Complete decontamination of robotic instruments “virtually impossible”

Robotic surgery involves the use of complex parts which may be difficult to clean

Robotic surgery seems to offer a number of impressive benefits for spinal surgery, from increased precision and accuracy to potentially lower radiation doses for operating room staff and patients. With Globus’ Excelsius and Mazor Robotics’ Mazor X recently unveiled at the annual meeting of the North American Spine Society (NASS; 26-29 October 2016, Boston, USA), the market for robotic devices is becoming increasingly saturated. However, new research from the University of Tokyo, Tokyo, Japan, suggests that the complexity of such equipment may make it impossible to properly clean, even when following the manufacturer’s own instructions.

The research—published in Infection Control & Hospital Epidemiology—investigated the levels of residual protein contamination observed after hospital cleaning. “Hospital staff in central sterile supply departments are troubled by the reprocessing of robotic instruments,” the authors write, “because they cannot be disassembled for cleaning like other endoscopic instruments.”

Forty-one robotic instruments and 27 open-surgical instruments were measured for contamination after collection immediately following operational use. Twenty-four robotic and 40 open-surgical instruments were analysed for contamination following in-house cleaning according to the manufacturers’ instructions.

Evaluation for contamination involved the flushing of each instrument in 200ml sterile water until immersed, followed by ultrasonification. Ultrasonification was performed once on the instruments collected postoperatively, and thrice for those analysed following in-house cleaning.

Before in-house cleaning, researchers found a significant difference (p<0.0001) in contamination between the robotic instruments (7.23 x 103μg protein/instrument) and open instruments (5.5 x 103μg protein/instrument). All measurements were adjusted to take into account the mass of each instrument.

Hypothesising that “the rate of decrease of the amount of protein released from instruments [is] proportional to total residual protein stuck to the surface of the instruments,” the researchers recorded the volume of protein release at each ultrasonification following in-house cleaning. For robotic instruments, 650, 550 and 530μg protein release per instrument was recorded, significantly greater (p<0.0001) at each point than for open instruments (16, 17 and 17μg protein/instrument). “The efficacy of cleaning,” the authors wrote, “was 97.6% for robotic instruments and 99.1% for ordinary instruments.”

Following further analysis, the authors estimate that the total amount of residual protein was 2.8 x 103μg protein per robotic instrument, compared with 98μg protein per ordinary instrument.

“Whether or not an instrument can be cleaned is solely dependent on its structure,” lead author Yuhei Saito (Tokyo, Japan) tells Spinal News International. “Narrow canals or clefts make instruments difficult to be cleaned, while they would introduce debris and body fluids into the inside of the instruments to a greater extent at use in operation.”

It is important to note that the robotic system assessed (Da Vinci Surgical Systems: Intuitive Surgical) is not indicated for use in spinal surgery. However, the results arguably raise concerns for all robotic surgery systems. “We believe that robotic instruments for spinal surgery must be cleaned carefully if they have such parts as braided wires, hollow shafts or hinges which have direct contact with blood or any debris in the surgical field,” Saito told Spinal News International.

The authors conclude that it is “virtually impossible to completely remove contamination from robotic instruments by manual cleaning.” Noting that new washers featuring cleaning methods specifically for narrow canals are beginning to appear on the market, the researchers emphasise the importance of establishing “a new standard for the cleaning of complex surgical instruments.”