SummaryWe have shown previously in patients with chronic bronchitis that correction of the hypoxaemia by continuous administration of oxygen substantially reduced the pulmonary hypertension by reversal of structural changes in the pulmonary resistance vessels. We have now demonstrated that such improvements may occur with less than continuous oxygen. Treatment with oxygen for 18 hours daily significantly decreased pulmonary arterial pressure and pulmonary vascular resistance. Oxygen therapy for 15 hours a day also decreased pulmonary vascular resistance; such a regimen is practicable in the home, is consistent with a working day free from the constraints of an oxygen supply, and should reduce the number of episodes of congestive cardiac failure. IntroductionPatients who are chronically hypoxaemic because of chronic bronchitis frequently develop pulmonary hypertension. This leads to right ventricular hypertrophy and right ventricular failure. In these patients the cardiac failure becomes a major part of their disability, and its presence carries a particularlypoor prognosis. Of a large series of patients with chronic

Postoperative haemodynamic evaluation was performed on 15 patients 7 to 14 years (mean, 11 years) after total intracardiac repair of Fallot's tetralogy. The average age of the patients at the time of postoperative catheterization was 20 years (range 12 to 29) and they were all asymptomatic. Before operation 11 patients were severely cyanosed and disabled and 4 had mild cyanosis with anoxic spells. The cardiac output and right heart pressures were measured at rest and after 5 minutes of submaximal exercise on a bicycle ergometer. It was shown that the degree of residual obstruction of the pulmonary outflow tract was slight and that the right ventricular/pulmonary arterial systolic gradient (RV/PA gradient) exceeded 20 mmHg (2-6 kPa) at rest in only 3 patients. The mean cardiac index at rest was 5-4 l min-1 m-2 which increased to 8-3 l min-1 m-2 during exercise. The response of the cardiac output during exercise was either normal or supranormal in 14 of the 15 patients. In the remaining patient the response was marginally below the normal range. Pulmonary valvular regurgitation was present in 8 patients but there was no detectable difference in the cardiac function of these patients compared with patients with competent pulmonary valves. Six of the patients investigated had also had cardiac catheterizations performed 1 to 4 years after operation. The results of the present study show that remarkably little change has occurred in their haemodynamic status in the intervening years. Though these results are encouraging, further studies are required to determine the eventual outcome of the RV pressure and volume overload.

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. (1977). Thorax, 32,[601][602][603][604][605]. Effect of intravenous terbutaline on arterial blood gas tensions, ventilation, and pulmonary circulation in patients with chronic bronchitis and cor pulmonale. Terbutaline sulphate was given intravenously to 10 patients with pulmonary vascular disease secondary to chronic hypoxia. The resting cardiac index increased after terbutaline in all the patients between 5 and 74% above the control level. The greatest change was seen in patients who had received the largest total dose. The rise in cardiac index was associated with a fall in pulmonary vascular resistance although mean pulmonary artery pressure remained unaltered. There was a significant increase in the venous admixture but this did not adversely affect the arterial oxygen tension.The peak expiratory flow rate did not change significantly but there was an increase in ventilation from a mean value of 4-36 1/min/m2 to 4-67 1/min/m2.The results show that terbutaline has little adverse effect on the pulmonary circulation or gas exchange in patients with irreversible airways disease who are in a stable state.

The light and electron microscopic changes in biopsy tissue from the lung of a 30-year-old housewife severeley incapacitated by diffuse pulmonary sarcoidosis with pulmonary hypertension are presented. The lung tissue was distorted by numerous granulomas in the interstitial tissues and within alveoli. Many pulmonary blood vessels including arteries were damaged by the granulomas. The ultrastructural features of the epithelioid cells were found to be distinctive and probably specific. The giant cells which accompanied the epithelioid cells contained two types of inclusion body: one appeared to be related to the Schaumann body but the nature and origin of the second type was not clear. Many of the granulomas were surrounded by avascular fibrous tissue which contained, in addition to mature fibroblasts, myofibroblasts and a primitive form of cell that appeared to be a fibroblast precursor. It was conjectured that the myofibroblasts, through their contractile powers, might increase the distortion of the lung architecture and thereby the patient's disability. The alveolar walls were thickened by a diffuse infiltrate of macrophages and epithelioid cells but there was no excess of collagen and elastic fibres. The evidence suggested that the epithelioid cells developed from macrophages. From the cellular nature of the diffuse infiltration of the alveolar walls and the absence of fibrosis it seemed that the disease was still at an early and active stage, a conclusion strengthened by the fact that treatment with corticosteroids led to marked and sustained clinical improvement.