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With replacement blood in perpetually short supply, more and more hospitals are focusing on ways to recover the patient's own blood during surgery and reinfuse it to eliminate the need for an outside source. Harvest Technologies LLC ( Plymouth, MA) is introducing a unique new surgical blood recovery system that allows them to do just that.
The BloodStream Recovery System features SmartSuction--a unique technology that controls the vacuum at very low levels to avoid damaging blood cells yet permits rapid clearance of the surgical field. An important component of the BloodStream System is a clear plastic chamber molded of Eastar MN100 copolyester that not only contains the evacuated blood but also acts as a mechanical component of the peristaltic pump that controls blood movement through the system.
During aspiration, an electronic system senses the operating conditions and continuously adjusts the suction within a safe window of -20 to -100 mm Hg. This allows the suction head to remain in constant contact with the wound without damaging the blood cells, permitting high flow rates up to 4 liters per minute for rapid clearance. A roller at the bottom of the plastic chamber continually squeezes and releases a section of clear plastic tubing to gently pump the blood without damaging delicate cells. The system includes a multistage filtration system. The final stage is a 40-micron filter within the unique blood reinfusion bag supplied with the system.
"In many types of surgical cases, the BloodStream System may be used in place of cell washing," says Wes Verkaart, inventor of the system and cofounder of Harvest Technologies. "This is often an advantage because cell washing gets rid of everything except red blood cells, so plasma (which comes from a donor) is usually required. With the BloodStream System, the only thing put back into the patient's body that wasn't already there is a small amount of citrate used as an anticoagulant, and it is quickly metabolized." Although not designed specifically as a lifesaving device, the BloodStream Recovery System has already been credited with saving patients lives in high blood loss cases.
Eastar MN100 copolyester, marketed globally by Eastman Chemical Company, was selected for the plastic chamber because of its clarity, toughness, blood compatibility and environmental friendliness when incinerated. "Because the plastic chamber is a mechanical component and a container, it needs to be able to withstand repeated stress," notes Verkaart. "It also needs to retain its clarity and not yellow after sterilization with either gamma radiation or ethylene oxide."
Like most materials used during surgery, the plastic chamber is eventually incinerated, so economic and environmental considerations were important factors in the selection of Eastar MN100 copolyester.
Measuring 15.24 cm in diameter and 22.63 cm in height, the plastic chamber has 3 integrally molded legs, each 1.47 cm long, that serve as both support and locating devices. Gently tapered, its walls are 0.20 to 0.24 cm thick. In addition to its legs, a platen for the roller pump, 2 latch-down points, a 90-degree elbow on the bottom, 2 tubing holders, filter mounting details and an interference seal for its HDPE cap are also molded in.
Tech Inc. ( Merrimack, N.H.) molds the chamber. While its complexity is not unique, its size is noteworthy. "This is the largest commercial medical device we have ever seen molded in Eastar copolyester," says Eastman's medical market manager. "It demonstrates the tremendous versatility of this material, as well as its ability to be molded into complex shapes, even in larger sizes."
Eastar copolyesters, which are gamma and EtO sterilizable, combine exceptional toughness, chemical resistance and clarity with excellent performance in close-tolerance injection molding. They can also be tinted amber for pharmaceutical packaging applications. |
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