Intraoperative thermal safety of endoscopic ear surgery utilizing a holder

Despite the ever-growing popularity of endoscopic ear surgery (EES), there are still concerns regarding the potential thermal risk associated with the use of light sources and also questions raised about the thermal safety of extended stationary applications of endoscopes with holders that allow the use of both hands in the middle ear. The temperature changes witnessed during EES when using different calipers on static endoscopes fitted with camera holders during true operations were measured, and effects of varying light source intensities, as well as the cooling effect of irrigation and suction, were investigated.

This study included 12 patients with chronic otitis who were scheduled to undergo myringoplasty surgery. Two of five different endoscopes with xenon light sources (4 mm-0°, 3 mm-0°, 2.7 mm-0°, 3 mm-45° and, 2.7 mm-30°) were used on each patient. Following irrigation and aspiration, gradually increasing heat measurements were recorded at two-minute intervals using a thermocouple thermometer for the entire period the endoscope remained in the ear. Three measurements obtained within the final 6 min, all of which were the same and reached a plateau, were considered to be the peak heat value. Measurements were repeated twice in each patient at 100% and 50% light intensities.

The highest heat was recorded by the 4 mm-0° endoscope, with heats at 100% and 50% light intensity recorded as 48.4 °C and 43.2 °C, respectively. The highest heat was measured by the 2.7 mm-0° endoscope, and heats recorded at 100% and 50% light intensities were 37.8 °C and 35.3 °C, respectively.

Stationary use of endoscopes with 3 mm and smaller calipers without irrigation or aspiration, the heat in the middle ear would appear to be safe, and at a level that does not cause thermal trauma to tissue. The present study demonstrates that frequent aspiration or intermittent irrigation may prevent potential thermal damage, even in procedures performed using endoscopes of a 4 mm caliper. Light intensity settings of 50% can be adopted as a further safety measure against potential thermal risk without compromising visual acuity.