“Delivery of Medication via Metered Dose Inhalers” by Craig Smallwood for OPENPediatrics
10
October

By Adem Lewis / in , , , , , , , , , , , , /


Delivery of Medication via Metered Dose Inhalers by Craig Smallwood. A metered dose inhaler consists of a cannister,
which contains a propellant– a compressed inert gas– and a medication. An actuator that the cannister is inserted
into, and when depressed, directs a specific amount of medication through the mouthpiece. And sometimes a counter, which retains a record
of the number of cannister depressions to help gauge when a cannister should be changed for
your subject. It’s important to note that there are several
different masks and interfaces when using MDIs. In general, it’s good practice with infant
and pediatric subjects to use an antistatic valved holding chamber or spacer, since they
may have difficulty with the coordination and control involved in using MDIs independently. A holding chamber, or spacer as commonly known,
is a device that is basically an aerosolized medication reservoir. It allows a collection of medication to be
held in a chamber, that can then be inhaled and not lost to the room during delivery. We have several different interface options. Depending on the patient’s size we have different
masks and different sized chambers. Additionally, we have spacers that are built
for endotracheal and/or tracheostomy tubes. Also, we have inline MDIs which can be used
during mechanical ventilation. I’ve selected a pediatric size chamber with
an appropriate mask for this patient. Some components of the chamber itself. The interface; an appropriate size interface
is essential to minimize leaks during use and optimize delivery of our medication. The one way inhalation valve separates the
chamber from the patient and ensures that upon inhalation, the patient draws gas through
the chamber that contains the medication. The one way exhalation valve ensures that
upon exhalation, gas is diverted through a separate channel out to the room and away
from the medication chamber. The exhalation valve helps to prevent dilution
of the medication from exhaled gases. The antistatic chamber and the MDI adapter;
the MDI adapter is where the chamber interacts with the MDI and is able to accept medication. One important thing to note when using MDIs
is to appropriately and vigorously shake the cannister before each actuation. About 30 to 40 seconds of aggressive shaking
between actuations will ensure that the highest proportion of the prescribed dose on the cannister
will be administered to your patient. Place it back into the plastic holder. Place it into our chamber, and let’s actuate
a puff here and give it to our patient. Now, it’s not essential for the patient to
synchronize breathing with the cannister actuation since we’re using a chamber that helps to
ensure the medication is delivered on demand. I’m going to shake for another 30 to 40 seconds
after that actuation before we give our second dose. I wait four to five breaths between actuations
to make sure that the patient inhales all the medication in the chamber possible.


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