The diagnosis of pulmonary thromboembolism in sickle cell disease

Abstract

The symptoms of thromboembolism in sickle cell anemia patients with acute chest syndromes are difficult to differentiate from the similar symptoms of painful thoracic crises and infectious pulmonary episodes. Furthermore, the chronic pulmonary abnormalities in sickle cell disease frequently contribute to the confusing results of noninvasive diagnostic procedures usually employed in evaluating pulmonary thromboembolism. In this study the chronic pulmonary status of asymptomatic sickle cell patients was defined, and this information was used in the evaluation of patients with acute chest syndromes suggestive of pulmonary thromembolism. Sixteen asymptomatic sickle cell patients were prospectively studied by chest roentgenography, spirometry, arterial gas analyses, and radioisotopic lung scans. There was an appreciable degree of preexisting chronic restrictive lung disease with mild to moderate arterial hypoxemia and abnormal lung scans in more than half of the patients. These prospective baseline data were incorporated into the diagnostic evaluation of four of these patients who later developed an acute chest syndrome suggestive of pulmonary thromboembolism. Determination of the cause of the chest pain was greatly faciliated by the existence of the baseline pulmonary data. In another patient persistence of abnormal studies following a presumed thromboembolic episode aided diagnostic evaluation when another episode of chest pain occurred. The findings indicate that comprehensive pulmonary studies in sickle cell patients while in an asymptomatic state will provide baseline data which aid the evaluation of possible pulmonary thromboembolism in acute chest syndromes without resorting to high-risk invasive studies.

Increased in vivo production of thromboxane in patients with sickle cell disease is accompanied by an impairment of platelet functions to the thromboxane A2 agonist U46619.

“…These data suggest that an indirect consequence of the red blood cell abnormality is the activation of platelets that may participate in some of the thrombotic complications of the disease. 4 ' 5 These results are consistent with our recent finding of increased urinary TX production in /3-thalassemic patients, another type of hemoglobin disorder. 6 Control subjects were taken from healthy individuals in the department whose sex and age matched those of the SCD patients.…”

“…In addition, thrombosis and vasospasm are involved in the pathogenesis of major organ damage, which may occur in this disease as a consequence of severe vascular damage and/or vascular intimal hyperplasia. 2 Similarly, patients with the thalassemia syndrome demonstrate increased platelet activation as reflected by a shortened platelet life span, 3 a hypercoagulable state, 4 and increased /3-thromboglobulin levels. 5 Recently, we presented evidence for an enhanced production of the proaggregatory thromboxane (Tx) A 2 in thalassemia intermedia in vivo as reflected by an increased excretion of its urinary metabolites.…”

Hemoglobin SC Disease Presenting as Acute Chest Syndrome with Ventilation-Perfusion Mismatches

“…Most episodes of acute chest syndrome were once thought to be pneumococcal in origin, although it is not easy to confirm bacterial pneumonia in acute chest syndrome [3,[5][6][7]. On the other hand, hypoxemia secondary to pneumonia causes poorly deformable sickled red cells, which results in microvascular occlusion of the pulmonary circulation.…”

Acute Chest Syndrome in Sickle Cell Disease

“…8,21,22 Further supporting evidence was provided by perfusion defects identified during ACS by computed tomography, angiography, and nuclear ventilation and perfusion (V/Q) scans. [23][24][25][26][27] Although it is suspected that pulmonary vascular occlusion by in situ thrombosis and thromboembolism account for some of these perfusion defects, current evidence suggests that many of these defects are due to fat emboli 3,7,14,21,22,[28][29][30][31][32][33][34][35] that originate from bone marrow that becomes infarcted during vaso-occlusive crises. Reduced blood flow to bone marrow during these crises can cause painful ischemia and necrosis of the marrow, and necrotic pieces of marrow that break loose can become emboli.…”

“…The dye load used in computed tomography pulmonary angiograms and traditional angiograms may precipitate further sickling of red blood cells, but this concern should not prevent imaging if clinically necessary. [23][24][25][26][27] …”