| abstract |
Method and apparatus for distending the blood vessels comprising the veins and the arteries in an isolated portion of a patient's body remote from the patient's heart to facilitate puncture with a cannula. The preferred method comprises placing the isolated portion of the patient's body within a chamber capable of supporting at least a partial vacuum and forming a substantially airtight seal between the chamber and the isolated portion of the patient's body. Venous blood flow from the isolated portion of the patient's body is then gradually restricted by circumferentially constricting the patient's body at a point approximately coinciding with the point at which the substantially airtight seal is formed. The isolated portion of the patient's body in the chamber is then subjected to a partial vacuum for a period of time sufficient for the patient's systolic arterial blood pressure to engorge the blood vessels with blood, to substantially equalize the pressure of the blood in the veins and the arteries and to substantially distend the blood vessels. Constriction of the patient's body is thereafter gradually increased until the arterial blood flow to the isolated portion substantially ceases. Finally, the vacuum chamber is vented to atmosphere and removed while the circumferential constriction is maintained to substantially prevent the flow of blood to and from the isolated portion of the patient's body. As a result, the blood vessels in the isolated portion of the patient's body are in an engorged, highly visible and highly distended condition. |