Inhaler Technique — Body Handbook

Breathing · §17

Inhaler Technique

You shake the inhaler, fire the dose, breathe in. The medicine goes straight to the back of your throat. Across forty years of studies covering tens of thousands of patients, about two in three people use their inhaler wrong — and the drug they don't inhale is the drug their lungs don't get. Fixing technique outperforms doubling the dose. A clinic visit that escalates therapy without checking the device first is putting more medicine where the old medicine already wasn't going.

Do · Daily Evidence Moderate Chapter Breathing

This is one of the highest-leverage things you can do in respiratory medicine, and it costs nothing. Ten minutes of training reliably moves a patient from ineffective to effective doses without changing what's in the prescription. The day-to-day payoff is real — fewer rescue puffs, fewer nights woken by tightness, fewer attacks. The catch is the daily discipline: every dose needs the right breath, every time.

The drug only works where it lands. The target is a particle between roughly 1 and 5 microns in size, deposited in the airways themselves — that's where the bronchi narrow and where the inflammation sits. Bigger droplets crash into the back of the mouth and get swallowed; smaller ones drift back out with the next breath. Get the breath wrong and most of the dose never reaches the place it's supposed to act on Laube et al. 2011.

Each device shapes that aerosol differently, and each demands its own breath:

A standard puffer — the canister-and-mouthpiece kind, technically a pressurised metered-dose inhaler — sprays a fast plume. You need a slow, deep four-to-five-second inhalation, timed to begin just before you press. Too fast and the plume hits the back of the throat. Out of sync and most of it never enters the airway.
A dry-powder inhaler — Symbicort Turbuhaler, Spiriva HandiHaler, Ellipta, Diskus, and the rest — is the opposite. You supply the energy. A sharp, forceful pull from the very first instant breaks the powder into the right-sized particles. A slow ramp doesn't work.
A soft-mist inhaler — Respimat is the common one — puts out a slow drifting cloud that lasts over a second. It tolerates clumsy timing better than a puffer. It still needs a slow, deep breath.
A spacer is a plastic reservoir between puffer and mouth. The cloud sits in the chamber for a few seconds; you inhale from the chamber through a one-way valve. Coordination stops mattering. Most of the big droplets that would have hit the throat catch on the chamber walls instead. Lung delivery becomes reproducible no matter how rusty your timing Cates et al. 2013.

How often this goes wrong

Sanchis and colleagues pulled together 144 studies of inhaler use covering 54,354 individual attempts from 1975 through 2014. The pooled correct-use rate was 31%. That figure had not moved in forty years Sanchis et al. 2016. An Italian real-world series of 1,664 patients in clinic found roughly one in three puffer and dry-powder users made at least one critical error — and those patients had measurably worse asthma and COPD control after adjusting for age, sex, and education Melani et al. 2011.

The CRITIKAL analysis then asked the next question: which specific errors actually drive worse outcomes? Across 3,660 asthma patients, two stood out. For puffer users, pressing the canister before the inhalation began was associated with worse control and a near-doubling of severe attacks in the previous year. For Turbuhaler and Diskus users, inhaling too gently produced the same picture.

Both major guidelines — GINA 2024 for asthma and GOLD 2024 for COPD — now put technique check ahead of any escalation in therapy. Doubling the dose of a drug the patient cannot inhale solves nothing — and even the smartest modern asthma regimen, the single-inhaler AIR/MART approach, is wasted if the device misses the airways.

What bad technique actually costs

You think your asthma is well-controlled because the rescue puffer "works." It mostly doesn't — not the way it could. The maintenance inhaler runs out faster than the calendar says it should. The night-time tightness you've gotten used to was never actually controlled. You learn this the hard way, when every two or three years an attack lands you in an emergency room and someone there teaches you in ninety seconds how to actually use the device. The exacerbations you didn't have to have, the rescue puffs you didn't have to take, the steroid bursts that ate your sleep for a week each time — those were the price of a breath nobody had ever corrected.

