Chronic sickle cell lung disease: new insights into the diagnosis, pathogenesis and treatment of pulmonary hypertension

COVID-19 in patients with anemia and haematological malignancies: risk factors, clinical guidelines, and emerging therapeutic approaches

Extensive research in countries with high sociodemographic indices (SDIs) to date has shown that coronavirus disease 2019 (COVID-19) may be directly associated with more severe outcomes among patients living with haematological disorders and malignancies (HDMs). Because individuals with moderate to severe immunodeficiency are likely to undergo persistent infections, shed virus particles for prolonged periods, and lack an inflammatory or abortive phase, this represents an overall risk of morbidity and mortality from COVID-19. In cases suffering from HDMs, further investigation is needed to achieve a better understanding of triviruses and a group of related variants in patients with anemia and HDMs, as well as their treatment through vaccines, drugs, and other methods. Against this background, the present study aimed to delineate the relationship between HDMs and the novel COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Besides, effective treatment options for HDM cases were further explored to address this epidemic and its variants. Therefore, learning about how COVID-19 manifests in these patients, along with exploiting the most appropriate treatments, may lead to the development of treatment and care strategies by clinicians and researchers to help patients recover faster. Video Abstract.

Evaluation of lung function in a German single center cohort of young patients with sickle cell disease using EIT and standard techniques

Background and objective

Sickle cell disease (SCD) is a very common autosomal recessive hemoglobinopathy leading to multiple pulmonary complications that are closely associated with mortality. The pathophysiology of chronic pulmonary involvement is not yet fully understood and no specific therapies are available.

Methods

The aim of this cross-sectional study was to characterize the lung function of children and young adolescents with SCD in a German single-center cohort and to extend conventional lung function testing by the use of a new imaging method. We performed spirometry and body plethysmography in 35 children and young adults with hemoglobin SS, SC, S/β-thalassemia as well as 50 controls. These data were compared with clinical characteristics and typical laboratory parameters of hemolysis and disease activity in SCD. To identify lung inhomogeneities, for example due to atelectasis, hyperinflation, air trapping or vascular occlusions, we used the promising new method of electrical impedance tomography (EIT) and calculated global inhomogeneity indices.

Results

Lung function of patients with SCD was significantly reduced compared to that of healthy controls. When the result was found to be pathological, the most commonly observed type of breathing disorder was classified as restrictive. Laboratory parameters showed typical features of SCD including decreased levels of hemoglobin and hematocrit and elevated levels of leucocytes, platelets, lactate dehydrogenase and total bilirubin. However, there was no correlation between blood values and reduced lung function. Electrical impedance tomography (EIT) revealed no abnormalities in SCD patients compared to healthy controls. In particular, we were unable to demonstrate any regional inhomogeneities in lung ventilation.

Conclusion

In our study, SCD patients showed impaired lung function, with a relevant percentage of patients suffering from restrictive breathing disorder. Signs of obstruction could not be detected. Electrical impedance tomography (EIT) measurements revealed no unevenness that would suggest air entrapment, blockage of blood vessels, excessive inflation, obstruction, or other forms of lung disease. Additionally, the reduction in lung function observed in SCD patients was not related to the disease severity or laboratory test results.

A microfluidic device for assessment of E-selectin-mediated neutrophil recruitment to inflamed endothelium and prediction of therapeutic response in sickle cell disease

Neutrophil recruitment to the inflamed endothelium is a multistep process and is of utmost importance in the development of the hallmark vaso-occlusive crisis in sickle cell disease (SCD). However, there lacks a standardized, clinically feasible approach for assessing neutrophil recruitment to the inflamed endothelium for individualized risk stratification and therapeutic response prediction in SCD. Here, we describe a microfluidic device functionalized with E-selectin, a critical endothelial receptor for the neutrophil recruitment process, as a strategy to assess neutrophil binding under physiologic flow in normoxia and clinically relevant hypoxia in SCD. We show that hypoxia significantly enhances neutrophil binding to E-selectin and promotes the formation of neutrophil-platelet aggregates. Moreover, we identified two distinct patient populations: a more severe clinical phenotype with elevated lactate dehydrogenase levels and absolute reticulocyte counts but lowered fetal hemoglobin levels associated with constitutively less neutrophil binding to E-selectin. Mechanistically, we demonstrate that the extent of neutrophil activation correlates with membrane L-selectin shedding, resulting in the loss of ligand interaction sites with E-selectin. We also show that inhibition of E-selectin significantly reduces leukocyte recruitment to activated endothelial cells. Our findings add mechanistic insight into neutrophil-endothelial interactions under hypoxia and provide a clinically feasible means for assessing neutrophil binding to E-selectin using clinical whole blood samples, which can help guide therapeutic decisions for SCD patients.

