Is morphine (opioid analgesic) recommended for anaphylactic reaction during cardiac catheterization?

Morphine is NOT Recommended for Anaphylactic Reaction During Cardiac Catheterization

Morphine should be avoided during anaphylactic reactions because it can worsen hypotension and cardiovascular collapse, and epinephrine is the only definitive first-line treatment for anaphylaxis. 1

Why Morphine is Contraindicated in Anaphylaxis

Hemodynamic Concerns

• Morphine causes severe hypotension in patients whose blood pressure is already compromised, which is precisely the situation in anaphylactic shock 2
• The FDA label explicitly warns that morphine should be administered with caution to patients in circulatory shock, since vasodilation produced by the drug may further reduce cardiac output and blood pressure 2
• Morphine produces orthostatic hypotension and can cause cardiovascular depression, bradycardia, and even cardiac arrest 2
• A case report documented cardiogenic shock induced by high-dose intravenous morphine, demonstrating its potential to cause severe cardiovascular compromise 3

Morphine Can Itself Cause Anaphylaxis

• Although extremely rare, cases of anaphylaxis to morphine have been reported 2
• A documented case exists of morphine-induced anaphylaxis before induction of anesthesia that resulted in pulseless electrical activity requiring chest compressions and epinephrine 4
• Morphine can cause histamine release, potentially worsening an existing anaphylactic reaction 2

Respiratory Depression Risk

• Morphine causes respiratory depression, which can be life-threatening in patients already experiencing bronchospasm from anaphylaxis 2
• Even usual therapeutic doses may decrease respiratory drive while simultaneously increasing airway resistance to the point of apnea 2

Correct Management of Anaphylaxis During Cardiac Catheterization

Immediate First-Line Treatment

• Epinephrine is the cornerstone and only definitive treatment for anaphylaxis 1, 5
• Administer IV epinephrine 50 mcg (0.5 mL of 1:10,000 solution) for adults immediately, repeated as needed 5
• If IV access is unavailable, give intramuscular epinephrine 0.2-0.5 mg (1:1000) into the lateral thigh 1
• Standard BLS and ACLS measures including airway management take priority 1

Continuous Epinephrine Infusion

• If multiple boluses are required, start continuous IV infusion: 1 mg (1 mL of 1:1000) in 250 mL D5W = 4 mcg/mL, infuse at 1-4 mcg/min initially, titrate up to 10 mcg/min 5
• Alternative preparation: 1 mg in 100 mL saline (1:100,000), infuse at 30-100 mL/h (5-15 mcg/min) 5
• Epinephrine has a short half-life requiring continuous infusion rather than bolus administration for sustained effect 6

Aggressive Fluid Resuscitation

• Administer normal saline 0.9% or lactated Ringer's at high rate through large-bore IV 5
• Adults: 1-2 L at 5-10 mL/kg in first 5 minutes, up to 7 L may be required 5
• Increased vascular permeability can transfer 50% of intravascular fluid to extravascular space within 10 minutes 5

Adjunctive Medications (Secondary to Epinephrine)

• Chlorphenamine 10 mg IV (adult dose) 5
• Hydrocortisone 200 mg IV (adult dose) 5
• Note: There is no proven benefit from antihistamines, inhaled beta agonists, and IV corticosteroids during anaphylaxis-induced cardiac arrest 1

Airway Management

• Secure airway and administer 100% oxygen - intubate if necessary 5
• Given the potential for rapid development of oropharyngeal or laryngeal edema, immediate referral to a professional with expertise in advanced airway placement, including surgical airway management, is recommended 1

Special Considerations for Cardiac Catheterization Setting

Contrast Media Reactions

• The incidence of anaphylactoid reactions to contrast media is 1%, with severe reactions occurring in 0.04% of cases 1
• Hypotension is the most frequent initial presentation of anaphylactic shock during cardiac catheterization (76.5% of cases) 7
• Unconsciousness at initial onset implies poor prognosis 7

Prophylaxis for High-Risk Patients

• Patients with prior anaphylactoid reaction to contrast media should receive steroid and antihistamine prophylaxis: 50 mg prednisone at 13 hours, 7 hours, and 1 hour before procedure, plus 50 mg diphenhydramine 1 hour before 1
• In practice, 60 mg prednisone the night before and morning of procedure plus 50 mg diphenhydramine 1 hour before is often used 1

Common Pitfalls to Avoid

• Do not administer morphine thinking it will help with patient comfort during anaphylaxis - it will worsen hypotension and potentially cause respiratory depression 2
• Do not delay epinephrine administration - it is the definitive treatment with alpha-agonist (vasoconstriction), beta-agonist (inotropy, bronchodilation), and mediator release inhibition properties 5
• Do not exclude anaphylaxis based on absence of cutaneous signs - 28% of cases lack skin manifestations 5
• Do not assume tachycardia will be present - bradycardia occurs in 10% of cases 5
• Stop all potential causative agents (IV colloids, latex, chlorhexidine, antibiotics) immediately 5

When Morphine IS Appropriate (Not During Anaphylaxis)

• Morphine may be reasonable for patients with unstable angina/NSTEMI whose symptoms are not relieved despite nitroglycerin, but this is a Class IIa recommendation that has been downgraded due to observational data showing higher adjusted likelihood of death (OR 1.41) 1
• Morphine should never be used as treatment for anaphylaxis itself 1, 5