In COPD the calculus sharpens. Each severe flare independently accelerates the long decline in lung function and shortens life expectancy GOLD 2024. The controller therapy that prevents flares only prevents them when it reaches the airways — which is why matching and mastering the device ranks among the handful of moves that matter most in the first ninety days after a COPD diagnosis. Family members start to notice the breathing first — the pause on the stairs you didn't used to need, the cough that comes back every winter and stays a little longer.

How to actually do it

The breath is everything. Two rules apply to every device: exhale fully before you start (you need room for the drug to land), and hold your breath for about ten seconds after (deposition finishes in the held breath, not the inhalation). The third rule depends on the device.

What people get wrong

The dominant belief is that pressing the canister puts medicine in the lungs. It doesn't. The breath does the work; the device is a delivery rocket and the payload depends entirely on whether you aim it. Three more, less obvious, things the clinic visit tends to skip:

The technique you learned at diagnosis decays. Studies tracking patients out from training show correct-use rates falling back toward baseline within months Sanchis et al. 2016. Re-checking every visit isn't paranoia, it's calibration.
"Easy" marketing on a dry-powder device doesn't make it error-proof. The most common dry-powder error — too gentle an inhalation — is silent. The patient feels they took the dose; the lungs disagree Lavorini et al. 2008.
Mixing device types in the same regimen multiplies error rate. A puffer for rescue and a dry-powder for maintenance demand opposite breaths — slow-deep versus sharp-fast. Patients revert to whichever they used last, and one of the two doses comes out wrong.

The specific moves that ruin a dose, by device:

Puffer: pressing the canister before or after the inhalation, inhaling too fast, no breath-hold, skipping the shake on a suspension formulation, firing two puffs back-to-back without a pause.
Dry-powder: too gentle an inhalation, exhaling into the device after loading the dose, not loading the dose fully (a half-click counts as nothing), holding the device in the wrong orientation while loading.
Soft-mist: skipping the priming sequence on first use, pressing the dose button before the lip seal is formed, inhaling too fast.
Spacer: firing multiple actuations before inhaling (the drug aggregates in seconds), waiting too long after the puff to start the breath (the cloud falls out of the chamber within five to ten seconds), and an unwashed or freshly-bought plastic spacer where static electricity grabs the drug — rinse with mild detergent, air-dry (no towel), monthly.

What changes when you fix it

The first thing you notice is the rescue inhaler working faster. A puff lands and within a minute the tightness eases — instead of two puffs, then three, then waiting it out. Within a couple of weeks the maintenance inhaler starts lasting through the calendar month it was supposed to last. By month two or three, the night-time wakings you'd written off as part of your sleep get rarer. Your partner mentions you're not coughing the same way in the mornings. The friends who'd quietly stopped inviting you on hikes start including you again.

On the longer horizon — twelve months and out — the exacerbation rate drops. The annual or biennial trip to urgent care that used to feel inevitable doesn't happen this year, and then doesn't happen the year after. In COPD specifically, that flatter exacerbation curve is what protects the lung function you have left.

None of this requires a different prescription. It is the prescription you were already on, finally delivered Melani et al. 2011.

Spacers, training, and the things to ask for

Spacers cost roughly $30–$70, last six to twelve months, and are usually not handed out automatically with a puffer prescription — you generally have to ask. There is no medical reason not to have one if you use a puffer. The trade-off is bulk: a spacer doesn't fit in a pocket, which is why a lot of people use the puffer plain in public and the puffer-plus-spacer at home for the maintenance dose, where bulk doesn't matter. Both deliver the drug; the spacer just makes the delivery reliable.

Brief technique training works. A pharmacist or respiratory nurse spending five to ten minutes the first time, then two minutes to reassess at follow-up, reliably moves correct-use rates from the 20–40% baseline to the 80–90% range right after the lesson, with about half of that gain retained at three months Laube et al. 2011. Worth doing. Worth redoing at every clinic visit.

