Commentary: How did that happen?

Todd L. Demmy, MD

Surgeons need to appreciate the general and device-specific mechanisms by which endomechanical staplers cause vascular injuries.

See Article page 76.

The article by Matsui and Murakawa demonstrates a mechanism of stapler-induced tissue injury that is probably more common than we appreciated. Furthermore, they were fortunate enough to capture the problem “in the act.” And because they were in control of the hand-fired stapler (rather than a motorized product going automatically through its cycle) stopping the action before injury was possible.

Like many unforeseen events, this one required the interaction of problems. First, was an errant staple with one end embedded firmly into the vessel and the another partially deformed (resembling a hook) ready to latch onto something. Although loose remnant staples pose their own laceration risks by becoming little knives wedged in instruments like suction holes, the partially embedded staple can catch things like dissecting sponge gauze and be avulsed.

The thing that caught the staple, in this case, was the external cap on the I-beam like component of the stapler reload, which moves along its tracks bringing together the anvil and cartridge. As it moves, this central component compresses the tissue, ejects the staples, and cuts the tissue with the external cap providing visual confirmation of the division and stapling progress. However, monitoring the progress of the stapler is also evident on the external handle. Therefore, there is not an expectation for surgeons to always keep the cap under visualization unless they happen to know about this unusual, potentially dangerous chain of events.

This might be why, on rare occasions, bleeding starts from vascular structures during thoracoscopic lung resections that were previously hemostatic. Without a mechanism like that depicted in this report, the titular question either goes unanswered or is attributed to other local factors like free staple bodies, loose clips, or trauma caused by retractor instruments or other stapler components while they were passed or fired.

Although this stapler design allows such an event, this unusual safety concern might be acceptable to surgeons who wish to avoid other problems. For instance, the design of another major vendor of staplers compresses the tissue upon closing of the stapler (as opposed to high-force compression that occurs only during firing as the cap and underlying components advance). Some surgeons, like myself, believe that this softer closure allows safer “test clamping” whereas others see this as a disadvantage because the tissue is not held as snugly within the stapler. In any case, high compression on delicate vessels can cause damage away from the closed ends of the divided structure leading one group of investigators to cite stapler gap distance as an important consideration during pulmonary stapling.

In any case, this report underscores the need to surveil for errant, partially embedded, and malformed staples while operating. To the extent that small vessel division might increase this problem because there is less vascular wall for staple incorporation, we might consider greater use of energy devices for such structures, which have been tested and appear safe and effective.