Previous publications from this laboratory have described (1, 2) a modification of the Krogh breath holding technique for measuring the pulmonary diffusing capacity for carbon monoxide (DL).6 This test can be performed quickly and simply and does not require arterial blood analyses. It has recently (2) been shown to provide an index of pulmonary diffusing capacity similar to that given by the DLo2 method of Lilienthal, Riley, Proemmel, and Franke (3) and the "steady state" method of Filley, MacIntosh, and Wright (4). 6 Since the combination of CO with intracellular hemoglobin occurs at a rate that offers an appreciable, and under some conditions the major, part of the resistance to the uptake of CO in the lungs (5, 6) it is desirable to distinguish between the "true" diffusing capacity, or that of the pulmonary capillary membrane alone (D.), and the apparent diffusing capacity of the whole lung (DL). These are related by the equation 1/DL = I/D. + I/)Vc where j is the rate of combination of CO with intracorpuscular hemoglobin in ml. per min. per mm. Hg CO tension per ml. blood, and Vo is the volume of blood in the pulmonary capillaries at any instant. 0 decreases as 0 tension increases (7), causing DL to decrease, since D.and Ve are presumably relatively independent of alveolar 0, tension (8). Normally a further subscript of CO or Q, would be used to indicate the gas to which the measurement applies. However, in this article, which is mainly concerned with CO, the subscript is omitted and can be assumed to be "CO" unless otherwise stated. normal values of DL as well as values in patients with various chest diseases. METHODSThe technique for the measurement of DL, which has been reported be'fore (1, 2), consists essentially of having the subject make a maximal inspiration of a gas mixture containing 10 per cent helium (He), 0.3 per cent CO and approximately 21 per cent 02 in N2 from the level of his residual volume, hold it for a measured time, and then rapidly expire. All of this expiration except the first liter is collected in a bag by the operator and analyzed as alveolar gas. The CO concentration which was present in this sample before any CO The apparatus used for the test is illustrated in Figure 1. It differs from that reported previously (1, 2) mainly in its greater simplicity; in these previous communications the expired alveolar He and/or CO concentrations were measured at the mouth by recording analytical instruments. The circuit is closed, permitting inspiration from the bag of the Donald-Christie apparatus and expiration into the space around the bag, a spirometer recording the change in respiratory volumes. Tap (A) is used by the operator for collecting the expired alveolar sample. Since the gas mixture is inspired from the level

The respiratory responses of 52 diabetics and 65 non-diabetic controls to hypoxia, hypercapnia, and exercise were studied. Twenty five per cent of the diabetics had evidence of impaired sensitivity to hypoxia or decreased ventilatory response to hypercapnia, while 7

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An inspiratory musical sound ("squawk") was recorded in 14 patients with diffuse pulmonary fibrosis. These were divided into two groups: nine patients suffering from extrinsic allergic alveolitis (seven with bird fanciei's lung and two with farmer's lung) and five patients with pulmonary fibrosis due to other causes, including rheumatoid disease, Wegener's granulomatosis, systemic sclerosis, and sarcoidosis. Clinical studies and phonopneumographic analysis of 10 consecutive squawks in each patient showed that the sound in the group with extrinsic allergic alveolitis was of shorter duration, occurred later in inspiration, and tended to be of higher frequency than the sound heard in the other group. Inspiratory crackles were present in all patients and in eight a single loud crackle preceded the squawk. We suggest that squawks, like crackles, result from the opening of airways and that the differences between the squawks in the two groups may reflect the size of the affected airways.

Objective: The role of preoperative localisation of abnormal parathyroid glands remains controversial but is particularly relevant to the management of patients with recurrent or persistent hyperparathyroidism and familial syndromes. We report our experience of the use of selective parathyroid venous sampling (PVS) in the localisation of parathyroid disease in such patients. Design: We report a retrospective 10-year experience (nZ27) of the use of PVS in complicated primary hyperparathyroidism and contrast the use of PVS with neck ultrasound, magnetic resonance imaging (MRI), computed tomography (CT) and sestamibi imaging modalities. Results: In 14 out of 25 patients who underwent surgery PVS results were completely concordant with surgical and histological findings and 88% of patients achieved post-operative cure. Out of 13 patients referred after previous failed surgery, 12 underwent further surgery which was curative in 9. In total PVS yielded useful positive (nZ13) and/or negative information (nZ6) in 19 out of 25 patients undergoing surgery. Using histology as the gold standard, 59% of PVS studies were entirely consistent with histology, as compared with 39% of ultrasound scans, 36% of sestamibi scans and 17% of MRI/CT scans. Conclusions: PVS is a valuable adjunct to MRI/CT and sestamibi scanning in selected patients with complicated hyperparathyroidism when performed in an experienced unit.European Journal of Endocrinology 155 813-821