The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

COMPARISON OF STANDARD VERSUS MODIFIED EXPIRATORY TECHNIQUES DURING SPIROMETRY

Tony Cowan, RRT, RPFT, is affiliated with Mobilcare, Mobile, Alabama. William Pruitt, RRT, CPFT, is affiliated with the Cardiorespiratory Care Department, College of Allied Health Professions, University of South Alabama, Mobile, Alabama. Madhuri Mulekar, PhD, is affiliated with the Mathematics & Statistics Department, College of Arts & Sciences, University of South Alabama, Mobile, Alabama. Allen Siebert, MD, FACP, is affiliated with Pulmonary Associates, Mobile, Alabama. Erica Kennedy, CRT, is affiliated with Springhill Medical Center, Mobile, Alabama. Hajed Al-Otaibi, CRT, CPFT, is affiliated with King Khalid National Guard Hospital in Jeddah, Saudi Arabia.

Background: The current standard technique for patients performing spirometry calls for maximal effort throughout the expiratory effort. We have observed that patients complain of discomfort, lightheadedness, dyspnea, and fatigue when performing this test and are reluctant to return to the PFT lab for serial measurements. 

OBJECTIVE:
We compared standard technique for performing spirometry to modified technique to see if the modification would yield the same measurements while decreasing patient discomfort and fatigue and increasing their willingness to repeat the test.

Methods:
110 outpatients were tested in the PFT lab using both the standard and the modified technique for spirometry. We used a crossover design and randomized the order in which the two techniques were performed. The standard technique had the patient give maximal effort throughout the entire expiratory maneuver until no more air could be exhaled. The modified technique had the patient start with a maximal expiratory effort, and then relax after three seconds while continuing to exhale until no more air could be exhaled. The patients were divided into four groups based on FEV1/FVC: Group 1 had severe airflow obstruction (AFO) - FEV1/FVC ratio <0.45. Group 2 had moderate AFO - FEV1/FVC ratio 0.45 to 0.60. Group 3 had mild AFO - FEV1/FVC ratio 0.61 to 0.74. Group 4 had little or no AFO - FEV1/FVC ratio >0.75. Test acceptability and reproducibility were assessed using the recommendations from current ATS Statement on the Standardization of Spirometry. Patients were asked to rate their perceptions of both techniques regarding discomfort, fatigue, lightheadedness, and dyspnea on a survey given immediately after the conclusion of the testing. The technologist doing the testing also rated each patient's compliance with performing both techniques as instructed.

RESULTS:
Analysis showed a high degree of agreement between the two techniques for acceptability and reproducibility. Comparison of measured results showed a clinically significant difference in FVC with the Group 1 patients (Mean FVC for modified technique was 3.329 L standard 3.078 L, p value = 0.0068). The study also found a statistical difference (but no clinical significance) in FVC and FEF25-75% with the Group 3 patients, in PEF with the Group 4 patients, and in FET100% with all four groups. When using the modified technique, patients reported lower subjective levels of discomfort, fatigue, etc., while reporting increased willingness to repeat the test as compared to using the standard technique. Technologist scoring of performance compliance was higher for the modified technique.

Conclusions:
The modified technique is comparable to the standard technique for obtaining clinically significant spirometry results for Groups 2, 3, and 4. In Group 1 patients (with severe AFO) FVC measured by the modified technique was increased significantly - we attributed this to a reduction in air trapping and dynamic airway compression for these patients. The modified technique showed decreases in discomfort, fatigue, etc. and increases in willingness to repeat the study in all four groups of patients as compared to the standard technique. Compliance with instructions and the patient's technique in performing the test properly also improved using the modified technique.

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