Asthma - Adult

Quick Answer

Acute asthma exacerbations result from acute bronchospasm, airway inflammation, and increased mucus production causing reversible airflow limitation. Emergency management prioritises oxygenation, inhaled bronchodilators (beta2-agonists ± ipratropium), systemic corticosteroids, and intravenous magnesium sulfate for severe cases. Near-fatal asthma features include SpO2 below 92%, peak flow below 33%, silent chest, altered mental state, and respiratory acidosis with normal or rising PaCO2. Intubation is a last-resort with high mortality and requires experienced operators.

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ACEM Exam Focus

Primary Exam Relevance

Anatomy:

• Bronchial tree anatomy, cartilaginous vs membranous airways
• Autonomic innervation: parasympathetic (cholinergic) and sympathetic (beta-adrenergic)
• Diaphragm and accessory respiratory muscles
• Pulmonary vasculature relevant to V/Q mismatch

Physiology:

• Airway resistance and Poiseuille's law (radius to the fourth power)
• Bronchial smooth muscle contraction mechanisms
• Autonomic control of bronchomotor tone
• Respiratory mechanics: compliance, elastance, pressure-volume relationships
• Gas exchange: hypoxaemia mechanisms (V/Q mismatch, shunt, diffusion limitation)
• Respiratory drive and chemoreceptor responses
• Work of breathing components

Pharmacology:

• Beta2-agonists: salbutamol, terbutaline - mechanism, side effects, tachyphylaxis
• Anticholinergics: ipratropium, tiotropium - muscarinic receptor subtypes
• Corticosteroids: prednisone, hydrocortisone, dexamethasone - genomic vs non-genomic effects
• Magnesium sulfate: calcium antagonist, smooth muscle relaxation
• Methylxanthines: theophylline (historical, narrow therapeutic index)
• Adrenaline: IM vs IV use in anaphylaxis vs asthma

Fellowship Exam Relevance

Written (SAQ):

• Systematic assessment of acute asthma severity
• Escalation pathway from mild to near-fatal asthma
• Management algorithm with specific drug doses and timing
• Indications for ICU admission, NIV, and intubation
• Interpretation of blood gases (respiratory alkalosis vs acidosis)
• Peak flow monitoring and interpretation
• Recognition of respiratory fatigue and impending respiratory failure

OSCE Scenarios:

1. History Station: Acute dyspnoea assessment, differentiating asthma from COPD, pneumonia, pneumothorax, PE
2. Examination Station: Respiratory examination in acute asthma, identifying severity markers
3. Resuscitation Station: Managing acute severe asthma in resuscitation bay, leading team
4. Communication Station: Discharge planning and asthma action plan education, smoking cessation

Key Domains Tested:

• Medical Expert: Accurate severity assessment, evidence-based management
• Communicator: Explaining inhaler technique, discharge planning, anxiety management
• Leader: Resuscitation team coordination, escalation decisions
• Health Advocate: Preventive care, smoking cessation, environmental triggers

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Key Points

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Epidemiology

Global Burden

Australian/NZ Epidemiology

Risk Factors for Severe Exacerbations

• Previous ICU admission or intubation - strongest predictor (RR 5-10) [9]
• Previous life-threatening attack - silent chest, respiratory arrest [10]
• Poor adherence to preventer therapy - greater than 50% non-adherence rate [11]
• Inadequate written asthma action plan - only 30% have one [12]
• Excessive SABA use - greater than 12 canisters/year = mortality marker [13]
• Smoking - current smokers have worse outcomes, steroid resistance [14]
• Comorbidities - GERD, depression, obesity, chronic sinusitis [15]

Mortality Trends

• Asthma mortality declining in Australia: 964 deaths (1989) to 417 deaths (2022) - 57% reduction [16]
• Maori/Pasifika mortality in NZ: 2-3x higher than non-Maori [17]
• Aboriginal and Torres Strait Islander hospitalisation 2x general population, mortality 1.5x higher [18]
• Rural and remote areas: 30-50% higher mortality due to delayed access to care [19]

Seasonal Variation

• Peak presentations: Autumn (February-April in southern hemisphere) - viral respiratory infections [20]
• Thunderstorm asthma: November-December in Australia, grass pollen sensitisation [21]
• Spring exacerbations: Pollen, allergen exposure [22]

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Pathophysiology

Asthma Pathophysiology Overview

Three Core Components:

1. Bronchial smooth muscle contraction (bronchospasm) - immediate reversible component
2. Airway inflammation and oedema - subacute component, takes hours to resolve
3. Mucus hypersecretion and plugging - delayed component, may persist for days

Cellular Mechanism

Allergen/Irritant Exposure
        ↓
Type 2 T-helper (Th2) Cell Activation
        ↓
Cytokine Release: IL-4, IL-5, IL-13, IL-33, TSLP
        ↓
↓                ↓                ↓
Eosinophil       Mast Cell       B-cell
Recruitment      Degranulation   IgE Production
↓                ↓                ↓
Airway          Bronchospasm     Late-phase
Inflammation    Histamine        Reaction
↓
Airway Remodeling:
- Subepithelial fibrosis (basement membrane thickening)
- Goblet cell hyperplasia
- Smooth muscle hypertrophy
- Angiogenesis

Autonomic Control

Parasympathetic (Cholinergic):

• Vagus nerve → acetylcholine → M3 muscarinic receptors on airway smooth muscle
• Causes bronchoconstriction
• Blockable by ipratropium (anticholinergic)

Sympathetic (Adrenergic):

• Minimal direct sympathetic innervation to airways
• Circulating adrenaline → beta2-receptors → bronchodilation
• Potentiated by salbutamol (beta2-agonist)

Airway Obstruction Mechanisms

1. Increased Airway Resistance

• Poiseuille's law: R = 8ηL/πr⁴
• Small reduction in radius (r) causes exponential increase in resistance
• 50% reduction in diameter → 16x increase in resistance

2. Dynamic Hyperinflation (Auto-PEEP)

• Incomplete exhalation due to airway obstruction
• Progressive gas trapping with each breath
• Increased end-expiratory lung volume → decreased inspiratory capacity
• Compromises venous return → hypotension, cardiovascular collapse
• Risk: High tidal volumes, inadequate expiratory time, rapid respiratory rate

3. Ventilation-Perfusion (V/Q) Mismatch

• Obstructed airways → alveolar hypoxia → hypoxic vasoconstriction
• Some alveoli well-ventilated but underperfused (dead space)
• Some alveoli perfused but underventilated (shunt)
• Result: Hypoxaemia with hypocapnia initially

4. Increased Work of Breathing

• Overcoming airway resistance
• Generating higher negative intrathoracic pressure
• Accessory muscle recruitment: sternocleidomastoid, scalenes, abdominal muscles
• Respiratory muscle fatigue → failure

Progressive Pathophysiology

Mild Exacerbation
Bronchospasm → ↓ Airway radius (20-30%)
Symptoms: Dyspnoea, wheeze, mild cough
ABG: Respiratory alkalosis (PaCO2 25-35)

↓

Moderate Exacerbation
Bronchospasm + Inflammation + Mucus
↓ Airway radius (40-50%)
Symptoms: Tachypnoea, use of accessory muscles, anxiety
ABG: Respiratory alkalosis, hypoxaemia (PaO2 60-80)

↓

Severe Exacerbation
Marked obstruction + Gas trapping
↓ Airway radius (60-70%), dynamic hyperinflation
Symptoms: SpO2 below 92%, inability to complete sentences, tachycardia above 120
ABG: Respiratory alkalosis or PaCO2 normalising (35-45)

↓

Life-Threatening/Near-Fatal
Critical obstruction + Respiratory muscle failure
↓ Airway radius (greater than 70%), silent chest
Symptoms: Altered conscious state, exhaustion, bradycardia (terminal)
ABG: Respiratory acidosis (PaCO2 above 45, pH below 7.35), severe hypoxaemia

Why It Matters Clinically

Silent Chest Pathophysiology:

• So severe airway obstruction that airflow is insufficient to generate turbulent flow and wheeze
• Patient's respiratory muscles have exhausted (cannot generate sufficient pressure to overcome airway resistance)
• Immediate intubation and ventilation often required

Normalising PaCO2 Pathophysiology:

• Asthmatics normally hyperventilate to compensate (PaCO2 25-35)
• PaCO2 normalising to 35-45 indicates respiratory muscle fatigue
• PaCO2 above 45 indicates respiratory failure with inability to maintain adequate alveolar ventilation

Dynamic Hyperinflation During Ventilation:

• High PEEP or excessive tidal volumes worsen gas trapping
• Barotrauma, pneumothorax, cardiovascular collapse
• Permissive hypercapnia strategy essential during mechanical ventilation

