Comparison of Wright scale and European scale peak flow meters with digital spirometer

摘要

Introduction: Peak expiratory flow (PEF) monitoring has been in use to measure airflow obstruction in patients with asthma. Most of the peak flow meter uses a traditional Wright scale to record PEF whilst after 2004 Peak flow meters with new European scale have been introduced. This study was done to assess the limits of agreement of PEF values measured with mini Wright's peak flow meter (Wright scale) or with new European scale with digital spirometer. Material and Methods: 582 healthy volunteers between the age group of 18-40 years were recruited for this study. PEF was measured with mini wright's peak flow meter with traditional wright scale and new EU PEF scale. Simultaneously Spirometery of each subject was performed with Sprobank G and FVC, FEV1, FEV1%, PEF were recorded. Results: PEF measured with wrights scale and new European scale both shows high and similar levels of correlation with digital spirometer (r=0.765 and 0.767). Despite a high correlation observed between measured PEF with different instruments, the limits of agreement are not acceptable for either of the scales. Conclusion: The measurement of PEFR with New European scale does not seem to provide any significant advantage over traditional scale. Work done at Department of PhysiologyKing George's Medical UniversityLucknow, UP, IndiaSupport receivedFinancial support through intramural research grant by King George's Medical University, Lucknow, UP, India Introduction Peak expiratory flow (PEF) monitoring has been in use to measure airflow obstruction in patients with asthma (1). The International Consensus Report on Diagnosis and Treatment of Asthma has made peak flow measurement one of the mainstays of asthma management (2). Peak flow measurement is a tool for treatment by the physician, and especially a tool of self-management by the patient. The widespread availability of inexpensive, portable devices has made ambulatory PEF monitoring easier & feasible. The PEF monitoring has facilitated individualized self-management using pre-established criteria and allowed more effective communication between patients and their physicians for the assessment of maintenance therapy. The ambulatory PEF monitoring in asthmatic patients can provide early warning of incipient asthma exacerbation and can measure the severity of worsening airflow obstruction. (3)PEF is the largest expiratory flow achieved with a maximum forced effort after maximum inspiration. Most of the digital spirometers measures PEF along with FEV1 (Force expiratory volumein one second) and FVC (Forced vital Capacity). Previous studies have found that different spirometers and different Peak Flow Meters can record PEF differently with error rates of up to 26% in laboratory calibration tests.(4) Most of the peak flow meter uses a traditional Wright scale to record PEF whilst after 2004 Peak flow meters with new European scale have been introduced in the market to reduce errors. (5) It has not formally been assessed whether the PEF values measured with digital spirometer are in close agreement with the PEF values measured with mini wright's peak flow meter (Wright scale) or with new European scale. Material and Methods Subjects: The study was conducted on 582 healthy volunteers between the age group of 18-40 years from university healthy population. Nature of the study was explained and informed consent was obtained from each subject prior to participation in study. The protocol of the study was approved by institutional ethics committee. A thorough history was taken and clinical examination of the subjects was performed to rule out any obvious cardio-pulmonary compromise. Subjects with history of smoking, history of severe chest trauma, with obvious chest and spinal deformity, with personal/family history of asthma, chronic obstructive pulmonary diseases and other cardio-respiratory diseases were excluded from the study. Devices: The Spirobank G (MIR; Rome, Italy) device is a turbine with an infrared in