Shaking and holding breath, are they necessary?

Sharing a case today on

Asthma inhalers

Patient came into Emergency Department with shortness of breath and frequent coughing few weeks ago. After treatment was given, I approach the patient.

Had some conversation with him, he complained that the Salbutamol pressurized metered-dose inhaler (pMDI), which he had received past few weeks was not effective in managing nor relieving his asthma attacks. He had 4 attacks in these recent weeks. After using the MDI, the asthma attack did not relieved.

Suspecting the patient might use the MDI wrongly, I asked the patient to demonstrate how he used it.

I was right. He did not shake the MDI before using it, neither did he hold his breath after adminster the medication. He insisted that, shaking the MDI before use was an extra work which waste his energy and holding breath is pointless as the medication is already administered.

After counselled him on the purpose of doing these actions, he went back home. Today, he came to see me, thanked me and told me that he realized these may be the reasons behind his recent exacerbations.

So, why there are so many steps while using a MDI?

1. Shaking a MDI before use

Nowadays, pMDI contains two types of propellants, chlorofluorocarbons (CFC) and hydrofluoroalkane(HFA). 

In CFC-type MDI, the drug particles exist in suspension form.The drug might not distribute evenly in the cannister due to dispersion or settlement. Shaking is a crucial step here in order to redisperse the medication to ensure sufficient amount of drug particles being delivered during actuation. Study conducted by Everand et al. had shown that the delivery of medication may be reduced by up to 50% as a result of improper dispersion arise from not shaking the MDI.

On the other hand, the drug particles exist in solution form for HFA-type MDI. Shaking is not necessary.

Though HFA-type MDI does not require shaking, shaking is still recommended for all MDIs as it helps patient to understand the technique of using MDI easily.

2. Holding breath for at least 5- 10 seconds 

After administering the medication from cannisters, breath should be held for at least 10 seconds. It may be attributed to how the disposition of drug particles in the airway after inhalation was performed. The findings from a study has shown that bioavailability of salbutamol absorbed through airway after holding a 10 second breath is greater than that without any breath-holding.

These are the rationales behind it. 

It may seem trivial at first, but it may leave an impact in managing the asthma condition.

 

Sometimes, small things make a big difference.

References:

1. Everand, M.L., Devadason, S.G., Summers, Q A. & Le Souef, P.N. (1995). Factors affecting total and 'respirable' dose delivered by a salbutamol metered dose inhaler. Thorax, 50, p746-749.

2. Levy, M.L., Dekhuijzen, P.N., Barnes, P.J. et al. (2016). Inhaler technique: facts and fantasies. A view from the Aerosol Drug Management Improvement Team (ADMIT), Primary Care Respiratory Medicine, 26(16017).

3. Hindle, M., Newton, D A.G. & Chrystyn, H. (1993). Investigations of an optimal inhaler technique with the use of urinary salbutamol excretion as a measure of relative bioavailability to the lung. Thorax, 48, p607-610.