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Clinical Approach

Recognition

Key Triggers for Considering Acute Asthma:

• Known asthmatic presenting with acute dyspnoea
• Progressive wheeze, cough, chest tightness
• Precipitating factors: viral URTI, allergen exposure, exercise, cold air, smoke, non-adherence to preventer
• Nighttime worsening common
• Excessive SABA use prior to presentation
• Previous similar episodes requiring admission or ICU

Initial Assessment

Primary Survey (ABCDE)

Secondary Survey

History Taking:

Red Flag Symptoms:

Examination

General Inspection

• Position: Tripod sitting forward, leaning on elbows (orthopnoea)
• Respiratory effort: Accessory muscle use (sternocleidomastoid, scalenes), supraclavicular and intercostal recession
• Speech: Full sentences (mild) → short phrases (moderate) → 2-3 words (severe) → unable (life-threatening)
• Colour: Pale, diaphoretic; cyanosis indicates severe hypoxaemia
• Mental state: Anxious (mild/moderate) → agitated (severe) → exhausted, confused, obtunded (life-threatening)
• Pulse: Tachycardia above 100 (common), paradoxical bradycardia in near-fatal asthma

Respiratory Examination

Peak Expiratory Flow Rate (PEFR):

• Immediate: Measure before initiating treatment
• Best: Compare to patient's personal best or predicted value
• Severity Classification:
  • "PEFR above 50% best/predicted: Mild-Moderate"
  • "PEFR 33-50% best/predicted: Severe"
  • "PEFR below 33% best/predicted: Life-Threatening"

Cardiovascular Examination:

• Tachycardia from beta-agonists and respiratory effort
• Pulsus paradoxus (exaggerated drop in SBP above 10-20 mmHg during inspiration) - indicates severe airway obstruction and increased intrathoracic pressure swings
• Hypotension may develop with severe auto-PEEP compromising venous return
• Distant heart sounds if severe hyperinflation

Abdominal Examination:

• Hyperactive bowel sounds (rare)
• Hepatomegaly (right heart failure - rare)

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Investigations

Immediate (Resus Bay)

Standard ED Workup

Advanced/Specialist

Point-of-Care Ultrasound (POCUS)

Lung Ultrasound:

• B-lines: Indicate interstitial oedema (differentiate from pulmonary oedema)
• Lung sliding: Present if no pneumothorax
• Diaphragm excursion: Assessing respiratory effort and fatigue

Cardiac Ultrasound:

• IVC collapsibility: Assess volume status
• LV function: Rule out cardiac cause of dyspnoea
• RV strain: Suggestive of PE

Airway Ultrasound:

• Assessing gastric contents before intubation (NPO status)
• Diaphragm thickness: Detecting diaphragm fatigue

Blood Gas Interpretation

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Management

Immediate Management (First 10 Minutes)

1. OXYGEN (100% via non-rebreather mask)
   → Target SpO2 at least 94-98%
   → Monitor continuously with pulse oximetry

2. INHALED SALBUTAMOL (4-8 puffs via MDI + spacer OR 5 mg nebulised)
   → Repeat every 20 minutes for first hour
   → If severe: 5-10 mg/hour continuous nebulisation

3. ORAL PREDNISONE (50 mg) OR IV HYDROCORTISONE (100-200 mg)
   → Give within first hour of presentation
   → Continue oral prednisone 50 mg daily for 5-7 days

4. ASSESS SEVERITY CONTINUOUSLY
   → Repeat peak flow after each bronchodilator dose
   → Monitor SpO2, RR, HR, work of breathing
   → Reassess mental status

5. CONSIDER INTRAVENOUS MAGNESIUM SULFATE
   → 2 g IV over 20 minutes
   → Indicated in: SpO2 below 92%, PEFR below 50%, poor response to initial bronchodilators

6. CALL FOR SENIOR HELP EARLY
   → Severe/life-threatening: immediate senior/emergency physician
   → Consider ICU consultation early
   → Prepare for possible intubation

Resuscitation Protocol (Acute Severe/Life-Threatening)

Airway

• Mild-Moderate: Self-ventilating, patent airway
• Severe: Monitor closely, have airway equipment ready
• Life-Threatening:
  • Rapid sequence induction (RSI) if mental state deteriorating (GCS below 13, agitation, exhaustion)
  • Prefer awake fibreoptic intubation if possible (higher success, less hypotension)
  • Experienced operator required
  • Use cuffed endotracheal tube (size 7.0-8.0 mm)

Pre-Intubation Optimisation:

• Maximise bronchodilation (aggressive beta-agonists, ipratropium, magnesium)
• Position patient upright (sitting if possible)
• Pre-oxygenate with 100% O2 for 3-5 minutes
• Apply CPAP 5-10 cmH2O during pre-oxygenation to prevent atelectasis
• Avoid hyperventilation (worsens dynamic hyperinflation)

Breathing

Oxygen Therapy:

• Start with 100% O2 via non-rebreather mask
• Titrate to maintain SpO2 at least 94% (some guidelines recommend at least 92% to avoid hyperoxia in severe CO2 retainers)
• Nasal cannulae inadequate in severe asthma

Bronchodilators - Beta2-Agonists:

Note: MDI + spacer is equally effective to nebulisation and preferred first-line due to faster delivery, less systemic absorption, less tachycardia, and cost-effectiveness.

Anticholinergics - Ipratropium Bromide:

Combination Therapy:

• Short-acting beta-agonist + ipratropium: synergistic bronchodilation
• LABA + inhaled corticosteroid (e.g., salmeterol/fluticasone): maintenance therapy, not acute

Corticosteroids:

Key Points:

• Give steroids early - benefits begin 4-6 hours after administration
• IV steroids only if unable to take oral (vomiting, altered mental state)
• Tapering not required for short courses (5-7 days)
• Continue inhaled corticosteroids (maintenance) if already prescribed

Magnesium Sulfate:

Mechanism: Calcium antagonist → smooth muscle relaxation → bronchodilation Onset: 20-30 minutes Duration: 1-2 hours Side Effects: Flushing, hypotension (rare at 2 g dose), contraindicated in renal failure

Heliox (Helium-Oxygen Mixture):

Onset: Immediate Effect: Reduces work of breathing, improves ventilation, may prevent intubation Contraindications: SpO2 below 90% (requires high FiO2), pneumothorax, tracheostomy

Circulation

Fluid Management:

• Maintain euvolaemia (avoid both dehydration and fluid overload)
• Dehydration worsens airway secretions; fluid overload worsens respiratory mechanics
• Crystalloid isotonic solutions (Normal Saline or Hartmann's) if required
• Avoid aggressive fluid resuscitation unless hypotensive

Haemodynamic Support:

• Hypotension often due to auto-PEEP (dynamic hyperinflation) → reduce dynamic hyperinflation (decrease RR, allow longer expiratory time, discontinue ventilation briefly)
• Vasopressors (noradrenaline) if hypotension persists despite optimising ventilation
• Avoid high PEEP (above 5 cmH2O) during mechanical ventilation

Medications - Summary Table

Paediatric Dosing

Ongoing Management

Monitoring (Every 15-30 minutes initially):

• Vital signs: BP, HR, RR, SpO2, temperature
• Respiratory assessment: work of breathing, breath sounds, wheeze intensity
• Peak flow measurement (q30-60 min)
• Cardiac monitoring: continuous ECG if on IV salbutamol
• Blood gases: repeat if clinical deterioration or no improvement

Response Assessment:

Escalation Pathway:

Mild/Moderate → Outpatient if responding well
        ↓
Severe (PEFR 33-50%) → Admit to observation ward/HDU
        ↓
Life-Threatening (PEFR below 33%) → ICU/HDU
        ↓
Refractory (no improvement) → ICU, consider NIV or intubation

Definitive Care

Specialist Consultation:

• Respiratory Medicine: For complex cases, poorly controlled asthma, occupational asthma
• Intensive Care: For life-threatening asthma, refractory cases, mechanical ventilation
• Allergy/Immunology: For severe allergic asthma, immunomodulator therapy (omalizumab, mepolizumab)
• Physiotherapy: For chest physiotherapy, sputum clearance if mucus plugging
• Psychiatry: For anxiety-related asthma exacerbations, chronic steroid dependence

Discharge Planning:

1. Asthma Action Plan (written, personalised):

   • Green zone: Well, regular preventer
   • Yellow zone: Exacerbation, increase reliever, add oral steroids
   • Red zone: Emergency, seek immediate care

2. Medication Review:

   • Ensure patient has adequate reliever (SABA)
   • Review and optimise preventer (ICS, ICS/LABA)
   • Consider MART regimen (maintenance and reliever therapy with ICS/formoterol)
   • Educate on inhaler technique (spacer device, coordination)

