Dobutamine - Dosage & Administration (Post-Operative Hypotension)

Important note: Dobutamine is a positive inotrope (increases cardiac output/contractility via beta-1 stimulation). It is used post-operatively when there is low cardiac output with hypotension - specifically when hypotension is from pump failure/low cardiac output, not from hypovolemia or vasoplegia alone. Always confirm the correct vasopressor/inotrope is indicated for the clinical picture before administration.

Route of Administration

• IV (intravenous) continuous infusion ONLY - never as a bolus
• Must be given via a central line or large peripheral IV with an infusion pump
• Must be diluted before use (if using the concentrated 12.5 mg/mL vial)

Standard Dosing for a 23-Year-Old Female (Post-Op Hypotension)

• Start at 2 mcg/kg/min = 120 mcg/min
• Effective range: 2-20 mcg/kg/min = 120 - 1200 mcg/min

How to Prepare the Infusion (Common Method)

1. Take 250 mg dobutamine (20 mL of 12.5 mg/mL) + add to 230 mL of D5W or NS = 250 mL total
2. This gives a concentration of 1 mg/mL (1000 mcg/mL)
3. Infusion rate (mL/hr) = (Dose in mcg/kg/min x Weight in kg x 60) / 1000

Monitoring (Mandatory)

• Blood pressure (every 5-15 min initially)
• Heart rate and rhythm (ECG monitoring) - tachycardia and PVCs can occur
• Urine output (marker of end-organ perfusion)
• SpO2
• Reduce or stop if HR >120/min, new arrhythmias, or worsening ischemia

Key Cautions for This Patient

• Correct hypovolemia first - if the patient is volume-depleted post-op, fluid bolus is the first step. Dobutamine in a hypovolemic patient can worsen hypotension.
• Avoid if IHSS/LVOTO (hypertrophic obstructive cardiomyopathy) - it is contraindicated
• Onset of action: ~1-2 min; peak effect: 10-20 min; half-life: ~2 min
• Can cause tachycardia - if HR rises significantly, reduce infusion rate
• If BP support AND inotropic support are both needed, consider adding norepinephrine as the vasopressor alongside dobutamine