RESUMEN
Deep venous thrombosis (DVT) and pulmonary embolization (PE) associated with air travel are directly related to the duration of flight and seating in non-aisle seats. In this study, we assessed a modification of a standard airline seat (NewSit) designed to decrease the incidence of DVT on long flights. This seat raises the feet from the floor, facilitates mobility, and permits intermittent calf compression. Air plethysmography (APG) was used to measure the ejected venous volume of the calves of 25 volunteers before and after sitting for 5 hours on the conventional and modified seats. The mean percent (+/- standard deviation [SD]) increase in venous volume for the conventional seat after 5 hours of continuous sitting was significantly greater than that for the modified seat (26.6 +/- 18.5% vs 3.5 +/- 13.1%, P < 0.0001 by paired, two-tailed t-test). Improvement (any) was seen in 23 of 25 patients, with 15 of the 23 (65%) being better than 1 SD of the mean (P < 0.0001 by Chi-square analysis). This study suggests that the leg movement and calf compression associated with the modified airline seat (NewSit) may decrease the probability of DVT due to prolonged periods of sitting by reducing venous stasis as measured by APG. Further studies involving a larger randomized patient cohort, as well as analysis of the effect of this modification on specific coagulation markers such as tissue plasminogen activator and fibrin D-dimer, are planned.
Asunto(s)
Aeronaves , Pierna/irrigación sanguínea , Pierna/fisiopatología , Viaje , Trombosis de la Vena/prevención & control , Trombosis de la Vena/fisiopatología , Adulto , Femenino , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Movimiento , Contracción Muscular , Pletismografía , Rango del Movimiento Articular , Flujo Sanguíneo Regional , Factores de Tiempo , Ultrasonografía Doppler Dúplex , Venas/diagnóstico por imagen , Venas/fisiopatología , Trombosis de la Vena/epidemiologíaRESUMEN
Autogenous arteriovenous access is the preferred access for hemodialysis patients with end-stage renal disease but is not feasible in a significant number of patients. The creation of a prosthetic arteriovenous access (PAVA) for hemodialysis using expanded polytetrafluoroethylene is technically simple and the short-term results are usually good, but the PAVA's 1-year patency rate is low (less than 60% in many centers). We have developed an integrated approach for the creation and maintenance of PAVAs, under the direction of a dedicated vascular access surgeon, involving preoperative imaging, anesthetic and surgical techniques, and a postoperative graft surveillance program, to improve patency rates. The design used was a prospective nonrandomized study. Between January 1, 1999 and December 31, 2001, 158 PAVAs were created (37.7% of the 419 fistulae created during this period). High-resolution duplex ultrasonography was added to careful clinical assessment in planning and follow-up of the dialysis access. The preferred method of PAVA creation was the forearm loop using tapered 4 to 7 mm stretch expanded polytetrafluoroethylene. After surgery, patients entered a program of close follow-up and regular graft surveillance and maintenance. Prophylactic surgical revisions and endovascular interventions were performed routinely according to ultrasonography findings to prevent thrombosis. Thrombolysis and thrombectomy were performed without delay when the PAVA thrombosed, minimizing the use of central venous access and salvaging the central veins. No patients were excluded from the study. One-, 2-, and 3-year assisted primary patency rates (including patients without occlusion but who were judged to require prophylactic revision) were 65%, 54.1%, and 48.8%, respectively. With surveillance-directed surgical revisions and endovascular treatment before or after occlusion, the 1-, 2-, and 3-year secondary patency rates (functional patency) were 91.4%, 84.3%, and 78.5%. Of the 158 grafts, 110 never occluded during the study period. There were 155 interventions in 74 PAVAs: 30 surgical revisions, 63 prophylactic endovascular procedures, and 52 instances of thrombolytic therapy combined with percutaneous transluminal angioplasty. The use of prosthetic arteriovenous access for hemodialysis, when autogenous arteriovenous access is not feasible, can still be associated with excellent long-term patency, in spite of previously published poor results, as long as good planning, close follow-up, and aggressive intervention (when indicated) are carried out.
Asunto(s)
Derivación Arteriovenosa Quirúrgica/métodos , Implantación de Prótesis Vascular/métodos , Diálisis Renal/métodos , Angioplastia de Balón/métodos , Femenino , Oclusión de Injerto Vascular/etiología , Humanos , Fallo Renal Crónico/fisiopatología , Fallo Renal Crónico/cirugía , Fallo Renal Crónico/terapia , Masculino , Grupo de Atención al Paciente , Cuidados Posoperatorios/métodos , Estudios Prospectivos , Diálisis Renal/efectos adversos , Reoperación , Terapia Trombolítica/métodos , Grado de Desobstrucción Vascular/fisiologíaRESUMEN
OBJECTIVE: The diagnosis of giant cell arteritis (GCA) usually requires a temporal artery biopsy. Recently it has been reported that a periluminal dark halo, detected by color Doppler ultrasonography (US) of the temporal arteries, is a characteristic sign of GCA. We evaluated the predictive value of this dark halo sign in diagnosing GCA. METHODS: During a period of 2 years 69 patients suspected of having GCA were examined by US of both temporal arteries. Temporal artery biopsy was performed in 32 of these patients. The diagnosis of GCA was made if a patient had a biopsy showing arteritis, or met all the following criteria: (1) American College of Rheumatology GCA classification criteria were fulfilled; (2) there was a prompt clinical response to treatment with 40-60 mg/day of prednisone; and (3) no other diagnosis related to the patient's symptoms was made during 6 month followup. RESULTS: Periluminal dark halo was observed in 24 of 69 patients. GCA was diagnosed in 12 of them, giving a positive predictive value (PPV) of only 50%. No halo was detected in 45 cases of which only 2 had GCA, resulting in a high negative predictive value (NPV) of 96%. The sensitivity and specificity of the halo sign for diagnosing GCA were 86% and 78%, respectively. CONCLUSION: The PPV of the halo sign in US of the temporal arteries is unsatisfactory for diagnosing GCA. However, the NPV is very high. Thus the lack of a halo can practically serve to rule out a diagnosis of GCA, and precludes the need for a biopsy in most instances.