When a child has fluid refractory hypotensive shock (shock which does not improve after fluid boluses are given), there are a number of IV medications that can be used to improve blood pressure.
The cause of the hypotension will determine the medication that is used.
Some causes of post-arrest hypotension are inadequate heart rate, poor contractility, and excessive vasodilation. Also, consider that there may be more than one cause that needs to be addressed.
When a child has fluid-refractory shock and presents with signs of poor perfusion and hypotension with vasoconstriction (mottled skin, delayed capillary refill), vasoactive medications should be used to improve blood pressure by increasing myocardial contractility with minimal vasoconstriction.
Epinephrine is the vasoactive medication of choice for infants and children with fluid refractory shock.
The infusion rate should be between 0.1-1 mcg/kg/min. This should be titrated to support blood pressure and systemic perfusion.
The infusion rate of dopamine for postarrest hypotension is 10-20 mcg/kg/min. In children, dopamine may not be the best choice when profound circulatory instability and hypotensive shock are present. In this case, epinephrine is preferred.
The infusion rate should be between 0.1-2 mcg/kg/min
Use norepinephrine to treat fluid refractory hypotensive shock with low systemic vascular resistance (vasodilation). Unlike the Dopamine, Norepinephrine can increase blood pressure without significantly increasing heart rate, stroke volume, or cardiac output.
When a child has fluid refractory shock but the blood pressure remains within a normal range treat the shock with the following IV medications.
Dobutamine is effective for the treatment of post-arrest normotensive shock because it can increase myocardial contractility (makes the heart squeeze harder) without increasing systemic vascular resistance (vasoconstriction).
The infusion rate should be between 2-20 mcg/kg/min and the infusion should be titrated to improve cardiac output.
Dopamine can also be used for normotensive shock in the post-arrest phase, however, the dose varies from that which is used for hypotensive shock. Instead of 10–20 mcg/kilogram/min the dosing is 2-20 mcg/kg/min. Why the lower dose for normotensive shock?: Higher doses of dopamine will cause unwanted vasoconstriction (increased BP). Low to moderate doses of dopamine increase cardiac output without increasing BP (systemic vascular resistance).
Medication should be started with the lowest dose 2 mcg/kg/min and titrated up for the desired effect of increasing cardiac output without significantly increasing blood pressure.
Epinephrine can be used for normotensive shock in the post-arrest phase, however, the dose varies from that which is used for hypotensive shock. Instead of 0.1-1 mcg/kg/min the dosing is 0.1-0.3 mcg/kg/min. Why the lower dose for normotensive shock?: Doses above 0.3 mcg/kg/min cause unwanted vasoconstriction (increased BP). Doses less than 0.3 mcg/kg/min increase cardiac output by increasing heart rate and contractility without significantly increasing BP (systemic vascular resistance).
Milrinone is a medication that can help increase cardiac output without increasing myocardial oxygen demand. In the post arrest phase, milrinone is indicated for the treatment of shock in the presence of myocardial dysfunction when there is increased systemic vascular resistance. Milrinone is given as a continuous infusion of 0.25–0.75 mcg/kg/min with loading bolus dose of 50 mcg per kilogram that is given over 10–60 minutes.
Caution: Vasodilation and expansion of the vascular space can occur when Milrinone is given. The administration of IV fluids can counter the decrease in blood pressure that can occur as a result of the increased vascular space.