M.L. Diament

EFFECT OF AEROSOL ISOPRENALINE ON BLOOD-GAS TENSIONS IN SEVERE BRONCHIAL ASTHMA

Abstract In 20 patients in status asthmaticus aerosol isoprenaline reduced airway obstruction but did not increase the lowered P a O 2 . It is suggested that isoprenaline by intensifying the ventilation/perfusion disturbance in the lung may be of no benefit to the patient in gas exchange, and should therefore be used with caution in status asthmaticus.

SPIROMETRY AND BLOOD-GAS TENSIONS IN BRONCHIAL ASTHMA AND CHRONIC BRONCHITIS

Abstract 22 asthmatic and 31 chronic-bronchitic patients with comparable airway obstruction had hypoxaemia of similar extent but the bronchitics had significantly greater arterial carbon-dioxide tensions than the asthmatics. Forced expiratory volume in 1 second (F.E.V. 1 ) increased in 4 asthmatics after isoprenaline, but there was no improvement in hypoxaemia. Reasons are given for regarding acute hypercapnia in the asthmatic as an important sign of impending deterioration, and the need for blood-gas-tension measurements in the management of the severe asthmatic is stressed.

EFFECT OF A SELECTIVE BETA-ADRENERGIC BLOCKER IN PREVENTING FALLS IN ARTERIAL OXYGEN TENSION FOLLOWING ISOPRENALINE IN ASTHMATIC SUBJECTS

Abstract Practolol, a cardio-selective beta-blocking drug, prevented the fall in arterial oxygen tension in 11 asthmatic subjects after isoprenaline without diminishing significantly the bronchodilator action of isoprenaline.

DYNAMIC AND STATIC LUNG VOLUMES AND BLOOD-GAS TENSIONS IN BRONCHIAL ASTHMA

Abstract The dynamic and static lung volumes, arterial blood-gas tensions, pH, and the single-breath carbon-monoxide transfer factor, were measured in seventy-two asthmatic patients with airway obstruction of increasing severity. As airway obstruction increased the lungs became progressively more hyperinflated and this was accompanied by increasing hypoxaemia. Hypocapnia occurred with milder degrees of airway obstruction, the P a CO 2 tending to return to normal as airway obstruction increased.

VENOUS/ARTERIAL PULMONARY SHUNTING AS THE PRINCIPAL CAUSE OF POSTOPERATIVE HYPOXÆMIA

Abstract THE effect of breathing 100% oxygen on arterial PO 2 was used to measure the venous/arterial pulmonary shunt before and after upper-abdominal surgery. An increased true shunt of 12·0% was found postoperatively. Since, in a previous study, an increased venous-admixture effect of 12·4% was found in comparable patients, it is concluded that postoperative hypoxaemia arises almost entirely from true pulmonary shunting probably as a result of spontaneous alveolar collapse. This collapse, in turn, is most likely due to progressive inactivation of the pulmonary surfactant through failure to take periodic deep breaths postoperatively.

SPIROMETRY FOR PREOPERATIVE ASSESSMENT OF AIRWAYS RESISTANCE

Abstract Chronic bronchitis is the most important single factor predisposing to the development of postoperative bronchopneumonia. The clinical diagnosis of early bronchitis is easily overlooked because symptoms are often absent or only intermittent, and physical signs are present only later. Preoperative spirometry showed that 35% of all patients having elective operations have unequivocal evidence of increased airways resistance although only 15% admitted to a productive cough. Spirometry is, therefore, a simple aid in the recognition of these high-risk patients, and should be used routinely.

HYPOXÆMIA IN BRONCHIAL ASTHMA

Abstract Forty-one patients in status asthmaticus had hypoxaemia without hypercapnia and severe obstructive and restrictive ventilatory impairment. The extent of the hypoxaemia was closely related to the restrictive but not to the obstructive ventilatory impairment. Reasons are given for regarding a decrease in lung compliance as a result of hyperinflation as of greater importance in the production of hypoxaemia in asthma than obstruction to bronchial air-flow.

The rheology of bronchitic sputum

Summary A continuous shear method using the Ferranti-Shirley cone and plate viscometer was used to study the rheological properties of bronchitic sputum. From the rheograms obtained it is shown to be a non-Newtonian material and gives a hysteresis loop and two yield points. There are differences between mucoid and mucopurulent sputum which probably reflect their different structure. The clinical implications of the rheological findings is discussed.

Relative contributions of obstructive and restrictive ventilatory impairment in the production of hypoxaemia and hypercapnia in chronic bronchitis.

Abstract Thirty-seven patients with chronic bronchitis had severe obstructive and restrictive ventilatory impairment with hypoxaemia and hypercapnia. The hypoxaemia was closely related to the degree of hypercapnia and also to the restrictive, but not at all to the obstructive, ventilatory impairment. Hypercapnia was also related to the restrictive and not to the obstructive ventilatory impairment. Despite the fact that chronic bronchitis is thought of as obstructive lung disease, the changes in blood-gas tensions seem to be more closely related to the restrictive ventilatory impairment.

Dynamic and static lung volumes, blood-gas tensions, and transfer factor in chronic obstructive bronchitis.

Abstract The dynamic and static lung volumes, arterial blood-gas tensions, pH, and the single-breath carbon-monoxide transfer factor (D.L. CO) were measured in 45 patients with chronic obstructive bronchitis with airway obstruction of increasing severity. As airway obstruction increased the lungs became progressively more hyperinflated and this was accompanied by increasing hypoxaemia and hypercapnia. Regression equations enable the residual-volume/total-lung-capacity, P a O 2 , and P a CO 2 to be predicted from the forced expiratory volume in one second. The D.L. CO was uniformly low and was independent of the degree of airway obstruction.