tailieunhanh - Chapter 099. Disorders of Hemoglobin (Part 6)

Clinical Manifestations of Sickle Cell Anemia Most patients with sickling syndromes suffer from hemolytic anemia, with hematocrits from 15–30%, and significant reticulocytosis. Anemia was once thought to exert protective effects against vasoocclusion by reducing blood viscosity. However, natural history and drug therapy trials suggest that an increase in the hematocrit and feedback inhibition of reticulocytosis might be beneficial, even at the expense of increased blood viscosity. The role of adhesive reticulocytes in vasoocclusion might account for these paradoxical effects. Granulocytosis is common. The white count can fluctuate substantially and unpredictably during and between painful crises, infectious episodes, and other intercurrent. | Chapter 099. Disorders of Hemoglobin Part 6 Clinical Manifestations of Sickle Cell Anemia Most patients with sickling syndromes suffer from hemolytic anemia with hematocrits from 15-30 and significant reticulocytosis. Anemia was once thought to exert protective effects against vasoocclusion by reducing blood viscosity. However natural history and drug therapy trials suggest that an increase in the hematocrit and feedback inhibition of reticulocytosis might be beneficial even at the expense of increased blood viscosity. The role of adhesive reticulocytes in vasoocclusion might account for these paradoxical effects. Granulocytosis is common. The white count can fluctuate substantially and unpredictably during and between painful crises infectious episodes and other intercurrent illnesses. Vasoocclusion causes protean manifestations. Intermittent episodes of vasoocclusion in connective and musculoskeletal structures produce painful ischemia manifested by acute pain and tenderness fever tachycardia and anxiety. These recurrent episodes called painful crises are the most common clinical manifestation. Their frequency and severity vary greatly. Pain can develop almost anywhere in the body and may last from a few hours to 2 weeks. Repeated crises requiring hospitalization 3 per year correlate with reduced survival in adult life suggesting that these episodes are associated with accumulation of chronic endorgan damage. Provocative factors include infection fever excessive exercise anxiety abrupt changes in temperature hypoxia or hypertonic dyes. Repeated micro-infarction can destroy tissues having microvascular beds that promote sickling. Thus the spleen is frequently lost within the first 18-36 months of life causing susceptibility to infection particularly by pneumococci. Acute venous obstruction of the spleen splenic sequestration crisis a rare occurrence in early childhood may require emergency transfusion and or splenectomy to prevent trapping of the entire arterial .