RESUMEN
The association between sickle cell trait (SCT) and adverse effects of exercise has been controversial. While individuals with SCT are at higher risk of sudden death, the mechanism for this outcome remains to be elucidated. In order to shed light on this controversy, we have monitored venous blood count and blood gas parameter values in normal and SCT subjects during treadmill exercise. White and red blood cell counts and hemoglobin changed significantly over time in both the SCT and normal groups, with peak exercise values different from pre-exercise or post-exercise values. Red blood cell counts showed significant group-time interaction; increase in count during exercise was accentuated in SCT subjects. All blood gas parameters showed significant changes over time in both groups. O2 content was significantly higher in SCT than AA at all time intervals. O2 saturation, pO2 and CO binding to hemoglobin showed significant group-time interaction. Furthermore, O2 saturation for the combined groups was significantly greater at peak exercise and at rest than before exercise. It is possible that treadmill exercise causes microvascular shunting in SCT subjects, leading to a decrease in the peripheral utilization of oxygen.
Asunto(s)
Recuento de Células Sanguíneas , Dióxido de Carbono/sangre , Ejercicio Físico/fisiología , Oxígeno/sangre , Rasgo Drepanocítico/sangre , Adulto , Bicarbonatos/sangre , Recuento de Eritrocitos , Hematócrito , Hemoglobinas/metabolismo , Humanos , Recuento de Leucocitos , MasculinoRESUMEN
The effect of iron chelation using subcutaneous desferrioxamine on the iron-overloaded heart was studied prospectively over 4 years in 23 asymptomatic patients (mean age 13.2 +/- 5.3 years) with thalassaemia major and transfusion-dependent anaemia. The haemoglobin was maintained greater than 10 g/dl by transfusion and chelation therapy to achieve a negative iron balance. Chelation was closely supervised to ensure compliance. Despite an increase in calculated iron load due to transfusion from 34 +/- 27 g to 63 +/- 28 g, there was a sequential fall in serum ferritin levels from 3148 +/- 1956 ng/ml to 2228 +/- 1825 ng/ml (P less than 0.05). Abnormalities of left ventricular (LV) function, assessed by radionuclide angiography, were present at rest or during exercise in 18 of 23 patients (78%) prior to therapy. Normal LV function was restored in 11 of these 18 patients, five continuing to have abnormal function and two dying. There was a significant increase in resting LVEF from 50 +/- 8% to 57 +/- 6% (P less than 0.01). Peak exercise LVEF rose from 51 +/- 11% to 65 +/- 7% (P less than 0.001). We conclude that the common subclinical abnormalities of LV function induced by iron overload in unchelated patients with thalassaemia major can be reversed with long-term subcutaneous infusions of desferrioxamine.
Asunto(s)
Terapia por Quelación , Deferoxamina/uso terapéutico , Cardiopatías/tratamiento farmacológico , Talasemia/tratamiento farmacológico , Adolescente , Adulto , Australia/epidemiología , Transfusión Sanguínea , Niño , Terapia Combinada , Femenino , Ferritinas/sangre , Cardiopatías/etiología , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/mortalidad , Humanos , Hierro , Masculino , Esfuerzo Físico , Volumen Sistólico , Talasemia/complicaciones , Talasemia/terapiaRESUMEN
The fungus Histoplasma capsulatum produces a spectrum of disease forms ranging from a benign self-limited illness to progressive disseminated disease with a 50 percent mortality rate. The drug of choice, amphotericin B, must be given intravenously over a prolonged course and carries a high incidence of toxicity. Thus, optimal managment of serious forms of histoplasmosis requires considerable clinical judgment.