Methods for reducing peak pressure in laparoscopic grasping

Abstract

During tissue retraction with a laparoscopic grasper, tissue-damaging pressures can occur. Past research suggests that peak pressures can be considerably reduced by rounding the edges or covering the tip of the end effector with a silicon sleeve. To identify grasping methods that limit tissue damage, the effects of (a) Young's modulus of the end effector, (b) curvature of the end effector, and (c) angle with which the tissue is pulled relative to the plane of the end effector, on the pressure generated on the tissue were investigated. Artificial skin was placed between two non-serrated jaws, a pressure-sensitive film was interposed between the skin and upper jaw, and the end effector was loaded with 13 N. End effectors with Young's moduli of 0.09, 0.67, 1.49 MPa, and 69 GPa, and with non-rounded and 5 mm rounded edges were tested under pulling angles of 25°, 50°, and 75°. For non-rounded end effectors, the maximum pressure and the area across which pressure exceeded the safety threshold for tissue damage increased with Young's modulus and pulling angle. For rounded end effectors, maximum pressure did not increase monotonically with Young's modulus. Instead, the end effector with the second lowest Young's modulus yielded significantly lower maximum pressure than the end effector with the lowest Young's modulus. For rounded end effectors, pressures were below the safety threshold for all Young's moduli. This indicates that to prevent tissue damage, soft graspers may not be needed; rounding the edges of metal graspers could suffice for preventing tissue damage.

A review of the bio-tribology of medical devices

“…Usually, the gripper is made of stainless steel, which can be toothed or toothless, or has patterns such as corrugations. High pressures were found to be generated at the tip of laparoscopic graspers, which can be reduced by rounding the edge of the jaw [181]. The laparoscopic graspers modified by refashioning the tip out of silicone (Fig.…”

Comparison of the Biomechanical Properties between Healthy and Whole Human and Porcine Stomachs

“…However, postoperative complications, such as gastric bleeding, anastomotic leakage, intestinal obstruction, gastroparesis, reflux esophagitis, postoperative infection, and dumping syndrome, significantly affect patients’ quality of life and pose safety threats [ 6 ]. Therefore, stomach tissue engineering has been proposed as a potential avenue to restore normal gastric mechanical and metabolic functions [ 7 , 8 , 9 ]. Identifying suitable materials for stomach repair or replacement could reduce the complexities and associated complications of current procedures.…”

Implementation of anisotropic soft pads in a surgical gripper for secure and gentle grip on vulnerable tissues

“…Studies have shown that high pinch forces can be reduced by replacing the metal forceps of the gripper with soft pads. 8,9 The grip of such pads on tissue is achieved thanks to their deformability in the normal direction, which enables a large contact area with the tissue. At the same time, the contact formed between the tissue and the pad is homogeneously distributed over the pad surface, eliminating the occurrence of local high peak forces on the tissue.…”

“…At the same time, the contact formed between the tissue and the pad is homogeneously distributed over the pad surface, eliminating the occurrence of local high peak forces on the tissue. 8,9 A general disadvantage of a soft pad is that deformations of the pad occur not only in the normal but also in the shear direction, which might lead to tissue slipping out of the gripper during pulling. An ideal soft gripping pad would thus need to be anisotropic, fulfilling two contradictory properties: being deformable in the normal (pinching) direction, so that a large contact is formed, and stiff in the lateral (shear) direction, so that the formed contact is preserved when the tissue is being pulled.…”