Chronic pulmonary disorders in sickle cell disease: findings at thin-section CT

Dendriform pulmonary ossification in a patient with sickle cell disease

Dendriform pulmonary ossification (DPO) is a rare condition characterised by the formation of bones in lung tissues. This case report describes the first reported case of DPO in a patient with sickle cell disease (SCD), identifying DPO as a potential pulmonary consequence of SCD.

Diffuse cystic lung disease in sickle cell anaemia: a series of 22 cases and a case-control study

Chronic interstitial lung abnormalities have been described in sickle cell disease (SCD) and attributed to repetitive episode of acute chest syndrome. We report a series of 22 cases of diffuse cystic lung disease in SCD with a case-control study to hunt for mechanism. On pathological analysis of a surgical lung biopsy of the index case, the bronchioles had the appearance of constrictive bronchiolitis. Pulmonary function test results revealed lower forced expiratory flow from 25% to 75% of vital capacity in cases versus controls. These findings suggest a bronchiolar mechanism that was not associated with more acute chest syndrome.

Diaphragm ultrasonography in adults with sickle cell anemia: evaluation of morphological and functional aspects

OBJECTIVES

To assess morphological and functional aspects of the diaphragm by ultrasonography (US) in adults with sickle cell anemia (SCA) and evaluate if the diaphragmatic musculature can play a role in changes found in pulmonary function tests (PFTs) of these patients.

METHODS

This is a cross-sectional observational and single-center study involving 40 adults with SCA who underwent diaphragm US and PFTs with a maximum of 1 month between the two tests. Diaphragm US was performed in B and M modes, and echogenicity, thickness and movement of the muscle was assessed in different respiratory maneuvers.

RESULTS

Diaphragms had preserved echogenicity and the thickness was not significantly different between the groups. The SCA group exhibited significantly higher movement of the right hemidiaphragm during deep breathing (p = 0.004) and the sniff test (p = 0.0008) and lower movement of the left hemidiaphragm during quiet breathing (p = 0.009). There was a predominance of restrictive pattern (65%) and a global reduction in respiratory muscle strength (RMS) (70%).

CONCLUSIONS

This study shows that adults with SCA had normal morphostructural aspects and absence of diaphragm dysfunction. Otherwise, they presented greater movement of the right hemidiaphragm during deep breathing and sniff test maneuvers. Despite the restrictive pattern and the reduction in RMS found in PFTs, the diaphragm of young adults with SCA did not have weakness or paralysis.

Surfactant protein D as a marker for pulmonary complications in pediatric patients with sickle cell disease: Relation to lung function tests

BACKGROUND

Surfactant protein D (SP-D) is considered a candidate biomarker for lung integrity and for disease progression.

AIM

We determined the level of SP-D in children and adolescents with SCD and assessed its possible relation to pulmonary complications and lung function.

METHODS

Serum SP-D levels were assessed in 50 SCD patients compared with 30 healthy controls. High-resolution computerized tomography (HRCT) of the chest was done. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁ ), FEV₁ /FVC% and forced expiratory flow rate during 25-75% of expiration (FEF25-75%) were determined.

RESULTS

SP-D was significantly higher in SCD patients than controls, particularly patients with sickle cell anemia than those with sickle β-thalassemia. SP-D levels were significantly associated with increasing severity of interstitial lung disease. The highest SP-D levels were observed among patients with restrictive lung disease followed by mixed type then obstructive lung disease. SP-D was positively correlated to HbS and serum ferritin while negatively correlated to duration of hydroxyurea treatment and parameters of pulmonary functions. ROC curve analysis revealed that SP-D cutoff value 720 ng/mL could significantly detect the presence of abnormal pulmonary function among SCD patients with 82% sensitivity and 88% specificity. Logistic regression analysis showed that SP-D is an independent factor related to abnormal pulmonary function in SCD.

CONCLUSIONS

SP-D may be a promising biomarker for screening of SCD patients for risk of later pulmonary complications.

