C Co ou ug gh hi in ng g f fr re eq qu ue en nc cy y i in n p pa at ti ie en nt ts s w wi it th h p pe er rs si is st te en nt t c co ou ug gh h: : a as ss se es ss sm me en nt t u us si in ng g a a 2 24 4 h ho ou ur r a am mb bu ul la at to or ry y r re ec co or rd de er r ABSTRACT: Cough is an important symptom of many respiratory disorders. We determined the frequency and diurnal variation of cough in normal subjects and in patients with asthma or with persistent cough of unknown cause. We used a portable, solid-state, multiple-channel recorder to record cough sounds over a 24 h period. The audio-signal was recorded from a unidirectional microphone strapped over the chest wall, and electromyographic (EMG) signals from the lower respiratory muscles were simultaneously registered with surface electrodes. The recorded digital data were examined on an IBM-compatible computer, and the typical signals induced by cough (as assessed by voluntary or experimentally-induced cough) were counted.In 12 normal subjects, only 0-16 coughs were recorded over 24 h. In 21 stable asthmatics with a history of chronic cough ("asthma") the median number was 282 (ranges: 45-1,577), and in 14 patients with the predominant symptom of daily dry coughs ("chronic coughers") the median number was 794 (64-3,639). In both groups of patients, there was a diurnal variation of coughs, such that the least numbers occurred between 2 and 5 a.m. (<3% of total). In the asthma group, there was no significant correlation between forced expiratory volume in one second (FEV 1 ) (% predicted) or diurnal variation of peak expiratory flow and cough frequency. In the chronic coughers, there was a significant correlation between daytime cough numbers and daytime cough symptom scores but not for the night-time values.Our data show that cough frequency is not determined by the severity of asthma in relatively stable asthmatics on inhaled steroids, and is reduced during sleep in both asthmatics and chronic cough patients. This portable cough recorder may be useful in the assessment of drug therapy for chronic cough.

Objective-To determine the effects of residual pulmonary regurgitation on exercise tolerance after complete repair of tetralogy of Fallot.Design-Prospective study of symptom free patients more than five years after complete repair. Results-There was a significant negative correlation between the degree of residual regurgitation and both total duration of exercise and maximal heart rate achieved. Maximal heart rate and total duration of exercise were significantly lower in the patients than in normal controls. Patients with an abnormal maximal oxygen uptake (less than 85% of the predicted normal value) had significantly greater residual pulmonary regurgitation than those in whom oxygen uptake was normal.Conclusions-Impaired exercise capacity after complete repair of tetralogy of Fallot is directly related to the degree of residual pulmonary regurgitation. These data should be taken into account when deciding the optimal timing and nature of corrective surgery. relation between the degree of impairment of exercise and the heart size on chest radiography, which led them to speculate that residual pulmonary incompetence may be related to exercise ability after operation.5We recently described a new method of measuring the amount of pulmonary regurgitation by analysing right ventricular pressure-volume loops.8 In our study there was a linear relation between the pulmonary regurgitant volume and right ventricular end diastolic and end systolic volumes. No such relation could be shown, however, between regurgitant volume and the right ventricular ejection fraction.In the present study we used this technique to examine the possible influence of pulmonary regurgitation on patients' exercise ability after complete repair. Patients and methods PATIENTSThe initial study group comprised 18 patients. In two patients data from cardiac catheterisation were unsatisfactory (residual ventricular septal defect (VSD) in one, unsuitable data for analysis in one), and a further four patients failed to achieve a respiratory quotient > 1 0 during graded exercise testing (see below). These six patients were not included in the analysis.Satisfactory data from cardiac catheterisation and exercise were therefore obtained for 12