Useful things to ask for, in order:

A spacer, if you're on any puffer and don't have one.
Five minutes with the pharmacist or nurse to watch you take a dose and correct what they see.
If you're on two different inhaler types, ask whether the regimen can be consolidated to a single device class — fewer manoeuvres in the head, fewer errors.
For a dry-powder inhaler, ask whether your inspiratory flow has been measured. Severe COPD and acute attacks can drop flow below the device's minimum and the patient never knows.

Inhaler technique sits next to a handful of decisions worth thinking about together: adherence to the maintenance prescription (a different problem from technique, and harder); written asthma or COPD action plans for what to do as symptoms escalate; home peak-flow monitoring to catch worsening before you feel it; identifying and removing the triggers that keep flares coming back (allergens at home, occupational dust, tobacco smoke, vaping). And — for anyone whose breathlessness feels disproportionate to known disease — the underlying diagnostic question of whether sleep-disordered breathing is part of the picture.

Related in the handbook

Helps

— The smartest asthma regimen does nothing if the device misses your lungs — check technique before dose.
— Matching and mastering the inhaler is one of the four pillars of early COPD care.

Alternatives

— Before stepping up to an expensive biologic for stubborn asthma, make sure the inhaled dose is actually reaching your lungs.

Substance and claimed effects

Inhaler technique is the set of physical actions a patient performs to get an aerosolised drug from the device into the small airways: shaking or priming the device, exhaling, coordinating actuation with inhalation, inhaling at the correct flow and depth, and holding breath afterwards. Three device families dominate: the pressurised metered-dose inhaler (pMDI), the dry-powder inhaler (DPI), and the soft-mist inhaler (Respimat). Each requires a different inhalation manoeuvre, and each fails in characteristic ways. Spacers (valved holding chambers) attach to pMDIs and decouple the coordination problem from the dose delivered. Claimed effects in scope for this entry: short-term symptom control (rescue and maintenance), exacerbation rate (severe asthma attacks, COPD flares), oropharyngeal side effects of inhaled corticosteroids (candidiasis, dysphonia), and the downstream consequences of poor control on energy, sleep, and mood. Beauty effects are absent. Longevity matters indirectly via exacerbation frequency in COPD GOLD 2024.

Evidence by addressing question

mechanism

Drug delivery to the lower airway depends on aerosol particle size and the inhaled-airflow profile. Particles in the 1–5 µm range (the "fine particle fraction") deposit in conducting airways and alveoli; larger particles impact in the oropharynx and are swallowed, contributing nothing to bronchodilation or anti-inflammatory effect at the target site Laube et al. 2011. Each device class shapes that aerosol differently:

pMDI. A liquefied propellant (HFA) expels a high-velocity plume of drug. The plume travels fast (~30 m/s for older CFC devices, slower for HFA) and demands a slow, deep inhalation (~30 L/min, 4–5 seconds) timed precisely to actuation. Without coordination, the plume hits the back of the throat instead of the airway Laube et al. 2011. Typical lung deposition without a spacer is 10–20% of emitted dose.
DPI. A passive device that depends on the patient's own inspiratory effort to disaggregate the powder formulation into respirable particles. Required peak inspiratory flow varies by internal resistance: low-resistance DPIs (e.g., Diskus, Ellipta) need ~60 L/min, high-resistance ones (e.g., HandiHaler) ~30 L/min. The inhalation must be forceful and fast from the start; a slow ramp under-disaggregates the powder. Lung deposition can reach 30–40% when flow is adequate Laube et al. 2011.
Soft-mist (Respimat). A mechanical spring atomises the dose into a slow-moving (~0.8 m/s), long-lasting (~1.5 s) cloud. The slow plume tolerates imperfect coordination far better than a pMDI; lung deposition is around 40–50% of emitted dose with proper technique Laube et al. 2011.
Spacers (valved holding chambers). A reservoir between pMDI and mouth that holds the aerosol cloud for one to a few seconds. The patient inhales from the chamber through a one-way valve. Three effects: coordination becomes irrelevant (the cloud is held until inhalation begins); the high-velocity propellant slows, allowing more large droplets to evaporate to respirable size; and oropharyngeal deposition drops sharply because the chamber catches the high-momentum fraction. Lung deposition with a spacer matches a well-coordinated pMDI but is reproducible across patients of all skill levels Cates et al. 2013.