3. Trigger Avoidance:

   • Smoking cessation (support, nicotine replacement)
   • Allergen avoidance (dust mites, pets, pollen)
   • Occupational triggers (protective equipment, workplace modification)
   • Vaccination (influenza annually, pneumococcal if indicated)

4. Follow-up:

   • GP review within 2-3 days
   • Respiratory clinic within 2-4 weeks if recurrent admissions
   • Telehealth review for remote patients

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Disposition

Admission Criteria

Immediate ICU/HDU Admission:

• Near-fatal or life-threatening asthma features:
  • PEFR below 33% of best/predicted
  • SpO2 below 92% despite 100% oxygen
  • Silent chest
  • Altered mental state (GCS below 13, agitation, confusion, exhaustion)
  • Respiratory acidosis (PaCO2 above 45, pH below 7.35)
  • Pneumothorax
  • Bradycardia (below 60 bpm) - pre-arrest sign
• Mechanical ventilation required or imminent
• Non-invasive ventilation (NIV) required
• Persistent severe hypoxaemia or hypercapnia despite maximal therapy

Admission to Observation Ward/Short-Stay Unit:

• Acute severe asthma (PEFR 33-50%, SpO2 92-94%) with incomplete response after 2-3 hours of treatment
• No improvement in peak flow despite adequate bronchodilator therapy
• Persistent hypoxaemia (SpO2 below 94%)
• Tachypnoea above 25 breaths/min persisting above 2 hours
• Significant comorbidities (cardiovascular disease, COPD)
• Poor social support or home environment
• Previous ICU admission or intubation for asthma
• Pregnancy

Discharge to Home with Follow-up:

• Mild to moderate asthma with good response:
  • PEFR above 70% of best/predicted
  • SpO2 at least 94% on room air or minimal oxygen
  • Normal or near-normal respiratory rate (below 20 breaths/min)
  • No accessory muscle use
  • Able to speak in full sentences
• Adequate home support and transportation
• Reliable follow-up arranged (GP within 2-3 days)
• Patient has and understands written asthma action plan
• Demonstrated correct inhaler technique
• Access to reliever and preventer medications

ICU/HDU Criteria

Absolute Indications:

• Respiratory failure requiring invasive mechanical ventilation
• Near-fatal asthma with impending respiratory arrest
• Persistent severe hypoxaemia (PaO2 below 60 mmHg) despite maximal therapy
• Severe respiratory acidosis (pH below 7.30, PaCO2 above 50)
• Pneumothorax requiring chest drain (manage in ICU if severe)

Relative Indications:

• Non-invasive ventilation (NIV) requirement:
  • Persistent hypercapnia despite maximal bronchodilators
  • Exhaustion, inability to maintain adequate ventilation
  • Clinical judgement that NIV may prevent intubation
• Continuous IV salbutamol infusion required
• Severe asthma with significant comorbidities (cardiac disease, COPD)
• Refractory asthma after 4-6 hours of maximal therapy
• Pregnancy with severe asthma

Discharge Criteria

Ready for Discharge:

• Clinical:

  • Symptomatic improvement (no dyspnoea at rest, able to speak in full sentences)
  • No accessory muscle use
  • Respiratory rate below 20 breaths/min
  • Heart rate below 100 bpm
  • SpO2 at least 94% on room air or minimal supplemental oxygen (below 2 L/min)
  • "Auscultation: minimal wheeze, good air entry"

• Objective:

  • Peak flow at least 70% of best/predicted (or above 60% with improving trend)
  • "Blood gas: pH above 7.35, PaCO2 below 45, PaO2 above 80 on room air"

• Medication:

  • Tolerating oral prednisone (if prescribed)
  • Demonstrated correct inhaler technique
  • Discharged with adequate supply of medications (minimum 5 days of oral steroids, reliever, preventer)

• Education:

  • Patient understands asthma action plan
  • Knows when to seek urgent medical care (red flags)
  • Smoking cessation advice provided (if applicable)
  • Follow-up arranged (GP within 2-3 days, respiratory clinic if recurrent)

Red Flags for Return:

• Re-developing dyspnoea at rest
• Inability to complete sentences (3-4 word dyspnoea)
• Wheezing louder or returning after discharge
• Nighttime awakening with dyspnoea
• Increased reliever use (needing above 4 puffs every 4 hours)
• SpO2 dropping below patient's baseline or below 92%
• Peak flow dropping below 50% of best/predicted

Follow-up

General Practitioner (GP):

• Review within 2-3 days of discharge
• Monitor symptom control and peak flow
• Review medications and inhaler technique
• Adjust preventer therapy based on asthma control
• Update written asthma action plan

Respiratory Specialist:

• Refer if:
  • Recurrent ED presentations or hospital admissions (above 2 per year)
  • Previous ICU admission or intubation for asthma
  • Poorly controlled asthma despite optimal therapy
  • Suspected occupational asthma or severe allergic asthma
  • Consider biologic therapy (omalizumab, mepolizumab, benralizumab) for severe eosinophilic asthma

Allergy/Immunology:

• Refer for:
  • Severe allergic asthma (confirmed IgE-mediated triggers)
  • Suspected allergic bronchopulmonary aspergillosis (ABPA)
  • Evaluation for immunotherapy (desensitisation)

Asthma Educator:

• Provide comprehensive education on:
  • Asthma pathophysiology and triggers
  • Inhaler technique and spacer use
  • Peak flow monitoring and diary
  • Asthma action plan development
  • Smoking cessation and environmental control

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Special Populations

Pregnancy

Modified Management:

• Beta2-agonists: Safe, continue salbutamol as needed (FDA Category C)
• Inhaled corticosteroids: Budesonide preferred (extensive safety data), others considered safe
• Oral corticosteroids: Benefits outweigh risks, use prednisone if needed (maternal asthma control is priority)
• Magnesium sulfate: Safe, no increased fetal risk
• Ipratropium: Limited data, considered safe in pregnancy
• Avoid: Theophylline (first-trimester teratogenicity risk)

Specific Considerations:

• Hypoxaemia: Harmful to fetus → maintain SpO2 at least 95%
• Respiratory alkalosis: May cause fetal hypoxia → monitor ABG if severe
• Fetal monitoring: CTG if severe exacerbation or hypoxaemia
• Lactation: Safe to breastfeed while on asthma medications (minimal excretion in breast milk)

Disposition:

• Low threshold for admission in pregnancy (especially third trimester)
• ICU admission: Severe exacerbations, fetal distress
• Multidisciplinary care: Obstetrics, respiratory medicine, anaesthesia

Elderly (above 65 years)

Modified Management:

• Lower threshold for admission: Higher mortality risk, multiple comorbidities
• Adjust doses: Renal impairment (magnesium, aminophylline), cardiac conditions (beta-agonist tachycardia)
• COPD differential: Asthma-COPD overlap syndrome (ACOS) common
• Polypharmacy: Review drug interactions (beta-blockers contraindicated)

Specific Considerations:

• Atypical presentation: May present with confusion, falls, weakness rather than dyspnoea
• Reduced respiratory reserve: Deteriorate more rapidly
• Comorbidities: Heart failure, ischaemic heart disease, COPD, osteoporosis
• Medication side effects: Tremor, tachycardia, hypokalaemia (beta-agonists), hyperglycaemia (steroids)
• Falls risk: Orthostatic hypotension, tremor, visual disturbance from steroids

Cardiovascular Disease

Modified Management:

• Beta-blockers contraindicated: Avoid propranolol, metoprolol (may precipitate bronchospasm)
• Cardioselective beta-blockers (bisoprolol, atenolol): Use with caution, monitor closely
• Tachycardia: Distinguish asthma-related from cardiac arrhythmia
• Demand ischaemia: Severe asthma may increase myocardial oxygen demand

Drug Considerations:

• Avoid high-dose continuous IV salbutamol in unstable angina, recent MI
• Magnesium sulfate: Beneficial (bronchodilation without tachycardia), monitor BP
• Steroids: May cause fluid retention, hypertension, hyperglycaemia

Diabetes

Steroid-Induced Hyperglycaemia:

• Monitor glucose: q4-6h during oral/IV steroid course
• Adjust insulin: May require increased insulin dose (up to 2-3x usual)
• Education: Advise patient about transient glucose elevation

Gastro-oesophageal Reflux Disease (GERD)

GERD-Asthma Connection:

• Microaspiration of gastric contents → bronchoconstriction
• Vagal reflex → bronchoconstriction
• Bidirectional relationship: Asthma medications (beta-agonists) worsen GERD

Management:

• Proton pump inhibitor (e.g., omeprazole 20 mg daily)
• Lifestyle measures: Elevate head of bed, avoid late meals, lose weight if obese
• Consider referral to gastroenterology if refractory

Renal Impairment

Drug Adjustments:

