RESUMEN
Limb venous compliance decreases with advancing age, even in healthy humans. To test the hypothesis that adrenergic mechanisms contribute to age-associated reductions in limb venous compliance, we measured calf venous compliance before and during acute systemic α- and ß-adrenergic blockade in eight young (27 ± 1 yr old, mean ± SE) and eight older healthy men (67 ± 2 yr old). Calf venous compliance was determined in supine subjects by inflating a thigh-collecting cuff to 60 mmHg for 8 min and then decreasing it (1 mmHg/s) to 0 mmHg while calf volume was indexed with a strain gauge. The slope (·10⻳) of the pressure-compliance relation (compliance= ß1 + 2·ß2·cuff pressure), which is the first derivative of the quadratic pressure-volume relation [(Δlimb volume) = ß0+ ß1·(cuff pressure) + ß2·(cuff pressure)²] during reductions in cuff pressure, was used to quantify calf venous compliance. Calf venous compliance was â¼30% lower (P < 0.01) in older compared with young men before adrenergic blockade. In response to adrenergic blockade calf venous compliance did not increase in young (-2.62 ± 0.14 and -2.29 ± 0.18 ml·dl⻹·mmHg⻹, before and during blockade, respectively) or older men (-1.78 ± 0.27 and -1.68 ± 0.21 ml·dl⻹ ·mmHg⻹). Moreover, during adrenergic blockade differences in calf venous compliance between young and older men observed before adrenergic blockade persisted. Collectively, these data strongly suggest that adrenergic mechanisms neither directly restrain calf venous compliance in young or older men nor do they contribute to age-associated reductions in calf venous compliance in healthy men.
Asunto(s)
Envejecimiento/fisiología , Receptores Adrenérgicos/metabolismo , Venas/fisiología , Adulto , Anciano , Elasticidad/fisiología , Humanos , Pierna/irrigación sanguínea , Masculino , Persona de Mediana Edad , Resistencia Vascular/fisiologíaRESUMEN
Venous thromboembolism is a common and often fatal problem in postsurgical patients. These patients are usually treated with either therapeutic anticoagulation or the placement of inferior vena cava (IVC) filters. Controversy surrounds the use of IVC filters, because no data exist proving survival benefit. In this study, 264 inpatient medical records of patients who underwent major surgical procedures and had the diagnosis of deep venous thrombosis or pulmonary embolism were examined. Among these patients, those who received IVC filters were identified, and the documented indications for filter placement were reviewed. Rates of IVC filter placement per venous thromboembolism event and specific indications were examined across surgical subspecialties and by type of medical consultant. Sixty percent of patients received IVC filters. IVC filter placement rates varied significantly across surgical subspecialties (p <0.0001), with the highest rate in the orthopedic surgery subgroup (80%). Rates of IVC filter use also differed significantly (p <0.0007) between medical consultants who specialized in antithrombotic medicine (46.8%) and those who did not (68.3%). Significant differences also existed in specific indications for filter placement between medical and surgical subspecialties. In conclusion, most of this study's population received IVC filters. Rates of IVC filter placement varied by the specialties of surgeons and medical consultants. The heterogeneity of treatment strategies coupled with the lack of data for this patient population highlights the need for future prospective studies to guide evidence-based treatment.