Decades of past research have made it common knowledge that when using Metered Dose Inhalers (MDIs), it’s critical to follow the steps of inhaler use correctly so that the right amount of medication gets dispensed from the MDI and we can maximize that reaching the lungs [1-7]. Each correct step adds to the drug deposited in the lungs, while with every mistake, we lose some on the way (mouth, throat, trachea or exhaled out). From the patient’s point of view, there’s no telling where the medication went, no way to measure it. So let’s delve a little bit deeper into the science behind the drug delivery in a series of posts called “How to use inhalers.” Part I looks at the orientation and placement of inhalers in the mouth.
The perfect angle
If you read some of the package inserts of commonly used MDIs, they provide a simple instruction to “Hold the inhaler with the mouthpiece down,” (as seen from Ventolin HFA packaging). While the instruction is easy to understand, it leaves a wide range of angles that the inhaler may be used at.
To find out how patients use their MDIs, I and my collaborators at Rice University and Baylor College of Medicine used the CapMedic digital MDI attachment (developed at Cognita Labs) to record how patients use their inhalers. It was a small pilot study [8] and we recorded inhaler use data from 23 patients (19 asthma, 4 COPD, 6 male, 17 female, aged 20-65) who used a placebo Ventolin MDI attached to CapMedic. We found that the subjects placed the inhaler at a range of angles spanning 50 degrees! Let’s call the angle at which the mouthpiece is horizontal (medication is released along the horizontal axis) as 0°, angled downward (toward the tongue) would be a negative angle and angled upward (toward the roof of the mouth) would be a positive angle. The patients used the inhaler positioned at angles from -9° to +41°.
We then looked at some of the literature for the correct orientation. One of the most detailed studies was by Delvadia et al. in 2013 [9] where they simulated the mouth throat deposition of medication based on the angle of insertion for Proventil MDI and confirmed it through an in-vitro study. The test was performed for the range of -20° to +20°. According to the study, the optimum orientation for the inhaler is from -10° to +20° which led to the in-vitro lung deposition range of 41.35 – 48.77% and was lower when the angles were increased in either direction. The highest in-vitro lung deposition (46.62-48.77%) was for inhalers positioned between 0°-10° orientation.
What happens when we orient inhalers incorrectly?
According to Delvadia et al., when the inhaler is oriented in the negative angle (<-10°), the medication spray is directed toward the tongue and a lot of the medication deposits in the mouth rather than reaching the lungs. However, if the inhaler is oriented too far positive (>20°), the medication is directed to the roof of the mouth and again increases the deposition of aerosol in the mouth.
What should patients do?
Based on what we read in the paper, the best way to orient the MDI is to
- First, keep your head upright. We want the medication to cross the 90° bend at the throat as easily as possible. The angle becomes sharper if the head is bent downward.
- Next position the inhaler such that the mouthpiece is pointing straight into the mouth or angled slightly (<10°) toward the roof of the mouth.
The figure on the left shows the inhaler oriented correctly. Figures on the right show what happens when the inhaler is positioned incorrectly.
How does CapMedic help?
Our smart inhaler device CapMedic can help with the precise positioning of the inhaler during use. CapMedic provides live feedback to let users know the correct orientation during use (in addition to the other steps of shaking, coordination and inhalation) and provides tips on the smartphone app on how to correctly use MDIs. Our early pilot study results [10-11] show that children (aged 10-17 years) when taught correct inhaler use with CapMedic were able to orient the inhaler correctly 75% of the time with feedback from CapMedic.
Of course, the other steps of inhaler use (shaking, inhalation flow, coordination timing of actuating the MDI and breath-hold) also contribute toward maximizing the drug deposition in the lungs. We’ll discuss each step one-by-one in the upcoming posts.
References
- Capstick TG, and Clifton IJ: Inhaler technique and training in people with chronic obstructive pulmonary disease and asthma. Expert Rev Respir Med. 2012;6:91–103.
- RubinBK: What does it mean when a patient says, ‘‘My asthma medication is not working?’’ Chest. 2004;126:972–981.
- Roche N, Chrystyn H, Lavorini F, and Agusti A: Effectiveness of inhaler devices in adult asthma and COPD. EMJ Respir. 2013;1:64–71.
- Melani AS, Bonavia M, Cilenti V, Cinti C, Lodi M, Martucci P, Serra M, Scichilone N, Sestini P, Aliani M, and Neri M: Inhaler mishandling remains common in real life and is associated with reduced disease control. Respir Med. 2011;105:930–938.
- Laube BL, Janssens HM, De Jongh FHC, Devadason SG, Dhand R, Diot P, Everard ML, Horvath I, Navalesi P, Voshaar T, and Chrystyn H: What the pulmonary specialist should know about the new inhalation therapies. Eur Respir J. 2011;37:1308–1331.
- Price, David B., et al. “Inhaler errors in the CRITIKAL study: type, frequency, and association with asthma outcomes.” The Journal of Allergy and Clinical Immunology: In Practice 5.4 (2017): 1071-1081.
- Biswas, Rajoshi, Nicola A. Hanania, and Ashutosh Sabharwal. “Factors determining in vitro lung deposition of albuterol aerosol delivered by Ventolin metered-dose inhaler.” Journal of aerosol medicine and pulmonary drug delivery 30.4 (2017): 256-266.
- Biswas, Rajoshi, et al. “Measuring Competence in Metered Dose Inhaler Use Using Capmedic Electronic Inhaler Monitoring Tool.” Chest Journal 150.4_S (2016).
- Delvadia, Renish R., et al. “In vitro tests for aerosol deposition. III: Effect of inhaler insertion angle on aerosol deposition.” Journal of aerosol medicine and pulmonary drug delivery 26.3 (2013): 145-156.
- Paronyan, E., et al. “Utilizing Capmedic Electronic Device to Measure and Improve Inhaler Technique in Clinic.” C32. FACTORS IN ADHERENCE AND CONTROL OF ASTHMA. American Thoracic Society, 2020. A4786-A4786.
- Landon, Chris, et al. “Remote monitoring of medication and lung function of asthmatic children.” (2020).
