spacers Flashcards
what are the 3 types of spacer devices available?
large vol
small vol
tube spacers
what are the two large volume spacers and their capacities?
Nebuhaler750 ml
Volumatic700 ml
what are the 3 small volume spacers and their capacities?
Nebuchamber250 ml
Aerochamber145 ml
Dynahaler60 ml
how do spacers work?
increase distance between inhaler mouthpiece and patient:
•Allows time for propellant to be driven off
•Decreases velocity of particles (lowers momentum)act as a filter system for larger particles
improve co-ordination
what happens when using a spacer? / why are they good?
mmadof emitted dose decreases
•amount of drug reaching patient may be same or less
•respirablefraction either the same or greater
•oropharyngealdeposition less
what is the type of variation that can occur in spacer devices?
from patient to patient for same spacer device
•with different spacer devices
•with different drug and drug formulations
how does the formulation affect the dose delivered?
chemical nature of the drug inclcontact angle, functional groups at surface, moisture uptake•particle density & porosity•particle size, shape & surface texture•particle surface contamination –surfactant, co-solvent, propellant, moisture•particle velocity•particle concentration & cloud morphology•electrostatic charge•for particles -electrostatic charge mainly influenced by size, polarity (dielectric constant), volume and surface resistivity, work function, moisture, contact event
how does the device affect the dose delivered?
•surface texture/condition•size & shape•valve design & facemask•Material type Nebuhaler–polycarbonate (non-polar)Volumatic-polyamideAerochamber–polyester (higher polarity)
how does the patient affect the dose delivered?
•breathing pattern & inspiratory effort•lapse time between actuation & inhalation•single or multiple actuations
handeling
