The present invention relates to a suction device for aspirating blood during a surgical procedure and, more particularly, to a device for adding and mixing an anticoagulant with blood as it is sucked into the device.
During surgical procedures, especially those involving the abdominal or chest cavities, a great deal of bleeding occurs normally and conventional practice has been to simply aspirate the blood and other fluids to keep the surgical site clear and subsequently dispose of the fluids so removed.
A relatively recent development in this area has been to convey the blood and other fluids which are aspirated during surgery to a centrifuge, extract the red blood cells and serum and return the thus purified fractions to the patient during the surgical procedure. Since the blood begins to clot immediately upon contact with air, it is necessary to add an anticoagulant to the fluids aspirated, preferably as they are removed from the patient.
During this type of procedure, it is common to provide the operator with a on/off switch or clamp to terminate the suction and flow of the anticoagulant when the aspirator is not needed. Besides being somewhat awkward, it is not uncommon for the operator not to turn off the flow of anticoagulant, particularly in an emergency situation. As a result, an excess of anticoagulant may be added to the aspirated blood, thus increasing the rate of bleeding as the blood is returned to the patient.
U.S. Pat. No. 4,547,186 to Bartlett discloses a device for automatically introducing an anticoagulant into aspirated blood. In this device a bag of anticoagulant is provided for supplying anticoagulant at the point of aspiration as well as at a point along the blood flow line between the suction nozzle and the collection bag. However, the anticoagulant bag must be positioned at a particular height relative to the suction nozzle for the system to operate properly. Thus, it can be seen that this system requires a certain amount of calibration prior to use which may prove to be inconvenient in emergency situations.
Another system for metering anticoagulant during aspiration of blood is shown in U.S. Pat. No. 4,540,406 to Miles in which anticoagulant may be accurately metered to a suction nozzle regardless of the height difference between the nozzle and the anticoagulant supply. The suction nozzle of this device requires that the operator place his or her finger over an opening in the nozzle side in order to actuate the suction. While this device provides an improved amount of control over termination of the suction, the operator is required to give additional attention to accurate placement of his or her finger over the opening in the suction nozzle and as such introduces an increased amount of inconvenience into the aspiration procedure.
Accordingly, what is needed is a device for aspirating fluids from a patient during a surgical procedure which is capable of accurately metering anticoagulant for mixing with the aspirated fluids. In addition, the device must be capable of initiating and terminating flow of anticoagulant upon initiation and termination of the flow of fluids through the suction device such that a minimum of attention from the operator is required during use of the device.