Devices for ischemic preconditioning of the pedicled groin flap.

BACKGROUND: Early division of the pedicled groin flap can be achieved by using ischemic preconditioning. The goal of this study was to investigate the devices available for ischemic preconditioning and determine which device is the most effective and results in lowest patient discomfort. METHODS: Rubber bands, custom-made Orthoplast sheets, long-nose locking pliers, intestinal clamps, and a pneumatic tourniquet device were used for ischemic preconditioning on 13 patients who sustained severe hand injuries with reconstruction of pedicled groin flaps. The devices were compared by using laser Doppler flowmetry and the patient's local pain levels. RESULTS: Twelve of 13 flaps were successfully divided at a mean period of 8.3 days by using a custom-made Orthoplast sheet or a pneumatic tourniquet device. All devices except the rubber bands could result in a biologic zero flow level. CONCLUSION: The pneumatic tourniquet device is the most desirable ischemic preconditioning device, having the advantages of excellent ischemic effect, easy application, and minimal discomfort.

Laser-induced multiphoton fluorescence of hemoglobin.

Hemoglobin (Hb) and other samples were irradiated by the 1064 nm nanosecond pulses of an Nd:YAG laser. At room temperature, we observed two red fluorescence bands, which resulted from the absorption of two 1064 nm photons in Hb, and measured the fluorescence emission spectra in the red spectral region for Hb and hematoporphyrin derivative. A red shift of the wavelength and a mirror image in the intensity of fluorescence emissions by two-photon excitation were observed. It is shown that the fluorescence of Hb originates from the heme group. In addition, we also observed fluorescence emission at 392 nm for Hb, which may be from its tryptophan groups.

Fluorescence of proteins induced by two-photon absorption.

At room temperature, the UV fluorescence of trypsin, thyroglobulin, hemoglobin and albumin are observed; these molecules undergo two-photon absorption when they are excited with the radiation of a frequency-duplicated Q-switched Nd:YAG laser. It is shown that the fluorescence of these proteins comes from the tryptophan residues and that it has a red shift of about 20 nm relative to the one-photon fluorescence. We suggest that the weak emission from tyrosine arises from the forbidden two-photon transition. The influence of concentration on the fluorescence of hemoglobin and tryptophan is discussed. The two-photon absorption cross-sections are estimated.