page204
Nebulisers
In England and Wales nebulisers and compressors
are not available on the NHS (but they are free of
VAT);
some nebulisers (but
not
compressors)
are
available on form GP10A in Scotland (for
details
consult Scottish Drug Tariff).
A nebuliser converts a solution of a drug into an aerosol
for inhalation. It is used to deliver higher doses of drug
to the airways than is usual with standard inhalers. The
main indications for use of a nebuliser are to deliver:
.
a beta
2
agonist or ipratropium to a patient with an
acute exacerbation
of asthma or of chronic obstruc-
tive pulmonary disease;
.
a beta
2
agonist,
corticosteroid, or ipratropium on a
regular basis
to a patient
with severe asthma or
reversible airways obstruction when the patient is
unable to use other inhalational devices;
.
an antibiotic (such as colistin) or a mucolytic to a
patient with cystic fibrosis;
.
budesonide or
adrenaline to a child with severe
croup;
.
pentamidine for the prophylaxis and treatment
of
pneumocystis pneumonia.
The use of nebulisers in chronic persistent asthma and
chronic obstructive pulmonary disease should be con-
sidered only:
.
after a review of the diagnosis;
.
after review of therapy (see Management of Chronic
Asthma, p.
172 and Chronic Obstructive Pulmonary
Disease,
p.
171)
and the patient’s
ability to use
hand-held devices;
.
after increased doses of inhaled therapy from hand-
held inhalers (with a spacer if necessary) have been
tried for 2 weeks;
.
if
the patient remains breathless,
despite correctly
using optimal therapy
Before prescribing a nebuliser,
a home trial
should
preferably be undertaken to monitor
response for
up
to 2 weeks on standard treatment and up to 2 weeks on
nebulised treatment.
If prescribed,
patients must:
.
have clear
instructions
from a doctor,
specialist
nurse or
pharmacist
on the use of
the nebuliser
(including maintenance and cleaning) and on peak-
flow monitoring;
.
be instructed not
to treat
acute attacks at
home
without also seeking help;
.
have regular follow up by a doctor,
specialist nurse
or physiotherapist after about 1 month and annually
thereafter
The proportion of a nebuliser solution that reaches the
lungs depends on the type of nebuliser and although it
can be as high as 30%, it is more frequently close to 10%
and sometimes below 10%.
The remaining solution is
left in the nebuliser as residual volume or is deposited in
the mouthpiece and tubing.
The extent
to which the
nebulised solution is deposited in the airways or alveoli
depends on the droplet size, pattern of breath inhalation,
and condition of the lung. Droplets with a mass median
diameter of
1–5 microns are deposited in the airways
and are therefore appropriate for
asthma,
whereas a
particle size of
1–2 microns
is
needed for
alveolar
deposition of
pentamidine to combat
pneumocystis
infection.
The type of
nebuliser
is
therefore chosen
according to the deposition required and according to
the viscosity of the solution (antibiotic solutions usually
being more viscous).
Jet
nebulisers are more widely used than ultrasonic
nebulisers.
Most jet nebulisers require an optimum gas
flow rate of
6–8 litres/minute and in hospital
can be
driven by piped air
or
oxygen;
in acute asthma the
nebuliser should be driven by oxygen. Domiciliary oxy-
gen cylinders do not
provide an adequate flow rate
therefore an electrical compressor is required for dom-
iciliary use.
For patients at risk of hypercapnia,
such as those with
chronic obstructive pulmonary disease,
oxygen can be
dangerous and the nebuliser should be driven by air (see
section 3.1).
If
oxygen is required,
it
should be given
simultaneously by nasal cannula.
Tubing
The Department of Health has reminded users of the
need to use the correct grade of
tubing when con-
necting a nebuliser
to a medical
gas
supply or
compressor.
Ultrasonic nebulisers produce an aerosol
by ultrasonic
vibration of
the drug solution and therefore do not
require a gas flow; they are not suitable for the nebulisa-
tion of some drugs,
such as dornase alfa and nebulised
suspensions.
Nebuliser diluent
Nebulisation may be carried out
using an undiluted
nebuliser solution or it may require dilution beforehand.
The
usual
diluent
is
sterile
sodium chloride
0.9%
(physiological saline).
Sodium Chloride
(Non-proprietary) A
Nebuliser solution
,
sodium chloride 0.9%,
net price
20 2.5 mL = £11.50
Brands include
Saline Steripoule
c
,
Saline Steri-Neb
c
3.2
Corticosteroids
Corticosteroids are used for the management of rever-
sible
and
irreversible
airways
disease.
An
inhaled
corticosteroid used for 3–4 weeks may help to distin-
guish asthma from chronic obstructive pulmonary dis-
ease;
clear
improvement
over
3–4 weeks
suggests
asthma.
Asthma
Corticosteroids are effective in
asthma
;
they
reduce airway inflammation (and hence reduce oedema
and secretion of mucus into the airway).
An inhaled corticosteroid is used regularly for prophy-
laxis of
asthma when patients require a beta
2
agonist
more than twice a week,
or if symptoms disturb sleep
more than once a week,
or if
the patient has suffered
exacerbations in the last 2 years requiring a systemic
corticosteroid or a nebulised bronchodilator (see Man-
agement of Chronic Asthma table,
p.
172).
Regular use
of inhaled corticosteroids reduces the risk of exacerba-
tion of asthma.
Current and previous smoking reduces the effectiveness
of
inhaled corticosteroids and higher
doses
may be
necessary.
Corticosteroid inhalers must be used regularly for max-
imum benefit; alleviation of symptoms usually occurs 3
184
3.2 Corticosteroids
BNF 61
3
Respiratory system