How is sniff nasal-inspiratory force (SNIF) measured in pulmonary function testing?

Updated: May 14, 2020
  • Author: Kevin McCarthy, RPFT; Chief Editor: Nader Kamangar, MD, FACP, FCCP, FCCM  more...
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The measurement of sniff nasal-inspiratory force (SNIF) shows promising utility in predicting mortality in patients with amyotrophic lateral sclerosis (ALS). [12] A standardized device is not commercially available. A polyethylene catheter ending in a plug is attached to a pressure transducer, and the plug end is inserted into a nostril. The contralateral nostril is occluded, and the patient is instructed to exhale to FRC, then close the mouth and take a deep sniff or a maximal inspiratory effort. Both nostrils are tested, and the highest of six recorded pressures sustained for at least 1 second is reported.

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