Pediatric pulmonary year in review 2021: Sleep medicine

Pediatric pulmonology publishes original research, review articles, and case reports on a wide variety of pediatric respiratory disorders. In this article, we summarized the past year's publications in sleep medicine and reviewed selected literature from other journals in this field. We focused on original research articles exploring aspects of sleep-disordered breathing in patients with underlying conditions such as cystic fibrosis, asthma, and sickle cell disease. We also explored sleep-disordered breathing risk factors, monitoring, diagnosis, and treatment; and included recent recommendations for drug-induced sleep endoscopy and ways to monitor and improve PAP adherence remotely.

Molecular Mechanisms of Hepatic Dysfunction in Sickle Cell Disease: Lessons From The Townes Mouse Model

Sickle cell disease (SCD) is an autosomal-recessive-genetic disorder that affects ~100,000 Americans and millions of people worldwide. Erythrocyte sickling, vaso-occlusion, sterile inflammation and hemolysis are the major pathophysiological pathways leading to liver injury in SCD. Although hepatic dysfunction affects up to 10-40% of SCD patients, therapeutic approaches to prevent liver injury in SCD are not known, and the molecular mechanisms promoting progressive liver injury in SCD remain poorly understood. Animal models have been beneficial in bridging the gap between preclinical and translational research in SCD. Recent advances in methodology have allowed the development of several humanized mouse models to address various aspects of SCD related liver diseases. This review provides an overview of current knowledge of the molecular mechanisms and potential therapeutic options of SCD associated liver dysfunction using the Townes mouse model.

Treatment dilemmas: strategies for priapism, chronic leg ulcer disease, and pulmonary hypertension in sickle cell disease

Sickle cell disease is a disorder characterized by chronic hemolytic anemia and multiorgan disease complications. Although vaso-occlusive episodes, acute chest syndrome, and neurovascular disease frequently result in complication and have well-documented guidelines for management, the management of chronic hemolytic and vascular-related complications, such as priapism, leg ulcers, and pulmonary hypertension, is not as well recognized despite their increasing reported prevalence and association with morbidity and mortality. This chapter therefore reviews the current updates on diagnosis and management of priapism, leg ulcers, and pulmonary hypertension.

Cross-Talk between Mechanosensitive Ion Channels and Calcium Regulatory Proteins in Cardiovascular Health and Disease

Mechanosensitive ion channels are widely expressed in the cardiovascular system. They translate mechanical forces including shear stress and stretch into biological signals. The most prominent biological signal through which the cardiovascular physiological activity is initiated or maintained are intracellular calcium ions (Ca²⁺). Growing evidence show that the Ca²⁺ entry mediated by mechanosensitive ion channels is also precisely regulated by a variety of key proteins which are distributed in the cell membrane or endoplasmic reticulum. Recent studies have revealed that mechanosensitive ion channels can even physically interact with Ca²⁺ regulatory proteins and these interactions have wide implications for physiology and pathophysiology. Therefore, this paper reviews the cross-talk between mechanosensitive ion channels and some key Ca²⁺ regulatory proteins in the maintenance of calcium homeostasis and its relevance to cardiovascular health and disease.

