Laboratory evaluation of laparoscopic vascular clamps using a load-cell device--are all clamps the same?

Purpose: The use of effective vascular clamps is key to successful laparoscopic partial nephrectomy. Based on our clinical experience the occlusive capabilities of vascular clamps appeared to be quite variable. We compared the occlusive force of currently available laparoscopic vascular clamps.

Materials And Methods: The jaw force of 3 laparoscopic vascular clamps (Aesculap(R), Klein Surgical Systems, San Antonio, Texas and Karl Storztrade mark) were measured by clamping a 2.2 mm compression load cell (Interface Advanced Force Measurement, Scottsdale, Arizona) in pound-force. The variables tested were handheld Satinsky, DeBakey and Storz clamps vs bulldog clamps, proximal, middle and distal application position, new vs used bulldog clamps and new vs used Satinsky handheld clamps. In addition, handheld clamps were tested according to the force generated by the notches in the locking mechanism. Force retention was also determined for all instruments after clamping a 20Fr latex rubber catheter for an hour. Finally, leak pressure studies were performed using a harvested porcine artery to determine the relationship between jaw force and leak pressure in mm Hg of bulldog and Satinsky handheld clamps using a pressure gauge (Cole-Parmer(R)).

Results: Handheld vascular clamps provided greater force than bulldog clamps. The proximal position closest to the hinge provided the greatest force across all instruments. Compared to new clamps the 2-year-old Klein Surgical Systems bulldog clamps showed a greater than 40% decrease in jaw force at all positions, whereas the 3-year-old Aesculap bulldog clamps decreased in jaw force by less than 9% at all positions. The 2-year-old Satinsky handheld clamps showed a decrease of 20%, 9% and 0% at the distal, middle and proximal jaw positions, respectively. Also, there was a positive correlation between force and the number of notches applied in handheld clamps. In addition, all instruments maintained jaw force after 1 hour of continuous clamping. Finally, leak pressure studies performed with used clamps showed that Klein Surgical Systems bulldog, Aesculap bulldog and Satinsky handheld clamps leaked at a pressure of 153 to 223, 465 to 795 and 1,500 to 2,600 mm Hg, respectively.

Conclusions: Vascular clamps have varying occlusive forces according to clamp type, manufacturer, jaw and teeth characteristics, jaw clamping position and duration of use. However, across all clamps the jaw force was greatest at the proximal position. This is most important when applying laparoscopic bulldog clamps. In contrast, all handheld vascular clamps generated higher force than intracorporeal bulldog clamps. At 1 notch the handheld vascular clamps provided supraphysiological occlusion force regardless of position or manufacturer.