RESUMEN
BACKGROUND: Laser-Doppler imaging (LDI) of cutaneous blood flow is beginning to be used by burn surgeons to predict the healing time of burn wounds; predicted healing time is used to determine wound treatment as either dressings or surgery. In this paper, we do a statistical analysis of the performance of the technique. METHODS: We used data from a study carried out by five burn centers: LDI was done once between days 2 to 5 post burn, and healing was assessed at both 14 days and 21 days post burn. Random-effects ordinal logistic regression and other models such as the continuation ratio model were used to model healing-time as a function of the LDI data, and of demographic and wound history variables. Statistical methods were also used to study the false-color palette, which enables the laser-Doppler imager to be used by clinicians as a decision-support tool. RESULTS: Overall performance is that diagnoses are over 90% correct. Related questions addressed were what was the best blood flow summary statistic and whether, given the blood flow measurements, demographic and observational variables had any additional predictive power (age, sex, race, % total body surface area burned (%TBSA), site and cause of burn, day of LDI scan, burn center). It was found that mean laser-Doppler flux over a wound area was the best statistic, and that, given the same mean flux, women recover slightly more slowly than men. Further, the likely degradation in predictive performance on moving to a patient group with larger %TBSA than those in the data sample was studied, and shown to be small. CONCLUSION: Modeling healing time is a complex statistical problem, with random effects due to multiple burn areas per individual, and censoring caused by patients missing hospital visits and undergoing surgery. This analysis applies state-of-the art statistical methods such as the bootstrap and permutation tests to a medical problem of topical interest. New medical findings are that age and %TBSA are not important predictors of healing time when the LDI results are known, whereas gender does influence recovery time, even when blood flow is controlled for.The conclusion regarding the palette is that an optimum three-color palette can be chosen 'automatically', but the optimum choice of a 5-color palette cannot be made solely by optimizing the percentage of correct diagnoses.
Asunto(s)
Quemaduras/diagnóstico por imagen , Flujometría por Láser-Doppler , Modelos Logísticos , Cicatrización de Heridas , Quemaduras/fisiopatología , Femenino , Humanos , Masculino , Valor Predictivo de las Pruebas , Radiografía , Factores Sexuales , Piel/irrigación sanguínea , Trasplante de Piel/diagnóstico por imagen , Factores de Tiempo , UltrasonografíaRESUMEN
The development of in vivo microdialysis has made it possible to monitor cutaneous free flaps in maxillo-facial surgery. A microprobe inserted in the free flap dermis collects a microdialysate enabling measurement of dermal metabolites such as glucose, lactate, pyruvate, or glycerol. The monitoring curves are predictive of ischemia-related tissue injury. Hourly measurements provide a reliable method for early diagnosis of venous or arterial thrombosis. Revision surgery can then be undertaken if needed to repair microanastomoses before clinical alteration. This technique has been compared with validated flaps monitoring systems such as temperature probe, transcutaneous oxygen tension monitoring, and laser Doppler flowmetry. Microdialysis has several advantages: objective measurements, different curves for venous and arterial thrombosis, early diagnosis. Accessibility to oral cavity or pharyngeal flaps requires careful clinical analysis (microprobe fixation, anatomy and choice of flap).
Asunto(s)
Microdiálisis/métodos , Monitoreo Fisiológico , Procedimientos Quirúrgicos Orales , Trasplante de Piel/patología , Colgajos Quirúrgicos/patología , Humanos , Flujometría por Láser-Doppler , Procedimientos de Cirugía Plástica , Temperatura Cutánea/fisiología , Trasplante de Piel/diagnóstico por imagen , UltrasonografíaRESUMEN
The technical factors of microangiography were studied, and the authors found that the main limiting factors in resolution were the injection pressure of the contrast medium and the thickness of the materials. A gentle manual hand pressure injection, with the aid of visual monitoring under the operating microscope, were keys to obtaining beautiful microangiograms.
Asunto(s)
Trasplante de Piel/diagnóstico por imagen , Colgajos Quirúrgicos/irrigación sanguínea , Angiografía , Animales , Masculino , Ratas , Ratas WistarRESUMEN
The hypothesis of whether or not flap perfusion remains persistent through its vascular pedicle up to 10 years after free tissue transfer was tested. Since 1982, more than 1,000 free tissue transfers have been performed at this institution. Of these, 40 patients were selected with comparable posttraumatic soft-tissue defects of the lower leg and surgical repair by a latissimus dorsi myocutaneous free flap. All patients had a postoperative course free of complications. Measurements of flap perfusion were started in groups 1 through 4 (each 10 patients) 3 to 5 weeks, 5 to 7 months, 4 to 6 years, and 8 to 10 years after free tissue transfer, respectively. Quantitative measurements of local flap perfusion were performed by means of the hydrogen clearance technique (Ameda, Switzerland) at definite sites intracutaneously and subcutaneously within the flap's skin paddle as well as in the adjacent intracutaneous and subcutaneous skin of the surrounding soft tissue. Simultaneously, the vascular pedicle of the flap was visualized by a duplex scanner (Toshiba, Japan). In each group nine measurements were performed before (phase A), during (phase B), and after closing the pedicle (phase C) by manual compression. Each measurement took about 10 minutes. Statistical evaluation of the obtained values was achieved by the Mann-Whitney U test and the Wilcoxon signed rank test. Local flap perfusion showed no statistical differences for phase A and C in all four groups of patients. In phase B, however, a statistically highly significant (p < 0.01) absence of local flap perfusion was registered in all four groups at the site of the flap's skin paddle. No statistically significant alterations of intracutaneous and subcutaneous blood flow was found in the surrounding soft tissue. In our clinical-experimental setting, flap perfusion persisted by means of its vascular pedicle even 10 years after free tissue transfer. Our findings support the importance of an intact vascular pedicle for permanent flap survival after free tissue transfer.
