CACPT Forum

1. 

   Tony Kajnar
   

   I was wondering what you are using for your methacholine provocations (2 minute tidal breathing method).

   When it comes to nebulizers, ATS has little to offer in specific models and selection criteria. As long as they can be calibrated to achieve the minimum .13mg/min output you could potentially use any nebulizer on the market.

   We use the Canadian Wright nebulizer but I have read that Dr. Cockcroft uses the Bennet Twin Jet for research and patient testing in Sask. It has taken some time but I was finally able to locate its product information

   We have been under tremendous pressure to adapt a disposable nebulizer but is that really the best option? There have been a few studies on disposable nebulizers that claim they can be adapted to use for methacholine provocations but most don't seem well suited for the 2 minute tidal breathing method. I have tried to calibrate a couple without success, their output is way too high that 1.5cc is nebulized in 45-60 seconds when you run them continuously (one at flows less than 4 lpm). Some only nebulizer during inspiration but that would make it more difficult to calibrate.

   I would like to see some comparison trial done that not only list the output at various flow rates but the actual particle size at the expected flow rates required to achieve the .13mg/min spec.

   Thoughts?

   Regards,

   Tony

   Posted 1 year ago #
2. 

   jamey.cacpt
   Member

   hi tony, jamey here in hlfx
   we use the wright from roxon, and seem to have no prob. with cal x 2 per year (.13mg/ml +/- 0.026)
   as for particle size, i was always under the impression that as long as the flow was more than 6 and less than 10 we were o.k., but speaking of particle size - our med. director will not sanction the use of the vial with the 1cc well???
   i do wonder if and when the APS system of meth. challenge will be researched and adopted? i think hamilton ont. are doing a comparison study and i thougt edmonton was too??

   Posted 1 year ago #
3. 

   Tony Kajnar
   

   The 1999 ATS guideline for methacholine provocation does outline nebulizer performance.

   - at least .13 ml/min output within 10%
   - nebulizers need to produce particle size with a mass median diameter between 1.0 and 3.6 um
   - 3 mls of diluent.

   Dr. Donald W. Cockcroft has published several trails and studies and seems to be the leader in nebulizer analysis. If you do and article search you will find hours of reading.

   Dr. Cockcroft did publish articles that outline methacholine protocols designed to minimize waste of methacholione, one used 1.5ml of diluent instead of 3 and showed no change in outcome with their 2 min tidal method. Several are linked from the ATS website and I can email you a few from work. I have calibrated my wright neb with 3, 1.5 and 1.0mls and found no difference in output. Not sure if the change in surface tension would alter particle size.

   His article "Methacholine Challenge Methods" mentions that when the particle size falls below 1.0 um the deposition and patient response falls significantly.

   Many of the articles we base our current model on are quite old and reference parent articles from the 1970's. Technology has changed significantly and I would like to see nebulizer manufactures quote the particle size as well as output required specifically for methacholine provocation testing.

   Tony

   Posted 1 year ago #
4. 

   jamey.cacpt
   Member

   tony, thank you, i should be able to find those articles
   this is most helpful and may save our lab on meth. cost
   i too have cal'd my neb with 1cc and found no change in output, but could not comment on particle size
   actually, i have no idea how one would do that, seems like it would be a very complicated task??

   Posted 1 year ago #

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