UCSF Laparoscopic Surgery | Ergonomic Redesign of Cautery/Suction Device
In the old days, surgeons could only perform one kind of surgeries — open, they would take a traditional №10 blade scalpel and open the patient up through a large incision. They would continue to cut through the skin, cut through the fat, cut through the muscles, get down to the organs, do the operation, and finally, close the patient. Only in the late 1980s, a new minimal invasive surgical technique called laparoscopic surgery became more common and accepted by the general surgeons. Laparoscopic surgery is performed in the abdomen or pelvis using small incisions with the help of a camera and elongated instruments. These days, laparoscopic surgical technique has rapidly become well established: nearly 15 million procedures are performed every year worldwide. According to Mayo Clinic Proceedings, the advantages of laparoscopic technique includes decreased postoperative pain and shortened recovery time. The BIE Cohort had an incredible opportunity to meet Dr. Jonathan Carter, a bariatric and general surgeon and a faculty member at UCSF Medical Center, to learn more about laparoscopy and any challenges that surgeons face while using the laparoscopic instruments.
My team members and I remotely joined Dr. Carter in a Zoom space to start the needs-finding process, while he directed us through the paradigm for the laparoscopic gallbladder surgery. The four small incisions on the abdomen allow plastic straws to be inserted down to the abdominal cavity. Then, through those straws a carbon dioxide gas inflates the abdominal cavity like a balloon in order to create working space and provide visualization for the surgeon. Then the camera that is on the end of a stick is placed through one of the straws, so that the surgeon can observe inside the abdominal cavity. According to an article “Laparoscopic Surgery”, the laparoscope magnifies the image as much as 16 times its actual size. The laparoscopic instruments are designed miniature and elongated, so that they can be fitted through the other straws. Some of the miniature instruments include scissors, a hook, a grasper, and many others. In order to demonstrate the surgical environment, Dr. Carter commented on his own teaching video performing laparoscopic cholecystectomy during our discussion. Thanks to Dr. Carter, irrespective of my team members being geographically dispersed and the hospital limitations for the visitors, my team was still able to gain a sense of how the laparoscopic instruments are used during an actual operation.
After a helpful overview of laparoscopic surgery, Dr. Carter addressed a specific need in a multifunctional cautery/suction instrument. This device has five performance capabilities with suction, irrigation, cutting and coagulation, and electrode retractability. The cutting and coagulation are performed by passing a current through the metal electrode in the shape of a hook or an L- hook to the tissue. Depending on the current density, the electrode could either cut the tissue like a scalpel or cauterize it like a hot burning poke. The irrigation technique is used to wash the blood off and provide better visualization. The suction allows the removal of fluids, tissue debris, and gases, while the electrode retractability helps to prevent any tissue damage by the hot electrode during extensive suction. Usually these device capabilities are not used simultaneously. The precise and accurate coordination of a surgeon moving the instruments inside the body is paramount in performing a laparoscopic surgery.
The handle of this device takes advantage of fine motor coordination skills surgeons develop from an early childhood using the tripod pencil grasp. The pencil like coordination provides surgeons with a great control and precision over the tip of the device. Even though this device was designed to increase efficiency by reducing the number of required instruments and help with the precision, there are still some unmet needs regarding the ergonomic design of the device that my team discovered in the conversation with Dr. Carter. The button placement on the handle causes surgeons to have unnatural and awkward hand movements during the laparoscopic surgery. Instead of having their hand to sit in one position and have access to all the functions at once, surgeons have to constantly move up and down the shaft of the device to access the different function buttons. Additionally, my team learned that the L-shaped hook of the electrode limits the degree of freedom for the surgeon and creates room for inadvertent injury of the tissue. Moreover, the diameter of the suction pipe must be large enough to draw any blood clotting and work efficiently throughout the course of surgery. During laparoscopic surgeries, the surgeon switches the five functions one-handed, without evoking the other hand. Redesigning the handle of such a multi-functional device could help surgeons carry the operation in a more coordinated fashion.
On a gallbladder surgery, this multifunctional cautery/suction device might be used for 30 minutes in an hour-long surgery, but with time and experience surgeons just get used to the uncomfortable movement and the struggle that they undergo each time they have to switch the functions of the device. As Dr. Carter shared with us, the residents are usually experiencing the excessive struggle learning how to use this device with precision and accuracy. As engineers, our goal is to assist surgeons by designing instruments that not only serve their purpose with maximum efficiency, but also bring confidence and comfort to surgeons working in such a highly coordinated and organized environment. Moving forward with this unmet need, my team and I would like to better understand in what ways the current design of the device affects the surgeons and residents, what products are currently available in the market, and how could this product be improved in the future.
The BIE Cohort would like to thank Dr. Jonathan Carter for joining us remotely and providing us with such a great exposure to laparoscopic surgery and challenges with the design of the cautery/suction device.
