4.3 Acute Anaphylaxis, Hypoglycaemia & Seizure Emergencies

Acute Anaphylaxis, Hypoglycaemia & Seizure Emergencies

Core Clinical Mandate: Medical emergencies on acute hospital wards develop rapidly and require decisive, evidence-based nursing interventions. Whether encountering sudden systemic anaphylaxis following medication administration, neuroglycopenic collapse from severe hypoglycaemia, or status epilepticus, the registered nurse must prioritize the ABCDE sequence, administer time-critical pharmacotherapy, and maintain patient safety.

1. Acute Anaphylaxis: Recognition & Management

Anaphylaxis is a severe, life-threatening, generalized or systemic hypersensitivity reaction characterized by rapid onset and compromised airway, breathing, or circulation. It is most commonly triggered in hospitalized patients by intravenous antibiotics (e.g., beta-lactams), radiocontrast media, blood products, neuromuscular blocking agents, chlorhexidine, latex, or certain foods.

Clinical Presentation: The ABC Approach

Anaphylaxis is diagnosed primarily on clinical grounds. Look for sudden onset (usually minutes to hours after trigger exposure) with rapid progression involving:

• A (Airway Compromise): Pharyngeal or laryngeal oedema, tongue/lip swelling (angioedema), hoarse voice, difficulty swallowing, inspiratory stridor.
• B (Breathing Compromise): Severe bronchospasm, audible expiratory wheeze, shortness of breath, chest tightness, tachypnoea, cyanosis, $\text{SpO}_2 <92%$.
• C (Circulation Compromise): Widespread vasodilation and increased capillary permeability leading to profound hypotension ($\text{SBP} <90\text{ mmHg}$), reflex tachycardia, weak thready pulse, clammy extremities, dizziness, syncope, and cardiovascular collapse.
• Skin and Mucosal Changes: Occur in $>80%$ of cases but may be absent in fulminant shock: generalized erythema, intense pruritus, urticaria (hives), and periorbital/facial angioedema.

Immediate First-Line Treatment: Intramuscular Adrenaline

• Drug of Choice: Adrenaline (Epinephrine) 1:1,000 ($1\text{ mg/mL}$ concentration).
• Adult Dose: $0.5\text{ mg}$ ($0.5\text{ mL}$) administered by Intramuscular (IM) injection.
• Site of Administration: Anterolateral aspect of the middle third of the thigh (vastus lateralis). The IM route in the thigh achieves significantly faster and higher peak plasma concentrations than subcutaneous administration or IM injection into the deltoid.
• Repeat Dosing: If there is no clinical improvement in airway, breathing, or circulation, repeat the IM adrenaline dose after 5 minutes.
• Mechanism: Alpha-1 receptor agonist activity reverses peripheral vasodilation and reduces mucosal/laryngeal oedema; Beta-1 activity increases myocardial contractility; Beta-2 activity relieves bronchospasm and inhibits further mast cell and basophil degranulation.

                    [Suspected Anaphylaxis]
                              │
              ┌───────────────┴───────────────┐
              ▼                               ▼
     [Stop Trigger Immediately]     [Call for Help / Dial 2222]
              │                               │
              └───────────────┬───────────────┘
                              ▼
     [First-Line Drug: Adrenaline 1:1,000 (0.5 mg IM) Vastus Lateralis]
                              │
              ┌───────────────┴───────────────┐
              ▼                               ▼
     [Position Correctly]            [High-Flow Oxygen (15 L/min)]
     • Lie flat with legs elevated   • Non-rebreather reservoir mask
     • (Sit up slightly if dyspnoea) • Target SpO2 94-98%
     • NEVER allow patient to stand!
                              │
                              ▼
     [IV Fluid Resuscitation: Crystalloid 500-1000 mL bolus]
                              │
                              ▼
     [Second-Line Adjuncts (Only AFTER Adrenaline)]:
     • IV Chlorphenamine 10 mg (slow IV / IM)
     • IV Hydrocortisone 200 mg (slow IV / IM)

Patient Positioning: Prevention of Caval Collapse

• Position flat with legs elevated to optimize venous return to the heart.
• If breathing difficulty or stridor is the predominant symptom, the patient may sit upright cautiously, but blood pressure must be monitored closely.
• CRITICAL WARNING: Never permit an anaphylactic patient to stand up, walk, or sit up abruptly. Sudden changes to an upright posture cause catastrophic pooling of blood in dilated lower-extremity capacitance vessels, leading to the "empty vena cava syndrome," pulseless electrical activity (PEA), and instantaneous death within seconds.