Asunto(s)
Músculo Esquelético/trasplante , Trasplante de Piel/patología , Colgajos Quirúrgicos/irrigación sanguínea , Adulto , Electroquímica/instrumentación , Electrodos Implantados , Estudios de Seguimiento , Supervivencia de Injerto , Humanos , Hidrógeno , Traumatismos de la Pierna/cirugía , Persona de Mediana Edad , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/diagnóstico por imagen , Presión , Flujo Sanguíneo Regional , Piel/irrigación sanguínea , Piel/diagnóstico por imagen , Trasplante de Piel/diagnóstico por imagen , Trasplante de Piel/fisiología , Traumatismos de los Tejidos Blandos/cirugía , Ultrasonografía Doppler DúplexRESUMEN
PURPOSE: This report reviews the results of immediate mandibular reconstruction performed with unosteotomized composite osteocutaneous forearm flaps using a lag screw technique for stabilization of the bone graft. PATIENTS AND METHODS: Six patients, reconstructed as described, were followed-up for a mean period of 21 months postoperatively (range, 13 to 36 months). RESULTS: Good initial stability was achieved, and healing was uneventful. At radiographic examination 12 months postoperatively, bony healing without dislocation of the segments was found in all patients. CONCLUSION: The lag screw technique provides good initial stability and allows functional stresses to be transmitted to the graft.
Asunto(s)
Tornillos Óseos , Trasplante Óseo/instrumentación , Mandíbula/cirugía , Trasplante de Piel/instrumentación , Adulto , Anciano , Anastomosis Quirúrgica , Trasplante Óseo/diagnóstico por imagen , Trasplante Óseo/métodos , Carcinoma de Células Escamosas/cirugía , Oclusión Dental , Femenino , Estudios de Seguimiento , Antebrazo , Humanos , Técnicas de Fijación de Maxilares/instrumentación , Masculino , Mandíbula/diagnóstico por imagen , Neoplasias Mandibulares/cirugía , Persona de Mediana Edad , Radiografía , Radio (Anatomía) , Trasplante de Piel/diagnóstico por imagen , Trasplante de Piel/métodos , Resultado del Tratamiento , Cicatrización de HeridasRESUMEN
Just as the dogma that skin flap survival depends on rigid length-to-width ratios has been refuted as a consequence of advances in understanding the anatomical basis of the cutaneous circulation, the generalization that distally based flaps are inherently inferior to proximally based flaps also deserves to be challenged. All else being equal, the truly critical factor for flap viability in either case is the nature of their intrinsic blood supply rather than any arbitrary configuration or orientation. Previous laboratory evidence has proved this fact and is now further validated by a clinical experience with 194 local fascia flaps in 174 patients. There was a 22.2 percent overall incidence of complications, but no statistically significant difference in this rate was observed whether the flap was distally based (18.8 percent of 16 flaps) or proximally based (23.5 percent of 162 flaps) (p = 0.669). Major complications, usually a failure of the intended coverage, actually were more common for proximally based flaps (12.9 percent) than those distally based (6.3 percent), although not statistically different (p = 0.436). Bipedicled fasciocutaneous flaps, which should have had augmented perfusion from their dual sources of inflow, sustained complications in 12.5 percent of 16 flaps. Although none was classified as a major problem, again no difference was apparent when compared with proximally based (Pprox = 0.316) or distally based (pdis = 0.626) flaps. Some caution is prudent in interpreting these retrospective data, not because of an admitted bias for more frequent selection of proximally based flaps, but because the choice for any of these local fasciocutaneous flap always followed a careful assessment of the status of the fascial plexus adjacent to any defect. Audible or color Doppler ultrasound localization of available cutaneous perforators can predetermine the feasibility of any option, thereby ensuring a reasonable success rate regardless of pedicle orientation.