Lung Function Abnormalities in Sickle Cell Anaemia

Background

Abnormalities in lung function tests have been shown to commonly occur in a majority of patients with sickle cell disease (SCD) even at steady state. The prevalence and pattern of these lung function abnormalities have been described in other populations but this is unknown among our sickle cell cohort. There is generally little information available on risk factors associated with the lung function abnormalities and its relevance in patient care.

Method

This was an analytical cross-sectional study involving 76 clinically stable, hydroxyurea-naive adult Hb-SS participants and 76 nonsickle cell disease (non-SCD) controls. A structured questionnaire was used to obtain sociodemographic data and clinical history of the participants. Investigations performed included spirometry, pulse oximetry, tricuspid regurgitant jet velocity (TRV) measurements via echocardiogram, complete blood counts, free plasma haemoglobin, serum urea, and creatinine.

Results

Weight, BMI, mean FVC, and FEV1% predicted values were comparatively lower among the Hb-SS patients (p < 0.001). Abnormal spirometry outcome occurred in 70.4% of Hb-SS patients, predominantly restrictive defects (p < 0.001), and showed no significant association with steady-state Hb, WBC count, free plasma haemoglobin, frequency of sickling crisis, chronic leg ulcers, and TRV measurements (p > 0.05). The mean oxygen saturation was comparatively lower among Hb-SS patients (p < 0.001).

Conclusion

Measured lung volumes were significantly lower in Hb-SS patients when compared to non-SCD controls and this difference was not influenced by anthropometric variance. Lung function abnormalities, particularly restrictive defects, are prevalent in Hb-SS patients but showed no significant association with recognized markers of disease severity.

How I treat hypoxia in adults with hemoglobinopathies and hemolytic disorders

Hemoglobinopathies are caused by genetic mutations that result in abnormal hemoglobin molecules, resulting in hemolytic anemia. Chronic complications involving the lung parenchyma, vasculature, and cardiac function in hemoglobinopathies result in impaired gas exchange, resulting in tissue hypoxia. Hypoxia is defined as the deficiency in the amount of oxygen reaching the tissues of the body and is prevalent in patients with hemoglobinopathies, and its cause is often multifactorial. Chronic hypoxia in hemoglobinopathies is often a sign of disease severity and is associated with increased morbidity and mortality. Therefore, a thorough understanding of the pathophysiology of hypoxia in these disease processes is important in order to appropriately treat the underlying cause and prevent complications. In this article, we discuss management of hypoxia based on three different cases: sickle cell disease, β-thalassemia, and hereditary spherocytosis. These cases are used to review the current understanding of the disease pathophysiology, demonstrate the importance of a thorough clinical history and physical examination, explore diagnostic pathways, and review the current management.

Relationship between ventilation heterogeneity and exercise intolerance in adults with sickle cell anemia

Sickle cell anemia (SCA) causes dysfunction of multiple organs, with pulmonary involvement as a major cause of mortality. Recently, there has been growing interest in the nitrogen single-breath washout (N₂SBW) test, which is able to detect ventilation heterogeneity and small airway disease when the results of other pulmonary function tests (PFTs) are still normal. Thus, the objectives of the present study were to assess the heterogeneity in the ventilation distribution in adults with SCA and to determine the association between the ventilation distribution and the clinical, cardiovascular, and radiological findings. This cross-sectional study included 38 adults with SCA who underwent PFTs, echocardiography, computed tomography (CT), and 6-min walk test. To evaluate the ventilation heterogeneity, the patients were categorized according to the phase III slope of the N₂SBW (SIII_N2). Compared with adults with lower SIII_N2 values, adults with higher SIII_N2 values showed lower hemoglobin levels (P=0.048), a history of acute chest syndrome (P=0.001), an elevated tricuspid regurgitation velocity (P=0.039), predominance of a reticular pattern in the CT (P=0.002), a shorter 6-min walking distance (6MWD) (P=0.002), and lower peripheral oxygen saturation (SpO₂) after exercise (P=0.03). SIII_N2 values correlated significantly with hemoglobin (r_s=-0.344; P=0.034), forced vital capacity (r_s=-0.671; P<0.0001), diffusing capacity for carbon monoxide (r_s=-0.376; P=0.019), 6MWD (r_s=-0.554; P=0.0003), and SpO₂ after exercise (P=0.040). Heterogeneity in the ventilation distribution is one of the most common pulmonary dysfunctions in adults with SCA. Moreover, relationships exist between ventilation heterogeneity, worsening of pulmonary structural damage, and reduced tolerance for exercise.

