Bronchial Mechanics in Healthy Subjects and Patients with Long-lasting Asthma

Asthma is one of the most common chronic diseases in children and adults in the Netherlands and in other countries with a 'Western Lifestyle'. It is characterized by recurrent excessive, mostly reversible, narrowing of airway caliber, in response to a variety of endogenous and exogenous stimuli. Increased bronchial responsiveness to the inhalation of non specific irritants is a hallmark of asthma and includes an increase in reactivity as well as in sensitivity of the airway. Asthma is considered to be a life long disease: it starts at a very young age and persists in approximately 40% - 60% of the children into adulthood. More than 50% of the adult patients with asthma still have symptoms after 25 years. Decreased airway patency in asthma is mainly caused by bronchoconstriction caused by an increased bronchial smooth muscle tone, hypersecretion and edema of the airway wall. These are the result of (chronic) inflammation of the airway wall, nowadays considered to be the major factor in the pathogenesis of asthma in association with bronchial hyperresponsiveness and the level of severity of the disease

Assessment of accuracy and applicability of a portable electronic diary card spirometer for asthma treatment

AbstractA pocked-sized turbine flowmeter and spirometer device, integrated with an electronic diary card (EDC-spirometer, Micro Medical, U.K.), was tested with a mechanical calibrator, in an outpatient clinic and in the home situation. A screen pneumotachometer was used as flow and volume reference.Ten devices were tested; interdevice variability was small with a mean variation coefficient of 1·1% for both forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF) (sd 0·5 and 0·4, respectively) for eight settings of the calibrator. Mean difference from reference was −0·131 (sd 0·04) for FEV1 (range 0·38–3·16) and 0·091 s−1 (sd 0·09) for PEF (range 4·2–11·7). No significant deviation from linearity was present.Results obtained in the outpatient clinic confirmed the accuracy of FEV1 and PEF data obtained with the calibrator. However, linear regression analysis showed a mean underestimation of 0·451 (sd of estimate 0·29) for forced vital capacity over the whole measurement range, probably due to a restricted integration time.In 10 optimally-treated chronic obstructive pulmonary disease patients in a family practice, PEF measurements were done in the home situation, both with the EDC spirometer and a mini-Wright peak flow meter. No significant differences in the diurnal variation of PEF were found. The PEF data from the mini-Wright meter were corrected for earlier reported flow-dependent systematic deviations. In the home situation, patients preferred the EDC spirometer. It is concluded that this device is applicable in the follow-up and treatment of asthma at home