XII 



M K( 'HAN K 'S OF IIES1' I RATION 



429 



pressure 

 of water. 



equal to - 80, during inspiration equal to - 102 mm. 



The simplest method for recording the oscillations of intrathoracic pressure 

 in animals is to introduce into the oesophagus, after previous oesophagotomy, 

 an elastic sound, or hollow metal tube, covered at one end with a fine rubber 

 membrane, which is connected with a writing tambour, after ligation of the 

 oesophagus (Fig. 192). This last operation is necessary to ensure the perfect 

 occlusion of the oesophagus above the exploring sound, while beneath it the 

 tonicitv of the cardiac orifice is 



sufficient to guarantee 

 at the moment of deg 



closure, save 



FIG. 192. Lnciani's oesophageal explorer. Elastic 

 sound, covered at the end with line rubber 

 sheath. 



lutition, which 



rarely occurs in the narcotised 

 animal. The imperfect closure of 

 the oesophagus, after introducing 

 the sound by the mouth or nostril, 

 makes it difficult to obtain these oscillations of inlrathoraeic pres>ure in 

 man (Rosenthal). It might be possible to remove this inconvenience by 

 the expedient employed by Pfliiger and Ludwig in their pulmonary catheter 

 (Fig. 170, p. 388). 



Bert's method may be employed for recording the infra-abdominal pressures. 

 This consists in the introduction into the rectum of a glass tube, fixed against 

 the anal sphincters by a kind of pessary to make it air-tight, and connected 

 with a water manometer and writing tambour (Fig. 193, A). The inter- 

 vention of a manometer is, however, superfluous, 

 and no special contrivance is required to ensure 

 closure of the anal orifice, which was sufficiently 

 guaranteed by the tonic contraction of the 

 sphincters. The same object can be effected by 

 the introduction of a short length of urethra! 

 catheter of large diameter, perforated in several 



places,' and provided at the ends and centre 

 with three circular ridges 



u. 11)3. Rectal explorers Bert (A) 

 and Luciani (B). A, Glass tube. 

 open at the end, which is in- 

 troduced into the rectum and 

 plugged in anal aperture by in- 

 flation of a hollow elastic pessary 

 joined to the tube. B, Elastic or 



r, perl 



t the i 



three circular ridges formed of rubber 

 rings, over which is drawn a thin membrane 

 (Luciani). This method is applicable to. man, 

 and is invariably successful, so long as the 

 precaution is taken of emptying the intestine 

 of the faeces accumulated at the lower end 

 (Fig. 193, B). 



covered 



sheath. 



XL Whatever the absolute values 

 these oscillations of pressure in the 

 a smaii tine t, NV o body cavities determined by re- 

 spiratory rhythm, it is evident that they 

 must have a considerable influence on the centripetal course of 

 the blood in the veins, and be an effective aid to the circulation 

 as controlled by the heart. 



This physiological doctrine is fairly ancient. Valsalva (1760) 

 and Haller (1766) seem to have been the first who observed on 

 man the swelling and emptying of the jugular vein coincident 

 with expiration and inspiration. David Barry (1825), from the 

 aspiration of coloured fluid along a tube fastened centrally in the 

 jugular, formed an exaggerated notion of the functional importance 

 of inspiratory thoracic aspiration. Wedemeyer (1828) repeated 



