Clinical Research On Improving The Safety Of Facial Fat Grafting By Pre-Vasoconstriction In Recipient Area

Background and ObjectionSince the 1980s,autologous fat grafting technique has been wildly used in reconstructive surgery.Fat is an ideal soft tissue filler for regional injection:it is autologous,wildly distributed over our body,and naturally 100%biocompatible to tissues.However,the successful rate of autologous fat grafting is often unpredictable.In the last decades,lipoaspirate injection was reported to cause devastating consequences in patients,i.e.pain,edema,nodule,hematoma or infection,and the most serious complications is artery occlusion and can lead to visual loss,neural system damage,and even death.Different from other surgeries of plastic surgery,in the process of filling the face area with autologous fat,due to the great variation of facial blood vessels,the risk of embolism is relatively high.Even the most experienced doctors may accidentally inject fat into the blood vessels and cause serious embolization complications.Pre-vasoconstriction technique is subcutaneous injection of dilute lidocaine with epinephrine that produces intense local vasoconstriction to protect vascular from injured and occlusion.Additionally,a vasoconstricted artery is harder to cannulate than a vasodilated one.Facial fat filler injection becomes increasingly popular in recent years but vascular events are major complications of regional facial autologous fat grafting.Because of high variability of facial arterial vasculature,there is a high risk of accidental intraarterial injections leading to adverse events,even for the most expert ones.Ciliary artery occluded by filler particles will lead to severe complications.Inspired by tumescent lidocaine anesthesia,this study was attempted to optimise autologous fat grafting by using pre-vasoconstriction liquid to perform a pretreatment in facial zone before fat filler injection,observing the local vasoconstriction effect of epinephrine in order to lower the risk of artery occlusion.Methods and materialsFacial 'risk region' is mainly in frontotemporal side,nasal zone,periorbital zone and glabellar zone.We recruited ten volunteer participants to inject 1.5ml pre-vasoconstriction fluid on both sides of forehead and frontotemporal side.All the subjects signed written informed consent and had no clinical evidence of infection,heart diseases,facial abnormalities,drug allergy history or pregnancy.Participants were treated with safety dosages of 10?g/ml(1:100,000)and 20?g/ml(1:50,000)epinephrine at each sites over 24 hours on separate occasions.Noninvasive measurements of microvascular cutaneous blood flow in superficial temporal artery,supraorbital artery and supratrochlear artery were perfomed using ultrasound Doppler flow measurement technique and laser speckle contrast imaging(LSCI).This study was approved by the Review Board of Nanfang Medical University.ResultsAll the participants treated with 1.5ml dilute lidocaine and epinephrine in facial zone kept stable heart beats without any obvious changes which indicates facial safety injection of epinephrine.Ultrasound Doppler measurements showed blood flow speed and resistance increased after pre-vasoconstriction solution injection,the maximal point occurred at 15 min,and then gradually returned to the base line at 30 minutes.Artery internal diameter decreased after the injection,the minimal diameter occurred at 15 min and lasted for almost 10 minutes.The images of laser speckle contrast imaging showed mean relative hemoglobin index values were dramatically changed at every time measurement before and after injection.First,the lidocaine plus epinephrine induced immediately and slightly increase of cutaneous hemoglobin concentration,and then dramatically decreased.The lowest cutaneous hemoglobin concentration was obtained at 15 minutes and maintained for longer than 30 minutes.There was no significant difference for the two dosages of epinephrine,supporting adequate dosage of 10?g/ml(1:100,000)epinephrine.Laser speckle contrast imaging is more stable and convenient than ultrasound Doppler flow measurement for measuring superficial microvascular cutaneous blood flow.ConclusionFacial arteries vary highly between the face sides and individuals that results in the accidental intraarterial injections.Epinephrine in pre-vasoconstriction fluid induces intense vasoconstriction of the facial region.The lowest cutaneous blood flow was abtained at about 15 minutes and which effect can last for more than 30 minutes.Pretreatment for facial receiving zone using pre-vasoconstriction fluid may lower the risk of artery occlusion for facial autologous fat grafting.Laser speckle contrast imaging is more stable and convenient than ultrasound Doppler flow measurement for measuring superficial microvascular cutaneous blood flow.