Instrument malfunction during robotic surgery: A case report.

Robotic assistance is the new dimension of minimally invasive surgery. Despite being the state-of-the-art technology, newer technical problems still occur during robotic surgeries which are not addressed in the trouble shooting manual. We report one such problem being encountered with the tip cover accessory of monopolar scissors. In the current report, we discuss the technical fault and its correction. We feel that this problem needs to be registered into the trouble-shooting manual to prevent such incidents in future.

INTRODUCTION

Instrument malfunction during robotic surgery is well known but the guidelines to tackle them are limited. With increasing robotic surgical cases, newer problems are encountered whose documentation helps in identifying and managing similar incidents in the future. In the current report, we discuss a unique problem, encountered right at the beginning of a robotic surgical case.

CASE REPORT

A 40-year-old female was planned for robot-assisted repair of vesico-vaginal fistula. Following port-placement and docking, the monopolar scissors got stuck in the cannula during insertion [Figure 1]. The instrument could neither be advanced nor withdrawn from the cannula. The system did not show any error signal or alarm. With some force, the scissors could be removed from the cannula. Assuming that there was a problem in the pulley system of the drape, the drape connection to the arm was checked and was found to be alright. We then inserted a bipolar forceps which went in smoothly. The same scissors were reintroduced after cleaning the pulleys on the scissors, but again the same problem occurred. Moreover, this time the scissors could not be brought out even with force. This time again there was no alarm and the emergency grip release wrench was of no use. Ultimately, de-docking was required to remove the robotic arm along with cannula and the instrument from the patient. The cannula was forcefully pulled away from the scissors to remove it. On close inspection, it was revealed that the tip-cover accessory of the scissors was over-advanced on to the shaft beyond the orange line during instrument preparation [Figure 1]. The tip cover was re-positioned, and the surgery went on uneventfully.

Figure 1

Scissors not getting negotiated across the cannula. Note the assembly more proximal to what it should have been (arrow)

DISCUSSION

Robot-assisted surgeries have been promoted in several specialties because of the better surgical outcome. However, instrument malfunction may result in undue anxiety, prolonged operative time, sometimes needing conversion to open or laparoscopic approach. In an extensive review by FDA in 2008, only 168 malfunctions of da Vinci system were reported out of more than 50,000 cases operated between 2000 and 2007.[1] Another report by Kim et al. reported an overall incidence of mechanical failure to be 2.4%, almost half of them were due to instrument malfunction.[2] One report showed that 56.8% of the urologists had experienced at least one intra-operative irrecoverable malfunction.[3] A multi-institutional review of 8240 cases reported critical failure rate of only 0.4%.[4] These reports point toward the safety of robotic surgical systems.

The monopolar scissor tip cover accessory provides insulation to prevent lateral thermal damage and electric arcing. One series reported an insulation failure rate of 2.6% during robotic surgery.[5] There is a mark on the shaft of the scissors which defines the proximal extent of the accessory. In our case, assistant staff advanced the tip cover accessory thinking that it will add to the safety. However, this led to increase in the diameter of the scissor at that point [Figure 2a–c]. The design of the cannula is such that the instruments snugly fit into its lumen for the efficient dexterity of the robotic arm and hence it does not accommodate even a slight increase in the girth of the instrument. This problem can occur only with the monopolar scissor because no other instrument requires a cover for safety. When two coaxial instruments (cannula and monopolar scissor in this case) get stuck, the most common reason is a change in diameter of one of them. We are reporting this case since such a problem will not be identified, either onsite or online by the system engineer, as the system would not have shown any error. In a monopolar scissor, the only site where its diameter can change is the tip cover accessory. In an instance of instrument getting stuck, the tip cover accessory (the most likely site) should be inspected.

Figure 2

(a) Robotic monopolar scissors without tip-cover-assembly. (b) A Properly placed tip-cover-assembly till the orange mark. (c) Over advanced tip cover increases the girth of distal shaft (bracket)

The malfunction led to increase in expected operative time and could probably result into conversion to the laparoscopic approach. However, its identification and correction led to uneventful surgery. With the technological advancements, newer technical problems are encountered. The presence of a well-trained technical expert provides prompt identification as well as an adequate response to a system malfunction.

CONCLUSION

The current case report adds to the list of technical problems encountered during robot-assisted surgeries. Such problems need to be registered in the trouble-shooting management protocols to help in prompt identification and rectification and avoid such incidents in future.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.