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)Â via release of endogenous NO
Dosemcg/kg/min | Clinical effect |
0.2-6 | Direct smooth muscle cell relaxationarterial > venous vasodilation |
Side effects:Â severe hypotension (titrate slowly), worsening V/Q mismatch, cyanide and thiocyanate intoxication, methaemoglobinemia, tachyphylaxis |
Glyceryl-trinitrate (GTN)Â via release of endogenous NO
Dosemcg/kg/min | Clinical effect |
1-10 | Direct smooth muscle cell relaxationvenous > arterial vasodilationimproved coronary perfusion |
Side effects:Â 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:Â severe hypotension |
Hydralazine via direct vasodilation by decreasing intracellular Ca++
Dosemcg/kg/min | Clinical effect |
10-50 | Vasodilation |
Side effects:Â reactive tachycardia |
Prostacyclin = PGI2 (epoprostenol)Â via increase in NO
Doseng/kg/min | Clinical effect |
2-20 (40) | Pulmonary vasodilation, treatment of PHT |
Side effects:Â systemic hypotension, haemorrhagic diasthesis due to Platelet aggregation inhibition |
Prostaglandin = Alprostadil = PGE1Â via release of endogenous NO
Doseng/kg/min | Clinical effect |
5-100 | Pulmonary vasodilationMaintaining PDA patency |
Side effects:Â systemic hypotension, fever, hypoventilation and apnoea, antiplatelet function |
Clonidine via presynaptic alpha 2 adrenergic action
Dosemcg/kg/hr | Clinical effect |
0.5-2 | VasodilationSedationAnalgesia |
Side effects:Â 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:Â systemic hypotension, decreases CO, avoid in LCOS |
Captopril (ACE-I)Â 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:Â systemic hypotension, renal dysfunction |
All Marc’s PICU cardiology FOAM can be found on PICU Doctor and can be downloaded as a handy app for free on iPhone or Android. A list of contributors can be seen here.