1. Field of the Invention
This invention relates to wound treatment, particularly to shield devices that protect medical personnel from patient body secretions that splash back during wound irrigation.
2. Discussion of the Prior Art
High-pressure irrigation (optimally 8 pounds per square inch) of traumatic wounds is widely recommended in the medical literature. It removes particulate matter, such as soil, as well as germs, both of which can increase the chances of wound infection. Such irrigation has generally been accomplished by the use of a syringe and hypodermic needle. Unfortunately, this recommendation is often ignored in practice because of the inconvenience and mess caused by irrigant fluid splashing back out of the wound. Moreover, this splash-back puts medical personnel and other bystanders at risk of infection when blood-borne germs (such as HIV or hepatitis) are sprayed about. These risks have been addressed in the past by the use of goggles, masks, gloves, gowns, and the like to protect the operator. But these solutions are expensive, cumbersome, and do not protect bystanders or other patients who might be in the area. Recently, a clear plastic shield has been marketed, bearing U.S. Pat. No. 4,769,003 to Stamler (1988) and sold under the trademark ZEROWET by Zerowet, Inc. of Palos Verdes, Calif. The Zerowet shield is designed to fit on the end of a syringe. Its central lumen produces a narrow jet of fluid without the need for a needle, eliminating the risk of an accidental needle-stick. Its shield contains the splashback, protecting the operator from contamination. The manufacturer states that the shield should be held in light contact with the wound edges. But this device has been criticized by many authorities, who point out that, when used as directed, the effluent irrigating fluid will necessarily re-enter the wound after reflecting off of the shield. Thus irrigation with this device may not only fail to remove germs and debris from within a wound, it may actually spread these noxious elements to previously uncontaminated areas, or even carry them from dirty intact skin at the wound margins into the wound itself. In an effort to overcome these limitations, many physicians use this device incorrectly, holding it several centimeters away from the skin. This results in inadequate access to the recesses of the wound, inadequate irrigant stream pressures, and a failure of the shield to fully contain the splashback.
U.S. Pat. No. 5,496,290, to Ackerman (1996), discloses a very similar device which is said to have the advantage of allowing the irrigation to take place at a shorter distance from the wound and at a greater angle of incidence to the wound site. However the shallowness of the concave shield will only increase the likelihood that effluent from the wound will reflect from the shield directly back into the wound.
Moreover, when the Zerowet shield or the Ackerman device is used, irrigant contaminated with blood and debris pours off the rim of the shield, as illustrated in FIG. 3 of Ackerman's patent. In practice, large volumes of bloody water spill onto the patient, the patient's clothing and bedclothes, the bed, and the floor. This necessitates the expenditure of time and materials to clean up after an irrigation, exposes staff and others to potentially infectious blood and secretions, and results in patients' dissatisfaction with their care.
Preparations such as positioning a basin or towel beneath the wound are often futile because the irregular shape of the human body often causes the effluent stream to drip in unexpected directions. Moreover, the wounded part often needs to be repositioned several times in order to amply irrigate it, making the positioning of basins and towels impractical.
U.S. Pat. Nos. 4,898,588 (1990) and 5,224,940 (1993) to Roberts and Dann, respectively, disclose shields which suffer from all the aforementioned disadvantages, as well as requiring the use of sharp needles with the accompanying risk of inadvertent needle-stick injury.
U.S. Pat. No. 4,692,140 to Olson entitled Lavage/Suction Tip With Dual Splash Shield (1987), discloses a device which includes concentric barrels terminating in a pair of flared shields; the inner barrel delivers irrigation to a surgical site and the outer barrel provides suction to remove the effluent. The first shield is pliable and fixed at the distal end of the barrels, while the second shield is rigid and can be moved to multiple positions along the barrel. The device is not designed for use with an ordinary syringe; thus it requires the purchase of a separate lavage/suction handpiece and appropriate pumps for use with it. While it may be suitable for use in the operating theater during joint replacement surgery (the only particular use mentioned explicitly in the patent), the design is unnecessarily complicated, making its cost prohibitive for routine use in the irrigation of minor wounds in an outpatient setting.
All the aforementioned devices suffer from the limitation that the irrigant is delivered through a single small aperture, greatly limiting the rate of fluid delivery and unnecessarily prolonging the time required to adequately irrigate a wound.
None of the aforementioned devices allows precise control of the pressure at which fluid is delivered. Because excessive pressures may cause needless tissue damage, and because low pressures may fail to remove small particles and germs, this is a significant disadvantage.
Finally, nearly all wounds need to be anesthetized prior to repair, if not prior to cleansing. None of the described devices is designed to deliver anesthetic at a precisely controlled volume or pressure in order to infiltrate a wound without the use of a needle. The use of a needle to deliver anesthetic has many disadvantages: it is frightening to most patients, especially children, and it creates the risk of inadvertent needle-stick injuries.