Diagnosis and treatment of smoke inhalation

Inhalation remains the most frequent and serious comorbid event that occurs in thermally injured patients. A thorough understanding of the pathophysiology enables individualization of therapy and appropriate triage of patients. We summarize our current knowledge of the pathophysiology, diagnosis, and treatment of inhalation injury, with a focus on newer treatment strategies that are evolving secondary to laboratory research.     

Gender relations: Alice Munro's "Differently" and "Carried Away"

In two of her works of short fiction--"Differently" (1989) and "Carried Away" (1991)--the eminent contemporary Canadian writer Alice Munro delineates a series of psychologically complicated interactions between heterosexual couples. These psychodynamics have not been identified and explored in existing literary criticism on these stories. Assisted by the clinical experiences and judgments of psychiatrists and psychologists who have analyzed the intricacies of romantic love and passion, the author examines the often puzzling behaviors exhibited in these narratives by characters involved in erotic relationships. She also identifies two paradigms for personal fulfillment implicit in both stories.     

Biomechanical Effects of e-PTFE Implant Structure on Soft Tissue Implantation Stability: A Study in the Porcine Model

Successful implantation of biocompatible materials depends on physical aspects of its structure. Meshed implants are stable but cannot be easily removed. Nonporous materials are easily removed, but subject to extrusion. We hypothesized that the microporous structure of expanded polytetrafluoroethylene(e-PTFE) would permit limited fibrous ingrowth into the substance of the material, and that tubular implant shape would increase tissue integration while preserving ease of removal. A two-tailed in vivo study was done comparing implant retention, strength of fixation, and removability between tubular and solid-strip e-PTFE implants. Differences in implant retention within tissues were assessed by implanting 396 implants subcutaneously in five swine for observation periods ranging from 3 weeks to 12 months. Strength of implant attachment to host soft tissues was measured at 52 sites by extraction with a tensiometer with forces both parallel and perpendicular to the implant used. Implant porosity was assessed with scanning electron micrography of tubular and solid-strip e-PTFE implants. Measurements of the force and stress tolerances of the implant-tissue interface demonstrated significantly stronger attachment in tubular than strip-shaped implants (P < 0.005). The 11 N (2.75 lb) force sustained by the tubular implant exceeded the 3.4 N(<1 lb) force for the e-PTFE strip by a statistically significant margin on two-tailed Student's t-test (P < 0.005). Even greater forces were tolerated when applied at right angles to the axis of the tubular implant, emulating tissue suspension (21 N, 5.25 lb). The forces and stresses tolerated by both e-PTFE implants far exceeded the fracture stress measured for the implants. Implant extrusion rates were significantly smaller in tubular (0.85%) than in strip-shaped (4.4%) e-PTFE implants (P< 0.05). Standard error of the mean (SEM) demonstrated lesser porosity in tubular than strip implants, suggesting lesser direct tissue attachment. Tubular e-PTFE implant structure facilitates ingrowth of soft tissue through the tube's lumen. This increases the attachment to surrounding soft tissues, increasing fixation strength, decreasing extrusion rate, but still allowing easy removal. These properties may improve clinical applications in facial implantation.     

Accelerated healing with a mesh autograft/allodermal composite skin graft treated with silver nylon dressings with and without direct current in rats

PURPOSE: Evaluation of the healing and persistence of a meshed composite skin graft applied without immunosuppression. METHODS: The contraction of wounds grafted with 9:1 split-thickness autograft/1.5:1 allodermal mesh composite skin grafts (auto/allo MCSGs) was investigated. No immunosuppressive agent was applied. Male ACI rats and female Lewis rats reciprocally served as allodermis graft donors and recipients. Autograft/dermal autograft and allograft/dermal allograft MCSGs were the controls. RESULTS:AT 3 months after grafting, when epithelized auto/allo MCSG wounds were measured by computerized morphometric analysis, the silver nylon (SN) dressing group displayed less contraction than the Vaseline (petroleum jelly) dressing group (p < 0.003), and direct current treatment (SNDC) was more effective than SN (p < 0.005). The histologic structures of the hair follicles appear to confine the rejection process to the allogeneic follicles of the graft. The focal nature of the rejection process and the relatively low antigenicity of the dermal matrix allowed the survival of the allodermis layer. Although direct current significantly enhanced MCSG healing, SN and SNDC were not the immunosuppressive agents that were confirmed. CONCLUSION: This type of MCSG can heal without immunosuppressive treatment.     

Diagnosis of pulmonary embolism: Ventilation perfusion scintigraphy versus helical computed tomography pulmonary angiography

The present study compared the accuracy of ventilation perfusion scintigraphy (VQS) and CT pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism. This was a prospective observational study of 112 patients with suspected pulmonary embolism (PE) who could be studied with both investigations within 24 h. Results were compared to final diagnosis at completion of 6-month follow up, using receiver operating characteristic (ROC) analysis. Pulmonary embolism was diagnosed in 27 referred patients (24%). The sensitivity and specificity of VQS and CTPA were similar to that reported from the literature. A normal VQ scan had the highest negative predictive value (100%), while a high-probability VQ scan had the highest positive predictive value (92%). There was no overall difference (area under the ROC curve (AUC)) between VQS (AUC (95% CI) = 0.82 (0.75,0.89)) and CTPA (AUC = 0.88 (0.81,0.94)) for the diagnosis of PE. Among patients with abnormal chest X-rays, CTPA (AUC 0.90 (0.83,0.97)) appeared somewhat better than VQS (AUC 0.78 (0.68,0.88)) but this difference did not reach statistical significance. In this instance, CTPA is at least as accurate as VQS and may provide an opportunity to make alternative diagnoses.     

Direct current reduces accumulation of Evans Blue albumin in full-thickness burns.

BACKGROUND: Application of direct current (DC) to a burn wound limits extension of the zone-of-stasis and reduces wound tissue edema. OBJECTIVE: To study the effects of DC on extravasation of plasma proteins after burn by using Evans blue (EB) as a marker of plasma albumin. MATERIALS AND METHODS: Male Sprague-Dawley rats with 20% total body surface area full-thickness scalds (100 degrees C/10 sec) were used as the experimental model. Burn wounds were treated with plain nylon, silver-nylon, silver-nylon and 40 microA DC, or no dressing. EB (30 mg/kg) was injected immediately or at variably delayed postburn (PB) times and accompanied by DC application at various time intervals PB. Tissue content of Evans blue was assessed at different times after injection of the dye or infliction of burn injury. RESULTS: Evans blue albumin (EBA) concentration in untreated burn wounds (307.7 microg/g tissue) was nine times greater than in unburned skin (36.5 microg/g tissue) at 48 hours PB. When animals received a DC and EB injection immediately PB, DC treatment reduced EBA concentration by 60% at any time point PB. When EB was injected immediately PB, or at variably delayed times PB, accompanied by DC immediately PB, or at variably delayed times PB, DC reduced EBA accumulation at all examined times PB by more the 50% (p < 0.001). CONCLUSION: EBA and edema fluid accumulation in burn wound change in concert after injury and show similar response to DC treatment.