No abstract

. (1977). Thorax, 32,[317][318][319][320][321] Secondary polycythaemia in chronic respiratory insufficiency. The relationship between polycythaemia, P50 and Saco (saturation in carboxyhaemoglobin) has been studied in 50 patients who were hypoxaemic due to chronic respiratory insufficiency. These patients were divided into two groups according to their haemoglobin concentration and haematocrit: 21 polycythaemic patients with haemoglobin>16 g/dl and haematocrit>50 % aDd 29 patients without polycythaemia. PaO2, PaCO2, plasma and erythrocyte pH, haemoglobin, haematocrit, and carbon monoxide saturation and intraerythrocytic 2-3 diphosphoglycerate concentration were measured during steady-state ventilation.All polycythaemic patients were smokers and their carbon monoxide level was significantly higher than that observed in patients without polycythaemia. Additionally, their P50 and 2-3 DPG concentration were significantly lower than in patients without polycythaemia.The correlations between P5o and Hbco and between Hb and Hbco were significant (r= -0-672; r=0-552 respectively: P<0-001).Eleven non-polycythaemic patients who were smokers had a high level of Hbco but normal P50. A group of 29 normoxic subjects was also studied, 14 non-smokers and 15 smokers with a high Hbco level. The mean value of P50 was lower in smokers and their haematocrit was higher although the difference was not significant for the latter.The Hbco increase by tobacco seems to be a factor in the occurrence of polycythaemia in patients with chronic respiratory insufficiency.The level of increase of Hbco and/or its duration and perhaps other individual factors could explain why all patients with high Hbco level and hypoxaemia were not polycythaemic.

Bronchial challenges were effected with carbachol in 76 subjects who were candidates for a scuba diving group. Bronchial reactivity was assessed through airway resistance and forced expiratory volume in 1 sec (FEV1) measurements. Medical interrogation had revealed symptoms of recent (RA) or ancient (AA) asthma, or allergic rhinitis (AL). Nearly half of the subjects (47%) presented bronchial hyperresponsiveness (BHR), which was much more frequent in the RA group, but whose strength did not depend on clinical presentation. Prevalence of BHR was fairly high (36%) in the AL group. BHR constituted a contraindication to scuba diving because it may promote pulmonary barotrauma.

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In patients with impaired lung function who are scheduled for lung surgery, a means of estimating the ventilatory consequences of parenchymal resection is needed. We have tested the ability of lung scanning with aerosolized and intravenous ¹³³Xe to fulfil this purpose in 100 pneumonectomized or lobectomized patients. Postsurgery VC and FEV₁ values were evaluated as follows: each lung was horizontally divided into two areas and lower and upper VC values were calculated as percentages of the total radioactivity count. Using the regional percentages and the absolute values of VC measured spirometrically, the VC expected postsurgery values were calculated according to the type of resection planned (e. g. if the left lung was to be removed and if it accounted for 50% of the radioactivity on the scan, the postsurgery VC would be halved). Postsurgery FEV₁ values were estimated by using the VC value and the FEV₁/VC ratio measured before surgery. A significant correlation (p < 0.001) was found between the values estimated in such way and the actual FEV₁ and VC values obtained shortly after surgery (between 6 and 15 days). From these results, we conclude that the xenon scan is a valuable technique for estimating the consequences of lung removal on ventilation.