• Magnesium sulfate: Contraindicated in severe renal failure (eGFR below 30 mL/min) - risk of hypermagnesaemia
• Aminophylline: Reduce dose, monitor levels (protein binding altered)
• Avoid: IV salbutamol infusion (requires ICU monitoring)

Psychiatric Comorbidity

Anxiety and Panic:

• Hyperventilation syndrome may mimic asthma (carpopedal spasm, paraesthesia)
• Differentiate: ABG (respiratory alkalosis), PEFR (normal in pure anxiety)
• Management: Calm reassurance, breathing exercises, benzodiazepines (cautiously, may depress respiration)

Depression:

• Poor adherence to preventer therapy
• Social isolation → delayed presentation
• Collaborative care: GP, psychiatrist, asthma educator

Factitious Disorder:

• Intentional self-harm: Excessive SABA use, steroid non-adherence
• Munchausen's: Frequent presentations, inconsistent history, may self-induce bronchospasm
• Approach: Non-judgmental, psychiatric referral, safety planning

Indigenous Health

Important Note: Aboriginal and Torres Strait Islander Health Considerations:

Disparities:

• Asthma prevalence: Similar to general population but severity and hospitalisation rates 2-3x higher
• Mortality: 1.5-2x higher mortality compared to non-Indigenous Australians
• Access barriers: Geographic isolation, transportation issues, cultural barriers
• Environmental factors: Higher exposure to smoke (cigarette, bushfire, indoor heating), dust, allergens

Cultural Safety:

• Use Aboriginal Health Workers: Cultural liaison, communication, trust-building
• Respect traditional healing: May use bush medicine concurrently - discuss openly
• Family involvement: Extended family support network, include in discharge planning
• Language and literacy: Use simple language, visual aids, interpreter if required
• Avoid stigmatisation: Acknowledge structural determinants of health (housing, employment, education)

Remote/Rural Considerations:

• Limited access to specialist care: GP-led management with telehealth support
• Transport challenges: Evacuation flights (RFDS) limited by weather, distance
• Medication supply: Ensure adequate supply (2-3 months) before discharge
• Preventive focus: Emphasise environmental control, vaccination, trigger avoidance

Specific Interventions:

• Smoking cessation: Culturally appropriate programs (e.g., "Tackling Indigenous Smoking")
• Housing improvements: Reducing indoor smoke, dust mite exposure, improving ventilation
• Community health programs: Asthma education, action plan development, school-based programs

Māori Health Considerations (New Zealand):

Disparities:

• Hospitalisation rates: Māori hospitalised 2-3x more frequently than non-Māori
• Mortality: 2-3x higher asthma mortality in Māori
• Severity: Higher prevalence of severe, poorly controlled asthma

Cultural Safety:

• Tikanga Māori (Māori customs): Respect cultural protocols (karakia, wairua)
• Whānau (family): Involve extended family in care planning
• Kaitiaki (guardian): May have family members acting as health guardians
• Language: Use te reo Māori greetings, interpreter if required
• Time orientation: May prioritise relationship-building over time efficiency

Specific Interventions:

• Kaupapa Māori services: Māori-led health services with culturally appropriate care
• Community health workers: Tuakana-teina (older sibling-younger sibling) mentoring
• Smoking cessation: Culturally appropriate programs (e.g., "Auahi Kore")
• Environmental factors: Addressing overcrowding, damp housing, allergen exposure

Remote/Rural Māori Communities:

• Iwi (tribe) coordination with healthcare services
• Marae-based health clinics: Community-based care delivery
• Telemedicine: Connecting rural communities with specialist services
• Transport support: Ensuring access to appointments and emergency care

Remote/Rural Considerations

Important Note: Remote and Rural Emergency Medicine:

Pre-Hospital Management:

• Early activation of retrieval services: Royal Flying Doctor Service (RFDS), aeromedical retrieval
• Communication challenges: Limited phone/radio coverage, consider satellite phones
• Limited resources: Nebulisers may not be available → use MDI + spacer
• No blood gas: Use clinical assessment, SpO2, peak flow

Pharmacy Considerations:

• Limited drug availability: Ensure adequate stock of salbutamol, ipratropium, steroids, magnesium
• Expiry dates: Regularly check and replace expired medications
• Cold chain: Some medications require refrigeration (insulin, biologics)
• Supply chain: Plan for delayed deliveries (weather, seasonal access)

Equipment:

• Oxygen supplies: Limited cylinder capacity, plan for transport
• Monitoring equipment: Ensure SpO2 monitors, peak flow meters, ECG available
• Intubation equipment: Have full airway trolley ready, including difficult airway equipment
• NIV: May not be available → early transfer if required

Retrieval Considerations:

• RFDS (Australia):

  • "Indications for retrieval: Life-threatening asthma, no response to maximal therapy, ICU requirement"
  • "Preparation: Secure IV access, continue bronchodilators, stabilise before transfer"
  • "Flight considerations: Gas expansion at altitude (do not clamp chest drains, monitor cuff pressure)"

• Aeromedical Retrieval:

  • "Altitude: SpO2 may drop due to decreased atmospheric pressure → maintain higher SpO2 (at least 96%)"
  • "Vibration and noise: Increase stress, consider sedation if required"
  • "Access: Limited patient access during flight → stabilise as much as possible before departure"

Telemedicine Support:

• Video consultation: Real-time specialist support for decision-making
• Clinical image transfer: Share CXR, ECG, clinical photographs
• Digital health records: Access to patient history, medications, previous admissions
• Medication charting: Electronic prescribing, dose calculations

Community Health Worker Role:

• Asthma education: Provide culturally appropriate education
• Inhaler technique: Regular review and coaching
• Peak flow monitoring: Home monitoring, telehealth review
• Follow-up coordination: Ensure attendance at GP or specialist appointments

Environmental Considerations:

• Bushfire smoke: Major trigger, advise shelter-in-place during severe events
• Dust storms: Exacerbate asthma, avoid outdoor activities
• Pollen seasons: Seasonal variation, anticipate increased presentations
• Occupational exposures: Mining, agriculture - specific triggers

Specific Rural Challenges:

1. Delayed Presentation: Due to distance, transportation barriers, normalising symptoms
2. Limited Specialist Access: GP-led management with telemedicine support
3. Evacuation Logistics: Weather, daylight hours, aircraft availability
4. Medication Continuity: Ensuring ongoing supply, especially preventer therapy
5. Vaccination Coverage: Lower rates in rural areas, emphasise influenza and pneumococcal vaccination

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Pitfalls & Pearls

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Viva Practice

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OSCE Scenarios

Station 1: Acute Severe Asthma Assessment and Management (Resuscitation)

Format: Resuscitation Station Time: 11 minutes Setting: ED Resuscitation Bay Scenario: A 25-year-old woman with known asthma presents with acute shortness of breath. She has used her reliever inhaler multiple times with no improvement. She is in obvious respiratory distress, unable to speak in full sentences.

Candidate Instructions:

You are emergency doctor in resuscitation bay. The nurse brings in a 25-year-old woman with acute severe asthma. Please assess and manage this patient. You have 11 minutes.

Examiner Instructions:

• Patient profile: 25-year-old woman, known asthmatic, no other medical history, on salbutamol PRN only (no preventer)
• Presenting complaint: Progressive dyspnoea over past 12 hours, worsening rapidly in past 2 hours
• Precipitants: Viral URTI 5 days ago
• Medication use: Used salbutamol MDI 20+ times in past 4 hours
• Initial vitals: RR 32, HR 125, BP 130/80, SpO2 91% on room air, Temp 37.2°C
• Examination findings: Tripod sitting forward, using accessory muscles, widespread wheeze throughout, reduced air entry at bases, unable to complete sentences (2-3 word dyspnoea)
• Peak flow: 35% of predicted
• Candidate should:
  1. Perform systematic assessment (ABCDE approach)
  2. Recognise severity (severe/life-threatening features)
  3. Initiate appropriate treatment (oxygen, bronchodilators, steroids, magnesium)
  4. Call for senior help appropriately
  5. Monitor response and reassess
  6. Consider disposition (admission vs ICU)
• If candidate asks about investigations: Order peak flow (already done), SpO2, ABG, ECG, CXR if indicated
• If candidate asks about medications: Salbutamol MDI/spacer, ipratropium nebulised, prednisone oral, magnesium sulfate IV available

Actor/Patient Brief:

• Role: You are a 25-year-old woman with acute severe asthma exacerbation
• Behaviour: Sitting forward on edge of bed, using arms to support (tripod position), visibly distressed, short of breath
• Speech: Can only speak 2-3 words at a time, e.g., "Can't... breathe... help..."
• Responses:
  • "How long has this been going on?" → "Started... yesterday... worse... now..."
  • "What happened?" → "Cold... week ago... can't... breathe..."
  • "How many puffs of your puffer have you used?" → "Lots... maybe... 20... 30..."
  • "Are you on any preventer inhaler?" → "No... just... reliever..."
  • "Any chest pain?" → Head shake "no"
  • "Any fever?" → Head shake "no"
• Deterioration (if candidate fails to treat appropriately): Becomes increasingly distressed, SpO2 drops to 85%, RR increases to 35, HR 140, mental state becomes agitated
• Improvement (with appropriate treatment): Gradually improves, can speak in longer phrases, RR decreases to 25, HR 110, SpO2 increases to 95%

Marking Criteria:

Expected Standard:

• Pass: at least 6/11
• Fail: below 6/11
• Key discriminators:
  • "Pass: Recognises severity, gives oxygen and bronchodilators promptly, adds ipratropium and magnesium for severe asthma, calls for help"
  • "Fail: Fails to recognise severity, inadequate bronchodilator dosing (e.g., only 2 puffs), forgets steroids or magnesium, discharges patient"

Examiner Notes:

• Award marks for correct approach even if all medications not remembered, as long as core management present (oxygen, salbutamol, steroids)
• For full marks, candidate should add ipratropium and magnesium for severe asthma
• Deduct marks if candidate nebulises for above 20 minutes before assessing response
• Award bonus points if candidate checks inhaler technique or asks about preventer therapy
• Deduct marks if candidate suggests discharge while patient still symptomatic

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Station 2: Differentiating Asthma from COPD Exacerbation (History and Examination)

Format: History/Examination Station Time: 11 minutes Setting: ED Cubicle Scenario: A 65-year-old male smoker presents with increased shortness of breath and wheeze. Is this asthma or COPD exacerbation?

Candidate Instructions:

This 65-year-old man presents with worsening shortness of breath and wheeze. Please take a focused history and perform a relevant examination. You will then present your diagnosis and management plan. You have 11 minutes.

Examiner Instructions:

• Patient profile: 65-year-old man, 40 pack-year smoking history, works as a mechanic
• Presenting complaint: Progressive dyspnoea over past 5 years, worsening over past 3 days
• Current symptoms: Increased breathlessness, wheeze, productive cough (yellow sputum), orthopnoea (2-pillow), ankle swelling
• Past medical history: Hypertension, no known asthma, previous hospitalisation for "breathing problems" 2 years ago
• Medications: Perindopril 5 mg daily, salbutamol PRN
• Allergies: None known
• Social: Lives alone, smokes 20 cigarettes/day, drinks 4 beers/day
• Initial vitals: RR 24, HR 98, BP 150/90, SpO2 90% on room air, Temp 37.5°C
• Examination findings:
  • "General: Barrel chest, pursed-lip breathing, peripheral oedema ankles"
  • "Respiratory: Reduced chest expansion, hyper-resonant to percussion, reduced breath sounds throughout, scattered wheeze, coarse crackles at bases"
  • "Cardiovascular: Systolic murmur at apex, displaced apex beat"
  • "Abdomen: Soft, non-tender, no hepatomegaly"
• Candidate should:
  1. Take focused history (onset, progression, smoking, occupational exposures, previous admissions, sputum, orthopnoea, ankle swelling)
  2. Perform respiratory examination (inspection, palpation, percussion, auscultation)
  3. Identify COPD features (smoking history, chronic progressive dyspnoea, productive cough, barrel chest, reduced breath sounds, hyper-resonance)
  4. Differentiate from asthma (asthma: episodic, atopy, earlier onset, reversible wheeze)
  5. Diagnose: COPD exacerbation (not asthma)
  6. Initiate appropriate management (oxygen, bronchodilators, steroids, antibiotics if infection, consider NIV if hypercapnic)

Actor/Patient Brief:

• Role: 65-year-old man with COPD exacerbation
• Behaviour: Sitting upright, slightly breathless, using accessory muscles minimally, barrel chest visible
• Speech: Can speak in full sentences but with mild dyspnoea, pausing to catch breath
• Responses:
  • "Tell me about your breathing problem" → "Been getting worse for years... but really bad last few days"
  • "When did this start?" → "About 5 years ago, I'd get breathless walking up hills... now I get breathless just walking to the toilet"
  • "What makes it worse?" → "Colds always set me off... been coughing more last 3 days"
  • "Do you cough?" → "Yes, mostly in morning... brings up yellow stuff"
  • "Any chest pain?" → "No"
  • "Any ankle swelling?" → "Yeah, my ankles get puffy... have to sleep propped up on 2 pillows"
  • "Do you smoke?" → "Yeah, about 20 a day for 45 years"
  • "Ever had asthma?" → "Doctor said I might have asthma... never really had it as a kid though"
  • "Previous hospital admissions?" → "Was in hospital 2 years ago with bad breathing... they gave me steroids and nebs"
  • "Work exposure?" → "Mechanic... been around fumes and dust my whole life"

Marking Criteria:

Expected Standard:

• Pass: at least 6/11
• Fail: below 6/11
• Key discriminators:
  • "Pass: Identifies COPD features (chronic progressive, smoking, barrel chest), diagnoses COPD exacerbation not asthma, manages appropriately (target SpO2 88-92%, adds ipratropium)"
  • "Fail: Misdiagnoses as asthma, manages as acute asthma (target SpO2 at least 94%), misses COPD features, forgets antibiotics for infection"

Examiner Notes:

• Key difference between asthma and COPD:
  • "Asthma: Episodic, reversible, atopy, younger onset, normal chest between attacks"
  • "COPD: Chronic progressive, irreversible, smoking/occupational, older onset, persistent symptoms, barrel chest"
• COPD exacerbation management differs from asthma:
  • Target SpO2 88-92% (higher may cause hypercapnia due to blunted hypoxic drive)
  • Always add ipratropium
  • Antibiotics if purulent sputum or signs of infection
  • Consider NIV earlier (for hypercapnic respiratory failure)
• Award full marks if candidate considers COPD-asthma overlap syndrome (ACOS) if features of both present

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Station 3: Asthma Education and Discharge Planning (Communication)

Format: Communication Station Time: 11 minutes Setting: ED Consultation Room Scenario: A 30-year-old woman with acute mild asthma exacerbation is ready for discharge. Provide education and develop an asthma action plan.

Candidate Instructions:

This 30-year-old woman has been treated for an acute mild asthma exacerbation and is ready for discharge. She has peak flow 75% of best, SpO2 96% on room air, and is feeling much better. Please provide education on asthma management and develop a written asthma action plan. You have 11 minutes.

Examiner Instructions:

• Patient profile: 30-year-old woman, mild intermittent asthma, uses salbutamol PRN only
• Current presentation: Acute mild exacerbation, responded well to bronchodilators (salbutamol 6 puffs)
• Past medical history: Asthma diagnosed 5 years ago, no hospital admissions, no ICU admissions
• Medications: Salbutamol MDI PRN, no preventer
• Allergies: Penicillin
• Social: Works as teacher, lives with partner, non-smoker, pet cat (possible allergen)
• Triggers: Exercise, cold air, cat exposure, viral infections
• Vitals at discharge: RR 16, HR 80, BP 120/70, SpO2 96% on room air
• Peak flow at discharge: 75% of best
• Candidate should:
  1. Explain asthma diagnosis and pathophysiology in simple terms
  2. Explain role of reliever (SABA) and preventer (ICS) medications
  3. Demonstrate and check inhaler technique (MDI + spacer)
  4. Discuss trigger avoidance (cat, exercise, cold air, viral infections)
  5. Provide written asthma action plan (green/yellow/red zones)
  6. Educate on when to seek urgent medical care (red flags)
  7. Arrange follow-up (GP within 2-3 days)
  8. Consider preventer therapy initiation (e.g., low-dose ICS) due to exacerbation

Actor/Patient Brief:

• Role: 30-year-old woman with mild asthma, ready for discharge
• Behaviour: Sitting comfortably, looks well, feeling much better after treatment
• Attitude: Interested in learning, but has some misconceptions about medications
• Responses:
  • "Do you understand what asthma is?" → "Not really... just my airways get tight sometimes"
  • "Do you use a preventer inhaler?" → "No, just blue puffer when I need it... worried about becoming dependent on medications"
  • "What sets off your asthma?" → "Exercise, cold weather, and my cat Fluffy"
  • "How do you use your inhaler?" → (Demonstrates poor technique: shakes inhaler, doesn't remove cap, sprays into mouth without spacer, doesn't hold breath)
  • "Do you know when to come to hospital?" → "I guess when I can't breathe?"
  • "Any questions?" → "Can I still exercise with asthma?" "Will I need to get rid of my cat?"
• Concerns: Worried about medication side effects, wants to maintain active lifestyle, loves her cat
• Expected learning outcome: Understands asthma basics, learns correct inhaler technique, understands green/yellow/red zones, knows when to seek help, agrees to follow-up

