Vasoactive Drips &
IV Infusion
Calculations:
Titration Formulas
and Critical Care
Drips
,1. Introduction
Vasoactive medications are used in shock states, heart failure, hypertensive
crises, and other critical care situations. They modify heart rate, contractility,
vascular tone, and perfusion. Proper titration requires mastery of IV flow
calculations, weight-based dosing, and continuous monitoring.
2. Key Principles of Vasoactive Infusions
1. Always use a pump—never gravity drip.
2. Confirm patient weight for accurate mcg/kg/min dosing.
3. Know the concentration (mg/mL) before calculating.
4. Check vitals frequently: BP, MAP, HR, SpO₂, urine output, mental status.
5. Titrate slowly to avoid overshooting the target effect.
6. Central line preferred for high-concentration vasopressors (risk of tissue
necrosis if extravasation occurs).
3. Step-by-Step IV Drip Calculation
Formula:
Dose (mcg/kg/min) × Weight (kg) × 60
Flow rate (mL/hr) =
Concentration (mcg/mL)
• Convert mg → mcg if necessary (1 mg = 1000 mcg).
• Multiply by 60 to convert minutes → hours for pump settings.
• Round to nearest decimal for pump accuracy.
Example: Dopamine 10 mcg/kg/min, 70 kg patient, concentration 1.6 mg/mL →
10 × 70 × 60
𝐹𝑙𝑜𝑤 = = 26.25𝑚𝐿/ℎ𝑟
1600
, 4. Common Vasoactive Drugs & Critical Care Notes
Drug Concentration Dose Range Effects / Use Notes
Low: renal
400 mg / 250
2–20 perfusion, Mid: Monitor HR,
Dopamine mL → 1.6
mcg/kg/min inotrope, High: arrhythmias
mg/mL
vasoconstrictor
Central line
Norepinephrine 8 mg / 250 mL 2–30 Vasoconstriction, preferred;
(Levophed) → 32 mcg/mL mcg/min shock monitor BP
every 2–5 min
Often used in
4 mg / 250 mL 2–10 Inotrope + cardiac arrest
Epinephrine
→ 16 mcg/mL mcg/min vasoconstrictor and
anaphylaxis
Protect from
Arterial & venous
50 mg / 250 mL 0.3–10 light; risk of
Nitroprusside dilator, hypertensive
→ 200 mcg/mL mcg/kg/min cyanide
crisis
toxicity
20 units / 100 Often fixed
0.03–0.04 Shock unresponsive
Vasopressin mL → 0.2 dose; not
units/min to catecholamines
units/mL weight-based
5. Advanced Titration Strategies
1. Titrate to effect, not just dose:
o Dopamine: increase for MAP <65 mmHg or low urine output.
o Nitroprusside: increase for BP > target; decrease if hypotension
occurs.
2. Check every 5–15 minutes initially, then every 30 minutes once stable.
3. Combine drugs if needed:
o Dopamine + norepinephrine for refractory shock.
o Nitroprusside + beta-blocker to prevent reflex tachycardia.
IV Infusion
Calculations:
Titration Formulas
and Critical Care
Drips
,1. Introduction
Vasoactive medications are used in shock states, heart failure, hypertensive
crises, and other critical care situations. They modify heart rate, contractility,
vascular tone, and perfusion. Proper titration requires mastery of IV flow
calculations, weight-based dosing, and continuous monitoring.
2. Key Principles of Vasoactive Infusions
1. Always use a pump—never gravity drip.
2. Confirm patient weight for accurate mcg/kg/min dosing.
3. Know the concentration (mg/mL) before calculating.
4. Check vitals frequently: BP, MAP, HR, SpO₂, urine output, mental status.
5. Titrate slowly to avoid overshooting the target effect.
6. Central line preferred for high-concentration vasopressors (risk of tissue
necrosis if extravasation occurs).
3. Step-by-Step IV Drip Calculation
Formula:
Dose (mcg/kg/min) × Weight (kg) × 60
Flow rate (mL/hr) =
Concentration (mcg/mL)
• Convert mg → mcg if necessary (1 mg = 1000 mcg).
• Multiply by 60 to convert minutes → hours for pump settings.
• Round to nearest decimal for pump accuracy.
Example: Dopamine 10 mcg/kg/min, 70 kg patient, concentration 1.6 mg/mL →
10 × 70 × 60
𝐹𝑙𝑜𝑤 = = 26.25𝑚𝐿/ℎ𝑟
1600
, 4. Common Vasoactive Drugs & Critical Care Notes
Drug Concentration Dose Range Effects / Use Notes
Low: renal
400 mg / 250
2–20 perfusion, Mid: Monitor HR,
Dopamine mL → 1.6
mcg/kg/min inotrope, High: arrhythmias
mg/mL
vasoconstrictor
Central line
Norepinephrine 8 mg / 250 mL 2–30 Vasoconstriction, preferred;
(Levophed) → 32 mcg/mL mcg/min shock monitor BP
every 2–5 min
Often used in
4 mg / 250 mL 2–10 Inotrope + cardiac arrest
Epinephrine
→ 16 mcg/mL mcg/min vasoconstrictor and
anaphylaxis
Protect from
Arterial & venous
50 mg / 250 mL 0.3–10 light; risk of
Nitroprusside dilator, hypertensive
→ 200 mcg/mL mcg/kg/min cyanide
crisis
toxicity
20 units / 100 Often fixed
0.03–0.04 Shock unresponsive
Vasopressin mL → 0.2 dose; not
units/min to catecholamines
units/mL weight-based
5. Advanced Titration Strategies
1. Titrate to effect, not just dose:
o Dopamine: increase for MAP <65 mmHg or low urine output.
o Nitroprusside: increase for BP > target; decrease if hypotension
occurs.
2. Check every 5–15 minutes initially, then every 30 minutes once stable.
3. Combine drugs if needed:
o Dopamine + norepinephrine for refractory shock.
o Nitroprusside + beta-blocker to prevent reflex tachycardia.