Secondary Interventions & Monitoring

• Intravenous Fluids: Rapid IV crystalloid bolus ($500\text{--}1,000\text{ mL}$ Hartmann's or $0.9%$ Saline) for persistent hypotension.
• Second-Line Drugs (Administer ONLY AFTER Adrenaline):
  • Antihistamine: Chlorphenamine $10\text{ mg}$ slow IV or IM (combats H1-mediated pruritus and urticaria).
  • Corticosteroid: Hydrocortisone $200\text{ mg}$ slow IV or IM (blunts late-phase inflammation and reduces risk of biphasic reactions).
• Observation Period: Monitor the patient for a minimum of 6 to 12 hours post-event, as biphasic anaphylaxis occurs in up to $20%$ of patients without renewed exposure to the allergen. Serial serum mast cell tryptase samples should be taken (immediately, at 1–2 hours, and $>24\text{ hours}$ baseline).

2. Acute Hypoglycaemia: The "Rule of 15"

Hypoglycaemia is an acute metabolic emergency characterized by plasma glucose falling below physiological requirements. In Irish acute hospitals, clinical guidelines define hypoglycaemia as a capillary blood glucose $<4.0\text{ mmol/L}$ ("Four is the Floor"), regardless of whether the patient exhibits overt symptoms.

Clinical Manifestations

Symptoms arise through two distinct pathophysiological mechanisms:

1. Autonomic (Neurogenic) Symptoms (Adrenaline release):
   • Diaphoresis (cold sweats), tremors/shakiness, tachycardia, palpitations, anxiety, pallor, hunger, pins and needles (paraesthesia).
2. Neuroglycopenic Symptoms (Direct cerebral glucose deprivation):
   • Confusion, drowsiness, slurred speech, behavioral changes, emotional lability, ataxia/unsteadiness, blurred vision, seizures, and eventual coma.

The "Rule of 15" Management Algorithm

                [Capillary Blood Glucose < 4.0 mmol/L]
                                  │
                 ┌────────────────┴────────────────┐
                 ▼                                 ▼
       [Patient Conscious & Able]        [Patient Unconscious / Dysphagic / NPO]
       [to Swallow Safely]                         │
                 │                                 ▼
                 ▼                        [Position in Recovery Position]
       [Step 1: Give 15-20g Fast Carb]    • Maintain patent airway
       • 150-200 mL Fruit Juice/Soda      • High-flow O2 if indicated
       • 4-5 Jelly Babies                          │
       • 3-4 Glucose Tablets                       ▼
       • 1 tube 40% Oral Glucose Gel      [IV Access Present?]
                 │                                 │
                 ▼                        ┌────────┴────────┐
       [Step 2: Wait 15 Minutes &]        ▼                 ▼
       [Recheck Blood Glucose]          [YES]              [NO]
                 │                        │                 │
       ┌─────────┴─────────┐              ▼                 ▼
       ▼                   ▼       [Give 100-150 mL   [Give 1 mg IM Glucagon]
[Still < 4.0 mmol/L] [≥ 4.0 mmol/L] 10% Glucose IV]   (Recheck BG in 10 min;
       │                   │       (over 10-15 min)    secure IV access)]
       ▼                   ▼              │                 │
[Repeat 15-20g      [Step 3: Give         └────────┬────────┘
 Fast-acting Carb;   Long-Acting Carb]             │
 Max 3 cycles]      • Slice of toast               ▼
                    • 2 plain biscuits    [Once BG ≥ 4.0 mmol/L & Alert]
                    • Scheduled meal      [Provide Long-Acting Complex Carb]

Detailed Treatment Pathways:

• Stage 1: Conscious, Alert Patient (Oral Route Intact):
  • Administer 15 to 20 grams of quick-acting simple carbohydrate:
    • $150\text{--}200\text{ mL}$ pure fruit juice (orange or apple juice);
    • 4 to 5 jelly babies or fruit pastilles;
    • 3 to 4 glucose tablets;
    • 1 tube of $40%$ oral glucose gel (e.g., Glucogel) massaged into buccal mucosa if cooperative but sluggish.
  • Wait 15 minutes and re-check capillary blood glucose.
  • If blood glucose is still $<4.0\text{ mmol/L}$, repeat the fast-acting carbohydrate (up to 3 cycles).
  • Once blood glucose is $\ge 4.0\text{ mmol/L}$, administer long-acting complex carbohydrate (e.g., a slice of bread/toast, 2 digestive biscuits, a glass of milk, or the patient's next scheduled meal) to prevent recurrent hypoglycaemia as circulating insulin continues to act.
• Stage 2: Unconscious, Confused, Dysphagic, or Nil-by-Mouth Patient:
  • Danger: Never attempt to administer fluids or solids orally to a drowsy or unconscious patient due to the catastrophic risk of aspiration.
  • Place patient in the lateral recovery position and summon the medical team (dial 2222 if unrousable or fitting).
  • If IV Access is available: Administer $100\text{ to }150\text{ mL}$ of $10%$ Glucose (Dextrose) intravenously over 10–15 minutes. Alternatively, administer $50\text{ mL}$ of $20%$ Glucose. Note: Avoid hypertonic $50%$ glucose if possible due to extreme hyperosmolarity, severe thrombophlebitis, and tissue necrosis if extravasation occurs.
  • If NO IV Access is available: Administer Glucagon $1\text{ mg}$ by Intramuscular (IM) or Subcutaneous (SC) injection.
    • Glucagon acts by mobilizing glycogen stores from the liver. It may take 10–15 minutes to raise blood glucose and is ineffective in patients with depleted glycogen stores (e.g., severe malnutrition, prolonged fasting, end-stage liver disease, or chronic alcohol misuse).
    • When the patient regains consciousness and can swallow safely, give oral complex carbohydrates immediately.

3. Acute Seizure Management & Status Epilepticus

An epileptic seizure is a transient occurrence of signs and symptoms resulting from abnormal excessive or synchronous neuronal activity in the brain. In general medical wards, seizures may stem from epilepsy, acute stroke, intracranial hemorrhage, alcohol withdrawal, electrolyte derangements (severe hyponatraemia, hypocalcaemia), meningitis, or drug toxicity.

Acute Seizure First-Aid: Protecting the Patient from Harm

When witnessing an acute convulsive (generalized tonic-clonic) seizure, the nurse's immediate priority is preservation of safety and airway:

1. Note the Time: Look at the clock immediately. Accurately timing the onset and duration of the seizure is critical for emergency drug escalation.
2. Prevent Physical Injury:
   • Guide the patient gently away from hazards (radiators, sharp furniture edges).
   • Cushion the patient's head using a soft pillow, folded blanket, or clothing.
   • Ensure padded bed rails are elevated if the patient is in bed.
   • Loosen tight clothing around the neck (ties, tight collars).
3. What NOT to Do (Universal Nursing Rules):
   • DO NOT restrain the patient: Restraining limbs during the tonic-clonic phase causes musculoskeletal tears, fractures, or joint dislocations.
   • DO NOT place anything in the patient's mouth: Never insert tongue depressors, airway adjuncts, spoons, or fingers. This can fracture teeth, trigger laryngospasm, and cause complete airway occlusion.
   • DO NOT attempt oral medication or fluids.
4. Maintain Oxygenation: Administer high-flow oxygen via a non-rebreather mask held near the face if the convulsive phase permits.
5. Post-Ictal Positioning: As soon as active clonic jerking stops, place the patient into the lateral recovery position to allow oral secretions and vomit to drain freely, preventing aspiration, and perform gentle suctioning if required.

Status Epilepticus Protocol

• Definition: A continuous convulsive seizure lasting $\ge 5\text{ minutes}$, or two or more sequential seizures without full recovery of consciousness between episodes.
• Pathophysiological Risk: Prolonged convulsive activity leads to hyperpyrexia, systemic lactic acidosis, rhabdomyolysis, respiratory compromise, neuronal necrosis, and permanent neurological deficit. It is a critical medical emergency requiring 2222 escalation.

4. Practical OSCE Guidance for NMBI Candidates

In the RCSI Overseas Aptitude Test OSCE, acute emergency stations frequently evaluate anaphylaxis, hypoglycaemic collapse, or seizure management:

1. Adrenaline Dose Verbalization: Never hesitate when asked for the anaphylaxis dose. State clearly: "Adrenaline 1:1,000, 0.5 mg, which is 0.5 mL, intramuscularly into the anterolateral aspect of the middle third of the thigh."
2. Hypoglycaemia Verification: Always check capillary blood glucose before administering emergency medications to an altered patient. Remember the rule: "Four is the floor—treat below 4.0 mmol/L with 15 to 20 grams of fast-acting sugar, wait 15 minutes, recheck."
3. Seizure Timing: During a simulated seizure station, look visibly at your watch or the wall clock and state: "I am noting the time of onset. The seizure has lasted 3 minutes; I am preparing emergency buccal midazolam or IV lorazepam if it reaches 5 minutes."
4. Post-Event Assessment: Always document post-event vital signs, neurological status (GCS/ACVPU), pupil size and reactivity, blood glucose, and any injury sustained.