Can intramuscular (IM) adrenaline be given to an adult patient in a primary setup with hypotension (low blood pressure) that is unresponsive to initial fluid resuscitation?

Intramuscular Adrenaline for Hypotension Unresponsive to Fluids in Primary Care

Yes, intramuscular (IM) adrenaline should be administered immediately in primary care settings when hypotension fails to respond to initial fluid resuscitation, as this represents anaphylaxis requiring urgent epinephrine as first-line therapy. 1

Immediate Management Algorithm

Step 1: Recognize Anaphylaxis and Administer IM Adrenaline First

• Administer IM adrenaline 0.3-0.5 mg (0.3-0.5 mL of 1:1000 solution) into the anterolateral thigh (vastus lateralis) immediately when hypotension persists despite fluid administration 1
• The thigh produces higher and more rapid peak plasma levels compared to deltoid injection, making it the preferred site 1
• There is no absolute contraindication to epinephrine administration in anaphylaxis, even in patients with cardiovascular disease, elderly patients, or those on beta-blockers 1
• Repeat every 5 minutes as necessary if hypotension persists 1

Step 2: Concurrent Fluid Resuscitation

• Administer crystalloid (normal saline or balanced salt solution) 500 mL-1 L as rapid bolus and repeat if inadequate response 1
• Large volumes may be required (up to 30 mL/kg in first hour for adults) as anaphylaxis can cause transfer of up to 35% of intravascular volume into extravascular space within minutes 1

Step 3: Supportive Measures

• Place patient in recumbent position with legs elevated 1
• Administer oxygen at 6-8 L/min 1
• Establish venous access if not already present 1

Critical Evidence Supporting IM Adrenaline

The most recent high-quality evidence demonstrates that early IM adrenaline prevents progression to severe hypotension. A 2016 incident case-control study found that adrenaline use in hemodynamically stable anaphylaxis patients was independently associated with a 75% lower risk of developing in-hospital hypotension (OR 0.254,95% CI 0.091-0.706) 2. This supports administering IM adrenaline even before severe hypotension develops.

Why IM Route is Appropriate in Primary Care

• IM adrenaline is safer than IV administration in settings without continuous hemodynamic monitoring 1
• Several anaphylaxis fatalities have been attributed to injudicious use of intravenous epinephrine 1
• IV epinephrine should only be used during cardiac arrest or in profoundly hypotensive patients who have failed to respond to multiple IM doses and IV volume replacement 1
• Adverse events from IM adrenaline are rare when properly administered 2

When to Consider IV Adrenaline (Only in Advanced Settings)

If the patient remains profoundly hypotensive after 2-3 IM doses and adequate fluid resuscitation, IV adrenaline may be necessary, but this requires:

• Transfer to emergency department or hospital setting 1
• Continuous hemodynamic monitoring 1
• Doses of 50 mcg (0.5 mL of 1:10,000 solution) for Grade III reactions, repeated every 2 minutes as needed 1

Common Pitfalls to Avoid

• Do not delay IM adrenaline while attempting to establish IV access - IM administration is faster and safer in primary care 1
• Do not use subcutaneous route - intramuscular injection produces higher and more rapid plasma levels 1
• Do not inject into the arm (deltoid) - the thigh (vastus lateralis) is superior for absorption 1
• Do not withhold adrenaline due to patient age or cardiovascular comorbidities - the risk of death from untreated anaphylaxis outweighs theoretical risks 1
• Do not substitute other vasopressors for initial adrenaline - epinephrine is the only first-line agent with alpha-agonist, beta-agonist, inotropic, bronchodilator, and mediator-release inhibition properties 1

Dosing Summary for Primary Care

Adults: 0.3-0.5 mg IM (0.3-0.5 mL of 1:1000 solution) into anterolateral thigh, repeat every 5 minutes as needed 1

Children: 0.01 mg/kg IM (maximum 0.3 mg), or use weight-based dosing:

• 12 years: 0.5 mg (0.3 mg if small) 1

• 6-12 years: 0.3 mg 1
• <6 years: 0.15 mg 1

Transfer Criteria

Arrange immediate transfer to emergency department if:

• More than 2-3 doses of IM adrenaline required 1
• Hypotension persists despite IM adrenaline and fluid resuscitation 1
• Respiratory compromise requiring advanced airway management 1
• Any patient who received adrenaline should be observed in hospital setting due to risk of biphasic reactions (10.3% incidence) 1