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Thermal effects of white light illumination during microsurgery: clinical pilot study on the application safety of
Raimund Hibst1, David Saal, Detlef Russ
1Universitat Ulm, Institut fur Lasertechnologien in der Medizin und Messtechnik an der Universitat Ulm, Ulm, Germany. raimund.hibst@ilm.uni-ulm.de
Abstract:
Modern operating microscopes offer high power illumination to ensure optimal visualization, but can also cause thermal damage. The aim of our study is to quantify the thermal effects in vivo and discuss conditions for safe use. In a pilot study on volunteers, we measured the temperature at the skin surface during microscope illumination, including the influence of anaesthesia and the effects of staining, draping, or moistening of the skin. Irradiation within the limit given by safety regulations (200 mW/cm(2)) results in skin surface temperature of 43 degrees C. Higher intensities (forearm 335 mW/cm(2), back 250 mW/cm(2)) are tolerated, resulting in reversible hyperaemia. At a very high illumination intensity (750 mW/cm(2)), pain occurs within 30 s at temperatures of 46 degrees C+/-1 degrees C (hand and forearm), and 43 degrees C+/-2 degrees C (back), respectively. Anaesthesia has no distinct effect on the temperature, whereas staining and drapes result in much higher temperatures (>100 degrees C). Moistening at practicable flow rates can reduce temperature efficiently when combined with a light absorbing and water absorbent drape. In conclusion, surgeons must be aware that surgical microscope illumination without protective means can cause skin temperatures to rise much above pain threshold, which in our study serves as a (conservative) benchmark for potential damage.
Insights
Surgical microscope illumination can cause thermal damage. Surgeons should use protective measures, as high intensities can exceed pain thresholds and lead to skin temperature increases.
Area of Science:
- Ophthalmology
- Surgical Technology
Background:
- Modern operating microscopes provide high-power illumination for enhanced visualization during surgical procedures.
- However, intense illumination poses a risk of thermal damage to patient tissues.
Purpose of the Study:
- To quantify the in vivo thermal effects of surgical microscope illumination on skin.
- To identify conditions and protective measures for safe microscope use.
Main Methods:
- A pilot study was conducted on volunteers measuring skin surface temperature during microscope illumination.
- Factors investigated included anesthesia, staining, draping, and moistening of the skin.
- Different illumination intensities were applied, and temperature thresholds for pain and hyperaemia were recorded.
Main Results:
- Illumination within safety limits (200 mW/cm²) resulted in skin temperatures of 43°C.
- Higher intensities (up to 750 mW/cm²) caused reversible hyperaemia and pain at temperatures of 43-46°C.
- Anesthesia had no significant effect, while staining and drapes markedly increased temperatures (>100°C). Moistening with specific drapes effectively reduced temperature.
Conclusions:
- Surgical microscope illumination can elevate skin temperature significantly above pain thresholds.
- Protective measures, such as specific drapes and moistening, are crucial for mitigating thermal risks.
- Surgeons must be aware of these thermal effects to ensure patient safety.
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