Biomarkers of clinical severity in treated and untreated sickle cell disease: a comparison by genotypes of a single center cohort and African Americans in the NHANES study

Haemolysis and vaso-occlusion underlie multi-organ system complications in sickle cell disease (SCD). We assessed real-world biomarkers in University of Illinois adult SCD patients, categorised as severe (HbSS/Sβ0 -thalassaemia; n = 342) or mild (HbSC/Sβ+ -thalassaemia; n = 100) genotypes and stratified according to treatment. African-American controls from the National Health and Nutrition Examination Survey (NHANES) were matched with each genotype category. Most measures of haemolysis, anaemia, inflammation and function of kidneys, liver and lungs differed markedly in untreated severe genotype patients compared to NHANES controls. These same biomarkers were significantly closer to the NHANES control range in untreated mild versus severe genotype patients, but they were not improved in severe genotype patients receiving treatment with hydroxycarbamide or blood transfusions, except that haemoglobin and HbF were higher with hydroxycarbamide. Systolic blood pressures did not differ among the SCD and NHANES groups, but diastolic pressures were higher in mild genotype patients. Ferritin in severe genotype patients on chronic transfusions was 50-fold higher than NHANES controls. The cross-sectional real-world biomarkers of patients on hydroxycarbamide or transfusions were not markedly improved compared to untreated patients. This may be due partly to poor compliance or more severe disease. Our findings highlight the need for more effective treatments.

Versatile cell ablation tools and their applications to study loss of cell functions

Targeted cell ablation is a powerful approach for studying the role of specific cell populations in a variety of organotypic functions, including cell differentiation, and organ generation and regeneration. Emerging tools for permanently or conditionally ablating targeted cell populations and transiently inhibiting neuronal activities exhibit a diversity of application and utility. Each tool has distinct features, and none can be universally applied to study different cell types in various tissue compartments. Although these tools have been developed for over 30 years, they require additional improvement. Currently, there is no consensus on how to select the tools to answer the specific scientific questions of interest. Selecting the appropriate cell ablation technique to study the function of a targeted cell population is less straightforward than selecting the method to study a gene's functions. In this review, we discuss the features of the various tools for targeted cell ablation and provide recommendations for optimal application of specific approaches.

Combined use of arginase II and tadalafil inhibitors for the correction of monocrotaline pulmonary hypertension

Introduction: The concept of the regulatory role of endothelium in the pathogenesis of pulmonary hypertension (PH) is fundamental.

Research objective: To study the protective effects of the selective arginase II inhibitors L207-0525 and L327-0346 in combination with tadalafil in a monocrotaline model of pulmonary hypertension in rats.

Materials and methods: Monocrotaline-induced pulmonary hypertension was simulated in 10 animals by a subcutaneous injection of an alcohol-water solution of monocrotaline (MCT) in the dose of 60 mg/kg. Seven days after the injection of MCT, the administration of L207-0525 and L327-0346 in the doses of 1 mg/kg and 3 mg/kg was started. The compounds were administered intragastrically once a day for 21 days.

Results and discussion: It was found that L207-0525 and L327-0346 in the dose of 3 mg/kg and tadalafil in the dose of 1 mg/kg prevented the development of pulmonary hypertension, which was expressed in a statistically significant decrease in the coefficient of endothelial dysfunction (CED, prevention of an increase in systolic pressure in the right ventricle, as well as Fulton, RV/BW and WT indices. The greatest activity was shown by L207-0525 and L327-0346 in the dose of 3 mg/kg in combination with tadalafil in the dose of 0.1 mg/kg.

Conclusions: The received results suggest the dose-dependent protective activity of selective arginase II inhibitors L207-0525 and L327-0346 and the development of the additive effect of their combined use with low doses of PDE-5 inhibitor tadalafil in relation to the development of monocrotaline pulmonary hypertension.

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.

