Vacuum Pressures during Autologous Fat Transfer (AFT): A Study of the Closed Syringe Type and other Aspirator Pressures

Abstract

Objective: Vacuum pressures have long been thought to damage the lipocytes during harvest. Several studies have described this as well as the need to reduce the pressure during harvest. The goals of this article are to increase awareness of the pressures associated with the closed syringe technique and other methods of harvesting for autologous fat transfer (AFT). Methods: The closed syringe pressures are presented for 60-, 30-, and 10-mL syringes. Note that the vacuum force for any manual syringe is the plunger and the position of the plunger will dictate the pressure that will be applied to the fat. Results: The closed syringe tests on 60-, 30-, and 10-mL syringes (three brands) show that a 60-mL syringe will produce an 18.5-in mercury vacuum pressure, but only when the plunger is withdrawn to maximum. The tests also showed that when the plunger is at 30 mL, the response is 16 in of mercury; at 10 mL the response is 6 in of mercury. Thus, the smaller the syringe capacity, the lower the vacuum pressure. This lessening of the vacuum pressure is not due to the plunger losing pressure around its gasket, but it is directly related to the empty space (volume) left in the syringe. Thus, a 60-mL syringe that is half full of fat renders an identical pressure to an empty 30-mL syringe, that being 16 in of mercury. Discussion: Electrically powered vacuum sources do not respond in this manner because the motor will maintain a relatively constant pressure throughout the procedure. The economic advantages of the closed syringe technique are discussed with emphasis on the availability of generic materials and thus lessened cost. The disadvantages include the varying downward pressures during harvest, the added time to decant or centrifuge the harvested material, and the need for added transfers. Also presented are the 2 filter-type harvest units on the market today (Lipivage and TissuTrans) that will save considerable time by separating out the unwanted material during the harvest and without additional transfers. Conclusion: Knowing the pressures administered (to fat) by the syringes or reservoirs used in all types of fat harvesting equipment is important and part of the standardization process.