Perfusion Monitoring of Advancement and Rotational Flaps. Oculoplastic Surgery and Laser Speckle Contrast Imaging
Abstract: Flaps are widely used in oculoplastic reconstructive surgery to cover defects following the removal of tumors, malformations, or trauma. Adequate blood perfusion of the flap is crucial for its survival. Knowledge about the perfusion in different type of flaps is therefore of great value. The main aim of the studies presented in this thesis was to investigate the changes in blood perfusion in advancement and rotational flaps using laser speckle contrast imaging (LSCI) on pigs and humans, in particular in oculoplastic surgery, but also to examine how the blood perfusion in these flaps is affected by the flap length and diathermic coagulation. Flaps from three different locations were used; random skin flaps on pig flank (Paper I), Hewes tarsoconjunctival eyelid flaps on pigs (Paper II) and human upper eyelid skin flaps (Papers III and IV).The results showed that blood perfusion decreased along the length of the random skin flap, and that the relationship between perfusion and distance from the base was nonlinear (Papers I, III, and IV). In human upper eyelid skin flaps the greatest decrease was seen in the first 15 mm. Beyond 15 mm the perfusion exhibited a constant low value (Papers III and IV).Stretching the nonrotated random skin flaps on the pig flank with a force of 3 N reduced the perfusion to 45%, while a force of 10 N reduced it to 29%, compared with the baseline value (Paper I). In human upper eyelids, stretching the nonrotated random skin flaps with 2 N reduced the perfusion to 43% (Paper IV). Simply rotating a random skin flap or a Hewes tarsoconjunctival flap appeared to have little effect on blood perfusion, however, the combination of rotation and stretching had considerable effects on perfusion (Papers I, II and IV). In human upper eyelid skin flaps, the combination of rotation (90°) and stretching with 2 N reduced the perfusion to 22%, compared with the baseline value (Paper IV).It was also found that diathermic coagulation had detrimental effects on blood perfusion, which was seen to decrease with increasing number of applications (Papers II and III).In conclusion, blood perfusion decreases rapidly with distance from the base of random skin flaps. Rotation combined with stretching reduced the blood perfusion significantly, and should thus be avoided in long flaps. Diathermic coagulation also reduced the blood perfusion, and its use should be carefully considered.
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