RESUMO
Since the very early manned missions in space, a state of anemia associated with reduced erythropoietin levels and reduced plasma volume was disclosed. The reduction in red blood cell mass is driven by a process of selective hemolysis, which has been named neocytolysis. This phenomenon also occurs in people living at a high altitude who descend rapidly to sea level. The origin of the signal leading to destruction of newly produced red blood cells probably is located in central circulation, but the operating mechanism is unknown. The importance of plasma cell volume reduction in the genesis of a lower red cell mass also is supported by the inverse correlation seen at moderate altitude. People arriving at moderate altitude have increased erythropoietin concentration that decreases after a few days and is in inverse correlation with central venous pressure. Studies under simulated microgravity conditions in human beings (bed rest, head-down tilt at -6 degrees , water immersion) and in rats provide further insight in unraveling the mechanism of astronauts' anemia, a problem difficult to study in space because of the limited availability of spaceflights.
Assuntos
Anemia/epidemiologia , Anemia/etiologia , Eritropoese/fisiologia , Eritropoetina/biossíntese , Voo Espacial , Ausência de Peso/efeitos adversos , Anemia/fisiopatologia , Animais , Estudos de Casos e Controles , Fenômenos Fisiológicos Celulares , Envelhecimento Eritrocítico , Eritropoetina/análise , Feminino , Decúbito Inclinado com Rebaixamento da Cabeça , Humanos , Incidência , Masculino , Modelos Animais , Ratos , Pesquisa , Medição de Risco , Sensibilidade e EspecificidadeRESUMO
Renal dysfunction is a constant feature of congestive heart failure and is a stronger predictor of mortality than left ventricular ejection fraction or New York Heart Association classification. In heart failure, a reduction of glomerular filtration rate and renal plasma flow occurs, although the filtration fraction increases. There are many reason for this pattern. A reduction in effective circulating volume stimulates sympathetic activity and the renin-angiotensin-aldosterone system, and it is associated with increased concentrations of atrial natriuretic peptide, brain natriuretic peptide, and tumor necrosis factor alpha. Because in chronic kidney disease heart dysfunction commonly is present, an efficient cardiologist-nephrologist interaction should be promoted.
Assuntos
Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/epidemiologia , Insuficiência Renal/diagnóstico , Insuficiência Renal/epidemiologia , Idoso , Cardiologia/métodos , Progressão da Doença , Feminino , Seguimentos , Taxa de Filtração Glomerular , Insuficiência Cardíaca/terapia , Humanos , Relações Interprofissionais , Testes de Função Renal , Masculino , Pessoa de Meia-Idade , Nefrologia/métodos , Insuficiência Renal/terapia , Fluxo Plasmático Renal/fisiologia , Medição de Risco , Índice de Gravidade de Doença , Análise de Sobrevida , Resistência Vascular/fisiologiaRESUMO
Clinical studies indicate that indices of glomerular filtration rate (GFR) as serum creatinine or creatinine clearance can predict the risk of death in congestive heart failure (CHF) and in heart transplantation. The study reports data on creatinine clearance before and after heart transplantation in 160 patients followed-up for 5 years at our Unit. Pre-transplant creatinine clearance averaged 83.5+/-32 mL/min x 1.73 m(2) and was not significantly associated with 5-year mortality. Creatinine clearance significantly decreased after heart transplantation with a linear trend up to 3 years for patients with complete follow-up. Data suggest that the relation between kidney function and mortality after heart transplantation is affected by several confounders with inclusion of cause of heart disease, co-morbidity, anemia, and post-transplant decrease in kidney function.