Local effects of high-powered neodymium-doped yttrium aluminium garnet laser systems on the pulmonary parenchyma: an experimental study on the isolated perfused pig lung lobe

Neodymium-doped yttrium aluminium garnet (Nd:YAG) laser systems (with a power output up to 100 W, wavelength 1318 nm) have been introduced into clinical practice for resecting lung metastases. However, the extent of the local effect on the lung parenchyma and the role of the application time are unknown. All experiments were performed on normothermal, whole-blood-perfused paracardiac pig lung lobes (n = 6). Lobes were not ventilated during the laser application. The laser itself was clamped into a hydraulic feed system that moves horizontally at two different constant rates (10 and 20 mm/s). A 30-mm focus distance from the pulmonary parenchyma was maintained at all times. At each feed rate, the laser was applied thrice along a horizontal path using laser power outputs of 40, 60 and 100 W. After lasering, we recruited the lungs via a ventilation tube using pressures of up to 40 cm H(2)O and tested lung tightness. Both a gross inspection and a histological examination revealed larger coagulation zones for higher power outputs and lower laser feed rates. Exposure to higher outputs for shorter application times reduced the laser effect. When lungs were manually recruited, all lungs were airtight up to a pressure of 40 mmHg. Reducing the exposure time reduces local tissue coagulation even when the laser power output is increased.