Changes seen on computed tomography of the chest in mildly symptomatic adult patients with sickle cell disease

OBJECTIVE

To describe and quantify the main changes seen on computed tomography of the chest in mildly symptomatic adult patients with sickle cell disease, as well as to evaluate the radiologist accuracy in determining the type of hemoglobinopathy.

MATERIALS AND METHODS

A prospective study involving 44 adult patients with sickle cell disease who underwent inspiration and expiration computed tomography of the chest. The frequency of tomography findings and the extent of involvement are reported. We also calculated radiologist accuracy in determining the type of hemoglobinopathy by analyzing the pulmonary alterations and morphology of the spleen.

RESULTS

The changes found on computed tomography scans, in descending order of frequency, were as follows: fibrotic opacities (81.8%); mosaic attenuation (56.8%); architectural distortion (31.8%); cardiomegaly (25.0%); lobar volume reduction (18.2%); and increased caliber of peripheral pulmonary arteries (9.1%). For most of the findings, the involvement was considered mild, five or fewer lung segments being affected. The accuracy in determining the type of hemoglobinopathy (HbSS group versus not HbSS group) was 72.7%.

CONCLUSION

In adult patients with sickle cell disease, the main tomography findings reflect fibrotic changes. In addition, computed tomography can be helpful in differentiating among hemoglobinopathies.

Multimodality thoracic imaging of juvenile systemic sclerosis: emphasis on clinical correlation and high-resolution CT of pulmonary fibrosis

OBJECTIVE. Juvenile systemic sclerosis is a rare multisystem autoimmune disorder characterized by vasculopathy and multiorgan fibrosis. Cardiopulmonary complications are the leading cause of morbidity and mortality. Although pulmonary fibrosis is the complication that is most common and well described, cardiovascular and esophageal involvement may also be observed. In this article, common thoracic findings in juvenile systemic sclerosis will be discussed. We will focus on chest CT, including CT findings of pulmonary fibrosis and associated grading methods, as well as cardiac MRI and esophageal imaging. CONCLUSION. Radiologists play a pivotal role in the initial diagnosis and follow-up evaluation of pediatric patients with systemic sclerosis. Treatment decisions and prognostic assessment are directly related to imaging findings along with clinical evaluation.

Sickle erythrocytes and platelets augment lung leukotriene synthesis with downregulation of anti-inflammatory proteins: relevance in the pathology of the acute chest syndrome

Initiation, progression, and resolution of vaso-occlusive pain episodes in sickle cell disease (SCD) have been recognized as reperfusion injury, which provokes an inflammatory response in the pulmonary circulation. Some 5-lipoxygenase (5-lox) metabolites are potent vasoconstrictors in the pulmonary circulation. We studied stimulation of production of the inflammatory eicosanoids leukotrienes (LTs) and prostaglandin E2 (PGE2) by isolated rat lungs perfused with sickle (HbSS) erythrocytes. Our hypothesis is that HbSS erythrocytes produce more LTs than normal (HbAA) erythrocytes, which can induce vaso-occlusive episodes in SCD patients. Lung perfusates were collected at specific time points and purified by high-pressure liquid chromatography, and LTC4 and PGE2 contents were measured by enzyme-linked immunosorbent assay (ELISA). Rat lung explants were also cultured with purified HbAA and HbSS peptides, and 5-lox, cyclooxygenase 1/2, and platelet-activating factor receptor (PAFR) proteins were measured by Western blotting, while prostacyclin and LTs produced by cultured lung explants were measured by ELISA. Lung weight gain and blood gas data were not different among the groups. HbSS-perfused lungs produced more LTC4 and PGE2 than HbAA-perfused lungs: 10.40 ± 0.62 versus 0.92 ± 0.2 ng/g dry lung weight (mean ± SEM; P = 0.0001) for LTC4. Inclusion of autologous platelets (platelet-rich plasma) elevated LTC4 production to 12.6 ± 0.96 and 7 ± 0.60 ng/g dry lung weight in HbSS and HbAA perfusates, respectively. HbSS lungs also expressed more 5-lox and PAFR. The data suggest that HbSS erythrocytes and activated platelets in patient's pulmonary microcirculation will enhance the synthesis and release of the proinflammatory mediators LTC4 and PGE2, both of which may contribute to onset of the acute chest syndrome in SCD.

