Arterial and Venous Pressure Readings During Open-Heart Operations
CONTINUOUS pressure readings, both arterial and venous, are necessary in open-heart surgery. These values may be obtained by means of a strain gauge and an oscilloscope screen (or direct writer). A simpler, more direct method of determining these pressures throughout the period of anesthesia and operation has proved to be satisfactory in more than 800 cases at the Cleveland Clinic Hospital.
Arterial pressures are read on an aneroid manometer that is connected by means of an arterial pressure set* (consisting of plastic tubing and various adaptors) to a cannula in the femoral artery. A 500-ml. flask of 5 percent dextrose containing 10 mg of heparin is attached to the screw cap (microdrip of the arterial set) (Fig. 1). The solution is allowed to fill the portion of the tubing covered with a sterile sleeve, and also another limb (which serves as a manometer connection) to within 4 in. of its end. One manometer is attached to this end (shown on the left in Figure 1) and another manometer (with pressure bulb) is attached to the flask as indicated.
A cut-down is made upon the femoral artery in the upper thigh, and the point of a Rochester needle* is passed into the lumen of the vessel. The sterile end of the arterial pressure set is now uncovered and is secured to the needle. By means of the pressure bulb, an air pressure of about 150 mm. of Hg is induced in the flask containing the dextrose and heparin solution. The solution. . .