1.3 Preoperative Allergy Screening & Sensitivity Protocols

Preoperative Allergy Screening & Sensitivity Protocols

Accurate identification of patient allergies and adverse drug sensitivities is essential for perioperative safety. The perioperative nurse must distinguish between non-allergic adverse drug events (e.g., gastrointestinal upset from erythromycin or nausea from opioids) and true immune-mediated hypersensitivity reactions. Immune-mediated reactions range from mild cutaneous eruptions to life-threatening Type I IgE-mediated anaphylaxis and pharmacogenetic crises such as Malignant Hyperthermia (MH).

Latex Allergy Protocols & Sensitivity Risk Stratification

Natural rubber latex (NRL) sensitivity remains a significant perioperative concern. Latex allergens consist of water-soluble proteins derived from the rubber tree (Hevea brasiliensis).

High-Risk Patient Populations

1. Spina Bifida / Myelomeningocele: Prevalence of latex allergy reaches up to 70% due to early, repeated mucosal and surgical exposure to latex catheters and gloves.
2. Congenital Urological Abnormalities: Bladder exstrophy, neurogenic bladder requiring chronic clean intermittent catheterization.
3. Multiple Surgical Procedures: History of 9 or more surgical operations.
4. Occupational Exposure: Healthcare workers, rubber industry workers.
5. Latex-Fruit Syndrome: Patients with documented food allergies to fruits containing cross-reactive proteins: banana, avocado, kiwi, chestnut, passion fruit, papaya, potato, and tomato.

Spectrum of Latex Reactions

• Irritant Contact Dermatitis: Non-immunological skin irritation caused by hand washing, powder, or mechanical friction. Characterized by dry, itchy, cracked skin. Not a true allergy.
• Type IV Delayed Hypersensitivity (Cell-Mediated): T-cell mediated reaction to chemical accelerators (thiurams, carbamates) added during rubber manufacturing. Symptoms appear 24 to 48 hours post-exposure as localized vesicular dermatitis.
• Type I Immediate Hypersensitivity (IgE-Mediated): True systemic allergic reaction triggered by IgE antibodies binding to latex proteins. Symptoms occur within minutes of contact or inhalation of airborne powder: generalized urticaria, angioedema, rhinitis, severe bronchospasm, laryngeal edema, profound hypotension, and cardiovascular collapse.

Perioperative Latex-Safe Protocol Implementation

• First Case of the Day: Schedule latex-allergic patients as the first operative case of the morning. This allows airborne latex allergen concentrations (attached to glove powder from previous cases) to settle overnight, maintaining ambient levels < 10 µg/m³.
• OR Environment Preparation: Post prominent "LATEX ALLERGY PRECAUTIONS" signage on all OR entry doors. Remove all latex-containing items from the room or place them in sealed plastic bags.
• Equipment Verification: Utilize glass ampules or dedicated latex-free drug vials. Do not puncture rubber vial stoppers with needles, as latex fragments can be coring-introduced into the medication solution. Verify that blood pressure cuffs, IV tubing injection ports, endotracheal tubes, wound drains, and surgical gloves are 100% latex-free synthetic material (nitrile, neoprene, silicone).

Antibiotic & Medication Cross-Reactivity Protocols

Beta-Lactam & Cephalosporin Cross-Reactivity

Preoperative antibiotic prophylaxis (e.g., cefazolin) must be administered within 60 minutes prior to surgical incision (120 minutes for vancomycin or fluoroquinolones). Managing reported penicillin (PCN) allergies requires precise risk evaluation:

• Mild, Non-IgE PCN Allergy (e.g., childhood maculopapular rash without hives): Cross-reactivity between penicillin and 1st-generation cephalosporins (cefazolin) is less than 1% to 2% (historical quotes of 10% were due to early manufacturing contamination). Cefazolin can be safely administered.
• IgE-Mediated PCN Anaphylaxis, Angioedema, or SJS: If the patient reports documented anaphylaxis, bronchospasm, urticaria, or Stevens-Johnson syndrome to penicillin, all beta-lactams (cephalosporins, penicillins, carbapenems) are contraindicated.
• Alternative Antibiotic Prophylaxis:
  • Vancomycin: Administered at 15 to 20 mg/kg IV (infused over 60 to 120 minutes to prevent Red Man Syndrome caused by histamine release).
  • Clindamycin: Administered at 900 mg IV.

