Active purification aspiration of fat particles is a necessary step in fat grafting to remove as much blood, anesthetic fluid, interstitial fluid, fragmented fat and fibrous tissue debris as possible that is mixed with intact fat particles. Although it has been suggested that the composition of swelling fluid has no significant effect on the survival rate of granular fat grafts, and it has also been suggested that filtering and washing removes the vascular matrix component of the aspirate, it has become a consensus among plastic surgeons that purifying fat, removing blood cells and inactive components from the aspirate, and separating fat cells from tissue fragments can help reduce the inflammatory response to the graft, thus improving the survival rate of fat tissue. One study found that epinephrine and lidocaine, contained in liposuction swelling solution, had a detrimental effect on the activity of fat by measuring glucose transferase. It was confirmed that both lidocaine and 1/500,000 epinephrine were able to significantly inhibit the activity of fat particles, but since local swelling anesthesia is necessary to obtain fat, the extracted fat should be rinsed immediately and thoroughly in order to reduce the effect of lidocaine and epinephrine on the activity of fat particles. The main methods of purification are resting, filtration, centrifugation, high flow rinsing, no rinsing, and gauze cotton pad concentration. The purpose of fat purification is to obtain fat that contains less water, red blood cells and oil as well as more fat stem cells to improve the viability of the fat. To achieve the ideal fat grafting technique, the processing of granulated fat should be handled gently and with fewer unnecessary steps in order to minimize damage to the fat graft. I. Sedimentation method The sedimentation method is a method of stratification by the difference in mass of liquid and fat after sedimentation. Usually multiple 50mL syringes are used, and the needles are removed and placed upside down on a test tube rack. The aspirate is injected into a 50mL syringe, saline at 4℃ is added, and rinsed 3-4 times repeatedly, and then rested, precipitated, purified, and left to be divided into 3 layers, the uppermost layer being lipid droplets, the middle layer being granular fat cells, and the lowermost layer being liquid components, and finally the upper liquid lipid droplets are discarded and the lowermost liquid mixture is discharged, and the liquid mixture is removed with The upper liquid lipid droplets were discarded, the lowermost liquid mixture was discharged, and large pieces of fibrous connective tissue were removed with a stirring rod. The resting time varies clinically from 1 to 15 min, but 3 min is usually considered sufficient. This method is simple and easy to use, but it has shortcomings such as long extraction time and incomplete impurity precipitation. The rinsing and filtering method is a method of rinsing and filtering with a filter under aseptic conditions. Specifically, the fat obtained by suction is placed in a sterile mesh filter and repeatedly rinsed 3 to 5 times with 4℃ saline (the ratio of fat to saline is 1:4) until the rinsing solution becomes clear, then the strips and fibrous connective tissues are removed with a long needle, and finally the fat is covered with a large piece of sterilized gauze at the bottom of the filter so that the fat can be dried. The filter can concentrate the fat particles and separate them from the liquid, grease and debris, and the subsequent rinsing can reject the residual foreign impurities. Third, gauze cotton pad adsorption method The aspirated fat particles are placed on 2 to 4 layers of gauze, and the fat is shaken and kneaded on the gauze with a sterile scalpel handle for 5 min without rinsing, then shoveled into a 10mL syringe with a small tongue depressor and transferred to a 1mL syringe through an interface adapter for injection. The granular fat in the syringe can also be dumped onto the surface of several layers of flat gauze (under which can be lined with cotton pads) and left for 10 min, and the residual swelling fluid and liquid lipid droplets within the granular fat are adsorbed by the gauze and cotton pads, and finally the fibrous tissue in the purified fat particles is removed with forceps, and the process can also be rinsed repeatedly with saline. Fourth, rinsing method Use to pour the aspirated granular fat mixture into a container, wash the solid fat repeatedly with a large amount of physiological saline until the physiological saline is clear and clarified, remove large pieces of fat and clumps containing more fibers with a stirring rod, and fish out the upper floating pure fat particles for transplantation. This method has certain damage to fat cells and also increases the probability of fat contamination. V. Centrifugal method Centrifugal method is a method of obtaining purified fat by centrifuging a mixture of fat particles through a centrifugal device. Specifically, the aspirate is placed in a 10mL disposable syringe, and the two tubes are kept in basic equilibrium in terms of mass and fat fraction, and after occluding the syringe head, the syringes are placed in sterile cannulae for centrifugation respectively. After centrifugation, the upper layer is the ruptured fat cells and oil layer, the lower layer is blood and swelling fluid, and the middle is purified fat.