Pathways to pulmonary hypertension in sickle cell disease: the search for prevention and early intervention

INTRODUCTION

Pulmonary hypertension (PH) develops in a significant number of patients with sickle cell disease (SCD), resulting in increased morbidity and mortality. This review focuses on PH pathophysiology, risk stratification, and new recommendations for screening and treatment for patients with SCD. Areas covered: An extensive PubMed literature search was performed. While the pathophysiology of PH in SCD is yet to be fully deciphered, it is known that the etiology is multifactorial; hemolysis, hypercoagulability, hypoxemia, ischemic-reperfusion injury, oxidative stress, and genetic susceptibility all contribute in varying degrees to endothelial dysfunction. Hemolysis, in particular, seems to play a key role by inciting an imbalance in the regulatory axis of nitric oxide and arginine metabolism. Systematic risk stratification starting in childhood based on clinical features and biomarkers that enable early detection is necessary. Multi-faceted, targeted interventions, before irreversible vasculopathy develops, will allow for improved patient outcomes and life expectancy. Expert commentary: Despite progress in our understanding of PH in SCD, clinically proven therapies remain elusive and additional controlled clinical trials are needed. Prevention of disease starts in childhood, a critical window for intervention. Given the complex and multifactorial nature of SCD, patients will ultimately benefit from combination therapies that simultaneously targets multiple mechanisms.

Placenta growth factor mediated gene regulation in sickle cell disease

Sickle cell anemia (SCA) is an autosomal recessive disorder caused by mutation in the β-globin gene. Pulmonary hypertension (PH), a complication of SCA, results in severe morbidity and mortality. PH is a multifactorial disease: systemic vasculopathy, pulmonary vasoconstriction, and endothelial dysfunction and remodeling. Placenta growth factor (PlGF), an angiogenic growth factor, elaborated from erythroid cells, has been shown to contribute to inflammation, pulmonary vasoconstriction and airway hyper-responsiveness (AH) in mouse models of sickle cell disease. In this review, we summarize the cell-signaling mechanism(s) by which PlGF regulates the expression of genes involved in inflammation, PH and AH in cell culture and corroborate these findings in mouse models of SCA and in individuals with SCA. The role of microRNAs (miRNAs) in the post-transcriptional regulation of these genes is presented and how these miRNAs located in their host genes are transcriptionally regulated. An understanding of the transcriptional regulation of these miRNAs provides a new therapeutic approach to ameliorate the clinical manifestations of SCA.

Antibiotics for treating community-acquired pneumonia in people with sickle cell disease

BACKGROUND

As a consequence of their condition, people with sickle cell disease are at high risk of developing an acute infection of the pulmonary parenchyma called community-acquired pneumonia. Many different bacteria can cause this infection and antibiotic treatment is generally needed to resolve it. There is no standardized approach to antibiotic therapy and treatment is likely to vary from country to country. Thus, there is a need to identify the efficacy and safety of different antibiotic treatment approaches for people with sickle cell disease suffering from community-acquired pneumonia. This is an update of a previously published Cochrane Review.

OBJECTIVES

To determine the efficacy and safety of the antibiotic treatment approaches (monotherapy or combined) for people with sickle cell disease suffering from community-acquired pneumonia.

SEARCH METHODS

We searched The Group's Haemoglobinopathies Trials Register (01 September 2016), which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched LILACS (1982 to 01 September 2016), African Index Medicus (1982 to 20 October 2016) and WHO ICT Registry (20 October 2016).

SELECTION CRITERIA

We searched for published or unpublished randomized controlled trials.

DATA COLLECTION AND ANALYSIS

We intended to summarise data by standard Cochrane methodologies, but no eligible randomized controlled trials were identified.

MAIN RESULTS

We were unable to find any randomized controlled trials on antibiotic treatment approaches for community-acquired pneumonia in people with sickle cell disease.

AUTHORS' CONCLUSIONS

The updated review was unable to identify randomized controlled trials on efficacy and safety of the antibiotic treatment approaches for people with sickle cell disease suffering from community-acquired pneumonia. Randomized controlled trials are needed to establish the optimum antibiotic treatment for this condition. The trials regarding this issue should be structured and reported according to the CONSORT statement for improving the quality of reporting of efficacy and improved reports of harms in clinical research. Triallists should consider including the following outcomes in new trials: number of days to become afebrile; mortality; onset of pain crisis or complications of sickle cell disease following community-acquired pneumonia; diagnosis; hospitalization (admission rate and length of hospital stay); respiratory failure rate; and number of participants receiving a blood transfusion.There are no trials included in the review and we have not identified any relevant trials up to September 2016. We therefore do not plan to update this review until new trials are published.

