MMAD (Mass Median Aerodynamic Diameter = size of particles)

Question

Hello,
- Which size of particles is ideal in case of inhalation with colistin and DNAse?
- Are these sizes achieved with the e-flow?
- The particle size should not fall below under which minimal size for both drugs (in case inhalation is performed with a different nebulizer)?
Many thanks

Answer

Hello,
we asked the physiotherapist Stefanie Rosenberger (hospital Schillerhöhe, Gerlingen, Germany) to answer this question. She writes:

"(...)In general, particles 1-5µm in size are respirable, this is also true for colistin and DNAse. Hereby, within this range a particle size of 2-3.5 µm is thought to be optimal.
This is achieved by the Pari e-flow, as well as by all other nebulizers used in CF therapy.
It is remarkable in this context that the deposition at 1-5 µm is influenced to a great extent by the inhaled volume (deep breath 1800ml 30% alveolar lung deposition in contrast to an alveolar deposition of under 10% at a breath volume of 350ml) and by the breathing flow (nearly double alveolar deposition at 200ml/s as a slow inspiration in contrast to a normal inspiration with 1000ml/s). This underlines the importance of a controlled breathing pattern during the inspiration.
The breathing flow is controlled at the Pari Sprint nebulizers via the Pif-control, however a further inspiration becomes suddenly impossible in case of a too fast inspiration (more than 25l/min), the drug is also nebulized during inhalation breaks and expiration.
The I-neb calculates via the breathing flow of a patient the duration of the inspiration and a drug-specific chip-card calculates the control of the breathing maneuver of the patient. Only during inspiration the drug is nebulized.
At the Akita Jet, the optimal breathing flow is controlled via visual feedback. The number of breathes is controlled via the inspiration volume of the patient and a drug specific chip. Similarly, aerosol is provided only in the inspiration period. The newest is the possiblity of combining an 02-adapter with the Akita.
In case the particle size falls below 1 µm, a great part of the particles are again expired, the rest can then reach the alveoli, this is not sensible.
In general it has to be taken into account, that a change of the inhalative medication (also the devices) should be controlled by the physician.
Yours sincerely,
Stefanie Rosenberger "

01.08.2011