End tidal water vapor tension 01 the expirale after nasal and then after oral inspiration was measured at the lips of seven normal subjects using a mass spectrometer. At a mean inspired air temperature of 23°C and PH.O of 14.7 mmHg, the mean end tidal PH.O was was 40.57 mmHg after nasal and 37.15 mmHg after oral inspiration. The difference was statistically significant. The evidence for complete saturation of expired gas is discussed. Assuming a 100% saturation of expired gas the average contribution of the nasal mucosa to the water content of the respired air in this experiment was 3 gm/'m3 or approximately 10% of the total water contributed by the respiraory tract.

The water vapour pressure in the expired air of normal subjects during rest and exercise was measured by a mass spectrometer. The mean vapour pressure was found to be 37.9 mm Hg during tidal breathing and 39.7 mm Hg after a vital capacity manoeuvre. The pressure was reduced to 36.1 mm Hg during exercise. This decrease was not significantly different from breathing at rest. When offering warm wet air with a water vapour pressure of about 75 mm Hg, the end-tidal pressure was found to be 47 mm Hg. The evidence for complete saturation of expired gas is discussed.

No abstract

No abstract

The relationships between flow, expired volume and elapsed time during forced expiratory manoeuvres have been investigated in normal subjects and in patients with chronic obstructive bronchitis, using gas mixtures of different densities and viscosities. The results are summarised as follows: (1)Peak-flow-rate and the expired volume at which this occurs are greater in normal subjects than in patients with chronic obstructive bronchitis; (2) the time to reach peak flow does not differ significantly between the two groups; (3) the effect of respired gas density on all three factors is more marked in normal subjects than in patients; (4) when the peak flow of normal subjects is reduced to that of patients by addition of an external resistance in series, the time to peak flow is increased.

From 1976 to 1977 308 patients were treated with multiple aorto-coronary vein-bypass. Fiftytwo patients receiving sequential bypasses were compared with 256 patients in whom conventional multiple anastomoses were performed. The rate of postoperative bypass failure did not differ significantly in the two types of anastomoses: 16 per cent in sequential as compared to 18 per cent in conventional bypass. In both cases the circumflex-system was afflicted by bypass failure more frequently (20 per cent each). The practical and theoretical advantages and disadvantages of the two procedures are discussed. Sequential aortocoronary vein-bypass is considered the method of choice for certain combinations of coronary stenoses and also if an adequate length of vein can not be obtained.

No abstract

No abstract