10/5/03 Evaluating a portable spirometer in the study of pediatric asthmaSummaryThe "gold standard" for assessing airways function in the clinical management of asthma has been an office-based spirometer which meets technical requirements promulgated by the American Thoracic Society. However, it is often very desirable, and sometimes necessary, to do repeated home- based monitoring of airway function in asthma. Peak expiratory flow rates (PEFR) can be obtained easily and repeatedly with inexpensive peak flow meters. However, there are real limitations to the clinical relevance of such peak flow monitoring. Therefore, home monitoring with an easily portable spirometer would potentially have real advantages. Mortimer et al of the Univ. of California Division of Public Health evaluated the agreement in a range of pulmonary function measurements carried out with a portable spirometer vs the traditional clinic- based spirometer in 92 children with chronic asthma. The portable spirometer was programmed with customized software to grade each spirometric curve for acceptability and reproducibility using American Thoracic Society criteria. The authors found very good agreement between the findings obtained for FEV-1 and FEF25 by the portable and the clinic spirometers. The quality in 74% of the spirometric curves obtained with the portable spirometer met the quality grade found in the clinic-measured spirometry. During repeated measurements over a 2 week period, at least 2 acceptable and reproducible curves were obtained in 84% of the children studied. The authors concluded that at least this portable spirometer can provide measurements that are highly comparable to those obtained by a high quality spirometer in a health care facility. Reference Chest 2003; 123:1899-907 Editor’s Comments Portable spirometer from several manufacturers have been in use for several years. Because of their relatively high cost (often not paid for by health insurance/HMO) my understanding is that these spirometers have been used mainly in studies. As I understand it, the portable spirometer reported here has the advantage of internal software for grading the quality of the spirometric curve, and alerting individuals to repeat the maneuver until a curve of acceptable quality is obtained. Not surprisingly, children of ä 8 years of age tended to provide better quality spirometric studies. Assuming that portable spirometry is feasible, how will the findings help in asthma management? Although PEFR requirements are strongly recommended in some asthma care guidelines, a number of studies have shown no significant additive benefit of repeated PEFR measurement at home to high quality office examinations on asthma outcomes. An occasional FEV-1 measurement in the office setting does correlate in general with asthma severity but a normal or only slightly abnormal FEV-1 is not an absolute predictor of a subsequent benign asthma course. Perhaps, frequently repeated FEV-1 (or other spirometric measures) in the home may be more predictive of the asthma course.
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