The prevalence of bronchial hyperresponsiveness in adult populations is not known. To document its prevalence and distribution and to determine the factors associated with it, a random sample of the adult population of Busselton, Western Australia, was studied. Spirometric function, bronchial responsiveness to histamine, and atopic responses to skin prick tests were measured. Respiratory symptoms were determined by questionnaire. Data were obtained from 916 subjects. Of these, 876 underwent a histamine inhalation test and bronchial hyperresponsiveness to histamine (defined as a dose of histamine provoking a 20% fall in FEV1 equal to or less than 3 9 jmol) was found in 10-5%. Another 40 subjects with poor lung function were tested with a bronchodilator and 12 were found to have bronchial hyperresponsiveness (defined as a greater than 15% increase in FEV1), making the total prevalence of bronchial hyperresponsiveness 11-4%. The prevalence of current asthma, defined as bronchial hyperresponsiveness plus symptoms consistent with asthma in the last 12 months, was 5-9%. The distribution of bronchial hyperresponsiveness in the studied population was continuous. There was a significant association between it and respiratory symptoms, atopy, smoking, and abnormal lung function (p < 0-001 for all associations). There was no association with age, sex, or recent respiratory tract infection.

To assess non-specific bronchial reactivity the effect of inhaling ultrasonically nebulised solutions of distilled water and hypotonic (0 3%), isotonic (0 9%), and hypertonic (27%, 3 6%) saline was investigated in 10 asthmatic patients and nine normal subjects. Expired ventilation and the maximum percentage fall in forced expiratory volume in one second (FEV,) were recorded. The sensitivity to the inhaled solutions was determined by measuring the ventilation required to induce a fall in FEV, of 20% from the prechallenge value. Hypotonic and hypertonic but not isotonic solutions caused a significant fall in FEV, in the asthmatic subjects. Normal subjects showed no response to either distilled water or 3 6% saline, the only solutions with which they were challenged.The method used for this challenge is rapid, simple, and inexpensive and provides a new means of diagnosing non-immunologically mediated bronchial hyperreactivity.

The airway response to the inhalation of ultrasonically nebulised distilled water was determined in 55 asthmatic patients and 16 normal subjects. We calculated the dose of water required to induce a 20% reduction (PD20) in forced expiratory volume in one second (FEVy) by measuring the output of the nebuliser and the volume ventilated by each subject. Forty-eight of the asthmatic patients had a PD20 of 9 ml or less but three patients required as much as 24 ml. A PD20 was not recorded in the normal subjects and the challenge was stopped after 33 ml. In 12 patients the challenge was repeated within six months and the airway response was shown to be reproducible at equivalent doses of water. In a separate group of 11 patients there was, however, a highly significant reduction in the percentage fall in FEV, when equivalent doses of water were given on two occasions 40 minutes apart. When the temperature of the inhaled water was increased from 22°C to 36°C eight of 10 patients had a similar change in FEV, with equivalent doses of water. The airways obstruction induced by the inhalation of water was readily reversed with salbutamol administered by aerosol. In some patients a challenge with water or 3.6% saline was repeated after pretreatment with sodium cromoglycate, atropine methonitrate, and verapamil hydrochloride, all given as aerosols. The airway response to the equivalent dose of water or saline was significantly reduced after treatment with sodium cromoglycate but not atropine or verapamil.The measurement of the airway response to the inhalation of ultrasonically nebulised solutions of hypotonic and hypertonic solutions provides a new approach for the investigation of nonimmunologically mediated bronchial reactivity.We have previously measured airway reactivity to these solutions by determining the total volume of inhaled aerosol (that is, ventilation) required to reduce the forced expiratory volume in one second (FEVy) For this reason we have determined the delivered dose required to induce a 20% reduction in FEV1 and compared the responses in FEV, to equivalent doses of water under different conditions. Furthermore, we have measured the proportion of a delivered dose which is retained by the patient. We have also studied the effects of sodium cromoglycate, atropine methonitrate, and verapamil hydrochloride on the airway response to the same dose of inhaled solution. MethodsWe studied 55 patients aged 11-56 years (mean ± SD 28-5 + 10-8 years) with clinically recognised asthma who were taking beta-sympathomimetic aerosols regularly for control of their symptoms. All medications were withheld for at least four hours before any test. The protocol was approved by the ethics review committee and informed consent obtained. Sixteen non-asthmatic subjects volunteered as controls. The FEVI was measured

Bronchiolitis obliterans (BO) following allogeneic haematopoietic stem cell transplantation (HSCT) affects peripheral airways. Detection of BO is presently delayed by the low sensitivity of spirometry.We examined the relationship between peripheral airway function and time since HSCT, and compared it with spirometry and clinical indices in 33 clinically stable allogeneic HSCT recipients. The following measurements were performed: lung function, exhaled nitric oxide, forced oscillatory respiratory system resistance and reactance, acinar (Sacin) and conductive airways ventilation heterogeneity and lung clearance index (LCI) measured by multiple breath nitrogen washout. 22 patients underwent repeat visits from which short-term changes were examined.Median time post HSCT was 12 months. Eight patients were clinically diagnosed as having BO. In multivariate analysis, time since HSCT was predicted by Sacin and forced expiratory volume in 1 s % predicted. 20 patients had abnormal Sacin with normal spirometry, whereas none had airflow obstruction with normal Sacin. Sacin and LCI were the only measures to change significantly between two visits, with both worsening. Change in Sacin was the only parameter to correlate with change in chronic graft-versus-host disease grade.In conclusion, peripheral airways ventilation heterogeneity worsens with time after HSCT. Sacin may be more sensitive than spirometry in detecting BO at an early stage, which needs confirmation in a prospective study.

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Combination therapy is associated with improvements in small airways function in COPD, despite an absence of change in FEV1. FOT may be a clinically useful marker of small airway function in COPD that is responsive to treatment.