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.

The experiments and methods are described in detail in the article "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" [http://dx.doi.org/10.1007/s11095-020-2769-2], and its supplementary material.  Data provided is unprocessed.

Five data sets imaging the physical properties of pig subcutaneous tissue that has been tumesced with saline.  Analysis of the data is presented in the article "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" [http://dx.doi.org/10.1007/s11095-020-2769-2].

1) MRI and Diffusion-Weighted MRI data on the size and apparent diffusion coefficient of pig subcutaneous tissue infused with 0-40 mL saline.  Files are in DICOM format.

2) CT data on the evolution of 2.5-20 mL saline injections into the subcutaneous tissue of a pig's abdomen on timescales 0-60 minutes.  Files are in DICOM format.

3) CT data on the evolution of 2.5-20 mL saline injections into the subcutaneous tissue of a pig's abdomen on timescales 0-7 hours.  Files are in DICOM format.

4) CT data on the evolution of 2.5-20 mL saline injections, with added epinephrine, into the subcutaneous tissue of a pig's abdomen on timescales 0-7 hours.  Files are in DICOM format.

5) 3D scans of a minipig's skin surface before and at several times after injection with 20 mL saline, over a time period of 0-20 minutes.  Files are in .obj format.