Interpretation of pulmonary function tests (PFT) - Twitter summary from 2012 #AAAAI meeting

This summary was compiled from the tweets posted by the following allergists/immunologists who attended the 2012 annual meeting of the American Academy of Allergy Asthma and Immunology (AAAAI): Sakina Bajowala, M.D ‏@allergistmommy. The tweets were labeled #AAAAI. The text was edited and modified by me.

Interpretation of pulmonary function tests (PFT) lecture by Joseph Spahn and Todd Hostetler:

Extra thoracic airway obstruction

Blunting of both inspiratory and expiratory loops on PFT is concurrent with fixed airway obstruction.

Isolated blunting of the inspiratory loop is concurrent with extra thoracic airway obstruction. Looking at the FEF50/FIF50 ratio can be helpful.

Unilateral vocal cord paralysis can be secondary to laryngeal nerve injury. Flexible laryngoscopy or video stroboscopy is needed to work through the diagnosis of extrathoracic obstruction. Don't assume VCD.

Restrictive lung disease

Restrictive pattern on spirometers does not always correlate with true restrictive disorder. There is a difference between restrictive pattern on PFTs and restrictive disease.

If restrictive disease is suspected, total lung volumes (whole body plethysmography) should be obtained.

Restrictive lung disease includes parenchymal, neuromuscular, and musculoskeletal causes.

As allergists, we usually deal with obstructive lung disease (asthma and COPD). Remember: restrictive lung disease is part of the differential diagnosis for dyspnea and cough.

Vocal cord dysfunction (VCD)

Functional residual capacity (FRC) is an effort-independent measure on PFT. If FEF50/FIF50 ratio is >150% of predicted, this is strongly indicative of vocal cord dysfunction (VCD).

Unilateral vocal cord paralysis can be secondary to laryngeal nerve injury. Flexible laryngoscopy or video stroboscopy is needed to work through the diagnosis of extrathoracic obstruction. Don't assume VCD.



PFTs (click to enlarge the image).

Dysfunctional breathlessness

Dysfunctional breathlessness is among the most common additional diagnoses in patients with refractory asthma. It is more common than vocal cord dysfunction (VCD). In dysfunctional breathlessness, airway resistance is not increased. This is in contrast to asthma.

Dysfunctional breathlessness can be treated with psychotherapy, biofeedback, and speech therapy.

Impulse oscillometry

Impulse oscillometry is an effort-independent test of pulmonary function. It can be performed in kids unable to perform forced maneuvers. Impulse oscillometry can reveal increased airway resistance, even when FEF25-75 is normal on PFTs.

Allergists achieved highest use of social media by any specialty

During the 2012 AAAAI meeting, the allergists achieved the highest use of social media by any specialty. There are more than 100 allergists on Twitter and 30 of them posted simultaneously from the annual meeting, broadcasting thousands of tweets tagged with #AAAAI. The annual AAAAI meeting was attended by approximately 5,000 people. In comparison, the 30 allergists on Twitter reached 250,000 people (measured by TweetReach.com on 03/04/2012).

This summary was compiled from some of the tweets posted by Sakina Bajowala, M.D ‏@allergistmommy. I would strongly encourage you to post updates on Twitter from the CME conferences that you are planning to attend in the future. Here is how to do it: Twitter for Physicians: How to use Twitter to keep track of the latest news and scientific meetings, and share information with colleagues and patients.

Disclaimer: The text was edited, modified, and added to by me. This is one of a series of posts that will be published during the next few weeks.

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