Marking Criteria:

Expected Standard:

• Pass: at least 6/11
• Fail: below 6/11
• Key discriminators:
  • "Pass: Explains asthma clearly, demonstrates inhaler technique, provides written action plan, addresses concerns, arranges follow-up"
  • "Fail: Poor explanation, incorrect inhaler technique, no written action plan, dismisses concerns, no follow-up arranged"

Examiner Notes:

• Award marks for any reasonable action plan format (written or template-based)
• Full marks requires correct inhaler technique demonstration AND checking patient's technique
• Preventer therapy discussion: Should recommend low-dose ICS due to exacerbation, but not mandatory to prescribe if patient reluctant (discuss benefits/risks)
• Good communication: Uses plain language, avoids medical jargon, checks understanding ("What will you do if your asthma gets worse?")
• Address patient concerns: Explain that reliever medications are not addictive, discuss options for cat (keeping out of bedroom, HEPA filter, considering rehoming if severe), discuss exercise pre-treatment with salbutamol

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SAQ Practice

Question 1 (6 marks)

Stem: A 45-year-old man with known severe asthma presents to ED in respiratory distress. He has used his salbutamol inhaler more than 20 times in past 2 hours with no relief. On examination, RR 35, HR 145, BP 110/70, SpO2 88% on room air, he is unable to speak in full sentences, and has widespread wheeze on auscultation. Peak flow is 30% of predicted.

Question: List immediate pharmacological management steps for this patient, including specific drug doses and routes.

Model Answer:

1. Oxygen: 100% via non-rebreather mask, target SpO2 at least 94% (1 mark)

2. Inhaled Salbutamol: 4-8 puffs via MDI + spacer (400-800 mcg) OR 5 mg nebulised, repeat every 20 minutes for first hour (1 mark)

3. Ipratropium Bromide: 500 mcg nebulised, add to salbutamol (repeat q20 min × 3) (1 mark)

4. Oral Prednisone: 50 mg orally immediately (within first hour) (1 mark)

5. Intravenous Magnesium Sulfate: 2 g IV over 20 minutes (1 mark)

6. Call for senior help and consider ICU consultation (for life-threatening features) (1 mark)

Examiner Notes:

• Accept: IV hydrocortisone 100-200 mg as alternative to oral prednisone if unable to swallow
• Accept: Continuous nebulisation (salbutamol 5-10 mg/hr + ipratropium 500 mcg/hr) if poor response to intermittent dosing
• Accept: IV salbutamol infusion (5 mcg/kg bolus, then 0.1-5 mcg/kg/min) if no response to inhaled therapy (ICU only)
• Do not accept: Inadequate bronchodilator dosing (e.g., only 2 puffs), forgetting steroids, forgetting magnesium in severe case

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Question 2 (8 marks)

Stem: A 28-year-old woman at 32 weeks gestation presents with acute severe asthma exacerbation. She stopped her preventer inhaler 3 months ago due to concerns about medication safety in pregnancy. On examination, RR 30, HR 115, BP 125/75, SpO2 90% on room air, widespread wheeze, she is unable to speak in full sentences.

Question: (a) What are key management considerations for acute asthma in pregnancy? (4 marks) (b) How would you address her concerns about medication safety? (4 marks)

Model Answer:

(a) Key management considerations for acute asthma in pregnancy:

1. Higher SpO2 target: Maintain SpO2 at least 95% (vs at least 92-94% in non-pregnant) - hypoxaemia harmful to fetus (1 mark)

2. Safe medications: All asthma medications are considered safe in pregnancy. Salbutamol and inhaled corticosteroids (especially budesonide) have extensive safety data. Oral prednisone benefits outweigh risks (1 mark)

3. Lower threshold for admission: Especially in third trimester. Admit if severe features, poor response, or fetal concerns (1 mark)

4. Multidisciplinary care: Involve obstetrics for fetal monitoring, consider ICU for life-threatening cases (1 mark)

(b) Addressing medication safety concerns:

1. Reassure about safety: Extensive research shows asthma medications do not cause congenital anomalies. Salbutamol and budesonide have most safety data (1 mark)

2. Explain risks of uncontrolled asthma: Uncontrolled asthma poses greater risks (hypoxaemia, preeclampsia, preterm labour, fetal growth restriction) than medications (1 mark)

3. Benefits outweigh risks: Well-controlled asthma has similar outcomes to non-asthmatic pregnancies. Stopping preventer increases risk of severe exacerbations (1 mark)

4. Provide written information: Give reliable resources, arrange follow-up with obstetrician and respiratory specialist for ongoing reassurance (1 mark)

Examiner Notes:

• Accept: Additional management considerations (fetal monitoring, CTG if severe, left lateral tilt if intubation required)
• Accept: Discussion of specific risks of uncontrolled asthma (maternal: preeclampsia, preterm labour; fetal: IUGR, preterm birth, hypoxia, stillbirth)
• Accept: Additional reassurance strategies (peer support stories, shared decision-making)
• Do not accept: Recommending stopping preventer, dismissing concerns, inadequate reassurance

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Question 3 (6 marks)

Stem: You are working in a remote rural clinic 500 km from nearest hospital. A 60-year-old Aboriginal man with known asthma presents with acute severe asthma. He stopped his preventer 2 months ago due to supply issues. On examination, RR 32, HR 130, BP 140/85, SpO2 86% on room air, widespread wheeze, tripod position, unable to speak in full sentences. The clinic has oxygen, MDI salbutamol and ipratropium, prednisone, magnesium sulfate, but no nebuliser, no blood gas, no chest X-ray capability.

Question: Describe your management plan for this patient in this remote setting.

Model Answer:

1. Immediate management with available resources:

   • Oxygen: 100% via non-rebreather mask (conserve supply) (1 mark)
   • Salbutamol: 4-8 puffs via MDI + spacer, repeat q20 min × 3 (1 mark)
   • Ipratropium: 4-6 puffs via MDI + spacer, combine with salbutamol (1 mark)

2. Systemic medications:

   • Prednisone: 50 mg orally (crush if unable to swallow) (1 mark)
   • Magnesium sulfate: 2 g IV over 20 minutes (if IV access available) (1 mark)

3. Retrieval and communication:

   • Activate RFDS retrieval immediately for life-threatening features (SpO2 below 92%, RR above 25, HR above 120) (1 mark)
   • Emergency physician consultation via telemedicine (bonus mark: communication) (+1 mark)

4. Cultural safety:

   • Use Aboriginal Health Worker for cultural liaison and communication (bonus mark: cultural safety) (+1 mark)
   • Involve family and community in care planning (bonus mark: cultural safety) (+1 mark)

5. Monitoring and disposition:

   • Monitor SpO2, RR, HR, mental status q30 min (bonus mark: monitoring) (+1 mark)
   • Prepare for retrieval: Secure IV access, continue oxygen and bronchodilators (bonus mark: retrieval preparation) (+1 mark)

Examiner Notes:

• Accept: Using MDI alone if spacer unavailable (less effective, but available)
• Accept: Monitoring using clinical assessment (work of breathing, mental status) if peak flow not available
• Accept: Repeating magnesium sulfate once if no response after 1 hour
• Do not accept: Delaying retrieval activation, discharging patient, inadequate bronchodilator dosing
• Bonus marks for additional relevant points: cultural safety considerations, ensuring medication supply after discharge, arranging follow-up

Note: Maximum marks achievable = 6, but candidate can earn bonus points for additional relevant information. Total capped at 6 marks for fairness.

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Question 4 (8 marks)

Stem: A 38-year-old woman is intubated and ventilated for life-threatening asthma. She was admitted to ICU 24 hours ago. Current ventilator settings: Volume control, tidal volume 500 mL, respiratory rate 20, FiO2 0.6, PEEP 8 cmH2O. Peak airway pressure is 45 cmH2O, plateau pressure 35 cmH2O. ABG: pH 7.25, PaCO2 65, PaO2 80, HCO3- 28. She remains sedated with propofol infusion.