evidence

Error prevalence has not improved in 40 years. A systematic review of 144 studies covering 54,354 inhaler manoeuvres from 1975 to 2014 found a pooled correct-use rate of 31% (95% CI 28–35%); the figure was statistically unchanged across decades Sanchis et al. 2016. Acceptable use sat at 41% and poor use at 31%; pMDIs and DPIs performed similarly poorly. Comparable real-life snapshots: in Melani's Italian cohort of 1,664 outpatients, at least one critical error was made by 12% of nebuliser users, 28% of pMDI users, 32–38% of DPI users (Aerolizer, Diskus, HandiHaler, Turbuhaler), and these errors tracked with worse asthma and COPD control after adjustment for age, sex, and education Melani et al. 2011. In Levy's UK primary-care series of 3,981 pMDI users, only 16% had correct technique; the misuse group had a 1.6× odds ratio for uncontrolled asthma by GINA criteria Levy et al. 2013.

Specific errors map onto specific clinical outcomes. The CRITIKAL cross-sectional analysis of 3,660 asthma patients linked individual error types to outcomes: for pMDI users, "actuation before inhalation" was associated with uncontrolled asthma (adjusted OR 1.55) and a higher rate of severe exacerbations (adjusted OR 1.89); for Turbuhaler and Diskus users, insufficient inspiratory effort drove the same outcomes Price et al. 2017. The finding earned the term "critical error": an error that, on its own, materially reduces drug delivery enough to register downstream.

Intervention trials. Cates' Cochrane review of 39 trials and 1,897 children plus 729 adults found that, for acute asthma exacerbations, a pMDI with a spacer was at least as effective as a nebuliser for bronchodilator delivery; spacers shortened ED stays in children by about 33 minutes and reduced tremor and tachycardia compared with nebulised delivery Cates et al. 2013. Brief inhaler-technique coaching by a pharmacist or nurse reliably moves the correct-use rate; the ADMIT working group's review summarises this and recommends technique review at every clinical encounter Broeders et al. 2009. GINA 2024 puts "check inhaler technique and adherence" as a step that precedes any escalation in controller therapy GINA 2024; GOLD 2024 mirrors the recommendation for COPD GOLD 2024.

protocol

Per ERS/ISAM consensus, device-specific manoeuvres are not interchangeable Laube et al. 2011:

pMDI without spacer. Remove cap. Shake vigorously (10 seconds; suspension formulations only — solution HFAs like Qvar do not require shaking). Exhale fully, away from device. Form a tight lip seal. Begin a slow, deep inhalation, then actuate within the first second. Continue inhaling for 4–5 seconds (target inspiratory flow ~30 L/min). Remove device. Hold breath ~10 seconds. Wait ~30–60 seconds before a second puff.
pMDI with spacer. Shake, attach to spacer, exhale, seal lips on mouthpiece, actuate once, inhale slowly for 4–5 seconds (one large breath) or breathe tidally for ~5 breaths (for children, infants via mask). One puff per actuation; never load multiple puffs into the chamber. Hold breath 10 seconds after the deep-inhalation variant.
DPI. Load the dose per device instructions (the loading mechanism varies). Exhale fully, away from the mouthpiece (humid breath into the device clumps the powder). Seal lips on mouthpiece. Inhale forcefully and deeply from the start — not a gradual ramp. Continue for ~2–3 seconds. Remove device. Hold breath ~10 seconds.
Soft-mist (Respimat). Prime per instructions on first use. Exhale fully. Lip seal. Press dose-release button at the start of a slow, deep inhalation; continue inhaling for ~5 seconds. Hold breath ~10 seconds.
After any inhaled corticosteroid. Rinse the mouth with water and spit, or brush teeth, to reduce oropharyngeal candidiasis and dysphonia.

