Introduction: Operating room fires are serious safety events that can harm both patients and caregivers.
Burn injuries and surgical drape fires are known potential complications of surgery
using endoscopes. The risk of cutaneous burns occurs around temperatures of 50°C.
Areas of potential danger include the endoscope tip, and more importantly, the end
of the light cable which can cause thermal damage when accidentally disconnected from
the endoscope. Automatic standby technology (AST) (Safelight by Stryker, Kalamazoo,
MI, USA) triggers the light source to immediately enter standby mode when the light
cable is disconnected from the endoscope, which should reduce the likelihood of burn
injuries and drape fires. This study interrogated this new technology versus a conventional
light source (Karl Storz, Tuttlingen, Germany), comparing temperature differences
at the endoscope tip and adapter, as well as the propensities of disconnected light
cables to burn surgical drapes.
Methods: AST and conventional light sources with standard light cables were connected to 4
mm rigid nasal endoscopes (Karl Storz, Tuttlingen, Germany). Temperature was measured
using a thermocouple sensor at the scope tip to compare AST and conventional light
sources (112 time points at 15-second intervals). Temperature at the adapter was also
measured comparing AST with the conventional light source (52 time points at 15-second
intervals). A thermal camera assessed the temperature of the light cable ends immediately
upon disconnection. Additionally, light cords were held to standard surgical drapes
immediately after disconnection for various times both with direct and indirect contact
(5 mm away from the drape).
Results: Average temperature at the scope tip was 24.0°C for AST and 25.2°C for the conventional
light source (p < 0.001). Average temperature at the adapter was 26.6°C for AST and 27.3°C for conventional
(p = 0.003). Upon disconnection of the light cable, temperature averaged 40.9°C for
cables attached to AST, versus 56.8°C for conventional light sources. Conventional
light cords showed notable drape burns at all time intervals with both direct and
indirect contact. Damage was significantly greater with indirect contact via thermal
radiation. The AST system did not burn the drapes with either direct or indirect contact.
Discussion: Both the scope tip and adapter were cooler using AST technology compared with conventional
light sources, though they did not meet the 50°C skin burn threshold. Immediately
upon disconnection, the temperature of the light cord was much lower with AST compared
with conventional technology and dropped well below 50°C. On disconnection from conventional
light sources, light cables produced significant burns in drapes at all time intervals,
most significantly on indirect contact. AST did not cause burns to surgical drapes
with direct or indirect contact. Radiative heat transfer, as opposed to conduction
with direct contact, appears to be more significant for thermal injury to occur.
Conclusion: AST technology provides significant safety value by removing radiative heat transfer
as a possible agent of patient and caregiver harm. This technology significantly and
rapidly lowers the temperature of an accidentally disconnected light cord to levels
well below the threshold for causing skin injury and drape burns.
