Size is an important characteristic of nebuliser
performance. Large particles do not reach the lower respiratory
tract depositing themselves in the mouth, upper airways and
gastrict tract. Particles too small will not be taken up by the
alveoli and are exhaled. Respirable particles taking part in lung
deposition has been accepted to range from 0.5 microns to 5.0
microns in diameter size.
Time is the time from starting nebulisation until
continuous nebulisation has ceased and depends on the flow rate,
compressed air and the construction of the nebuliser. These are a
major influence on aerosol size distribution. Optimal flow rates
recommended are between 6-8 litres per minute, with 8l/min
providing a smaller particle size and shorter nebuliser time, the
time it takes for the volume to completely nebulise. A SVN should
deliver at least 80% of the solution within 15 minutes.
|Reconcentration is a SVN
is greater at a diluent volume of 2ml than one of 4 ml and for that
reason it is suggested 4ml maybe superior than 2ml as a diluent
Volume is the volume of medication not delivered to
the patent during nebulisation and exists as the volume left in the
nebuliser at the end of nebulisation.
Mass is the combination of aerosolised drug output
and the percentage of particles in the respirable range. This is
the amount of aerosolised drug available to the patient on