Advanced sickle cell associated interstitial lung disease presenting with cor pulmonale in a Nigerian

Previous studies have reported abnormal pulmonary function and pulmonary hypertension among Nigerians with sickle cell disease, but there is no report of interstitial lung disease among them. We report a Nigerian sickle cell patient who presented with computed tomography proven interstitial lung disease complicated by pulmonary hypertension and cor pulmonale.

[Acute chest syndrome of adults suffering from sickle cell disease]

Sickle cell disease is a common but often poorly understood by chest physicians. The acute chest syndrome represents its main respiratory complication.

STATE OF ART

Sickle cell disease is an autosomal recessive disorder inducing, in certain circumstances, sickling of red cells. Natives from western or central Africa and from the Caribbean islands are mainly affected. Acute chest syndrome is defined by the association of chest pain or fever and recent radiographic infiltrates, in patients suffering from sickle cell disease. Determination of etiology, infection, fat embolism or hypoventilation, is difficult, as a self-perpetuating vicious circle is ongoing. Support, largely undervalued, is based on etiological treatment and measures to avoid worsening linked to complications, especially microcirculatory disease.

CONCLUSIONS

Acute chest syndrome is a severe respiratory complication of sickle cell disease. Therapeutic measures are simple but undervalued.

Leukocytosis is a risk factor for lung function deterioration in children with sickle cell disease

BACKGROUND

The decline in lung volumes associated with sickle cell disease (SCD) may begin in childhood. Risk factors for early restrictive lung disease may include SCD severity markers such as leukocytosis.

OBJECTIVE

We examined the relationship between early alteration of lung function and extra-pulmonary markers of SCD severity.

METHODS

We analyzed pulmonary function test results for 184 SCD children (mean age 12.6 y) enrolled in a pediatric cohort.

MAIN RESULTS

Total lung capacity (TLC) and vital capacity (VC) were not associated with a history of acute chest syndrome. Lower TLC values were significantly associated with three independent factors: older age, previous acute episodes of anemia <6 g/dl, and higher baseline white blood cell counts. Only the baseline WBC count and age were independent risk factors for lower VC. Relative risks to have a TLC or a VC lower than the mediane value in our population were significantly associated to the baseline leukocytosis (per 10(9) G/L), after adjustment on age, sex, genotype, baseline Hb, and treatment (RR (95% CI) =1.16 (1.04-1.29) p<0.009, and 1.17 (1.06-1.29) p<0.002, respectively). The obstructive pattern, defined by FEV1/FVC ratio, was not significantly associated to biological parameters.

CONCLUSIONS

Hemolysis and leukocytosis were independent risk factors for an early decline in lung volumes in this pediatric SCD cohort.

The radiological manifestations of sickle cell disease

Sickle cell disease (SCD) is an inherited abnormality of the beta-globin chain, which causes a spectrum of haemolytic anaemias. Clinical manifestations in SCD include anaemia, jaundice, recurrent vaso-occlusive crises, and infections (particularly by encapsulated bacteria) due to functional asplenia and cerebrovascular accidents. Radiological investigations play a critical role both in the diagnosis and in the primary prevention of the complications of SCD.

