Treatment of Hypotension Episodes
The treatment of hypotension should be based on the underlying cause, including vasodilation, hypovolemia, bradycardia, and low cardiac output, with specific therapies targeted to each mechanism. 1
Initial Assessment and Classification
When evaluating hypotension (typically defined as systolic BP <90 mmHg or MAP <70 mmHg), it's essential to determine the etiology through:
- Clinical presentation: Symptoms (dizziness, lightheadedness, weakness, fatigue)
- Signs of end-organ hypoperfusion: Altered mental status, oliguria, elevated lactate
- Hemodynamic pattern: Using ultrasound when available to determine shock type
Classification of Hypotension Types
- Cardiogenic shock: Hypoperfusion characterized by systolic pressure <90 mmHg and central filling pressure >20 mmHg, or cardiac index <1.8 l/min/m² 2
- Distributive shock: Vasodilation with normal or high cardiac output (sepsis, anaphylaxis)
- Hypovolemic shock: Decreased preload due to fluid loss
- Obstructive shock: Mechanical obstruction to cardiac output
- Neurogenic/orthostatic hypotension: Autonomic dysfunction
Treatment Algorithm by Hypotension Type
1. Hypovolemic Hypotension
- First-line: IV fluid resuscitation with normal saline (10-20 ml/kg; maximum 1,000 ml) 1
- Assessment: Use passive leg raise test to predict fluid responsiveness
- Special situations: Consider colloid solutions in patients with capillary leak and hypoalbuminemia
2. Cardiogenic Hypotension
- First-line for myocardial depression: Inotropes (dobutamine, dopamine, phosphodiesterase III inhibitors) 2
- For persistent hypotension with tachycardia: Add norepinephrine 2
- For bradycardia: Consider dopamine (initial dosage 2.5–5.0 μg/kg/min) 2
- For afterload-dependent states (aortic/mitral stenosis): Use phenylephrine or vasopressin 2
- For pulmonary congestion: Start dobutamine at 2.5 μg/kg/min, gradually increase to 10 μg/kg/min 2
3. Distributive Hypotension (e.g., sepsis)
- First-line: Norepinephrine after adequate fluid resuscitation 2
- Second-line: Add vasopressin (up to 0.03 UI/min) if hypotension persists 2
- For myocardial depression: Add dobutamine to norepinephrine or use epinephrine as a single agent 2
4. Orthostatic Hypotension
Non-pharmacological interventions:
- Increased salt intake (6-10g daily)
- Physical counter-pressure maneuvers
- Compression garments providing 30-40 mmHg pressure 1
Pharmacological treatment:
Dosing and Administration of Key Medications
Norepinephrine (Levophed)
- Preparation: Add 4 mg to 1,000 mL of 5% dextrose solution (4 mcg/mL)
- Initial dose: 2-3 mL/min (8-12 mcg/min)
- Maintenance: 0.5-1 mL/min (2-4 mcg/min)
- Target: Maintain systolic BP 80-100 mmHg or 40 mmHg below baseline in previously hypertensive patients 4
Dobutamine
- Initial dose: 2.5 μg/kg/min
- Titration: Increase gradually at 5–10 min intervals up to 10 μg/kg/min 2
Special Considerations
Cardiogenic Shock Management
- Oxygen should be administered immediately
- Consider endotracheal intubation if oxygen tension remains <60 mmHg despite 100% oxygen
- Monitor blood gases and electrolytes regularly
- Consider invasive hemodynamic monitoring for severe cases 2
Monitoring and Targets
- Target MAP of 65 mmHg in most patients
- Use continuous arterial pressure monitoring when possible to reduce severity and duration of hypotension 2
- Monitor other markers of perfusion: lactate clearance, urine output, mental status 1
Common Pitfalls to Avoid
- Assuming all hypotension is due to hypovolemia
- Focusing on BP numbers rather than symptoms and end-organ perfusion
- Administering vasopressors without adequate fluid resuscitation
- Delaying vasopressors in patients with life-threatening hypotension 1
- Treating hypertension too aggressively, which can lead to hypotension 2
By following this structured approach based on the underlying cause of hypotension, clinicians can effectively manage episodes of hypotension and improve patient outcomes.