Tumescent injections in subcutaneous pig tissue disperse fluids volumetrically and maintain elevated local concentrations of additives for several hours, suggesting a treatment for drug resistant wounds

Purpose Bolus injection of fluid into subcutaneous tissue results in
accumulation of fluid at the injection site. The fluid does not form a
pool. Rather, the injection pressure forces the interstitial matrix to
expand to accommodate the excess fluid in its volume, and the fluid
becomes bound similar to that in a hydrogel. We seek to understand the
properties and dynamics of externally tumesced (swollen) subcutaneous
tissue as a first step in assessing whether tumescent antibiotic
injections into wounds may provide a novel method of treatment. Methods
Subcutaneous injections of saline are performed in live and dead pigs and
the physical properties (volume, expansion ratio, residence time, apparent
diffusion constant) of the resulting fluid deposits are observed with
diffusion-weighted magnetic resonance imaging, computed tomography, and 3D
scanning. Results Subcutaneous tissue can expand to a few times its
initial volume to accommodate the injected fluid, which is dispersed
thoroughly throughout the tumescent volume. The fluid spreads to
peripheral unexpanded regions over the course of a few minutes, after
which it remains in place for several hours. Eventually the circulation
absorbs the excess fluid and the tissue returns to its original state.
Conclusions Given the evidence for dense fluid dispersal and several-hour
residence time, a procedure is proposed whereby tumescent antibiotic
injections are used to treat drug-resistant skin infections and chronic
wounds that extend into the subcutaneous tissue. The procedure has the
potential to effectively treat otherwise untreatable wounds by keeping
drug concentrations above minimum inhibitory levels for extended lengths
of time.