What is the dosing for epinephrine (epi) in mcg/min for an adult patient with acute hypotension on high-dose norepinephrine in the cath lab?

Epinephrine Dosing for Acute Hypotension in the Cath Lab

For an adult patient with acute hypotension on high-dose norepinephrine in the cath lab, start epinephrine at 0.05 mcg/kg/min (approximately 3.5-5 mcg/min for a 70 kg patient) and titrate up to 2 mcg/kg/min (140 mcg/min) in increments of 0.05-0.2 mcg/kg/min every 10-15 minutes to achieve a mean arterial pressure of 65 mmHg. 1

Preparation and Initial Dosing

Standard concentration preparation:

• Dilute 1 mg (1 mL) of epinephrine in 1,000 mL of 5% dextrose solution to produce a 1 mcg/mL concentration 1
• This diluted solution can be stored for up to 4 hours at room temperature or 24 hours under refrigeration 1
• Avoid administration in saline solution alone 1

Starting dose:

• Begin at 0.05 mcg/kg/min (approximately 3.5 mcg/min for a 70 kg adult) 1
• This translates to roughly 210 mL/hour using the standard 1 mcg/mL concentration 1

Titration Strategy

Dose escalation protocol:

• Adjust every 10-15 minutes in increments of 0.05-0.2 mcg/kg/min 1
• Maximum dose: 2 mcg/kg/min (approximately 140 mcg/min for a 70 kg patient) 1
• Target: Mean arterial pressure ≥65 mmHg 1

Administration Route and Monitoring

Vascular access:

• Administer through a large vein whenever possible 1
• Avoid catheter tie-in techniques that may cause stasis and increased local drug concentration 1
• Avoid leg veins in elderly patients or those with occlusive vascular disease 1

Monitoring requirements:

• Blood pressure every 5-15 minutes during initial titration 2
• Continuous cardiac monitoring for arrhythmias 3
• Assess tissue perfusion markers: capillary refill, urine output, mental status 2

Clinical Context for Epinephrine Addition

When to add epinephrine to norepinephrine:

• When norepinephrine reaches 0.25 mcg/kg/min and hypotension persists 2
• For refractory hypotension despite adequate fluid resuscitation (minimum 30 mL/kg crystalloid) 2, 4
• In the context of perioperative allergic reactions (Grade III-IV) where vasopressors are insufficient 5

Alternative approach for severe refractory shock:

• If inadequate response after 10 minutes, consider epinephrine infusion at 0.05-0.1 mcg/kg/min 5
• For Grade IV reactions (cardiac arrest), follow advanced life support guidelines with 1 mg IV boluses 5

Weaning Protocol

Once hemodynamic stabilization achieved:

• Wean incrementally over 12-24 hours 1
• Decrease doses every 30 minutes 1
• Monitor for recurrent hypotension during weaning 1

Critical Pitfalls to Avoid

Volume status:

• Never start epinephrine without addressing hypovolemia first 2, 4
• Ensure at least 30 mL/kg crystalloid bolus before or concurrent with vasopressor initiation 4

Drug compatibility:

• Do not mix epinephrine with sodium bicarbonate or other alkaline solutions, as adrenergic agents are inactivated in alkaline solutions 2

Extravasation risk:

• If extravasation occurs, immediately infiltrate 5-10 mg phentolamine diluted in 10-15 mL saline at the site to prevent tissue necrosis 2, 3

Excessive vasoconstriction:

• Monitor for cold extremities, decreased urine output, and signs of end-organ hypoperfusion 2
• Consider adding dobutamine up to 20 mcg/kg/min if myocardial dysfunction with persistent hypoperfusion despite adequate vasopressors 2

Special Considerations for Cath Lab Setting

Myocardial oxygen demand:

• Use cautiously in patients with ischemic heart disease, as epinephrine increases myocardial oxygen consumption 3
• This is particularly relevant in the cath lab where patients may have acute coronary syndromes 3

Alternative vasopressor options:

• If arrhythmias develop with epinephrine, consider switching to phenylephrine or adding vasopressin 0.03-0.04 units/min 2
• Vasopressin should be added when norepinephrine reaches 0.25 mcg/kg/min before escalating to epinephrine in septic shock, but in cardiogenic or anaphylactic shock, epinephrine may be more appropriate 2, 6