Laparoscopic surgery, or minimally invasive surgery, is an operation performed in the abdomen or pelvis with the aid of viewing tubes or laparoscopes. A laparoscope is typically connected fiberoptically to a video camera, which transmits the picture to a TV monitor. A plurality of small incisions (typically 0.5-1.5 cm in length) are made in the skin, through which surgical trocar assemblies or other similar puncturing devices are inserted to create “ports” traversing the abdominal wall. For example, surgical instruments can be inserted through one or more of the small ports, an air insufflation device can be inserted through a different small port, and a laparoscope for viewing can be inserted through yet another small port. Laparoscopic surgery has replaced many standard invasive abdominal surgical procedures that require large incisions. When compared to open abdominal surgery, laparoscopic technology provides decreased postoperative pain, a decreased hospital stay, shorter-term postoperative ileus, improved wound healing and mobility, smaller scars (improved cosmesis), earlier return to daily activity, decreased cost, and increased patient satisfaction.
A typical trocar assembly used to puncture the abdominal wall in laparoscopic surgery includes a central obturator and a hollow sleeve, or cannula. The obturator is typically elongate and has a sharpened distal end suitable for efficiently yet safely puncturing the layers of the abdominal wall. The hollow sleeve fittingly slides over the outer diameter of the obturator, and the two are typically used together to access the intraperitoneal space. Once the intraperitoneal space is visualized, the obturator is removed and the sleeve remains as a port or interface. The proximal or external end of the sleeve is typically attached to a hub for introducing and removing various surgical instruments therethrough. The hub is typically fitted with air insufflation components and various pneumostasis valves for sealably receiving the surgical instruments. The intraperitoneal space is typically insufflated with pressurized carbon dioxide to provide more room and better exposure for viewing the anatomy and manipulating instruments through the ports. Scissors, dissectors, retractors, and biopsy instruments can be manipulated through a plurality of surgically placed ports, together with viewing devices such as endoscopes or laparoscopes, to perform the planned surgery or diagnostic procedure.
Because of increasing medical and hospitalization costs, it is desirable to perform laparoscopic procedures on an outpatient basis. A major post-operative hurdle for laparoscopy patients, however, is “port site pain” resulting from the trauma caused by the obturator when puncturing the abdominal wall. To decrease and/or prevent post-laparoscopy port site pain, local anesthesia can be advantageously administered pre-operatively, in combination with general anesthesia during the procedure. Pre-operative local injection of anesthetics such as lidocaine and/or bupivacaine can decrease the amount of general anesthesia needed, and speed up recovery time. As a result, most current outpatient laparoscopic procedures utilize pre-operative administration of a local anesthetic. Liquid anesthetic medication is injected at the planned point of insertion of the obturator, and along the anticipated obturator wound tract through the abdominal wall. While useful if properly done, satisfactory pre-operative placement of local anesthetic into a proposed wound tract is difficult to perform by hand. The path of injection of the liquid medication is often indiscriminate and inaccurate, resulting in its application in the wrong place.
For example, injection of the skin at the proposed incision point and along the projected path of the obturator does not always place the anesthetic along the true path later traveled by the obturator through the abdominal wall. This is complicated by the fact that the obturator path typically travels at an angle relative to the skin incision. This can result in incomplete anesthesia of the “port site wound”, i.e. the surgical wound created by the true path taken through the abdominal wall by the puncturing trocar assembly. Port site wound pain can lead to patient discomfort during the procedure and an increased reliance on the general anesthetic to complete the procedure. In addition, post-operative “break through pain” can result, even with accurate placement of local anesthetic, due to metabolization of the pre-operatively administered local anesthetic during the surgical procedure. This can lead to an increased reliance on post-operative narcotics and a slower recovery time.
In addition to the pre-operative administration of local anesthetic noted above, current surgical practice commonly includes the administration of local anesthetic at the conclusion of surgery, directly into the walls of the port site wound. The goal is to provide local anesthetic at maximum strength in the tissues forming the port site wound, both intra-operatively and immediately post-operatively, in order to prevent port site pain and/or break through pain. Timing can be important, because if the surgeon administers the local anesthetic too late at the end of the procedure, there may not be time for the medication to adequately take effect before the patient wakes up. Too early, and the local anesthetic effect may be gone. Either way, if the timing is off the patient may suffer immediate post-operative port site pain. Indeed, providing maximum intra- and post-operative local anesthetic effect at the tissues around the trocar wound has been difficult to accomplish.
U.S. Patent Pub. No. 2007/0073248 to Moenning discloses a trocar assembly for a laparoscopic procedure which can intra-operatively dispense a biologically active compound such as a cancer medication. The obturator sleeve includes an interior cavity connected to a fluid delivery channel at the hub, with apertures located down the length of the sleeve communicating with the internal cavity so that medication can be dispensed to the outside surface of the sleeve. While beneficial, the present inventor has found that such a trocar assembly is not always sufficient for post-operative pain relief. Notably, it has been observed that local anesthetic, which is a liquid, upon injection into the sleeve simply follows the path of least resistance and flows out of the apertures of the sleeve and into the abdominal cavity. This is potentially hazardous, since the absorption dynamics of local anesthetics such as bupivacaine into the peritoneal membranes are less predictable as compared to absorption into the tissues of the abdominal wall. This is especially true if the abdominal wall is thin, such that the apertures empty directly into the insufflated peritoneal space. In addition, since an injected liquid has a tendency to pool into the most gravity-dependent portion of the sleeve, uneven distribution of the medication within the trocar wound tract often results. If the obturator is placed into the patient at an angle, as is typically done in practice, injection of local anesthetic through the sleeve will not uniformly anesthetize the wound path.
It is apparent from the above discussion that there is a need in the laparoscopic surgical arts for more effective delivery of local anesthesia medication to the tissues surrounding a port site trocar wound. It would therefore be beneficial to provide a device and method for accurately delivering a liquid local anesthetic medication along the true path of a port site wound during a laparoscopic procedure. It would also be advantageous if such a device and method could be utilized by surgeons having a variety of different skill levels. It would also be advantageous to provide an improved means for reducing post-operative port site pain, breakthrough pain, and narcotic use, which can improve patient comfort and enhance the outpatient capabilities of laparoscopic procedures.