Is plasma transfusion used in the treatment of anaphylaxis?

Is Plasma Given to Anaphylaxis?

No, plasma transfusion is not used in the treatment of anaphylaxis and has no role in standard anaphylaxis management protocols.

First-Line Treatment: Epinephrine Only

The cornerstone of anaphylaxis treatment is intramuscular epinephrine, not plasma or any blood product. Epinephrine 0.01 mg/kg (maximum 0.5 mg in adults, 0.3 mg in children) administered intramuscularly into the anterolateral thigh is the only first-line treatment for anaphylaxis. 1 This achieves peak plasma concentrations in 8±2 minutes, far faster than any alternative route or medication. 1, 2

Volume Resuscitation: Crystalloids, Not Plasma

When fluid resuscitation is needed for anaphylactic shock, crystalloid solutions (normal saline or lactated Ringer's) are the appropriate choice, not plasma or colloids. 2

• For Grade II reactions: initial bolus of 0.5 L crystalloids 2
• For Grade III reactions: initial bolus of 1 L crystalloids 2
• Repeat boluses up to 20-30 mL/kg based on clinical response 2
• In children: up to 30 mL/kg within the first hour 2

The rationale is straightforward: anaphylaxis causes vasodilation and capillary leak, requiring rapid volume expansion to restore preload. 2 Crystalloids accomplish this effectively without the risks, cost, or delays associated with plasma products.

Why Plasma Has No Role

The pathophysiology of anaphylaxis involves mast cell and basophil degranulation with release of histamine, tryptase, and other mediators, leading to vasodilation, increased vascular permeability, bronchospasm, and cardiovascular collapse. 1 None of these mechanisms are addressed by plasma transfusion. Plasma does not:

• Reverse vasodilation (epinephrine does via α-adrenergic effects) 1
• Relieve bronchospasm (epinephrine does via β2-adrenergic effects) 1
• Stabilize mast cells (epinephrine does) 1
• Provide inotropic support (epinephrine does) 1

Complete Anaphylaxis Treatment Algorithm

Immediate actions (in order):

1. Intramuscular epinephrine 0.3-0.5 mg (adults ≥30 kg) or 0.01 mg/kg (children, max 0.3 mg) into mid-outer thigh; repeat every 5-15 minutes if symptoms persist 1, 2, 3
2. Position supine with legs elevated (unless respiratory distress) 2, 3
3. Call for emergency assistance immediately 2, 3
4. Establish IV access and begin crystalloid resuscitation if cardiovascular involvement 2
5. Supplemental oxygen 6-8 L/min for respiratory symptoms 2

Second-line adjuncts (after epinephrine):

• H1 antihistamines (diphenhydramine 25-50 mg IV) for urticaria only—does not treat airway obstruction, bronchospasm, or shock 1, 2
• H2 antihistamines (ranitidine 50 mg IV) with minimal evidence of benefit 1, 2
• Inhaled albuterol for persistent bronchospasm after epinephrine 2
• Corticosteroids are not recommended for acute anaphylaxis due to slow onset (4-6 hours) and no proven benefit in preventing biphasic reactions 1, 2

Refractory anaphylaxis:

• IV epinephrine infusion 0.05-0.1 µg/kg/min if more than 3 boluses required 2
• Alternative vasopressors (norepinephrine, vasopressin, phenylephrine) for persistent hypotension 2
• Glucagon 1-2 mg IV for patients on β-blockers 2

Critical Pitfalls to Avoid

• Never delay epinephrine while establishing IV access or administering other medications—delayed epinephrine is directly associated with anaphylaxis fatalities 1, 3
• Never substitute antihistamines or corticosteroids for epinephrine—they do not prevent cardiovascular collapse or airway obstruction 1, 4
• Never use plasma or colloids for volume resuscitation—crystalloids are the standard 2
• There are no absolute contraindications to epinephrine in anaphylaxis, even in elderly patients with cardiovascular disease 1, 2

Post-Treatment Requirements

• Observe minimum 4-6 hours in a facility equipped to manage anaphylaxis 2
• Extended observation (≥6 hours) or admission for patients requiring >1 epinephrine dose, severe initial presentation, wide pulse pressure, unknown trigger, or cardiovascular comorbidity 2
• Discharge with two epinephrine autoinjectors and written emergency action plan 2, 3
• Referral to allergist within 1-2 weeks 2