contraindications

No absolute contraindications to inhaled therapy as a class; the contraindications belong to the drug, not the technique. Device-selection contraindications matter: DPIs are unsuitable when peak inspiratory flow falls below the device's threshold — common in severe COPD exacerbations, severe asthma attacks, very young children, frail elderly, and post-operative patients Laube et al. 2011. For these, pMDI-plus-spacer or soft-mist is preferred. Coordination failures (manual dexterity, cognitive impairment, paediatrics under ~5) push the same decision toward spacer or nebuliser GOLD 2024.

misconceptions

Patient and prescriber misconceptions are well-catalogued. The dominant patient belief is that simply pressing the canister releases drug into the lungs; surveys show patients commonly do not understand that the breath does the work of delivery Melani et al. 2011. Prescriber misconceptions: assuming patients trained at diagnosis retain technique (Sanchis shows decay back to baseline within months Sanchis et al. 2016), assuming that an inhaler labelled "easy" (the marketing claim for several DPIs) is error-proof, and assuming that breath-actuated devices solve the coordination problem (they help with timing, not with the inspiratory-flow requirement). The persistence of the 31% correct-use figure across four decades indicates that "just write the prescription" never produced learning by accident Sanchis et al. 2016.

failure-modes

The most frequent critical errors by device class, drawn from CRITIKAL, Melani, and Lavorini's DPI review Price et al. 2017 Melani et al. 2011 Lavorini et al. 2008:

pMDI. Actuation before or after the inhalation begins (coordination); inhaling too fast (the plume impacts in the throat); no breath-hold; failing to shake suspension formulations; two puffs fired back-to-back without a pause.
DPI. Insufficient inspiratory flow (the most common DPI-specific critical error); exhaling into the device after loading the dose; holding the device incorrectly during loading (some DPIs require the device upright to load); failure to puncture or click the dose mechanism fully.
Soft-mist. Failure to prime on first use; pressing the dose-release button before lip seal; inhaling too fast.
Spacer. Multiple actuations into the chamber before inhaling (drugs aggregate in seconds); waiting too long after actuation to inhale (cloud falls out within 5–10 seconds); static electricity on new plastic spacers reducing delivered dose (rinse with detergent and air-dry to dissipate); using an unwashed spacer (drug builds up on walls).

Mixing device types in the same regimen sharply increases error rate, because each device's manoeuvre is different and patients revert to the most-recently-used pattern Lavorini et al. 2008.

practicalities

Spacers cost roughly $30–$70 in most markets and are not always automatically prescribed alongside a pMDI; patients often have to request one. Cleaning matters: weekly mild-detergent rinse (no rubbing inside), air-dry, no towel drying (towels reload static). Most spacers last 6–12 months. Inhaler technique training takes 5–10 minutes per device the first time and ~2 minutes for reassessment; pharmacists and respiratory nurses can both deliver it. GINA and GOLD now place technique review at every visit on the basis that decay is rapid and undetected GINA 2024 GOLD 2024. Many manufacturers post video demonstrations; the Asthma UK and Lung Foundation Australia libraries are device-specific and widely used in clinics.

stakes

Poor technique sits upstream of every other asthma/COPD intervention: a doubled dose of a controller corticosteroid delivers less drug than a halved dose with good technique Lavorini et al. 2008. The downstream consequences are tracked in the CRITIKAL data: in pMDI users, the critical-error group had a 53% higher odds of severe exacerbation in the prior year, with corresponding increases in oral steroid bursts and ED visits Price et al. 2017. Melani similarly found a roughly 50% increase in ED visits and hospitalisations in the critical-error group Melani et al. 2011. For COPD specifically, exacerbations independently predict accelerated FEV₁ decline and mortality, making technique non-trivially linked to longevity in this population GOLD 2024.

