Abstract
Background Heat accumulation might induce thermal damage of the surrounding lung tissue, especially
when multiple lesions are resected in one session. The present study aimed to investigate
whether heat accumulates in the immediate vicinity of the resection surface and leads
to thermal damage of the lung parenchyma, and what is the most effective cooling strategy
in this situation.
Materials and Methods In normothermic perfused paracardial swine lobes (n = 6), four punctiform laser lesions forming a square were created. Each lesion was
lasered at a power of 100 W for 5 seconds. Two test conditions with square sides of
either 1.0 or 0.5 cm were compared. Temperatures were recorded immediately after completing
the laser procedure in the square center and in the corners using a thermal camera
and continued during the cooling process at 10-second intervals until normothermia
(37°C). We examined two cooling methods: rinsing with ice-cold (4°C) Ringer solution
during the laser procedure (group B, n = 6) or submerging the lung in ice-cold water for 5 seconds immediately after laser
application (group C, n = 6). In the control group A (n = 6), there was no cooling.
Results In the 0.5 cm squares, mean temperature in the center immediately after laser application
was 103.17 ± 8.56°C, significantly higher than in the corners (76.39 ± 2.87°C, p < 0.05). Normothermia in the quadrant corners was reached after 81 ± 14 and after
108 ± 29 seconds in the centers. Tissue in the square center revealed histological
signs of thermic cell damage. In the 1.0 cm squares, mean temperature in the center
was 64 ± 5°C, and in the corners was 77 ± 3.1°C (p < 0.05). Normothermia was regained after 93 ± 22 seconds in the center and 120 ± 21 seconds
in the corners. Histological examination in the 1.0-quadrant centers revealed no signs
of thermic cell damage. Submerging the lobe into ice-cold water lowered the temperature
rapidly to under 40°C, and normothermia was regained after 75 ± 1.3 seconds.
Conclusion Laser application to the lung parenchyma causes considerable heat accumulation in
closely related lesions. To prevent such cell damage, a distance of at least 1.0 cm
between laser targets should be maintained. If no topical cooling method applied,
sufficient time for spontaneous tissue cooling before additional laser application
should be provided. The most effective cooling strategy against heat accumulation
is submerging in ice-cold water for at least 5 seconds.
Keywords
experimental - metastases/metastasectomy - surgical equipment
