On the respiratory changes of the intrathoracic pressure : measured in the mediastinum posterior / By Dr. S.J. Meltzer.

  • Samuel James Meltzer
Date:
[1892]
Catalogue details

Licence: Public Domain Mark

Credit: On the respiratory changes of the intrathoracic pressure : measured in the mediastinum posterior / By Dr. S.J. Meltzer. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    end a little backwai'd to facilitate its entrance into the mediastinum posterior, as there is a tendency for the lower end of the katheter, while entering the thorax, to stumble against the incisura sterni, on account of the convexity of the spinal column in this region. In fact, the entrance of the katheter into the chest is the main difficulty, in older animals more so than in younger ones, not only for the reason of the greater curvature of the spinal column, but also on account of the greater firmness of the connective tissue obstructing the entrance of the chest. Drawing back the katheter should be avoided, as this might, as it would be seen later, destroy the entire experiment. Elevating the outer end of the katheter, which would facilitate its entrance into the chest, should also be avoided, as this makes the channel leading to the mediastinum too wide and facilitates the entrance of air beside the katheter. This latter should be of a very small calibre; with an English katheter No, 5 (lumen about two millimeters) I never found an insurmountable obstacle in pushing it in. The katheter is blind at the end, and has one side opening near it; I made another opening opposite the first one. The lower half of the katheter was divided by marks (small cuts) in 5 millimeters distances. The amount of pressure in the mediastinum was ascertained by connecting the katheter either with a water manometer, or with a Marey's tambour. In the latter case the respiratory undulations of the mediastinum have been recorded graphically in the usual manner, on a revolving cylinder covered with smoked paper. Below the lever writing these undulations another lever was placed marking the time in seconds. The distance between the two lines traced upon the graphic table before connecting the tambour with the mediastinum, represents the atmo- spheric pressure; a smaller distance means a negative, a greater distance positive pressure. The manometer, or the Marey's tambour, was con- nected with the katheter by means of rubber tubing, which had to be long enough to facilitate the handling of the katheter. The connection was made of course before the katheter was introduced behind the pharynx; there was no clamp or stopcock between the katheter and the manometer. Before the katheter entered into the chest, there was usually no difference in the level of the water in the two sides of the mano- meter, but if there was any difference, it was of course taken into account. The pushing was done, as stated, in 5 millimeters distances. At each step notes of the pressure were taken as it presented itself during the inspi- ration and expiration, the time of observation being from 5—6 minutes. There was hardly any necessity for taking the mean of a number of obser-