Propofol, Egg & Soy Allergies

Propofol (Diprivan) is formulated as a 1% lipid emulsion containing 10% soybean oil, 1.2% purified egg phospholipid, and 2.25% glycerol.

• Clinical Distinction: Most egg allergies are triggered by proteins in the egg white (ovalbumin). Purified egg phospholipid used in propofol is derived from the egg yolk and contains negligible protein residue.
• ASA Guidelines: Routine avoidance of propofol in patients with simple egg or soy allergies is not recommended unless the patient has a documented history of severe Type I IgE-mediated anaphylaxis specifically to egg yolk or soy protein.

Malignant Hyperthermia (MH) Crisis Management

Malignant Hyperthermia is an autosomal dominant pharmacogenetic disorder of skeletal muscle calcium regulation, primarily involving mutations in the RYR1 gene (ryanodine receptor).

Triggering Agents

1. All Volatile Inhalational Anesthetic Gases: Sevoflurane, desflurane, isoflurane, halothane.
2. Depolarizing Neuromuscular Blocker: Succinylcholine (Anectine).

Clinical Manifestations of MH Crisis

Triggering Agent Exposure (Volatile Anesthetics / Succinylcholine)
                           │
                           ▼
Uncontrolled Calcium Release from Sarcoplasmic Reticulum
                           │
                           ▼
Hypermetabolic State (Massive O2 Consumption & CO2 Production)
                           │
            ┌──────────────┴──────────────┐
            ▼                             ▼
   EARLY CLINICAL SIGNS          LATE CLINICAL SIGNS
   • Unexplained ETCO2 Rise     • Hyperthermia (> 41°C / 105.8°F)
     (Most Sensitive Indicator)  • Rhabdomyolysis & Myoglobinuria
   • Masseter Muscle Rigidity     (Cola-colored urine)
     (MMR after succinylcholine) • Severe Hyperkalemia & DIC
   • Sinus Tachycardia / Tachypnea

• Early Signs: Unexplained, precipitous rise in End-Tidal CO2 (ETCO2) that does not respond to increased minute ventilation (most sensitive early indicator). Masseter muscle rigidity (trismus) following succinylcholine, unexplained sinus tachycardia, diaphoresis, and mottling.
• Late Signs: Rapidly escalating hyperthermia (temperature rising 1°C to 2°C every 5 minutes, exceeding 41°C / 105.8°F), hyperkalemia, profound mixed metabolic/respiratory acidosis, rhabdomyolysis, myoglobinuria (cola-colored urine), and Disseminated Intravascular Coagulation (DIC).

Emergency MH Protocol Steps

1. Discontinue Triggers: Immediately stop all volatile gases and succinylcholine. Inform surgeon to halt procedure; switch to total intravenous anesthesia (TIVA with propofol/opioids).
2. Hyperventilate: Administer 100% oxygen at high flow (≥ 10 L/min) using a clean circuit.
3. Call for MH Cart & MHAUS Hotline: Call 1-800-644-9737 (MHAUS hotline).
4. Administer Dantrolene Sodium:
   • Initial dose: 2.5 mg/kg IV push rapidly through a large-bore IV.
   • Repeat dose every 5 to 10 minutes until hypermetabolic symptoms subside (max initial dose up to 10 mg/kg).
   • Reconstitution: Standard Dantrolene (Revonto/generic) requires reconstituting each 20 mg vial with 60 mL of sterile water without a bacteriostatic agent. Concentrated Dantrolene (Ryanodex) requires 250 mg reconstituted in only 5 mL of sterile water.
5. Cool Patient: Initiate active cooling (cold IV 0.9% saline, ice packs to axillae/groin, stomach/bladder cold lavage) until core body temperature drops below 38.5°C (101.3°F) to prevent hypothermia rebound.
6. Treat Hyperkalemia: Administer calcium chloride, IV insulin with dextrose, and sodium bicarbonate for severe acidosis.

Exam Traps & Clinical Pitfalls

• Exam Trap: Assuming high fever is the first sign of MH. Increased ETCO2 and unexplained tachycardia are the earliest signs; hyperthermia is a late sign.
• Clinical Pitfall: Puncturing rubber vial stoppers with a needle when preparing medications for a latex-allergic patient. Always pop off the stopper or use glass ampules.