What is the recommended treatment for acute hypotension?

Management of Acute Hypotension

Norepinephrine is the first-line vasopressor for acute hypotension, initiated at 0.2-1.0 μg/kg/min targeting a mean arterial pressure (MAP) of 65 mmHg, administered preferably through a central line after rapid volume assessment. 1, 2, 3

Initial Assessment and Fluid Resuscitation

• Correct volume depletion first whenever possible before administering vasopressors, as blood volume depletion should always be addressed as fully as feasible 3
• Administer 30 mL/kg of crystalloids (approximately 1-2 L in adults) as an initial rapid bolus, using balanced crystalloids (lactated Ringer's) or normal saline 2
• In life-threatening hypotension, norepinephrine can be started before and concurrently with blood volume replacement to prevent cerebral or coronary artery ischemia 3
• Early norepinephrine administration (simultaneously with fluid resuscitation) should be prioritized in patients with profound hypotension defined by diastolic blood pressure ≤40 mmHg or diastolic shock index (heart rate/diastolic BP) ≥3 4

Norepinephrine Administration Protocol

• Dilute 4 mg/4 mL in 1,000 mL of 5% dextrose solution (final concentration 4 mcg/mL); administration in saline alone is not recommended 3
• Starting dose: 2-3 mL/min (8-12 mcg/min), then titrate to maintain MAP 65 mmHg or systolic BP 80-100 mmHg 3
• Maintenance dose typically ranges from 0.5-1 mL/min (2-4 mcg base/min), though individual variation is substantial 3
• Central venous access is strongly preferred to minimize tissue necrosis risk from extravasation 1, 2
• In previously hypertensive patients, raise blood pressure no higher than 40 mmHg below pre-existing systolic pressure 3

Context-Specific Modifications

Cardiogenic Shock with Hypotension

• Add dobutamine 2-20 μg/kg/min once blood pressure is stabilized with norepinephrine if persistent hypoperfusion with myocardial depression exists 5, 1, 2
• Dobutamine is initiated without bolus and causes less tachycardia than alternatives 2
• In patients with bradycardia, dopamine may be considered, but only in those with low tachyarrhythmia risk 5
• Avoid diuretics in acute heart failure patients with hypotension (SBP <90 mmHg) until adequate perfusion is restored 5, 1

Refractory Hypotension

• Add vasopressin up to 0.03 units/min to norepinephrine when MAP target is not achieved or to reduce norepinephrine requirements 5, 1, 2
• Vasopressin should not be used as the single initial vasopressor 2
• Epinephrine 0.05-0.5 μg/kg/min can be added or substituted when additional blood pressure support is needed 5, 1, 2
• If extremely high norepinephrine doses are required (>68 mg base daily), suspect occult blood volume depletion and correct it 3

Hemorrhagic Shock

• Fluid resuscitation must accompany vasopressor therapy, targeting systolic BP 80-90 mmHg until major bleeding is controlled 6
• Vasopressors can be used transiently in life-threatening hypotension but definitive hemorrhage control is paramount 5
• In pelvic trauma with hemorrhagic shock, immediate pelvic binder placement takes priority over aggressive fluid resuscitation 6

Critical Monitoring Requirements

• Continuous ECG and invasive arterial blood pressure monitoring is mandatory for accurate titration and detection of arrhythmias or myocardial ischemia 1, 2
• Monitor oxygen saturation, urine output, and serum lactate to assess end-organ perfusion 1, 2
• Central venous pressure monitoring is helpful in detecting occult blood volume depletion in patients requiring high vasopressor doses 3
• Echocardiography should be performed to evaluate volume status, cardiac function, and mechanical complications 2

Common Pitfalls to Avoid

• Never use vasodilators (nitrates, nitroprusside) in patients with SBP <90 mmHg as they reduce central organ perfusion 5
• Avoid abrupt withdrawal of norepinephrine; reduce infusion gradually once adequate blood pressure and tissue perfusion are maintained 3
• Do not delay norepinephrine for complete fluid resuscitation in profound, life-threatening hypotension, as prolonged hypotension worsens outcomes 4, 7
• Dopamine has fallen out of favor as first-line therapy due to increased adverse effects compared to norepinephrine and should only be used in highly selected patients 5, 1
• In patients with aortic or mitral stenosis, vasodilators can cause marked hypotension; phenylephrine or vasopressin are preferred if vasopressors are needed 5