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THE sickle cell trait is generally considered to be benign, because the presence of hemoglobin A in a concentration of more than 50 percent in the red cells of persons heterozygotic for hemoglobin A and hemoglobin S (hemoglobin A/S) prevents the polymerization of the remaining hemoglobin S under physiologic conditions.1 Occasional reports suggest, however, that after extreme physical stress or hypoxia, the sickle cell trait can be associated with serious morbidity and even death.2–4 In most cases, the diagnosis of this trait is straightforward: hematologic measures such as hemoglobin, hematocrit, red-cell indexes, and the reticulocyte count are normal, and electrophoretic . . .

Desaturation in patients with sickle cell anemia (SCA) can lead to intravascular sickling and vascular occlusion. The increased metabolic demands of exercise tend to increase oxygen extraction, giving rise to a fall in saturation in the capillary bed that may predispose to sickling. This could be minimized with an increase in cardiac output. The aims of this study were to assess the role of increased stroke volume (SV) in augmenting cardiac output (Q) and to estimate the role of enlarged arteriovenous O2 content difference in maintaining O2 transport in children with SCA. A group of 30 children with SCA (Hb 65 to 133 g/L) and 16 healthy controls of the same racial group and of similar height and weight performed incremental and steady-state exercise at 50% Wmax. Cardiac output (Q) was measured by the indirect (CO2) Fick method during steady state. The slope of delta HR/delta VO2 during incremental exercise was higher in SCA subjects compared with controls (4.01 +/- 1.73 versus 2.80 +/- 0.61 bpm per ml/min/kg VO2, p = 0.001). Q for VO2 was abnormally high in patients, particularly older ones with lower Hb levels. HR (% predicted) was higher in patients than in controls (106 +/- 11 versus 92 +/- 8% predicted, p less than 0.0001), as was SV (113 +/- 16 versus 98 +/- 14% predicted, p = 0.002). Multiple linear regression of Q % predicted and SV % predicted on Hb and age showed a positive correlation with age and a negative correlation with Hb (r = 0.84 for Q and r = 0.76 for SV).(ABSTRACT TRUNCATED AT 250 WORDS)

Adults with sickle cell anemia (SCA) have restrictive lung impairment, increased alveolar dead space, and hypoxemia. These factors, together with increased anaerobic metabolism, are thought to cause exercise hyperventilation. To assess the role of each of these in children, 34 patients with SCA and 16 control subjects performed pulmonary function and exercise tests. Twenty-eight patients with SCA had spirometric values and lung volumes, and all but two patients with SCA had arterial saturation greater than 91% during exercise. Despite a low VO2max (30.07 +/- 6.55 ml/min/kg), the ventilatory anaerobic threshold (VAT) in the patients occurred at a similar %VO2max as in the control subjects (69 +/- 9% versus 63 +/- 12%). The slope of the delta VE/delta VCO2 relationship for sub-VAT work was steeper in the patients (29.4 +/- 6.5 versus 24.7 +/- 5.2, p = 0.01), and the ventilatory equivalent for CO2 (VE/VCO2) in steady-state exercise was greater in the patients than in the control subjects (33.2 +/- 3.5 versus 30.8 +/- 3.5, p = 0.03). End-tidal PCO2 did not differ (38.3 +/- 3.0 versus 39.2 +/- 3.1), indicating equivalent alveolar ventilation. The patients had a higher dead space:tidal volume ratio (VD/VT) than did the control subjects (0.204 +/- 0.033 versus 0.173 +/- 0.024, p = 0.0005). The PaCO2 was significantly lower in those with lower Hb, but there was no difference in pH. In conclusion, children with SCA have an increased exercise ventilatory response caused in part by increased physiologic dead space, and in part by their low Hb. The greater dead space may be the result of sickle cells impairing capillary perfusion to ventilated alveoli.

Characteristics of sickle ceil disease History Epidemiology and genetics Association with malaria Inheritance Clinical features Modifiers of clinical severity Pathophysiology Haemoglobinopathy Oxygen affinity Blood viscosity Cell membrane damage Micrncirculatory changes Molecular biology of sickle eelI anaemia Diagnosis Clinical examination Peripheral blood film and CBC Haemoglobin e]ectrophoresis I~rnergeney use of sodium metabisulphate preparation Neonatal diagnosis Prenatal diagnosis Treatment Supportive Specific therapies Augmentation of haemoglobin F Bone marrow transplantation Transfusion therapy Organization of Sickle Cell Centres in North America Management of general anaesthesia Preoperative considerations Technique of anaesthesia Sielde ceil crisis intraoperatively Controversies in anaesthetic management Preoperative use of blood transfusions The obstetric patient Neonates and infants The patient for open heart surgery

The number and scope of published articles dealing with computed tomography of interstitial lung disease are limited. We present seven cases in which computed tomography detected the presence or extent of interstitial lung disease better than conventional radiography: two patients with histiocytosis X, one with bronchopulmonary dysplasia, one with bleomycin lung toxicity, and three with radiation-induced lung injury. The computed tomography appearance of histiocytosis X and bronchopulmonary dysplasia have not been previously described. Transverse computed tomography images provide information regarding stage of activity and nature of interstitial lung processes not available with standard imaging techniques. We advocate the use of computed tomography in the initial investigation and follow-up of patients with histiocytosis X. Post-radiation pneumonitis and fibrosis can be detected earlier with computed tomography as well.

• Endogenous circulating anticoagulants are unusual in children without a congenital factor deficiency. In particular, the lupus anticoagulant has only rarely been reported in children. Despite its functioning in vitro to prolong the partial thromboplastin time, patients more frequently have problems with thrombosis than bleeding, unless there is a coexistent prothrombin deficiency or thrombocytopenia. We report the cases of three children with the lupus anticoagulant. Two children had associated thromboses. One had a thrombosis of the iliofemoral system and the other had a partial Budd-Chiari syndrome, a thrombosis of the deep calf veins and ureteric obstruction. The third child had a concomitant prothrombin deficiency and bleeding after tooth extraction. Associated findings in these patients included a positive antinuclear antibody test in two, a positive anti-DNA antibody test in two, a false-positive VDRL test in two, and an antiphospholipid antibody test in two. ( AJDC 1984;138:1132-1135)