Eight patients with severe bronchopulmonary dysplasia underwent cardiac catheterisation. Seven had a pulmonary vascular resistance >3 mm Hg.l-' min.m2 (mean 8-9, range 2-2-13-8). All had raised intrapulmonary shunts (mean 25-6%, range 5-4-50%, normal <5%). Two had a high alveolar dead space, and two had unsuspected congenital heart disease. Epoprostenol (prostacyclin), but not 100% oxygen, caused a significant fail in pulmonary vascular resistance. Death was associated with a high pulmonary vascular resistance and a high shunt. Morphometric studies in three cases showed normal numbers of airways, but increased thickness of bronchial muscle. The numbers of alveoli were reduced and the wails thickened. There was increased medial thickness in small pulmonary arteries with distal extension of muscle. In the oldest child some vessels were obliterated by fibrosis. We speculate that measurements of pulmonary vascular resistance and shunt may have prognostic value; that a trial of pulmonary vasodilators other than oxygen might be worthwhile in patients with poor prognosis; and that abnormalities of the pulmonary circulation contribute to the difficulties of managing patients with bronchopulmonary dysplasia.

SUMMARY Inhalation of 100% oxygen by nine children with pulmonary vascular disease increased pulmonary blood flow measured at cardiac catheterisation; there was no significant change in pulmonary artery pressure. Fifteen children with pulmonary vascular disease that was severe enough to preclude corrective cardiac operation were studied to determine the effect of long term oxygen treatment on pulmonary vascular disease. Nine received long term domiciliary oxygen for a minimum of twelve hours a day for up to five years. Though the untreated group closely resembled the treated group their survival was significantly less good. All nine treated children are alive whereas five of the six children who did not receive oxygen have died.Pulmonary vascular resistance is often raised in children with congenital heart defects and is always raised in those with primary pulmonary hypertension, which is a rare condition. In many such children the pulmonary vascular resistance can be reduced by a pulmonary vasodilator such as oxygen, tolazoline, or epoprostenol (prostacyclin). But when the resistance remains >8 mm Hg.l -'.min.m2 (640 dyn.s.cm-5.m2) during optimal ventilation with 100% oxygen, surgical repair of the cardiac defect is associated with an unacceptably high risk of perioperative death or may lead to accelerated deterioration in the pulmonary vascular bed.' 2 These children have hypertensive pulmonary vascular disease, and pathological changes in the pulmonary arterioles are invariably found at biopsy.34 They also have reduced exercise tolerance and a poor prognosis. At present there is no effective and accepted treatment.Measurements during cardiac catheterisation (both published5 and our own which are described below) show that in all cases that were studied inhalation of 100% oxygen produced some fall in pulmonary vascular resistance compared with that in air. This shows that there is an additional but

Nocturnal cough reporting on diary cards has been shown to be unreliable and inconsistent. Whether subjective reporting of daytime cough is equally unreliable remains unknown. We have, therefore, developed a new and easily portable device (RBC-7) that records electromyographic (EMG) and audio cough signals for at least a 24-hr period, with a capacity of over 48 hr. Additional information is obtained from electrocardiographic (ECG) signals, and from an accelerometer indicating the level of the subject's activity. The RBC-7 can be set up with the aid of a notebook computer at the subjects home, school or workplace. Initial studies utilizing a prototype device were performed to determine the optimal position of the EMG leads and the microphone. The optimal position for the EMG leads was determined as the positive electrode in the sixth intercostal space (ICS) in the midclavicular line on the left, the negative electrode in the same position on the right, and the reference electrode in the midline over the abdomen. This position was shown to give the highest EMG voltages and the greatest difference in voltages between cough and other signals. The optimal microphone position for signal strength and comfort was over the first ICS, either right or left, close to the sternum. Recordings were performed simultaneously in 20 subjects with conventional tape recorders and the multiparametric cough monitoring system (RBC-7). Conventional tape recordings limited the duration of the studies due to the inherent restrictions. No significant difference in the number of single coughs recorded by each system was detected (correlation coefficient = 0.996). The RBC-7 offers a unique opportunity to obtain objective information on cough in ambulatory subjects over at least a 24-hr period, and to relate cough to time, activity and heart rate, while normal activities are pursued.