Neuroendoscopy - Is it safe?

The effect of heat in endoscopic instruments used for laparoscopy and hysteroscopy has been well-studied. Reports of thermal injury from nasal endoscopes have also been reported. However, there are no experimental studies, which have objectively documented and provided recommendations for safe use of endoscopes in neurosurgery.

To study the heat generated at the tip of the endoscope and the subsequent thermal damage caused to a cotton drape placed in proximity, by varying the intensity of light delivered through different optical cables, ambient (operating room) temperatures and working distances.

The study was carried out in the operation theater using a 300 watt xenon light source connected to the endoscope with 3.5 mm and 4.8 mm optical cables. A digital thermometer was used to record the heat generated at the tip of the endoscope.

The heat generated at the tip of the endoscope reached its peak in the first 6 min and attained a plateau at 15 min after turning on a light source of 60% intensity. Thermal injury to the cotton drape took a longer time with a 3.8 mm cable compared with 4.8 mm cable. The heat generated at the tip of the endoscope, and thereby the thermal injury caused was found to be lower when the ambient temperature was close to 20°C.

Complications related to thermal injuries caused by heat generated at the tip of an endoscope can be reduced by using a smaller diameter cable, light intensity of 60%, increasing the working distance (as permissible), reducing the time spent for dissection while keeping the endoscope very close to the target and lowering the ambient temperature to 20°C.