The Use Of Laser Speckle Contrast Imaging To Evaluate The Post-operative Changes In Regularity Of Perfusion Pattern On Different Kind Of Flaps

Objective:After microsurgical flap reconstruction,it is essential to observe tissue perfusion in a timely and accurate manner.There used to have two types of observation methods in the past;one is clinical observation,which is subjective and inaccurate.The other is an observation with instruments.The data obtained by this type of monitoring method is relatively objective,however,most of them are contact type,which may contaminate wounds and influence the tissue blood flow.Therefore,clinicians need a new type of blood flow monitoring technique to achieve sensitive and accurate data without damaging the flap,besides can achieve continuous and real-time monitoring,additionally,are suitable for all kind of flaps.The Laser Speckle Contrast Imaging(LSCI)provides a non-contact and rapid visualization of cortical flow dynamics in speckle patterns for monitoring microcirculation of a large area of tissue.Nevertheless,for the transplanted flap,the different data measured by LSCI portend what information,or what clinical significance do these data carry for the transplanted flap?There was no relevant detailed information in the past.To this point,we decided to obtain a clinically meaningful result through the measurement of transplanted flaps:at which value range does it indicate normal blood flow of the flap;at which value range does it indicate poor blood flow but the flap may still survive;and at which value the flap will inevitably encounter necrosis and must be explored immediately.Method:We performed reconstructive flap surgeries on 40 patients with different kind of wounds,among them 10 ALT flaps,10 groin flaps,7 median plantar artery flaps,and 13 local flaps.The research was carried out using a laser speckle contrast imager(PeriCam PSI)produced by Perimed AB.During the measurement,a distance of 15-20 cm was kept between the camera and the flap surface.Moreover,the regions of interest(ROIs)were set on the distal portion along the axis running centrally to the flap of a 2cm x 2cm area.In the temperature-controlled ward(25? temperature was maintained),the blood flow was observed every hour,a total of 24 times a day,and each scan lasted for 30 seconds.We scanned the mean perfusion until the seventh post-operative day(POD 7).Later,the acquired data were transferred to a GraphPad Prism version 8.0 and analyzed offline graphically.Result:In our study,1.Of the 40 cases,33 flaps had a blood perfusion value higher than 40 PU(P<0.003),and the flaps survived satisfactorily.2.Three cases of blood perfusion value ranged between 31 and 39PU(P>0.03),after using the artificial heating source,locally administrated heparin injection,losing the stitches and other means for additional care,successfully survived.3.In four other cases at perfusion value below 30 PU(P<0.001)caused partial tissue necrosis.One of them received exploratory treatment and three did not.Conclusion:This research shows that:1.LSCI has the advantages of non-contact,non-invasive,rapid imaging advantages.It can continuously observe the transplanted flap in real time,provide a dependable data,and it is very suitable for observing different kinds of flaps which provides an objective basis for the microsurgeon to observe and judge the changes in blood flow to portend their vitality.2.We divided the obtained data into three reference intervals.a.Flaps with perfusion value above 40 PU survived successfully.b.Flaps with perfusion value between 31-39 PU needs additional care.c.Flaps with perfusion value less than 30 PU encountered tissue morbidity.3.Having the sensitivity to the morphological changes and velocity of the scattering objects makes it predominantly fit for blood flow cytometry as well as observing the progress of cell parameters clinically.