What are the medications used to treat hypotension?

Medications for Treating Hypotension

Norepinephrine is the first-line vasopressor for treating hypotension, initiated at 0.1-0.5 mcg/kg/min (or 0.2-1.0 μg/kg/min) via central line to maintain mean arterial pressure ≥65 mmHg. 1, 2

Initial Management Algorithm

Step 1: Rapid Volume Assessment and Fluid Resuscitation

• Administer crystalloids immediately if the patient shows signs of hypovolemia or has a positive passive leg raise test 1, 2
• Give an initial bolus of 30 mL/kg (approximately 1-2 L in adults) of crystalloids rapidly, preferably lactated Ringer's solution or normal saline 1, 2
• Continue fluid administration as long as hemodynamic parameters (blood pressure, heart rate, peripheral perfusion) improve 2
• Albumin may be added when patients require substantial amounts of crystalloids 1

Step 2: First-Line Vasopressor Therapy

• Start norepinephrine as the primary vasopressor after rapid volume assessment 3, 1, 2
• Target mean arterial pressure (MAP) ≥65 mmHg 1, 2
• Central line administration is strongly preferred to minimize risk of tissue necrosis from extravasation 1, 4
• Typical starting dose: 0.1-0.5 mcg/kg/min, titrated to effect 1

Step 3: Second-Line Vasopressor Options (If Norepinephrine Insufficient)

When norepinephrine alone fails to maintain adequate blood pressure:

• Add vasopressin at 0.03 units/min (do not exceed this dose) to raise MAP or decrease norepinephrine requirements 1, 2
• Alternatively, add epinephrine at 0.05-0.5 μg/kg/min as a second-line agent for refractory shock 3, 1, 2
• Avoid dopamine due to risk of tachyarrhythmias, except in highly selected patients with relative bradycardia 2, 5

Step 4: Inotropic Support for Low Cardiac Output States

When hypotension is due to reduced cardiac output (cardiogenic shock):

• Add dobutamine at 2-20 μg/kg/min (start at 2-5 mcg/kg/min) after blood pressure is stabilized with norepinephrine 3, 1, 2
• Dobutamine is given without a bolus dose 1
• Consider milrinone (25-75 μg/kg bolus over 10-20 min, then 0.375-0.75 μg/kg/min) if tachycardia is problematic with dobutamine 3
• Levosimendan (0.1 μg/kg/min, adjustable to 0.05-0.2 μg/kg/min) may be used if counteracting beta-blocker effects is necessary 3

Specific Clinical Scenarios

Cardiogenic Shock with Severe Hypoperfusion

• Norepinephrine first to maintain MAP ≥65 mmHg 6, 2
• Then add dobutamine (2.5-10 μg/kg/min) if evidence of low cardiac output persists 6, 2
• Reserve inotropes for patients with such severe reduction in cardiac output that vital organ perfusion is compromised 3

Refractory Shock Requiring High-Dose Vasopressors

• Add hydrocortisone 50 mg IV every 6 hours (or 200-mg continuous infusion) for 7 days or until ICU discharge 1
• Consider epinephrine as an additional agent or substitute for norepinephrine 2

Dopamine Dosing (When Used Despite Limitations)

• Low dose (<3 μg/kg/min): Potential renal effect (uncertain benefit) 3, 5
• Medium dose (3-5 μg/kg/min): Inotropic effect 3
• High dose (>5 μg/kg/min): Inotropic plus vasopressor effect 3
• Monitor arterial oxygen saturation as dopamine may cause hypoxemia; administer supplemental oxygen as needed 3

Critical Monitoring Requirements

• Continuous monitoring of ECG, blood pressure, oxygen saturation, and urine output 6, 1, 2
• Arterial blood gas and serum lactate levels to assess tissue perfusion 6, 2
• Invasive hemodynamic monitoring (arterial and central venous catheter) may be needed for adequate assessment and titration 1
• Echocardiography to evaluate volume status, cardiac function, and mechanical complications 1

Important Caveats and Pitfalls

Vasopressor-Related Risks

• Norepinephrine can cause tissue necrosis if extravasation occurs; central line administration is mandatory 6, 1
• Inotropes cause sinus tachycardia and may induce myocardial ischemia and arrhythmias; there is long-standing concern about increased mortality 3
• Epinephrine overdosage may produce extremely elevated arterial pressure, cerebrovascular hemorrhage, pulmonary edema, and fatal cardiac arrhythmias 4

Drug Interactions

• Tricyclic antidepressants potentiate cardiovascular effects of adrenergic agents 5
• Beta-blockers antagonize cardiac effects of dopamine and dobutamine 5
• Butyrophenones and phenothiazines can suppress dopaminergic renal vasodilation 5
• Phenytoin administration to patients receiving dopamine may lead to hypotension and bradycardia; consider alternatives 5

Fluid Therapy Considerations

• Avoid excessive fluid administration as hypotension is associated with higher mortality when blood pressure drops too low 3
• Balanced crystalloids (lactated Ringer's) are preferred over normal saline 1, 2
• Use fluid challenge technique: continue administration only as long as hemodynamic improvement occurs 1