We have monitored oscillations in arterial pH (of respiratory frequency) in normal man at rest and during exercise. The pH oscillations are known to reflect respiratory oscillations in arterial carbon dioxide tension generated at the lungs. We have found that the pH oscillations increase in their upslope and downslope during exercise. This means that oscillations in arterial carbon dioxide tension can be considered as a control signal.

Summary:A questionnaire on the pattern of drug taking was completed by 185 patients with chronic airflow obstruction. Of these, 49% admitted to taking their prescribed therapy regularly and 33% could be regarded as being fully compliant. The use ofincreasing numbers ofdrugs was not accompanied by a fall in compliance. Regular drug taking was better in patients (particularly females) with asthma than in patients with chronic bronchitis and emphysema. During acute exacerbations of airflow obstruction, excessive use of bronchodilators beyond the recommended increase in medication was rare; indeed, underuse of therapy in this situation was commoner. These conclusions must be regarded as tentative since the questionnaire was not validated by repeat interviewing or measurement of drug usage.

Breathing during sleep was monitored in 8 diabetic patients with objective evidence of autonomic neuropathy and in 8 diabetic patients without neuropathy. Thirty or more periods of apnoea lasting 10 seconds or longer during one night's sleep were demonstrated in 3 of the diabetic patients with autonomic neuropathy. Such apnoeic periods may be related to the high incidence of cardiorespiratory arrests reported in such patients, particularly in association with anaesthesia or pneumonia.

Eight patients with chronic severe asthma, poorly controlled by conventional doses of inhaled bronchodilator, were treated with high-dose inhaled terbutaline (4 mg four times daily), via either wet nebulisation of terbutaline respirator solution, or by tube-spacer aerosol, using cannisters delivering 1 mg terbutaline per metered dose. All patients improved objectively and subjectively on these higher dosage regimens during both day and night. A trial of high-dose inhaled beta2 sympathomimetic therapy should be considered in any patient with chronic severe asthma who fails to obtain benefit from standard doses of inhaled bronchodilator.Patients with chronic severe asthma often respond poorly to inhaled bronchodilators in conventional dosage. Such patients are usually very disabled, require frequent hospital admissions, and are commonly prescribed long-term oral corticosteroids. Domiciliary high-dose inhaled bronchodilator therapy, delivered by wet nebulisation, may improve some patients with chronic asthma sufficiently for oral steroids to be discontinued.' However, the air compressors necessary for the domiciliary nebulisation of bronchodilator are expensive and inconvenient. We decided, therefore, to compare the efficacy of high-dose bronchodilator therapy delivered by wet nebulisation and by a new aerosol device, the tube-spacer.2 The tube-spacer was chosen because it achieves higher penetration of aerosol into the lung than does conventional aerosol,3 and also because it may be more effective than conventional aerosol in the management of some patients with asthma.4-6 The tube-spacer is cheaper and more convenient than the wet nebuliser. MethodsEight patients (four male and four female) with chronic severe asthma participated in the study. Mean first second forced expired volume (FEV1) was 0 83 I BTPS (range 0I5-1V61 BTPS).

ratings rose as the drug was withdrawn but subsequently subsided, suggesting that the symptoms represented a true withdrawal syndrome and not the revival of the original anxiety. Furthermore, the perceptual changes, such as intolerance to light and sound, unsteadiness, and a feeling of motion, are untypical of anxiety. Some patients have complained of strange smells and a metallic taste. Both our patients were originally taking other benzodiazepines before transferring to clobazam. They developed a typical syndrome on withdrawal of clobazam. We have not yet encountered a patient who has developed dependence on clobazam alone but would expect such cases to become apparent in due course.