Assessment of cardiac functions in children with sickle cell anemia: doppler tissue imaging study

BACKGROUND AND AIMS

The extent in which sickle cell anemia (SCA) impacts myocardial function in children is unclear. Doppler tissue imaging (DTI) was introduced as a new non-invasive echocardiographic method for assessment of ventricular systolic and diastolic functions. We undertook this study to assess subclinical impact of SCA on global myocardial performance in affected children using DTI and to correlate it with mean hemoglobin concentration.

METHODS

Eighty five children with SCA (mean age 11.82 ± 3.7 years) was included as the study group and 55 age- and sex-matched healthy children as the control group. Conventional two-dimensional echocardiography was performed in both groups and DTI was used to determine right ventricular (RV) and left ventricular (LV) Tei indexes. Mean Hb concentration was correlated to the cardiac functions of SCA children.

RESULTS

RV and LV Tei indexes were significantly higher in SCA group (mean ± SD: 0.54 ± 0.19 vs. 0.27 ± 0.01, p <0.0001 and 0.47 ± 0.09 vs. 0.30 ± 0.07, p <0.0001, respectively). Also, mean Hb concentration was correlated negatively with both LV Tei index (r = -0.611, p <0.0001) and with RV Tei index (r = -0.894, p <0.0001). On the contrary, fractional shortening (FS) did not correlate with mean Hb concentration (r = -0.044, p = 0.681).

CONCLUSIONS

DTI technique appears to be more sensitive than conventional echocardiography in the early detection of myocardial dysfunction in children with SCA. This provides insights into the value of early screening and the potential for preventive therapy in children to avert cardiac morbidity and mortality in adults with SCA.

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.

Sickle-cell disease in Malawian children is associated with restrictive spirometry: a cross-sectional survey

BACKGROUND

A proportion of children with sickle-cell disease (SCD) demonstrate clinical findings consistent with the diagnosis of asthma. These children are at increased risk of complications, including acute chest syndrome.

OBJECTIVE

To assess lung function and symptoms of asthma in children with SCD in Blantyre, Malawi.

DESIGN

Twenty-five children aged 7-16 years with electrophoretically confirmed SCD were recruited to undergo spirometry and questionnaire screening of asthma symptoms. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio were compared with local and international reference ranges. Symptoms were assessed using the International Study of Asthma and Allergies in Childhood questionnaire.

RESULTS

Mean spirometric indices, represented as Z-scores derived from international reference ranges, were low: FEV1 -1.64 (95%CI -2.04 to -1.23), FVC -1.49 (95%CI -1.90 to -1.09), FEV1/FVC -0.39 (95%CI -0.76 to -0.03). Comparison with local reference ranges, represented as percentage of predicted value, revealed similar impairments: FEV1 86.9 (95%CI 81.1 to 92.7), FVC 89.0 (95%CI 83.5 to 94.4), FEV1/FVC ratio 97.7 (95%CI 95.4 to 99.9). The prevalence of wheeze was 16.7%.

CONCLUSION

We present spirometric abnormalities suggestive of restrictive lung disease with no evidence of obstructive defects or increased prevalence of wheeze.

Antibiotics for treating community acquired pneumonia in people with sickle cell disease

BACKGROUND

As a consequence of their condition, people with sickle cell disease are at high risk of developing an acute infection of the pulmonary parenchyma called community-acquired pneumonia. Many different bacteria can cause this infection and antibiotic treatment is generally needed to resolve it. There is no standardized approach to antibiotic therapy and treatment is likely to vary from country to country. Thus, there is a need to identify the efficacy and safety of different antibiotic treatment approaches for people with sickle cell disease suffering from community-acquired pneumonia.

OBJECTIVES

To determine the efficacy and safety of the antibiotic treatment approaches (monotherapy or combined) for people with sickle cell disease suffering from community-acquired pneumonia.

