Why Inhaler Technique Is a High-Yield OSCE Station
Poor inhaler technique is one of the most common and most correctable reasons for poorly controlled asthma and COPD in the UK. Inhaler technique stations test your ability to assess a patient's current technique, identify errors, demonstrate the correct method, and check understanding using teach-back. This is a practical and communication station combined.
Types of Inhaler — Know the Differences
| Inhaler type | How it works | Common examples | Key requirement |
|---|---|---|---|
| Pressurised MDI (pMDI) | Aerosol released on actuation | Salbutamol (blue), Clenil (brown) | Coordination of press and inhale |
| MDI + Spacer | Spacer holds aerosol cloud | Any MDI + Volumatic or AeroChamber | No coordination needed; preferred for poor technique |
| Dry Powder Inhaler (DPI) | Breath-actuated; powder released on fast inhalation | Turbohaler, Accuhaler, Handihaler | Requires fast, forceful inhalation — wrong for acute bronchospasm |
| Breath-Actuated MDI (BA-MDI) | Activates automatically on inhalation | Autohaler, Easi-Breathe | No coordination needed; still requires slow inhalation |
| Nebuliser | Converts liquid to mist | Hospital setting, severe exacerbations | Requires a machine; not for home maintenance |
Correct MDI Technique — Step by Step
🧠 Mnemonic
SHARES — the MDI technique in order
S — Shake the inhaler (5–6 times)
H — Head slightly tilted back, exhale fully (not into the inhaler)
A — Actuate (press once) at the start of a slow, deep inhalation
R — Remain inhaling slowly and deeply (over 3–5 seconds)
E — End with breath-hold for 10 seconds (or as long as comfortable)
S — Space out further doses by at least 30–60 seconds; replace cap
Key points to emphasise to the patient:
- Remove the cap and check the mouthpiece is clear
- Shake well before each puff
- The most common error is firing the inhaler before starting to inhale, or inhaling too fast
- For preventer inhalers (steroids): rinse the mouth and gargle with water after use to prevent oral candidiasis
Using a Spacer — When and How
A spacer is indicated when:
- The patient cannot coordinate actuation with inhalation
- The patient is a child
- High-dose inhaled corticosteroids are prescribed (reduces oral deposition)
- The patient is having an acute exacerbation
Spacer technique:
- 1Attach inhaler to spacer, shake
- 2Place spacer mouthpiece in mouth (or mask over face for children)
- 3Fire one puff into spacer
- 4Take 5 slow, tidal breaths through the mouthpiece — or one slow deep breath with 10-second hold
- 5Remove, wait 30 seconds, repeat for further puffs
- 6Wash spacer monthly in warm soapy water, leave to air dry
💡 Tip
Only one puff per spacer actuation — firing two puffs into the spacer before inhaling significantly reduces drug delivery.
Correct DPI Technique — Key Differences from MDI
DPIs require the opposite breathing technique to MDIs:
- Load the dose as per device-specific instructions (Turbohaler: twist base; Accuhaler: slide lever)
- Breathe out away from the device (exhaling into a DPI wastes the dose)
- Place mouthpiece between teeth, seal lips
- Inhale FAST and DEEP (high inspiratory flow triggers powder release)
- Hold breath for 10 seconds
- Check for powder residue on tongue — if present, dose was inhaled correctly
⚠️ Red Flag
DPIs do not work during acute severe bronchospasm — the patient cannot generate enough inspiratory flow. In an acute attack, use an MDI with spacer or nebuliser instead. Mention this if asked about device choice in an acute asthma scenario.
Peak Flow Measurement
Peak expiratory flow (PEF) measures airflow obstruction. Normal values depend on age, height, and sex — use a chart.
Technique:
- 1Patient stands (or sits upright if unable to stand)
- 2Set marker to zero on the peak flow meter
- 3Patient takes a full deep breath in
- 4Place mouthpiece in mouth, seal lips
- 5Blow out as hard and fast as possible (not a sustained blow — a short sharp blast)
- 6Record the reading, reset to zero
- 7Repeat three times — record the highest value
💎 Clinical Pearl
In asthma monitoring, PEF is expressed as a percentage of the patient's personal best. Under 50% personal best = severe asthma; under 33% = life-threatening. In an OSCE, state: "I would compare this reading to their personal best and to predicted values for their age and height."
Checking Understanding — Teach-Back
After demonstrating, ask the patient to show you:
- "Would you be able to show me how you'd use it at home?"
- Observe silently — do not prompt during the demonstration
- After: identify 1–2 specific errors and correct them positively: "That was really good — the one thing that will make a big difference is..."
- Provide a written action plan or refer to asthma/COPD nurse
Frequently Asked Questions
"What is the most common inhaler technique error in an OSCE?"
The single most common error is firing the MDI before starting to inhale — the aerosol hits the back of the throat rather than reaching the airways. The second most common error is inhaling too quickly (a fast breath disperses aerosol onto the oropharynx). Demonstrate slow, coordinated inhalation and use teach-back to confirm the patient has understood.
"When should I recommend a spacer instead of a standard MDI?"
A spacer is recommended when the patient cannot coordinate pressing the inhaler and inhaling at the same time, for young children who cannot use an MDI alone, when high-dose inhaled corticosteroids are prescribed (reduces oral and pharyngeal deposition), and during acute exacerbations when inspiratory flow may be reduced.
"What is the difference between a reliever and a preventer inhaler?"
A reliever inhaler (typically a short-acting beta-2 agonist, such as salbutamol — blue inhaler) is used on demand for acute symptom relief. A preventer inhaler (typically an inhaled corticosteroid, such as beclometasone — brown inhaler) is used regularly to reduce airway inflammation and prevent symptoms. Patients must rinse their mouth after using steroid inhalers to prevent oral candidiasis.
"Why can't a dry powder inhaler be used during an acute asthma attack?"
DPIs require a high inspiratory flow rate (at least 30–60 L/min) to disaggregate the powder and carry it into the airways. During an acute severe asthma attack, bronchospasm significantly reduces inspiratory flow, meaning the patient cannot generate sufficient flow to activate the device. An MDI with spacer or a nebuliser should be used instead.
"What peak flow percentage indicates a severe asthma attack?"
A peak expiratory flow rate below 50% of the patient's personal best (or predicted) indicates a severe acute asthma attack; below 33% indicates a life-threatening attack. In an OSCE, also mention associated features of severity: inability to complete sentences, SpO2 below 92%, respiratory rate over 25, heart rate over 110, and a silent chest on auscultation.
Related guides: [How to Take a Respiratory History OSCE](/blog/how-to-take-a-respiratory-history-osce) · [Respiratory Examination OSCE](/blog/respiratory-examination-osce) · [Prescribing Safety OSCE](/blog/prescribing-safety-osce)