What is the recommended dosage of adrenaline (epinephrine) infusion for a patient with potential anaphylaxis or severe hypotension in the context of Thrombotic Thrombocytopenic Purpura (TTP) management?

Adrenaline (Epinephrine) Infusion Dosage

For adults with anaphylaxis requiring continuous epinephrine infusion after failed intramuscular injections and volume resuscitation, prepare 1 mg (1 mL) of 1:1000 epinephrine in 250 mL D5W (yielding 4 mcg/mL) and infuse at 1-4 mcg/min initially, titrating up to a maximum of 10 mcg/min based on clinical response. 1

Preparation Methods

Standard Adult Infusion (Preferred Method)

• Add 1 mg (1 mL) of 1:1000 epinephrine to 250 mL D5W to yield a concentration of 4.0 mcg/mL 1
• Infuse at 1-4 mcg/min (15-60 drops per minute with microdrop apparatus where 60 drops/min = 1 mL = 60 mL/h) 1
• Titrate up to a maximum of 10 mcg/min for adults and adolescents 1

Alternative Adult Infusion (With Infusion Pump)

• Prepare 1:100,000 solution: 1 mg (1 mL) epinephrine in 100 mL normal saline 1
• Initial rate: 30-100 mL/h (5-15 mcg/min) 1, 2
• Titrate up or down based on clinical response or epinephrine toxicity 1

Pediatric Dosing

Standard Pediatric Dose

• 0.01 mg/kg (0.1 mL/kg of 1:10,000 solution; maximum single dose 0.3 mg) 1

"Rule of 6" for Pediatric Infusion

• 0.6 × body weight (kg) = number of milligrams diluted to total 100 mL saline 1
• Then 1 mL/h delivers 0.1 mcg/kg/min 1

Critical Indications for IV Infusion

IV epinephrine should ONLY be used in these specific circumstances: 1, 2

• Cardiac arrest 1
• Profoundly hypotensive patients who have failed to respond to:
  • IV volume replacement (1-2 L normal saline at 5-10 mL/kg in first 5 minutes for adults) 1
  • Several intramuscular epinephrine injections 1, 2

Monitoring Requirements

Essential Monitoring

• Continuous hemodynamic monitoring is mandatory when available (emergency department or ICU setting) 1
• If continuous monitoring unavailable but IV epinephrine deemed essential: 1
  • Every-minute blood pressure measurements
  • Continuous pulse monitoring
  • Electrocardiographic monitoring if available

Rationale for Strict Monitoring

The risk of potentially lethal arrhythmias necessitates extreme caution with IV epinephrine administration. 1

Cardiac Arrest Dosing (Distinct from Anaphylaxis Infusion)

Adult Cardiac Arrest from Anaphylaxis

• High-dose IV epinephrine: 1-3 mg (1:10,000 dilution) slowly over 3 minutes, then 3-5 mg over 3 minutes, followed by 4-10 mg/min infusion 1

Pediatric Cardiac Arrest

• 0.01 mg/kg (0.1 mL/kg of 1:10,000 solution, maximum 0.3 mg) repeated every 3-5 minutes 1
• Alternative: Start epinephrine infusion delivering up to 10 mg 1

Alternative for Severe Hypotension (Non-Cardiac Arrest)

IV Bolus Method (When Infusion Not Immediately Available)

• Aqueous epinephrine 1:1000,0.1-0.3 mL in 10 mL normal saline 1
• Administer IV over several minutes 1
• Repeat as necessary for anaphylaxis not responding to IM injections and volume resuscitation 1

Contemporary Evidence for IV Bolus

• 0.05-0.1 mg IV (5-10% of cardiac arrest dose) has been used successfully for anaphylactic shock when IV access already established 1

Common Pitfalls and Critical Safety Points

Concentration Confusion (Life-Threatening Error)

• 1:1000 (1 mg/mL) is for IM injection ONLY 2, 3
• 1:10,000 (0.1 mg/mL) is for IV bolus use 2, 3
• 1:100,000 or 1:250,000 are for continuous infusion 1, 2
• Confusion between concentrations has caused iatrogenic overdoses with transient severe systolic dysfunction and potentially lethal cardiac complications 3

When NOT to Use IV Epinephrine

• Never use IV route as first-line treatment 2
• Intramuscular route is safer and preferred for initial anaphylaxis management 2
• IV epinephrine carries significant risk of dilution/dosing errors and serious adverse effects 2

Premature Escalation to IV Route

• Most patients (90-80%) respond to 1-2 intramuscular doses of epinephrine 2
• Repeat IM dosing every 5 minutes before considering IV infusion 1, 2
• There is no maximum number of IM doses—continue until symptoms resolve 2

Supporting Therapies During Infusion

Concurrent Vasopressor if Refractory

• Dopamine 400 mg in 500 mL D5W at 2-20 mcg/kg/min if hypotension persists despite epinephrine and volume 1
• Titrate to maintain systolic BP >90 mmHg 1

Beta-Blocker Complication

• Consider glucagon 1-5 mg IV over 5 minutes (20-30 mcg/kg in children, maximum 1 mg) followed by infusion at 5-15 mcg/min 1
• Beta-blockade can cause refractory anaphylaxis with paradoxical worsening from epinephrine through unopposed alpha-adrenergic effects 1

Clinical Evidence Supporting Infusion Protocol

A prospective study of 19 adults with anaphylaxis (8 with systolic BP <90 mmHg) received 1:100,000 epinephrine IV at 30-100 mL/h (5-15 mcg/min) titrated to response. 1

• 18 of 19 patients achieved symptomatic improvement and BP >90 mmHg within 5 minutes 1
• Infusion discontinued 30 minutes after resolution of all symptoms 1

Context for TTP Management

While the question references TTP, these epinephrine dosing guidelines apply universally to anaphylaxis or severe hypotension regardless of underlying condition. 1 The presence of TTP does not alter standard anaphylaxis management protocols, though additional supportive care for TTP-related complications may be necessary concurrently.