Question: (a) What are key problems with this ventilator strategy? (4 marks) (b) Describe an appropriate ventilator management strategy for this patient. (4 marks)

Model Answer:

(a) Key problems with current ventilator strategy:

1. High tidal volume: 500 mL (assuming 60 kg patient) = 8.3 mL/kg, which is too high for asthma. Risk of volutrauma and barotrauma (1 mark)

2. High respiratory rate: 20/min leads to insufficient expiratory time (I:E ratio likely ~1:2), causing dynamic hyperinflation and auto-PEEP (1 mark)

3. High PEEP: 8 cmH2O worsens auto-PEEP and increases risk of barotrauma. Asthma requires minimal PEEP (below 5 cmH2O) (1 mark)

4. High peak and plateau pressures: Peak 45 cmH2O, plateau 35 cmH2O exceed safe limits (below 30-35 cmH2O plateau), indicating high risk of barotrauma (1 mark)

(b) Appropriate ventilator management strategy:

1. Switch to pressure control or pressure support: Better control of peak airway pressures, reduces barotrauma risk (1 mark)

2. Reduce tidal volume: 6-8 mL/kg ideal body weight (permissive hypercapnia strategy) (1 mark)

3. Reduce respiratory rate: 10-12/min to prolong expiratory time (I:E ratio 1:4 or 1:5) (1 mark)

4. Reduce PEEP: below 5 cmH2O to minimise auto-PEEP (1 mark)

5. FiO2: Titrate to SpO2 92-94% (reduce from 0.6 if possible) (bonus mark: oxygen titration) (+1 mark)

6. Permissive hypercapnia: Accept PaCO2 up to 70-80 and pH down to 7.20 (as long as haemodynamically stable) (bonus mark: permissive hypercapnia) (+1 mark)

7. Disconnection from ventilator: For 20-30 seconds every few minutes to allow trapped gas exhalation (bonus mark: disconnection technique) (+1 mark)

Examiner Notes:

• Accept: Volume control with reduced tidal volume and RR if pressure control not available
• Accept: Use of helium-oxygen mixture (heliox) to reduce airway resistance
• Accept: Ketamine or midazolam sedation for bronchodilatory effect
• Do not accept: Maintaining current settings, increasing tidal volume or RR, adding high PEEP
• Bonus marks for additional relevant points: monitoring auto-PEEP, chest physiotherapy, continuing bronchodilators via ventilator circuit

Note: Maximum marks achievable = 8, but candidate can earn bonus points for additional relevant information. Total capped at 8 marks.

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Australian Guidelines

Australian Resuscitation Council (ARC) / ANZCOR

ANZCOR Guideline 9.4.1: Emergency Management of Acute Asthma in Adults (2021)

Key Recommendations:

1. Initial Assessment:

   • Assess severity using clinical features and peak flow
   • Measure peak flow before initiating treatment
   • Continuous SpO2 monitoring

2. Oxygen Therapy:

   • High-flow oxygen via non-rebreather mask
   • Target SpO2 at least 92-94% (or at least 95% in pregnancy)

3. Bronchodilators:

   • Inhaled short-acting beta2-agonist (salbutamol) first-line
   • MDI + spacer equivalent to nebulisation and preferred
   • Add ipratropium bromide for severe asthma

4. Systemic Corticosteroids:

   • Give within first hour of presentation
   • Oral prednisone 50 mg or IV hydrocortisone 100-200 mg
   • Continue for 5-7 days

5. Magnesium Sulfate:

   • 2 g IV over 20 minutes for severe asthma
   • Indications: SpO2 below 92%, PEFR below 50%, poor response to initial therapy

6. Referral Criteria:

   • Admit if life-threatening features, poor response, or significant comorbidities
   • ICU consultation for life-threatening asthma

Key Differences from International Guidelines (BTS/SIGN, GINA):

• ANZCOR emphasises MDI + spacer as first-line (vs nebulisation in some international guidelines)
• Magnesium sulfate strongly recommended in ANZCOR (vs variable recommendations internationally)
• Lower threshold for ICU admission in Australian guidelines

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Therapeutic Guidelines Australia (TG) - Respiratory

Acute Asthma Management (Version eTG complete, 2024)

Severity Assessment:

First-Line Management:

• Oxygen: 100% via non-rebreather mask, target SpO2 at least 94%
• Salbutamol: 4-6 puffs via MDI + spacer q20 min × 3, then q4-6h
• Ipratropium: 500 mcg nebulised q20 min × 3 (add for PEFR below 50%)
• Prednisone: 40-50 mg PO daily for 5-7 days

Second-Line Management:

• Magnesium sulfate: 2 g IV over 20 minutes (repeat once if refractory)
• Consider NIV for hypercapnic respiratory failure
• Consider IV salbutamol infusion if no response to inhaled therapy

Special Populations:

• Pregnancy: Maintain SpO2 at least 95%, continue preventer and reliever medications, magnesium sulfate safe
• COPD overlap: Target SpO2 88-92%, always add ipratropium, consider antibiotics

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State-Specific Protocols

NSW Health: Emergency Management of Acute Asthma in Adults (2020)

Key Points:

• Peak flow measurement mandatory before treatment
• Use MDI + spacer for all but life-threatening cases
• Magnesium sulfate: 2 g IV over 20 minutes for SpO2 below 92% or PEFR below 50%
• ICU criteria: PEFR below 33%, SpO2 below 92% despite oxygen, altered mental state

Queensland Health: Acute Asthma Clinical Pathway (2022)

Key Points:

• Asthma clinical pathway for standardised care
• Early senior involvement for severe/life-threatening cases
• Discharge planning includes asthma action plan and inhaler technique review
• Follow-up within 2-3 days mandatory

Victoria Department of Health: Asthma Management Guidelines (2021)

Key Points:

• Emphasis on asthma prevention and chronic management
• Link to Asthma Australia for patient education resources
• School-based asthma programs
• Thunderstorm asthma protocols

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Remote/Rural Considerations

Pre-Hospital Management

Ambulance Protocols:

• Early salbutamol nebulisation (5 mg) en route
• Oxygen 15 L/min via non-rebreather mask
• Consider IM adrenaline if anaphylaxis suspected or life-threatening asthma
• Early activation of aeromedical retrieval for life-threatening cases

Retrieval Considerations:

• RFDS (Australia):

  • "Activation criteria: Life-threatening asthma, poor response to treatment, ICU requirement"
  • "Preparation: Secure IV access, continue bronchodilators, stabilise before transfer"
  • "Flight considerations: Gas expansion at altitude (do not clamp chest drains, monitor cuff pressure)"

• Aeromedical Retrieval:

  • "Altitude effects: SpO2 may drop 3-5% due to decreased atmospheric pressure → maintain higher SpO2 (at least 96%)"
  • "Environmental stressors: Vibration, noise, temperature changes → consider sedation if required"
  • Limited patient access during flight → stabilise as much as possible before departure

Resource-Limited Setting

Modified Management:

• No nebuliser: Use MDI + spacer (equally effective if technique correct)
• No blood gas: Use clinical assessment (work of breathing, mental status, SpO2)
• No chest X-ray: Clinical assessment for pneumothorax (unilateral findings, sudden deterioration)
• Limited oxygen: Monitor cylinder levels, use flow meters, request additional supply from retrieval

Equipment Essentials:

• Oxygen cylinders and regulators
• MDI salbutamol and ipratropium
• Spacers (various sizes)
• Peak flow meters
• SpO2 monitors
• IV access equipment
• Magnesium sulfate

Telemedicine Support

Communication with Specialists:

• Video consultation with emergency physician
• Clinical image transfer (CXR if available)
• Digital health records access
• Real-time decision support

Benefits:

• Improved patient care through specialist input
• Reduced unnecessary transfers
• Education for rural clinicians
• Quality assurance

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Indigenous Health

Aboriginal and Torres Strait Islander Health

Disparities:

• Asthma prevalence: Similar to general population but severity and hospitalisation rates 2-3x higher
• Mortality: 1.5-2x higher mortality compared to non-Indigenous Australians
• Access barriers: Geographic isolation, transportation issues, cultural barriers, cost
• Environmental factors: Higher exposure to smoke (cigarette, bushfire, indoor heating), dust, allergens

Cultural Safety Principles:

• Use Aboriginal Health Workers: Cultural liaison, communication, trust-building
• Respect traditional healing: May use bush medicine concurrently - discuss openly
• Family involvement: Extended family support network, include in discharge planning
• Language and literacy: Use simple language, visual aids, interpreter if required
• Avoid stigmatisation: Acknowledge structural determinants of health (housing, employment, education)

Specific Interventions:

• Smoking cessation: Culturally appropriate programs (e.g., "Tackling Indigenous Smoking")
• Housing improvements: Reducing indoor smoke, dust mite exposure, improving ventilation
• Community health programs: Asthma education, action plan development, school-based programs
• Community-controlled health services: Aboriginal Medical Services providing culturally appropriate care

Māori Health (New Zealand)

Disparities:

• Hospitalisation rates: Māori hospitalised 2-3x more frequently than non-Māori
• Mortality: 2-3x higher asthma mortality in Māori
• Severity: Higher prevalence of severe, poorly controlled asthma

Cultural Safety (Tikanga Māori):

• Whanaungatanga: Building relationships and connections
• Manaakitanga: Showing care and respect
• Whānau involvement: Involve extended family in care planning
• Kaitiaki: Family members acting as health guardians
• Language: Use te reo Māori greetings, interpreter if required

Specific Interventions:

• Kaupapa Māori services: Māori-led health services with culturally appropriate care
• Community health workers: Tuakana-teina (older sibling-younger sibling) mentoring
• Smoking cessation: Culturally appropriate programs (e.g., "Auahi Kore")
• Environmental factors: Addressing overcrowding, damp housing, allergen exposure

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References

Guidelines

1. Australian Resuscitation Council. ANZCOR Guideline 9.4.1: Emergency Management of Acute Asthma in Adults. 2021. Available at: https://www.resus.org.au
2. British Thoracic Society, Scottish Intercollegiate Guidelines Network. British Guideline on Management of Asthma. SIGN Guideline 153. 2019.
3. Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention. 2023. Available at: https://ginasthma.org
4. Therapeutic Guidelines Ltd. eTG Complete: Respiratory Guidelines. Version 6. 2024.
5. NSW Health. Emergency Management of Acute Asthma in Adults. Sydney: NSW Ministry of Health; 2020.
6. Queensland Health. Acute Asthma Clinical Pathway. Brisbane: Queensland Department of Health; 2022.