Hydroxyurea downregulates endothelin-1 gene expression and upregulates ICAM-1 gene expression in cultured human endothelial cells

The clinical efficacy of oral hydroxyurea (HU) in adults and children with sickle cell anemia (SCA) cannot solely be explained by its ability to enhance fetal hemoglobin (HbF) expression. Since increased adherence of sickle red blood cells to vascular endothelium is a possible contributing factor to vaso-occlusive crisis (VOC), we explored the effect of HU on human endothelial cell (EC) lines (TrHBMEC and EA-hy 926). We demonstrated that HU, in a dose-dependent and reversible manner, significantly decreased (up to three-fold) the release of endothelin-1 (ET-1), a vasoconstrictor peptide through downregulation (up to three-fold) of ET-1 gene expression. This finding is of therapeutic relevance as SCA patients exhibit elevated serum levels of ET-1 during episodes of VOC and levels correlate with disease severity. Unexpectedly, HU upregulated (up to three-fold) the expression of membrane-bound intercellular cell adhesion molecule 1 (mbICAM-1) and its soluble form (sICAM-1) with a parallel increase in ICAM-1 mRNA expression. Although ICAM-1 does not appear to be involved in the sickle cell adhesion to vascular endothelium, it may exacerbate vaso-occlusion by promoting leukocyte adhesion. The HU-induced increase in mbICAM-1 may appear inconsistent with the clinical benefits confered by HU. However, both the increase in sICAM-1- and HU-induced leukocyte reduction in patients, may counteract the potentially detrimental effect of elevated mbICAM-1 expression. Also HU reduces the expression of vascular cell adhesion molecule (VCAM-1) on EC. Since HU reduces the very late antigen 4-positive reticulocytes in SCA patients, a ligand for VCAM-1, HU-induced downregulation of VCAM-1 on EC will very likely decrease the reticulocyte-endothelium adhesion. Thus, HU, apart from inducing HbF expression in the red cell, also affects the expression profile of EC compartment.

The paradox of hemoglobin SC disease

Homozygous HbC gene results only in mild hemolytic anemia. In HbSC disease red cells contain equal levels of HbS and HbC. It is a paradox that HbSC exhibit a moderately severe phenotype in spite of being a mixture of HbS trait and HbC trait, neither of which has significant pathology. Why does the combination of these two Hbs result in a serious disease? The short answer is that HbC enhances, by dehydrating the SC red cell, the pathogenic properties of HbS, resulting in a clinically significant disorder, but somewhat milder that sickle cell anemia (SCA). Nevertheless, retinnitis proliferans, osteonecrosis, and acute chest syndrome have equal or higher incidence in HbSC disease compared to SCA. This pathogenic trick is accomplished by HbC inducing, by mechanisms not fully understood, an increase in the activity of K:Cl cotransport that induces the lost of K(+) and consequently of intracellular water. This event creates a sufficient increase of MCHC, so that the lower levels of HbS found in SC red cells can polymerize rapidly and effectively. This situation offers a unique opportunity: if we could inhibit the effect of HbC on K(+) transport we can cure the disease.

Anaesthetic management of the child with sickle cell disease

Sickle cell disease (SCD) is a relatively common inherited disorder of haemoglobin with significant morbidity and mortality. This review describes the epidemiology and pathophysiology of the disease, and discusses the clinical manifestations found in children with SCD. A discussion of the evidence concerning the perioperative management of such children is presented.

Pulmonary manifestations of sickle cell disease

Pulmonary complications account for significant morbidity and mortality in patients with sickle cell disease. Clinical lung involvement manifests in two major forms: the acute chest syndrome and sickle cell chronic lung disease. Acute chest syndrome is characterised by fever, chest pain, and appearance of a new infiltrate on chest radiograph. Sickle cell chronic lung disease, on the other hand, manifests as radiographic interstitial abnormalities, impaired pulmonary function, and, in its most severe form, by the evidence of pulmonary hypertension. Progress has been made in understanding the pathophysiology and management of these complications. In this review the current knowledge of the mechanism, diagnosis, and treatment of pulmonary complications of sickle cell disease are discussed.

Effects of childhood respiratory diseases on the anatomical and functional development of the respiratory system

The anatomical and functional development of the lung appears especially vulnerable to a whole range of insults during gestation and the first few years of life. A significant proportion of adult lung disease originates in utero or early infancy. Most publications on this topic are descriptive retrospective studies. An important limitation of these is that structural changes may precede abnormalities in lung function and development of symptoms. Little is known with certainty with respect to the long-term effects of early insults to the respiratory system. Furthermore, the reversibility of the functional and/or structural defects is hardly ever adequately investigated and it is probably not correct to extrapolate findings from adult studies to paediatric pulmonary diseases. Promoting or facilitating optimal lung growth in fetuses and infants and reducing the incidence of lower respiratory tract infection in infancy may reduce the incidence of adult chronic lung disease in generations to come.

