Abstract
Pulmonary embolism is responsible for many postoperative deaths in almost every extensive surgical practice. As yet no adequate means of combating this menace has been devised and the present study was undertaken in the hope that new leads in the direction of its prevention might be forthcoming.
The apparatus used is composed of an arterial and a venous cannula connected peripherally by a transparent, semipermeable collodion tube, the whole forming a U-shaped system. The cannulas are inserted into the carotid artery and jugular vein of a rabbit after the apparatus is filled with physiologic sodium chloride solution, and the membrane portion rests in a solution of this saline. When circulation is established the blood flows through the system and back to the animal without contact with air.
The influence of many factors on the rate and type of thrombosis may be determined by means of this device. It makes it easy to vary, control, and assay mechanical, chemical, physical, pharmacologic, and pathologic factors. The process of thrombosis can be followed with the unaided eye; the membrane may be detached at any time and studied as fresh tissue or it may be embedded in paraffin and sectioned for microscopic study.
When the original technic (side tubes paraffined and cannulas with clean glass surfaces) is used with the normal animal, flow ceases through the apparatus in from 10 to 20 minutes, most often on account of obstruction of the venous cannula by white thrombi. The microscopic structure of these thrombi (and those on the membrane) is identical with that reported by Welch, 1 Aschoff, 2 and others. With circulatory and metabolic stimulants such as thyroxin and ephedrin, the flow was maintained as long as forty minutes.
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