payoff

The intervention literature is small but consistent: brief, device-specific coaching moves correct-use rates from baseline 20–40% to 80–90% immediately post-training, with about half the gain retained at 3 months Broeders et al. 2009. Sustained correct use, in observational data, is associated with the same reduction in severe exacerbations and rescue-inhaler use that adding a controller would buy. The felt-experience payoff is "the inhaler works for the first time" — symptom relief from a rescue puff lands within seconds rather than not at all, and the run-out date of the maintenance inhaler stretches because each dose hits its target.

out-of-scope

Beyond technique itself: the underlying pharmacology (ICS, LABA, LAMA, SABA classes), adherence to maintenance therapy (a separate behavioural problem from technique), home peak-flow monitoring, action plans for exacerbations, and trigger control (allergens, smoke, occupational exposures). All sit adjacent to this entry but are independent decisions.

The credibility range

Optimist case. Inhaler technique is one of the cheapest, highest-leverage interventions in respiratory medicine. The error prevalence is settled (Sanchis 2016 covers 54,354 manoeuvres); the link from specific errors to outcomes is settled (CRITIKAL); the link from spacer use to deposition is settled (Cates 2013, Laube 2011); guideline bodies have aligned on technique-first since 2014. A clinician who spends 10 minutes per visit on technique is, on the evidence, more likely to reduce exacerbations than one who escalates to a more expensive controller. The case for spacers in pMDI users is essentially closed: same efficacy, lower side-effect burden, no downside beyond cost.

Skeptic case. Most of the outcome evidence is observational: error categorisation and exacerbation rate are both measured cross-sectionally, leaving room for confounding (sicker patients are also less able to coordinate complex manoeuvres). The handful of randomised technique-training trials are small, single-site, and short-followup; long-term retention of training is poor and the effect at 12 months is closer to break-even than baseline-versus-immediate. Industry has a strong incentive to publish device-comparison studies that favour their own platform, and the meta-analytic literature on "which device is best" is contaminated by this. The spacer literature is methodologically strong for acute asthma in children but thinner for adults on maintenance therapy.

Author's call. The credibility range is narrow on the input claim (technique errors are common, technique errors degrade outcomes) and slightly wider on the magnitude of the gain from intervention. The entry lands on the optimist side: high-evidence on the central mechanism-and-prevalence claims, moderate-evidence on the magnitude of clinical gain. evidence = 4, controversy = 1. The intervention has zero downside risk — nobody is harmed by correctly using their inhaler — so even at the skeptic edge of effect estimates, the recommendation stands.

Stakeholder + incentive map

Device manufacturers (GSK, AstraZeneca, Boehringer Ingelheim, Chiesi, Teva) have a strong incentive to publish data favouring their own platform's ease-of-use. The DPI market is fragmented across many proprietary devices, and prescribers face a real cognitive load in remembering each manoeuvre. This dynamic contributes to the "multiple inhalers" failure mode in patients on combination therapy.
Guideline bodies (GINA, GOLD, NICE, ATS, ERS) are aligned and have been escalating the prominence of technique checking since the early 2010s.
Pharmacists and respiratory nurses are the realistic delivery channel for technique training; primary-care physician time is too constrained. Several countries have funded community-pharmacy programmes (notably the UK and Australia) with documented success.
Spacer manufacturers (e.g., AeroChamber, Vortex) have a smaller market than inhaler manufacturers and lower marketing reach; uptake depends on clinician prescription habit.
Patient communities. Asthma and COPD patient organisations have produced high-quality device videos but reach is limited; most patients learn or fail to learn technique in the clinic.

