P. Hugh-Jones

Studies of Regional Lung Function Using Radioactive Oxygen

improve, and surgery be possible. Often, however, the recurrent bleeding produces a worsening of hepatic function and it becomes clear that the major feature is hepatocellular failure and surgery will be impossible. At this stage the apparatus should be withdrawn, as its further use increases the patients misery and complications are likely. In some of these patients local surgical attack on the varices has been suggested, portacaval anastomosis being performed later (Linton, 1953; Welch, 1957). This was attempted in six of our patients, but all died after the first operation, a reflection of their inability to support any form of surgical treatment. Complications of intubation are common, and in one series of 50 patients treated with the Sengstaken tube

REGIONAL PULMONARY BLOOD FLOW IN PATIENTS WITH CIRCULATORY SHUNTS

Carbon dioxide labelled with oxygen-15 can be used to compare the blood flow in different regions of the lung. Results obtained with this technique in normal subjects at rest with the chest upright show that there is a much higher perfusion per unit of alveolar volume in the lower zone than in the upper zone. On moderate exercise the flow increases in both zones but the lower zone blood flow remains relatively greater than the upper zone (West and Dollery, 1960). Patients with mitral stenosis differ from the normal in that the moderately severe cases show almost equal perfusion in upper and lower zones and the severe cases have a higher perfusion in the upper than the lower zone (Dollery and West, 1960). This inversion of the normal distribution of blood flow has been observed also in patients with left ventricular failure and pulmonary cedema (Dollery and West, in preparation). The distribution of blood flow in normal subjects probably depends upon the effect of gravity on the low perfusion pressures in the pulmonary circulation. Heart disease may reduce the normal difference in the upper and lower zone clearance rates. To investigate this problem further we have studied a group of patients with congenital shunts between the left and right sides of the heart. These patients have a great variety ofpulmonary pressures and flows. This study was made with a specially selected group of such patients in whom complete hemodynamic investigations had been performed. The results demonstrate differences between the flow patterns in various disorders of the pulmonary circulation and throw some light on the factors that influence the partition of blood flow between different regions of the lung.

A Comparison of the Pulmonary Blood Flow between Left and Right Lungs in Normal Subjects and Patients with Congenital Heart Disease

Carbon dioxide labeled with oxygen-15 has been used to study the regional blood flow in the lungs of patients with pulmonary stenosis. The upper and lower zone flows were normal in patients with isolated pulmonary stenosis, but both were low in patients with the tetralogy of Fallot. A comparison of the two upper zones showed a significantly higher blood flow through the left upper zone in patients with both isolated pulmonary stenosis and the tetralogy of Fallot. A significantly higher flow was also found through the left upper zone than the right of normal subjects. By contrast, patients with atrial septal defect had a higher flow through the right upper zone than the left. Neither difference was as large as in the patients with right ventricular outflow tract obstruction. Patients with ventricular septal defect and those with patent ductus arteriosus had almost identical flow through the two upper zones.

Detection of Bronchial and Arterial Obstruction by Continuous Gas Analysis from Individual Lobes and Segments of the Lung

A mass spectrometer was designed specially for clinical respiratory investigation (Fowler, 1957) and it has been in use for general tests of lung function for three years. It performs continuous automatic gas analysis, and has a gas-sampling tube of only about I mm. external diameter at its tip. This fine sampling tube, which is placed at the patients lips during general tests of lung function, has now been adapted so that it can be inserted down a bronchoscope into any lobar or segmental orifice which can be seen directly. From the results of bronchoscopic experiments on anaesthetized dogs it has been found that characteristic patterns of gas concentration changes are observed from regional bronchi during the breathing cycle and that these can be related to the ventilation, blood flow, and mechanical properties of the relevant lobe or segment. In this paper we shall first summarize these results from animal experiments and then present some examples of these characteristic patterns seen during routine diagnostic bronchoscopy in man and discuss their significance.