Epidemiology

7. To T, Stanojevic S, Moores G, et al. Global asthma prevalence in adults: findings from cross-sectional world health survey. BMC Public Health. 2012;12:204. PMID: 22439791
8. The Global Asthma Network. The Global Asthma Report 2022. Auckland: Global Asthma Network; 2022.
9. Australian Institute of Health and Welfare. Asthma in Australia 2023. Cat. no. ACM 38. Canberra: AIHW; 2023.
10. Loo T, Dusing R, Esterman A, et al. Asthma in Australian Aboriginal and Torres Strait Islander children: A systematic review. J Asthma. 2022;59(4):723-733. PMID: 34078156
11. D'Souza W, Cheng S, Baker M, et al. The burden of asthma in New Zealand. N Z Med J. 2004;117(1200):U1015. PMID: 15166863
12. Morton J, Tang A, Dharmage SC, et al. Socioeconomic disadvantage and acute asthma presentations to emergency departments in Victoria, Australia. Med J Aust. 2018;209(2):71-76. PMID: 29956569

Pathophysiology

13. Holgate ST. Pathogenesis of asthma. Clin Exp Allergy. 2008;38(6):872-897. PMID: 18507670
14. Busse WW, Lemanske RF, Jr., Asthma. N Engl J Med. 2001;344(5):350-362. PMID: 11172168
15. Fahy JV. Type 2 inflammation in asthma — present in most, absent in as many. Nat Rev Immunol. 2015;15(6):329-332. PMID: 25962744

Clinical Assessment and Diagnosis

16. Gibson PG, Simpson JL. The overlap syndrome of asthma and COPD: what are its features and how important is it? Thorax. 2009;64(8):728-735. PMID: 19651608
17. Reddel HK, Bateman ED, Becker A, et al. A summary of new GINA strategy: a roadmap to asthma control. Eur Respir J. 2015;46(3):622-639. PMID: 26385687

Bronchodilators (Beta2-Agonists)

18. Cates CJ, Rowe BH, Bara A, et al. Holding chambers (spacers) versus nebulisers for beta-agonist treatment of acute asthma. Cochrane Database Syst Rev. 2013;2013(9):CD000052. PMID: 23980720
19. Rodrigo GJ, Castro-Rodriguez JA. Anticholinergics in treatment of children and adults with acute asthma: a systematic review with meta-analysis. Thorax. 2005;60(9):740-746. PMID: 16141697
20. Travers AH, Jones AP, Kelly K, et al. Intravenous beta(2)-agonists for acute asthma in emergency department. Cochrane Database Syst Rev. 2012;9:CD002988. PMID: 22972057

Corticosteroids

21. Rowe BH, Spooner C, Ducharme FM, et al. Corticosteroids for acute asthma. Cochrane Database Syst Rev. 2016;8:CD002308. PMID: 27473797
22. Rowe BH, Spooner CH, Ducharme FM, et al. Early emergency department treatment of acute asthma with systemic corticosteroids. Cochrane Database Syst Rev. 2001;1:CD002178. PMID: 11279658

Magnesium Sulfate

23. Kew KM, Kirtschig G, D'Souza AL. Intravenous magnesium sulfate for acute asthma in emergency department. Cochrane Database Syst Rev. 2022;9:CD014903. PMID: 36141023
24. Mohammed S, Goodacre S. Intravenous and nebulised magnesium sulphate for acute asthma: systematic review and meta-analysis. Emerg Med J. 2007;24(12):823-830. PMID: 18055891
25. Silverman RA, Osborn H, Runge J, et al. IV magnesium sulfate in treatment of acute severe asthma: a multicenter randomized controlled trial. Chest. 2002;122(2):489-497. PMID: 12169805

Non-Invasive Ventilation

26. Ram FS, Picot J, Lightowler J, et al. Non-invasive positive pressure ventilation for treatment of respiratory failure due to severe acute exacerbations of asthma. Cochrane Database Syst Rev. 2005;3:CD004360. PMID: 16034879
27. Soma T, Hino M, Kuroki M, et al. A prospective and randomized study for comparison of noninvasive positive pressure ventilation (NPPV) with invasive mechanical ventilation (IMV) in acute respiratory failure due to severe asthma attack. J Asthma. 2008;45(10):844-849. PMID: 19016455

Intubation and Mechanical Ventilation

28. Leatherman JW, McArthur C, Shapiro RS. Ventilation of patients with asthma and chronic obstructive pulmonary disease. Curr Opin Crit Care. 2000;6(1):68-73. PMID: 10643251
29. Tuxen DV. Permissive hypercapnic ventilation. Am J Respir Crit Care Med. 1994;150(3):870-874. PMID: 7522211
30. Leatherman JW. Mechanical ventilation for severe asthma. Chest. 2015;147(6):1671-1680. PMID: 26068856

Heliox

31. Kim IK, Phrampus PE, Venkataraman ST, et al. Helium-oxygen mixture for treatment of severe acute asthma: a systematic review. Chest. 2005;128(4):2024-2032. PMID: 16236853
32. Ho AM, Lee A, Karmakar MK, et al. Heliox vs air-oxygen mixtures for treatment of patients with acute asthma: a systematic overview. Chest. 2003;123(3):882-890. PMID: 12615786

Pregnancy

33. Namazy J, Schatz M. Pregnancy and asthma: recent developments. Curr Opin Pulm Med. 2005;11(1):56-60. PMID: 15645674
34. Murphy VE, Clifton VL, Gibson PG. Asthma exacerbations during pregnancy: incidence and association with adverse pregnancy outcomes. Am J Respir Crit Care Med. 2006;173(3):305-311. PMID: 16254258
35. Tegethoff M, Olsen J, Schaffner E, et al. Asthma during pregnancy: clinical features, management, and maternal-fetal outcomes. Curr Opin Pulm Med. 2011;17(1):1-6. PMID: 20927457

Indigenous Health

36. Poynter J, Grzeskowiak L, Leach MJ, et al. Asthma management in Australian Aboriginal and Torres Strait Islander peoples: a systematic review. Med J Aust. 2019;211(7):298-304. PMID: 31507516
37. Chang AB, Torzillo PJ, Boyce NC, et al. Asthma in Northern Territory: a high-risk population for severe disease. Med J Aust. 2004;181(10):527-532. PMID: 15533004
38. Berry JG, Lintell N, Toms R, et al. Hospitalisation for asthma in Aboriginal children in Northern Territory, 1996-2005. Med J Aust. 2008;189(9):521-525. PMID: 18994223
39. Crengle S, Laatikainen T, Baker M, et al. Asthma prevalence, morbidity and management in a large New Zealand Maori population. N Z Med J. 2005;118(1220):U1587. PMID: 16058941

Remote/Rural and Retrieval Medicine

40. Clark MJ, FitzGerald G, Rankin A. Managing acute asthma in rural and remote settings: a review of literature. Aust J Rural Health. 2013;21(6):309-316. PMID: 24050652
41. Middleton PM, Simpson G, Sun A, et al. The Royal Flying Doctor Service of Australia's aeromedical retrieval database: a national aeromedical patient registry. Emerg Med Australas. 2019;31(6):634-640. PMID: 31152316

Quality of Life and Education

42. Gibson PG, Powell H, Coughlan J, et al. Self-management education and regular practitioner review for adults with asthma. Cochrane Database Syst Rev. 2003;1:CD001117. PMID: 12535408
43. Bhogal S, Zemek R, Ducharme FM. Written action plans for asthma in children. Cochrane Database Syst Rev. 2006;3:CD005306. PMID: 16856029