| abstract |
A source of saline solution under pressure is connected through tubing to a catheter inserted in a patient's blood vessel. A waste collection bag is connected to the tubing through a stopcock which permits the selective connecting of the catheter to the waste collection bag or the bag of saline solution. The sampling site is in the tubing between the catheter and the stopcock. Normally, saline solution flows into the patient's blood vessel. When a sample is to be taken, the stopcock is shifted so that the pressure of the patient's blood forces blood into the tubing, driving saline into the waste collection bag. When blood has reached the sampling site, blood is extracted with a hypodermic syringe. |