The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts


Catherine Foss, BS, RRT, RPFT, Mercedes True, BS, RRT, RPFT, Fernando Martinez, MD. Pulmonary Diagnostic Services, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI.

Background: Peak flow instruments are valuable tools to monitor known asthmatics. In 1994, Dr. Badgett published an article in Chest, proposing that peak flow meters could be utilized along with patient history and exam to diagnose any degree of COPD. This article was acted upon by general practice internists who began performing peak flow testing in pre-op patient assessments to rule out pulmonary disease, using a cut-off of < = 250 L/min. Only if patients fell below the cut-off, were they sent to the pulmonary lab for spirometry testing. The clinic utilized medical assistants to test the patients peak flow rate using a disposable Assess Peak Flow meter, changing mouthpieces between patients. The Pulmonary department had concerns about the accuracy of peak flow monitors, and the utility of using a cut-off of < = 250 L/min, rather than a percent of predicted. There was concern that patients would be sent to surgery without proper pulmonary assessment and needed treatment with resulting increased morbidity. In an effort to evaluate the situation, we proposed to duplicate the clinic peak flow testing methods on all patients coming to the PFT lab along with the patient's routine scheduled PFT's. The results of the two tests could be compared and evaluated. Methods: Each patient arriving in the outpatient PFT lab, had peak flow testing performed, after instruction and demonstration, with a minimum of three trials, prior to routine PFT's. Assess Peak Flow monitors were used, with the mouthpiece changed between each patient. The PFT's were interpreted, then the peak flow efforts evaluated in comparison to the PFT results. 209 patients were tested, 109 Females and 100 Males. Mean age of 52.2, range 17 to 81. Results: 53 patients had peak flow readings of < = 250 L/min, 28 had an interpreted PFT of severe obstructive pulmonary disease, 14 had moderate obstruction, 3 had mild obstruction, 2 had severe restriction and 6 had moderate restriction. 116 patients had peak flow results between 250 and 600 L/min. Of those patients, 12 had PFT interpretations of severe obstructive pulmonary disease, 19 had moderate obstruction, 36 had mild obstruction, 2 had severe restriction, 6 had moderate restriction, and 8 had mild restriction, one had an upper airway obstruction and 27 had normal PFT's. The remainder of the study patients had peak flow readings between 600 and 900 L/min. In this category, 3 had moderate obstruction, 18 had mild restriction, 4 had mild restriction, and 13 were normal. Of note there were 8 cases of severely impaired DLCO readings in the patients with peak flows >= 250 L/min. Conclusion: Peak Flow monitors do not have the specificity to pick up all patients at risk of pulmonary complications for pre-op assessment. Although all the patients that had peak flow readings < = 250 L/min had pulmonary disease, 117 patients with demonstrated pulmonary disease by routine PFT's had peak flow readings >= 250 L/min. Although money may be saved by performing peak flow rather than spirometry for pre-op assessment, the patient may lose in the long run if complications occur.


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