Spacers
We have also to consider the use of a holding chamber, reverse-flow spacer or spacer in combination with pMDI. This reduces the need for patiënt coördination and pharyngeal deposition.Spacer devices are also known as add-on devices, ac- cessory devices, extension devices, and holding chambers. They are attachments to pMDI actuators, with volumes ranging from 20 mL to 750 mL in commercially available models. Spacers perform several functions. By placing some distance
(and, thus, time) between the point of aerosol generation and the patient’s mouth, they reduce oro-pharyngeal deposition and increase lung deposition. Spacers make pMDIs easier to use by reducing or eliminating the need for coordination between actuation and inhalation, and reducing the cold gas effect. These benefits are achieved at the expense of making the pMDI system substantially larger and less convenient. Spacers can be grouped into 3 categories :