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Expedient primary excision of deep dermal and full-thickness burn wounds with subsequent skin grafting is the standard of care in most burn institutions, but differentiating full-thickness from partial-thickness burns is often difficult. Because accurate early assessment of burn depth may improve care, a variety of technical methods have attempted to measure burn depth but these methods have had limited success. We describe a new technique to determine burn depth that uses infrared (840- to 850-nm) fluorescence emission from intravenously administered indocyanine green following excitation with infrared (780 nm) and UV light (369 nm). Full-thickness and partial-thickness burns in hairless rat skin were distinguished based on the infrared-induced and UV-induced fluorescence intensity ratios relative to normal, unburned skin immediately after the burn and on post-burn days 1 through 3 and 7. Dual-wavelength excitation of indocyanine green infrared fluorescence can delineate full-thickness from partial-thickness burns at an early date, allowing prognosis, surgical planning, and early primary excision and grafting.

ObjectiveTo compare the long-term clinical and histologic outcome of immediate autografting of full-thickness burn wounds ablated with a high-power continuous-wave C02 laser to sharply d6-brided wounds in a porcine model. Summary Background DataContinuous-wave CO2 lasers have performed poorly as tools for burn excision because the large amount of thermal damage to viable subeschar tissues precluded successful autografting. However, a new technique, in which a high-power laser is rapidly scanned over the eschar, results in eschar vaporization without significant damage to underlying viable tissues, allowing successful immediate autografting. MethodsFull-thickness paravertebral burn wounds measuring 36 cm2 were created on 11 farm swine. Wounds were ablated to adipose tissue 48 hours later using either a surgical blade or a 1 50-Watt continuous-wave CO2 laser deflected by an x-y galvanometric scanner that translated the beam over the tissue surface, removing 200 ,um of tissue per scan. Both sites were immediately autografted and serially evaluated clinically and histologically for 180 days. ResultsThe laser-treated sftes were nearly bloodless. The mean residual thermal damage was 0.18 ± 0.05 mm. The mean graft take was 96 ± 1 1% in manual sftes and 93 ± 8% in laser sites. On postoperative day 7, the thickness of granulation tissue at the graftwound bed interface was greater in laser-d6brded sites. By postoperative day 180, the manual and laser sites were histologicalty identical. Vancouver scar assessment revealed no differences in scarning at postoperative day 180. ConclusionsLong-term scarring, based on Vancouver scar assessments and histologic evaluation, was equivalent at 6 months in laserablated and sharply excised sites. Should this technology become practical, the potential clinical implications include a reduction in surgical blood loss without sacrifice of immediate engraftment rates or long-term outcome.Although early excision and grafting of deep dermal and full-thickness burns has improved patient survival rates,'

Pulsed laser damage in CVD-grown ZnSe has been studied at 1.06 and 10.6 μ. At 1.06 μ the intrinsic damage intensity was measured to be 1.2 GW/cm2. Damage at 10.6 μ was observed to be the result of inclusion absorption with the damage intensity dependent on focused beam diameter. A statistical model of inclusion damage is developed to account for this dependence. By comparing the predictions of the model to damage intensities measured under two conditions of external focusing, the average density of potentially damaging inclusions is calculated to be about 107 cm−3.

/ Unclassified SECURITY CLASSIFICATION OF THIS PAGEfHTien Dmlm Enlermd)During the first six months of the program, experimental studies of all polishing techniques began. Acceptable conventional polishing techniques for polycrystalline calcium fluoride and zinc selenide were developed, and preliminary grinding steps of the process were identified as requiring further study. Bowl-feed " superpolishing" was shown to improve the surface quality of conventionally polished zinc selenide and calcium fluoride substantially.During the second report period, grinding damage was shown to be effectively removed from polycrystalline fluoride and selenide surfaces by removal by means of polishing a layer somewhat thicker than the diameter of the abrasive used to generate the ground surface.Zinc sulfide powders were evaluated as infrared-transparent abrasives for potassium chloride and found to be inferior to alumina. Since chemical polishing has been found to remove abrasives from the surfaces, transparent abrasives no longer appear to be required and thic part of the experimental program was terminated.Light scattering measurements demonstrated that ion milling could be used to "lean surfaces prior to deposition of optical coatings without seriously degrading them, but that more extensive material removal sharply increased scattering at angles close to the specular direction.Chemical polishing studies of all materials were begun. An ammoniurr chloride solution was found to be a promising chemical-mechanical polish for calcium fluoride. An approximately 0.2 molar alkaline solution of potassium ferricyanide was chosen as an optimum chemical polishing agent for zinc selenide. Etch rates of single and polycrystalline potassium chloride in hydrochloric acid were found to be en the order of 10 micrometers per minute This is likely to be too rapid for controlled etching of large halide optics and attempts to decrease the etch rate by additions to the acid have begun. Profilometer traces of a polycrystalline surface from which approximately 10 micrometers had been removed by hydrochloric acid etching showed typical grain-to-grain variations in height of only approximately 500 angstroms. This sort of variation should be quite acceptable on the optical surfaces. During the first report period, preliminary experimentation in all the project areas began and techniques for conventional polishing and bowlfeed " superpolishing" of calcium fluoride and zinc selenide were developed. Cleavage damage produced during grinding of the polycrystalline materials was identified as a potential source of defects in conventionally polishing surfaces.During this report period, systematic studies of the polishing of ground selenide and fluoride surfaces demonstrated that the removal of a surface layer somewhat greater in thickness than the particle size of the abrasive originally used to grind the surface essentially eliminated grinding damage as a source of defects in conventionally polished material.Glycerol triacetate (triacetin), a compound first ut...

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At Raytheon Company, Dr. C.B. Willingham was the principal investigator of the project. R. Cosgro and F. Taylor performed the experimental polishing work. Optical property measurements were made by Dr. T. Kohane, M. Schapira and T. Varitimos. Scanning electron microscopy was performed by Dr. O. Guentert and X-ray diffraction analysis by D. Howe. Ion beam polishing experiments were performed by Mr. John Gale at Ion Optics, Inc., Winchester Mass. and at Raytheon by C. Dunnrowicz. The zinc selenide polishing effort carried out at Itek Corporation, Lexington, .Mass. was directed by W.P. Barnes. Laser damage experiments were conducted at the Air Force Cambridge Research Laboratories with the assistance of Mr. R. Bradbury. Others contributing to the project included Drs. P.A. Miles, D.W. Readey and R. T. Newberg. This report has been given an internal number of S-1856.