What intravenous (IV) medications can be given as a bolus for hypotension?

Intravenous Bolus Medications for Hypotension

Yes, several medications can be given as intravenous bolus for hypotension, with phenylephrine (50-250 mcg) being the most commonly used for perioperative hypotension, and push-dose epinephrine (10-20 mcg) serving as an alternative for refractory cases, though the choice depends critically on the underlying cause of hypotension. 1, 2

Initial Assessment Before Bolus Administration

Before administering any vasopressor bolus, you must determine the cause of hypotension through rapid bedside assessment 3:

• Check for hypovolemia: Look for tachycardia, oliguria, decreased skin turgor, and perform a passive leg raise (PLR) test—if PLR corrects hypotension, the patient needs fluid, not vasopressors 3, 4
• Assess for vasodilation: Warm extremities with low blood pressure despite adequate filling suggests need for vasopressors 4
• Evaluate cardiac output: Cold extremities, cyanosis, decreased mentation, and pulmonary congestion indicate low cardiac output requiring inotropes instead of vasopressors 4
• Rule out arrhythmia: Obtain immediate ECG to identify bradycardia or other rhythm disturbances 4

Primary Bolus Vasopressor Options

Phenylephrine (First-Line for Perioperative Hypotension)

For perioperative hypotension with neuraxial or general anesthesia, give 50-250 mcg IV bolus, with 50-100 mcg being the most frequently reported initial dose. 1

• Preparation: Dilute 10 mg (1 mL of 10 mg/mL) in 99 mL of normal saline or D5W to create 100 mcg/mL solution 1
• Critical caveat: Phenylephrine causes reflex bradycardia, so it should be preferentially used when hypotension is accompanied by tachycardia 3
• Avoid phenylephrine as first-line in preload-independent states where reflex bradycardia can worsen cardiac output 4
• For septic or vasodilatory shock, phenylephrine is given as continuous infusion (0.5-6 mcg/kg/min) rather than bolus 1

Push-Dose Epinephrine (Alternative for Refractory Hypotension)

For hypotension refractory to fluid resuscitation or as a bridge to continuous vasopressor infusion, give 10-20 mcg IV push every 2 minutes until systolic blood pressure ≥90 mmHg or MAP ≥65 mmHg. 2

• Preparation: Use 1:100,000 epinephrine concentration (10 mcg/mL) 2
• Median MAP increase is 13 mmHg per dose with minimal heart rate increase (median 2 bpm) 2
• Resolves hypotension in approximately 58.5% of cases 2
• Particularly useful in post-cardiac arrest hypotension refractory to IV fluids 5
• Adverse events are rare when properly dosed, though transient extreme hypertension can occur 2

Norepinephrine Bolus (Emerging Alternative)

Norepinephrine 6 mcg IV bolus can be used as an alternative to phenylephrine, with the advantage of causing significantly less bradycardia (10.7% vs 37.5% with phenylephrine). 6

• Results in 71% relative reduction in bradycardia compared to equipotent phenylephrine doses 6
• Reduces need for rescue ephedrine boluses (7.2% vs 21.4% with phenylephrine) 6
• Provides superior hemodynamic profile with less heart rate fluctuation 6

Push-Dose Vasopressin (Novel Option for Septic Shock)

One unit of IV vasopressin push bolus can improve hemodynamics in vasodilatory septic shock, with effects lasting approximately 120 minutes. 7

• Case reports demonstrate rapid improvement in blood pressure within 1 minute of administration 7
• May serve as bridge to continuous vasopressor infusion 7
• Limited evidence currently available; requires further validation before routine use 7

When NOT to Use Bolus Vasopressors

Do not give vasopressor boluses in the following situations 3, 4, 8:

• Hypovolemia: If PLR test is positive or patient shows signs of volume depletion, give 250-500 mL crystalloid bolus first 4, 8
• Low cardiac output states: Cold extremities with pulmonary congestion require inotropes (dobutamine 2-5 mcg/kg/min), not vasopressors 3, 4
• Acute heart failure with hypoperfusion: Avoid all vasopressors until adequate perfusion is restored with fluid or inotropes 3

Critical Pitfalls to Avoid

• Approximately 50% of hypotensive patients are NOT fluid-responsive, making reflexive fluid administration before PLR testing potentially harmful 3, 4, 8
• Never use phenylephrine in bradycardic patients or those with suspected low cardiac output, as reflex bradycardia will worsen hemodynamics 3, 4
• Correct acidosis before vasopressor administration, as acidosis reduces vasopressor effectiveness 1
• Monitor continuously during and after bolus administration for arrhythmias, excessive hypertension, and end-organ perfusion 3
• Transition to continuous infusion if repeated boluses are needed—bolus dosing is meant as temporary measure or bridge therapy 7, 2

Special Considerations for Anaphylaxis

In anaphylaxis with profound hypotension refractory to epinephrine injections and volume replacement, give IV epinephrine 0.01 mg/kg (0.1 mL/kg of 1:10,000 solution; maximum 0.3 mg) slowly over 3 minutes with continuous hemodynamic monitoring. 3

• This is reserved only for profoundly hypotensive patients who have failed multiple IM epinephrine doses and IV fluids 3
• Risk of potentially lethal arrhythmias requires continuous ECG monitoring 3
• For refractory hypotension despite epinephrine, add dopamine infusion 2-20 mcg/kg/min 3