg/kg/min Clinical effect
10-50 Vasodilation
Side effects: reactive tachycardia

Prostacyclin = PGI2 (epoprostenol) via increase in NO

Doseng/kg/min Clinical effect
2-20 (40) Pulmonary vasodilation, treatment of PHT
Side effects: systemic hypotension, haemorrhagic diasthesis due to Platelet aggregation inhibition

Prostaglandin = Alprostadil = PGE1 via release of endogenous NO

Doseng/kg/min Clinical effect
5-100 Pulmonary vasodilationMaintaining PDA patency
Side effects: systemic hypotension, fever, hypoventilation and apnoea, antiplatelet function

Inhaled nitric oxide (iNO)


Sildenafil


Clonidine via presynaptic alpha 2 adrenergic action

Dosemcg/kg/hr Clinical effect
0.5-2 VasodilationSedationAnalgesia
Side effects: systemic hypotension, avoid in Porphyria, may decrease CO

Dexmedetomidine via presynaptic alpha 2 adrenergic action

Dosemcg/kg/hr Clinical effect
0.2-1 VasodilationBradycardia (can be used therapeutically)SedationAnalgesia
Side effects: systemic hypotension, decreases CO, avoid in LCOS

Captopril (ACE-I) via angiotensin converting enzyme inhibition

Dosemcg/kg Clinical effect
Test dose: 0.1 VasodilationImprove in CO
TDS or QID, increase dose by 0.1 mg/kg until clinical effect achieved
Side effects: systemic hypotension, renal dysfunction

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Marc Anders is a paediatric intensivist.

Author: Marc Anders Marc Anders is a paediatric intensivist.

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