Asunto(s)
Fascia/trasplante , Trasplante de Piel/métodos , Colgajos Quirúrgicos/patología , Anastomosis Quirúrgica , Sesgo , Distribución de Chi-Cuadrado , Fascia/irrigación sanguínea , Fascia/diagnóstico por imagen , Estudios de Factibilidad , Supervivencia de Injerto , Humanos , Microcirugia , Reproducibilidad de los Resultados , Estudios Retrospectivos , Piel/irrigación sanguínea , Piel/diagnóstico por imagen , Trasplante de Piel/efectos adversos , Trasplante de Piel/diagnóstico por imagen , Trasplante de Piel/patología , Colgajos Quirúrgicos/efectos adversos , Resultado del Tratamiento , Ultrasonografía Doppler , Ultrasonografía Doppler en Color , Insuficiencia Venosa/etiologíaRESUMEN
UNLABELLED: Platelet-activating factor is an extremely potent lipid-inflammatory mediator implicated in the pathophysiologic mechanism of reperfusion injury in a variety of organs. The purpose of this study, employing a porcine latissimus dorsi flap model, was to (1) examine the expression of platelet-activating factor and (2) evaluate the possible benefit and mechanism of action of platelet-activating factor antagonism in musculocutaneous flap reperfusion injury. Experiment 1: In 6 pigs, bilateral flaps underwent 8 hours of arterial ischemia followed by 12 hours of reperfusion. Biopsies were collected sequentially and analyzed immunohistochemically for platelet-activating factor expression. Different processing techniques, however, were unable to detect specific tissue expression of platelet-activating factor. Experiment 2: In 11 pigs, bilateral flaps underwent 8 hours of arterial ischemia followed by 20 hours of reperfusion. A lipophilic platelet-activating factor receptor antagonist (L-659,989) was administered as a single dose to treated flaps by a local intraarterial route prior to reperfusion. This treatment augmented the survival of both muscle (48.3 versus 19.7 percent) and skin (49.8 versus 42.0 percent) components of the flaps in a statistically significant fashion (p = 0.001). Experiment 3: In 3 pigs, a radiolabeled structural analogue of L-659,989 (14C-L-680,573) was administered to flaps in a fashion similar to experiment 2. After 8 hours of ischemia, sequential full-thickness flap biopsies were collected over the initial 6 hours of reperfusion. The radio-labeled platelet-activating factor receptor antagonist was found to be highly concentrated within treated flaps, with gradual decay over the initial 6 hours of reperfusion. Experiment 4: Thirty minutes prior to completion of 8 hours of arterial ischemia, autologous neutrophils labeled with indium-111 were reintroduced into the systemic-circulation of 5 pigs. Prior to reperfusion, treated flaps received L-659,989 as in experiment 2. Over the initial 4 hours of reperfusion, the flaps were imaged in situ by a gamma camera at 3-minute intervals. The platelet-activating factor receptor antagonist was found to significantly attenuate the accumulation of radioactivity within treated flaps. CONCLUSION: Platelet-activating factor expression within musculocutaneous flaps subjected to ischemia and reperfusion was non directly demonstrated in this study. Still, we have shown that (1) the specific platelet-activating factor receptor antagonist L-659,989 is beneficial to the survival of both muscle and skin flap components, (2) a single, prereperfusion local dose of this lipophilic drug remains concentrated within the flap during the early inflammatory phase of reperfusion, and (3) during reperfusion, platelet-activating factor antagonism is able to directly or indirectly diminish the accumulation of acute inflammatory cells in musculocutaneous flaps.
Asunto(s)
Músculo Esquelético/trasplante , Factor de Activación Plaquetaria/fisiología , Daño por Reperfusión/etiología , Trasplante de Piel/patología , Colgajos Quirúrgicos/patología , Animales , Arterias , Biopsia , Radioisótopos de Carbono , Femenino , Furanos/administración & dosificación , Furanos/uso terapéutico , Expresión Génica , Supervivencia de Injerto/efectos de los fármacos , Inmunohistoquímica , Radioisótopos de Indio , Inyecciones Intraarteriales , Isquemia/patología , Isquemia/fisiopatología , Recuento de Leucocitos/efectos de los fármacos , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/diagnóstico por imagen , Neutrófilos/efectos de los fármacos , Neutrófilos/patología , Factor de Activación Plaquetaria/análisis , Factor de Activación Plaquetaria/antagonistas & inhibidores , Factor de Activación Plaquetaria/genética , Cintigrafía , Radiofármacos , Reperfusión , Daño por Reperfusión/tratamiento farmacológico , Daño por Reperfusión/patología , Trasplante de Piel/diagnóstico por imagen , Colgajos Quirúrgicos/irrigación sanguínea , PorcinosRESUMEN
Clinical assessment of the perfusion of the musculocutaneous portion of composite iliac crest free flaps was compared to 99mTc-diphosphonate (HDP) uptake in 14 patients who underwent primary oromandibular reconstruction after ablative cancer surgery. Bone scanning was performed on average at the 9-10th postoperative day (range 4-48) 3 h after intravenous injection of 550 MBq 99mTc-HDP. Eleven patients showed complete concordance between 99mTc-HDP uptake and soft-tissue status. Two patients showed uptake and viable muscle in spite of necrotic skin. One patient had a viable musculocutaneous flap but a photopenic defect in the bone graft; 6 months later, a small corresponding part of the bone was sequestrated. In this study, bone scanning and clinical assessment of muscle perfusion were 100% accurate in predicting viability of bone grafts. Skin viability was a less reliable parameter. It is concluded that bone scanning is not indicated as a routine investigation for revascularized iliac crest flaps and that clinical assessment of muscle perfusion is a reliable monitor of the early function of such flaps.