Population variability

Inspiratory-flow capacity is the single biggest population-variability axis: children under ~5 cannot reliably generate the flow needed for DPIs, severe COPD patients in exacerbation often cannot meet the 30–60 L/min threshold, and frail elderly may struggle on the same grounds Laube et al. 2011. For these groups, pMDI-plus-spacer (with face mask in young children) or soft-mist is the appropriate substitution. Coordination capacity is the second axis: manual dexterity, cognitive impairment, arthritis (canister-press strength), and language barriers all push toward devices with fewer steps. Adherence is the third axis: regimens that combine pMDI and DPI in the same patient produce reliably more errors than single-device regimens, because the manoeuvres differ Lavorini et al. 2008. Age and education correlate with error rate in observational series, but the correlation is weak compared with the regimen-complexity and inspiratory-flow effects Melani et al. 2011.

Knowledge gaps

Long-term retention of technique training is the largest gap: studies typically follow patients out to 3–6 months, with little data past 12. The optimal frequency for re-checking technique is therefore set by convention rather than evidence — GINA's "every visit" is conservative but defensible. The dose-response of spacer use in adult maintenance therapy (as opposed to acute paediatric asthma) is less well characterised than the clinical recommendation implies. Digital inhalers with built-in inhalation-quality sensors are entering the market; their outcome data are early. Finally, the role of technique in newer breath-actuated and smart-spray devices has not been independently audited at the scale of Sanchis 2016 — an opportunity for the next decade of work.

Scope decisions:

The brief named drug delivery, symptom control, exacerbation risk, and the role of spacers. All four are covered in the article (mechanism, evidence/payoff, stakes, and spacer-in-protocol/practicalities respectively). No narrowing relative to the brief.
Pharmacology of the underlying drugs (SABA, LABA, ICS, LAMA classes) is deliberately out of scope. The entry is about the device interface, not the medicine. Drug-class entries should sit alongside as siblings.
Nebulisers are mentioned only as the comparison arm of the Cates 2013 Cochrane review. A standalone nebuliser-vs-inhaler entry would be valuable in the future, especially for paediatric and severe-exacerbation contexts; flagged as a future-link candidate.
Adherence (does the patient actually take the prescribed dose at all?) is upstream of technique and a distinct behavioural problem. Mentioned in the closing pointers; warrants its own entry.

Rating calls:

health_short_term = 4 was the hardest call. The substance is genuinely transformative for the subset of asthma and COPD patients whose poor control was driven by technique — but for a patient already using technique correctly the effect is zero. Scored against the population the entry actually targets (those whose technique is currently wrong, which is ~two thirds of users per Sanchis 2016), not the catalogue average.
longevity = 2 reflects the COPD-mortality link via exacerbation reduction and is intentionally conservative — the causal chain is technique → controller delivery → exacerbation rate → FEV₁ trajectory → mortality, each link with its own attenuation.
focus = 0 was contested with myself; the link from inhaler technique to cognitive performance via sleep and hypoxia exists but is too thin to score honestly. Left at zero.
evidence = 4 not 5: Sanchis 2016 is meta-analytic and definitive on prevalence, but the outcome literature (CRITIKAL, Melani) is observational and cross-sectional. A multi-centre RCT of technique-coaching-versus-usual-care with hard outcomes at 24+ months would buy the fifth point.

Future-link candidates:

Nebuliser therapy — sibling entry on when nebulisation beats inhaler-plus-spacer (mostly never, per Cates 2013, but the edges matter).
Inhaled corticosteroid maintenance — drug-class entry; cross-link from the mouth-rinse warning callout.
Asthma action plan — what to do when symptoms escalate; pairs with this entry as the "how" and the "when".
Adherence to chronic medication — the upstream behavioural problem.
Peak-flow monitoring — the home diagnostic to catch worsening early.

Audience scoping: deliberately not gender- or age-scoped. The substance applies to anyone using an inhaler, and the per-population guidance (children needing tidal-breathing technique through a spacer, frail elderly losing inspiratory flow on dry-powder devices) is delivered as inline editorial notes rather than as scoped audience blocks, on the grounds that every reader benefits from understanding the variability.