Quantification of Cannula Influence on Negative Pressure in Syringe-Assisted Liposuction

To achieve successful autologous fat transfer results, suction, preparation, and reapplication parameters must be well understood. Because syringe-assisted liposuction is frequently used for small-volume procedures, the authors quantified the influence of the cannula on negative pressure. For these experiments, the authors used a digital manometer to which a syringe and one of 7 different cannulas were connected. Data were collected and analyzed using LabVIEW and MATLAB. The volume of the measurement setup was calculated using the Boyle-Mariotte law to ease interpretation, which revealed a volume of 2.82 ± 0.03 mL. The volume of the measurement setup significantly affected the measurement results. Therefore, the authors accounted for this factor and calculated the theoretical values accordingly. Statistical analysis shows a significant influence on negative pressure across different cannulas, except for 2 pairs, which had minimal volume differences. For cannulas with volumes less than 1.75 mL, a 2-mL syringe plunger pull was sufficient to create a -0.5 bar (-14.8 in Hg) negative pressure. The current data indicate that the size of the suction cannula must be considered in syringe-assisted suction to ensure that a specific negative pressure is not exceeded. Other research groups have demonstrated that adipocyte vitality and the amount of stromal vascular fraction are reduced by excessively strong negative pressure. To prevent this, the surgeon can easily calculate the cannula volume using the inner diameter and length, then refer to our graph to determine the syringe plunger deflection needed to maintain the desired negative pressure. The results presented in this article provide an initial framework under controlled static conditions. In future work, dynamic factors should be integrated, potentially requiring adaptation of the recommended values.