In the past decade there has been an increasing number of surgeons using staples in lieu of conventional sutures in many internal organ procedures ranging from the esophagus to the rectum. This trend is due largely to the fact that the use of stapes is much easier and a number of difficult procedures are rendered much simpler through the use of staples. Perhaps of even greater importance, however, is the fact that the use of staples is a very much faster procedure, substantially reducing the time required for suturing and, therefore, the length of time the patient must be maintained under anesthesia.
Along with the above noted advantages, surgical stapling procedures also present certain problems. For example, it is necessary to select the proper staple size for the thickness of the tissue to be joined. Furthermore, it is quite possible that even if the proper staple size is selected, the staple could be formed in the tissue either too tightly or too loosely. If the surgical staples are formed too tightly, the blood supply needed for the healing process is cut off and the tissue will become necrotic. On the other hand, if the staples are formed too loosely, then hemorrhaging and/or leakage can occur. Both too tightly and too loosely formed staples can cause serious problems and complications.
It is precisely these problems, inherent in surgical stapling, that cause the need for an instrument to measure the thickness of tissue to be joined by surgical staples. Surgical staples are available in various sizes. Many surgical stapling instruments are provided with means enabling the adjustment of the gap between the cartridge or head containing the staples and the anvil against which the staples are formed, thereby determining the amount by which the staples are clinched. If the thickness of the tissue to be joined is known, appropriately sized staples can readily be selected and the above noted gap can be properly set.
The very nature of living tissue makes it somewhat difficult to measure because of its soft, elastic and resilient properties. Studies have been conducted to determine the optimum healing pressure, for example, for intestinal tissue. The optimum healing pressure varies with various types of tissue. Lung tissue, for example, is quite different from intestinal tissue. Therefore, the tissue measuring device of the present invention would have to be designed to apply the optimum healing pressure during the tissue measuring operation for the particular type of tissue being measured. This can readily be done and the same principles and mode of operation of the tissue measuring instrument of the present invention would be involved with each type of tissue.
For purposes of an exemplary showing, the tissue measuring instrument of the present invention will be described in its application to the measurement of the thickness of intestinal tissue. Prior art workers have developed various types of intralumenal anastomosis surgical stapling instruments. Exemplary, but nonlimiting, examples of such instruments are taught in U.S. Pat. No. 3,552,626, copending application Ser. No. 890,262, filed Mar. 27, 1978 in the name of Carl T. Becht and entitled INTRALUMENAL ANASTOMOSIS SURGICAL STAPLING INSTRUMENT and copending application Ser. No. 06/124,954, filed Feb. 26, 1980 in the name of Robert G. Rothfuss and entitled INTRALUMENAL ANASTOMOSIS SURGICAL STAPLING INSTRUMENT. These instruments join the tubular body parts substantially in end-to-end relationship, engaging the tubular parts internally and removing excess portions of the tubular parts adjacent the annular set or sets of staples implanted by the instrument, through the use of a cylindrical scalpel or the like. These instruments are adapted to use cylindrical cartridges of staples of one or more sizes and are provided with means to preset the gap between the staple containing cartridge and an annular anvil member against which the staples are formed. The adjacent tubular body parts to be joined together are located within the gap. The tissue measuring instrument of the present invention is intended to be used with such exemplary surgical stapling instruments provided with gap setting means (as for example that taught in the last mentioned copending application), the calibration of which is identical to that of the tissue measuring instrument.
The tissue measuring instrument of the present invention attaches to the tissue with a clamping action, making the actual tissue thickness measurement independent of the surgeon. The instrument, during the measuring process, will clamp on the tissue to be measured with a force substantially equivalent to the above mentioned optimum healing pressure. This is true over a predetermined range of tissue thicknesses. The instrument has at least one scale and indicator means by which the tissue thickness can be readily and directly read by the surgeon. The clamping jaws of the instrument are so configured as to provide easy engagement thereby of intestinal tissue where access is limited. The instrument may be provided with a second scale from which the diameter of the intestinal lumens can be determined for selection of a cylindrical staple cartridge of the proper diameter.