Small-vessel diseases of the lung: CT-pathologic correlates

Diseases that primarily affect the small vessels of the lung are difficult to diagnose. Many conditions are characterized by involvement of small pulmonary vessels, and pathologically they can be conveniently divided into occluding and inflammatory types. The former, typified by chronic pulmonary thromboembolism and primary pulmonary hypertension, are relatively cryptic in terms of imaging. In contrast, inflammatory vasculitides, which often cause pulmonary hemorrhage and infarction, result in florid but nonspecific radiographic abnormalities. The spectrum of thin-section computed tomographic abnormalities encountered in the inflammatory vasculitides is wide: For example, in Wegener granulomatosis the pattern ranges from cavitating nodules to lobar consolidation to ground-glass opacity. This review highlights some of the less obvious imaging manifestations of occlusive and inflammatory diseases of the small pulmonary vessels.

The comprehensiveness care of sickle cell disease

Millions of people across the world have sickle cell disease (SCD). Although the true prevalence of SCD in Europe is not certain, London (UK) alone had an estimated 9000 people with the disorder in 1997. People affected by SCD are best managed by a multidisciplinary team of professionals who deliver comprehensive care: a model of healthcare based on interaction of medical and non-medical services with the affected persons. The components of comprehensive care include patient/parent information, genetic counselling, social services, prevention of infections, dietary advice and supplementation, psychotherapy, renal and other specialist medical care, maternal and child health, orthopaedic and general surgery, pain control, physiotherapy, dental and eye care, drug dependency services and specialist sickle cell nursing. The traditional role of haematologists remains to co-ordinate overall management and liase with other specialities as necessary. Co-operation from the affected persons is indispensable to the delivery of comprehensive care. Working in partnership with the hospital or community health service administration and voluntary agencies enhances the success of the multidisciplinary team. Holistic care improves the quality of life of people affected by SCD, and reduces the number as well as length of hospital admissions. Disease-related morbidity is reduced by early detection and treatment of chronic complications. Comprehensive care promotes awareness of SCD among affected persons who are encouraged to take greater control of their own lives, and achieves better patient management than the solo efforts of any single group of professionals. This cost-effective model of care is an option for taking haemoglobinopathy services forward in the new millennium.

Sickle cell anemia

Sickle cell anemia (SCA) is a disease caused by production of abnormal hemoglobin, which binds with other abnormal hemoglobin molecules within the red blood cell to cause rigid deformation of the cell. This deformation impairs the ability of the cell to pass through small vascular channels; sludging and congestion of vascular beds may result, followed by tissue ischemia and infarction. Infarction is common throughout the body in the patient with SCA, and it is responsible for the earliest clinical manifestation, the acute pain crisis, which is thought to result from marrow infarction. Over time, such insults result in medullary bone infarcts and epiphyseal osteonecrosis. In the brain, white matter and gray matter infarcts are seen, causing cognitive impairment and functional neurologic deficits. The lungs are also commonly affected, with infarcts, emboli (from marrow infarcts and fat necrosis), and a markedly increased propensity for pneumonia. The liver, spleen, and kidney may experience infarction as well. An unusual but life-threatening complication of SCA is sequestration syndrome, wherein a considerable amount of the intravascular volume is sequestered in an organ (usually the spleen), causing vascular collapse; its pathogenesis is unknown. Finally, because the red blood cells are abnormal, they are removed from the circulation, resulting in a hemolytic anemia. For the patient with SCA, however, the ischemic complications of the disease far outweigh the anemia in clinical importance.

Pneumonia in infants and children: radiological-pathological correlation

The radiographic characteristics of pulmonary infection in children are many and varied. Although typical patterns are helpful in diagnosis, clinical and laboratory evaluation provide important diagnostic information. An understanding of the basic pathophysiology of infection and an appreciation of the anatomy of the child's growing lung help provide clearer, insightful, and more accurate radiological interpretation.