Dry Powder Inhalers: You Need to Breathe In “Hard and Fast”to Get the Powder Deep into the Lungs

Dry Powder Inhalers Have Internal Resistances

Background: Inhaled bronchodilators are the cornerstone for treatment of those with COPD. However, it is important that the person be able to inhale the medication deep into the lungs in order to open the airways and make it easier to breathe.

Of the four different inhaling devices for bronchodilators, the most common is called the pressured metered-dose inhaler shown in the figure below. Simply pressing the canister down releases a spray (aerosol) from the mouthpiece.

Example of metered-dose inhaler. This is a different system than dry powder inhalers.

Pressurized metered-dose inhaler.

Many bronchodilators are available in dry powder inhalers (see below). All dry powder devices have an internal resistance. As a result, you need to inhale “hard and fast” to literally pull the powder out of the device and inhale it deep into the lungs.

Different dry powder inhalers

Dry powder inhalers have an internal resistance.

There is a simple breathing test to determine if you have enough inspiratory force to inhale the powder successfully out of the inhaler. This test is called peak inspiratory flow rate (abbreviated PIFR). Here is a picture of the In-Check DIAL used to measure PIFR.

In-Check DIAL to measure the resistance of dry powder inhalers

In-Check DIAL to measure peak inspiratory flow rate

Study: Dr. Loh and colleagues at the Winston-Salem Baptist Medical Center in North Carolina measured PIFR in patients just before discharge from the hospital for a flare-up (exacerbation) of COPD. The study results are published on-line in the Annals of the American Thoracic Society on April 13 (doi: 10.1513/AnnalsATS.201611-903OC).

Results: 52% of the 123 subjects had a PIFR below 60 liters/min. A value of 60 or higher is considered “optimal” to inhale the powder deep into the lungs.   Those with PIFR less than 60 liters/min were more likely to be readmitted to the hospital over 90 days for another COPD flare-up (28%) compared with subjects who had PIFR at least 60 or higher (14%).

Conclusions: The authors concluded that a low PIFR is common in those admitted to the hospital for a COPD flare-up. They recommended that the medical team measure PIFR before discharge, especially if a dry powder is being prescribed.

My Comments: With a PIFR of less than 60, it more likely that some or most of the powder stays in the mouth and throat. IF you are taking a dry powder bronchodilator and IF you find that it does not help you breathe easier, then you should ask your health care provider to measure your PIFR. If an In-Check DIAL is not available to test your PIFR, then you should ask about a different delivery system – possibilities include a pressurized metered-dose inhaler, a soft mist inhaler, or a nebulizer.

Woman inhaling aerosol from nebulizer

Soft mist inhaler

Errors are Common in Inhaler Use: A Systematic Review

Errors in Inhaler Use – both Metered-dose and Dry-powder 

Background: Correct use of inhalers is “key” for those with COPD to benefit from best available medications. Unfortunately, the medical profession has not done a good job in providing on-going education on proper use.

Study: Dr. Sanchis and colleagues performed a systematic review of articles published over 40 years (1975 – 2014) which reported on direct observation of inhaler technique by trained nurses and respiratory therapists. The purpose was to identify common errors and the percentage of patients.  The article was published on-line on April 6, 2016, in the journal CHEST.

Results: Information was available in 54,354 subjects. The most common errors with pressurized metered-dose inhalers were:

Example of pressurized metered-dose inhaler.

Example of pressurized metered-dose inhaler.

  1. no breath hold after full inhalation – 46%
  2. poor co-ordination between pushing down the canister and inhaling – 45%
  3. incorrect speed and/or depth of breathing in – 44%

The most common errors with dry-powder inhalers were:

Examples of dry-powder inhalers

Examples of dry-powder inhalers

  1. not breathing out completely before inhaling the powder – 46%
  2. no breath hold after full inhalation – 37%
  3. not preparing the inhaler correctly – 28%

Conclusions: Incorrect inhaler technique is common and has not improved over the past 40 years. There is an urgent need for new approaches in education.

My Comments: Many of those with COPD need repeated review of correct inhaler use. Remember, the medication needs to reach the small breathing tubes deep in the lungs to make it easier to breathe. If you are not sure that you are inhaling correctly, ask your health care provider or nurse to watch you perform all of the steps.