1. Field of the Invention
This invention relates generally to bone marrow aspiration and biopsy procedures and more particularly to a device and procedure for attenuating the pain associated with such procedures.
2. Description of the Related Art
In order to diagnose the presence of numerous blood-related diseases, such as blood infections, leukemia and other malignancies, and the cause of blood abnormalities, such as anemia, hematologists often examine the bone marrow of their patients. Two types of specimens are often removed from a patient for analysis. In one procedure, bone marrow is extracted, or aspirated, from the cavity of a bone. In a second procedure, one or more pieces of bone, called "core biopsies," or "bone plugs," are also removed for diagnosis. The entire process typically lasts anywhere from ten to thirty minutes, depending on numerous factors, including the amount of marrow needed, the difficulty of positioning and inserting the needle, the hardness of the bone, the experience of the physician, etc.
These two procedures are often performed in succession. First, a specialized, biopsy needle having a removable trocar, or stylet, fully inserted into the needle lumen is inserted into and through an appropriate bone structure of the patient, such as the posterior iliac spine (i.e. pelvic bone) or sternum, and into the bone marrow cavity. The trocar is removed and an appropriate method for aspirating the desired amount of marrow tissue into the needle lumen is used. Aspiration may be accomplished by rapidly retracting the plunger of an attached syringe thereby creating a upward, suction force, by employing an aspirator bulb, or by another method known in the art.
In order to perform the subsequent procedure, the needle is typically retracted a few millimeters until it exits the bone structure from which the marrow was aspirated. Then, the needle is reinserted, this time without the trocar inserted in the lumen, into a neighboring area of the bone in order to effectively core out a piece of bone into the lumen for removal and analysis. The physician often needs to apply a considerable amount of force when coring the bone plug.
Both the aspiration and coring procedures can cause significant discomfort and pain to the patient. First, the insertion of the needle through the skin, subcutaneous tissue and muscle tissue usually causes moderate pain. Further, as the needle passes through the bone, a strong, pressure-like sensation is experienced. The part of the aspiration procedure causing the most pain, however, is the actual aspiration action. This pulling sensation, which lasts as long as the syringe plunger is retracted, has been described by some as agonizingly painful, while others perceive less intense pain, depending on the patient's pain threshold and level of apprehension and fear. Further, while the bone coring procedure has not been described as acutely painful as the aspiration procedure, it does cause moderate to severe discomfort. Accordingly, it has been a goal of medical practitioners to find ways to ameliorate the discomfort and pain associated with these procedures.
The injection of local anesthesia, such as lidocaine, prior to these procedures, is effective in desensitizing soft tissue and the bone surface, or periosteum, to be pierced. Unfortunately, local anesthesia cannot anesthetize the inside of the bone and thus is ineffective to reduce the pain associated with the aspiration and coring actions.
While the use of general anesthesia would, of course, be expected to eliminate the perceived pain, it is not commonly used for these procedures due to the risks related to general anesthesia. As an alternative, some physicians elect to prescribe a benzodiazepine or another mild tranquilizer for patients having a high degree of apprehension prior to these biopsy procedures. However, no known viable and completely safe procedure presently exists to eliminate or significantly reduce the pain associated with the aspiration and coring steps of these procedures. Thus, the bone marrow aspiration and coring procedures have continued to cause a great deal of anxiety, discomfort and pain in many patients of all ages who must undergo them.
Accordingly, it should be appreciated that there exists a definite need for an improved product and method which tends to significantly reduce or eliminate the pain associated with the aspiration and bone coring steps of the conventional bone marrow procedure.