To Nebulize or Inhale? That is the Question

Vintage image of a nebulizer

Nebulizers and inhalers of short-acting bronchodilators are in no short supply at most urban emergency departments. When someone comes in with an acute asthma exacerbation, the front-line ED nurses are quick to start them on some sort of bronchodilator. Of all the EDs I’ve worked at, this is a universal truth.

The method of delivery, however, is another issue. At my emergency department in Alberta, a typical asthma exacerbation order for bronchodilators is:

Salbutamol 4-6 puffs inhaler with spacer q20-30mins times 3 doses

Conversely, at my emergency department in British Columbia, it is:

Salbutamol 5 mg nebs q20-30mins times 3 doses

Metered-dose-inhaler (MDI) with spacer versus nebulizer: staff at both sites are quick to take sides with one route and talk about the failures of the other. Of course, this raises the question: is one side better than the other? Are both equally good?

The Short Answer: Generally, They’re Both Equally Good

Several studies and reviews of asthma exacerbation treatments in the emergency department are quick to point out that nebulizers or MDI with spacers are equally efficacious in improving peak flow rates and symptoms in adult and pediatric populations [1-4].

The Long Answer: …But MDI with Spacer is Probably the Better Choice

There are a few things that MDI with spacer has going for it that makes it the better choice [5]:

  • Better dose-to-dose reliability
  • Decreased potential for patient-to-patient contamination
  • Less expensive

They’re not super “change your practice” differences, but things to consider between nebulizers and MDI with spacer.

Dose-to-Dose Reliability

It’s important to understand what the spacer is doing when you’re using an MDI. If you use an MDI alone, the patient needs to coordinate their inhalation with the propelling of the medication from the MDI. Too soon or too later and the medication basically collects in the back of the throat. The beauty of the spacer is that it takes away some of the coordination of breathing. Rather than coordinating the breath with the inhaler spray, the patient simply needs to inhale once the medication has collected in the spacer. One study estimates that up to 65% of medication collects in the oropharynx when MDI is used alone; the use of a spacer drops the deposition rate to 6.5% [6]! Therefore, so long as a person is correctly using an MDI with spacer, they should be getting the same dose each time.

Compare this to nebulized treatment: while logically it would make sense that a person who is continually exposed to treatment would get more of the medication, this is is reliant on:

  • A perfect seal of the nebulizer mask to avoid a lot of medication escaping into the environment
  • The patient keeping the mask on to completion of treatment

Potential for Patient-to-Patient Contamination

A lot of medication can escape into the environment in the non-ideal use of nebulizer treatment. These tiny particles of aerosolized medication that scatter into the environment are the perfect vehicle for bacteria and viruses to anchor on to. They’re also very good for triggering cough, potentially causing infectious agents to spread in the air. Of course, that’s all theoretical – observational studies only show some risk or are inconsistent in demonstrating nosocomial infections from nebulizer user [7]. The risk is there, but not sure to what degree.

Unless multiple patients share the same MDI and spacer – which infection control would definitely not allow – inter-patient contamination when using MDI plus spacer falls back to poor hand hygiene. Or one patient coughing on another.


All of the studies mentioned so far that made mention of monetary costs showed that medication and equipment are far cheaper for MDI with spacer over nebulizer treatment. One small observational study in Nova Scotia found a lower incidence of hospital admission when MDIs were used in the emergency department – and by lower: 4.4% – which if more studies showed similar decreases, could mean decreased hospital costs [8].

The Caveats

Inhalers aren’t the clear winner for two additional reasons.


Using MDI with a spacer requires trained coordination which generally means that the first few times that MDIs are administered, a nurse or respiratory therapist should be at the bedside. This is probably the reason that nebulizers are favoured by many emergency nurses: it essentially allows them to start treatment and then leave to attend to another patient. Using MDIs would require the nurse or RT to properly coach the patient on their first (and possibly subsequent) dose.

This isn’t necessarily a bad thing. Many patients with asthma exacerbations come in because they haven’t used their inhalers for awhile or have been using them incorrectly. Proper coaching and training of the MDI and spacer by a nurse or RT could have the added benefit of reducing the recurrence of a repeat attack if they’re using their inhalers at home correctly.

Patient Effort

There is also the obvious issue that if a patient is too anxious or if their breathing is too irregular or shallow, they probably can’t (or won’t) coordinate their breaths or take a deep enough breath from an MDI with spacer. The nebulizer wins that round.

The Pragmatic Answer: …But the Culture Probably Dictates What Gets Done

It should be obvious that all other things considered, the MDI with spacer is probably the better choice of the two for an acute asthma exacerbation. I brought this up to the emergency department where nebulizers were the preferred choice and it’s definitely one of those topics where there are many opinions abound – but for good reason:

  • Staffing shortages and an ever-increasing patient population practically means less face-to-face time and “shortcuts” are important to keep the sanity of the department
  • Proper patient education and care goes beyond the emergency department and requires a strong foundation of primary care to back it up
  • Patients just don’t like it

This particular emergency department works with a large financially-disadvantaged population that already has difficulty being connected with health resources and so the emergency department is their effective solution for getting their asthma treatments. Trying to encourage an MDI with spacer is met with arguments from patients like “those never work for me” or “you guys aren’t giving me good care.” One ED doctor I worked with suggested that the lengthy period of time that a nebulizer is put on for has a “psychological calming” effect on patients versus the “six puffs and you’re done” strategy.

Unfortunately, trying to change those attitudes goes beyond the typical timeframe of an emergency department visit and the nebulizer is provided simply to appease to the patient’s satisfaction (even when MDI and spacer were ordered by the provider). At the end of the day, the MDI with spacer is a route to advocate for practice but that is going to be a difficult change for many ED sites. To create a culture of change requires an overhaul of the underlying determinants of health that act as a barrier to what the emergency department staff hopes to remedy.


[1] Dhuper S et al. 2008. Efficacy and cost comparisons of bronchodilator administration between metered dose inhalers with disposable spacers and nebulizers for acute asthma treatment. The Journal of Emergency Medicine, 40(3), 247-255.

[2] Newman KB et al. 2002. A comparison of albuterol administered by metered-dose inhaler and spacer with albuterol by nebulizer in adults presenting to an urban emergency department with acute asthma. Chest, 121, 1036-1041.

[3] Rodrigo C and Rodrigo G. 1998. Salbutamol treatment of acute severe asthma in the ED: MDI versus hand-held nebulizer. The American Journal of Emergency Medicine, 16(7), 637-642.

[4] Cates et al. 2013. Holding chambers (spacers) versus nebulisers for beta-agonist treatment of acute asthma. Cochrane Database of Systematic Reviews, 13(9).

[5] Dolovich et al. 2005. Device selection and outcomes of aerosol therapy: Evidence-based guidelines: American College of Chest Physicians/American College of Asthma, Allergy, and Immunology. Chest, 127(1), 335-371.

[6] Dolovich et al. 1983. Clinical evaluation of a simple demand inhalation MDI aerosol delivery device. Chest, 84, 36-41.

[7] Tran et al. 2012. Aerosol Generating Procedures and Risk of Transmission of Acute Respiratory Infections to Healthcare Workers: A Systematic Review. PLoS ONE, 7(4).

[8] Spin et al. 2017. A cost analysis of salbutamol administration by metered-dose inhalers with spacers versus nebulization for patients with wheeze in the pediatric emergency department: Evidence from observational data in Nova Scotia. Canadian Journal of Emergency Medicine, 19(1), 1-9.

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