LAUSR

The volume effect of fat grafting is highly dependent on the presence of viable adipocytes and other nucleated cells within the lipoaspirate. We suspected that one of the crucial factors influencing cell viability is the negative pressure applied during the fat graft harvesting and the suitability of various harvest sites when compared to others. Despite much discussion, there is no consensus on the optimal negative pressure or the best site for harvesting so we designed an experiment to test this. Fat graft taken under low negative pressure (− 200 mmHg) or high negative pressure (− 700 mmHg) from the thigh or abdominal regions from 21 healthy human donors was evaluated. The principal variables studied were: a) total number and viability of nucleated cells, b) liposuction duration and c) blood admixture. Other variables studied were body mass index, the impact of age and enzymatic digestion. The absolute number and viability of nucleated cells and the blood admixture did not differ significantly between lipoaspirates obtained under different vacuum conditions or from different regions. The time taken to acquire the same volume of lipoaspirate was significantly increased using low negative pressure. The time taken to collect cells in the thigh region significantly increased with increasing BMI but this correlation was not found when harvesting in the abdominal region. The BMI and age did not impact the results in any of the measured variables. The enzymatic digestion rate was independent of the negative pressure used to harvest. Our results indicate that neither the negative pressure used nor the area chosen has any significant influence on the viability and yield of harvested cells. The time taken to obtain lipoaspirate using low pressure is significantly longer than when using high pressure. No significant difference was found in the value of blood admixture using different vacuum pressures, and no correlation exists between the body mass index and the cell viability or age of the patients and the time of liposuction. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine Ratings, please refer to Table of Contents or online Instructions to Authors www.springer.com/00266.