SEARCH METHODS

We searched The Group's Haemoglobinopathies Trials Register (25 May 2012), which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched LILACS (1982 to 27 April 2012), African Index Medicus (1982 to 27 April 2012) and WHO ICT Registry (27 April 2012).

SELECTION CRITERIA

We searched for published or unpublished randomized controlled trials.

DATA COLLECTION AND ANALYSIS

We intended to summarise data by standard Cochrane Collaboration methodologies, but no eligible randomized controlled trials were identified.

MAIN RESULTS

We were unable to find any randomized controlled trials on antibiotic treatment approaches for community-acquired pneumonia in people with sickle cell disease.

AUTHORS' CONCLUSIONS

The updated review was unable to identify randomized controlled trials on efficacy and safety of the antibiotic treatment approaches for people with sickle cell disease suffering from community-acquired pneumonia. Randomized controlled trials are needed to establish the optimum antibiotic treatment for this condition. The trials regarding this issue should be structured and reported according to the CONSORT statement for improving the quality of reporting of efficacy and improved reports of harms in clinical research. Triallists should consider including the following outcomes in new trials: number of days to become afebrile; mortality; onset of pain crisis or complications of SCD following CAP; diagnosis; hospitalisation (admission rate and length of hospital stay); respiratory failure rate; and number of participants receiving a blood transfusion.There are no trials included in the review and we have not identified any relevant trials up to May 2012. We therefore do not plan to update this review until new trials are published.

Atherosclerosis in sickle cell disease - a review

Acute, vaso-occlusive crises are the most common and earliest clinical manifestations of sickle cell disease. Recent thoughts about development of atherosclerosis as a result of this disease are presented. Current insights into the pathogenesis of atherosclerosis in sickle cell disease are reviewed, in particular the role of endothelial dysfunction, homocysteine and platelets. Common and uncommon sites of atherosclerosis are described. Radiological assessment and potential therapeutic agents to slow the progression of atherosclerosis are discussed. Finally, treatment of atherosclerosis in certain sites is evaluated and reviewed.

Proteinuria is associated with elevated tricuspid regurgitant jet velocity in children with sickle cell disease

BACKGROUND

Sickle cell disease (SCD) affects multiple organ systems. Complications of SCD such as pulmonary hypertension (PHT) and sickle cell nephropathy (SCN) are associated with an increased mortality. Both PHT and SCN have some common risk factors. In adults, PHT has been found to be associated with albuminuria, a manifestation of SCN. There is no data on this association in children. We conducted a study to determine if elevated pulmonary artery systolic pressures estimated on echocardiogram was associated with proteinuria in children with SCD.

METHODS

A detailed retrospective chart review was conducted on a cohort of sickle cell patients screened with echocardiograms from June 2005 to July 2010. Patients who had an initial screening echocardiogram and urine analysis within 1 year were included. Longitudinal data from all subsequent echocardiograms and urine analyses were collected.

RESULTS

Eighty-five patients were included. On initial echocardiograms 32.9% had an elevated tricuspid regurgitant jet velocity (TRV) ≥2.5 m/second. On follow up, in the 28 patients with elevated TRV, 49.27% of all repeat echocardiograms showed persistent elevation. In the 57 patients with normal baseline TRV, 73.6% of all repeat echocardiograms continued to have normal TRV. On initial screening 7.14% of patients with elevated TRV had proteinuria compared to 1.75% without elevated TRV. On follow up, 19.08% of repeat urinalysis had proteinuria in patients with elevated baseline TRV compared to 12.35% in patients with normal baseline TRV (P = 0.04).

CONCLUSIONS

Elevated TRV ≥ 2.5 m/second is significantly associated with proteinuria on longitudinal follow up in children with SCD.

Under-recognized complications in patients with paroxysmal nocturnal haemoglobinuria: raised pulmonary pressure and reduced right ventricular function

Pulmonary hypertension is becoming a recognized complication of the hereditary and acquired haemolytic anaemias, associated with a poor prognosis. Recently we reported that patients with paroxysmal nocturnal haemoglobinuria (PNH) have high levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), a biomarker associated with both right and left ventricular dysfunction and cardiac dysfunction. In the current study we evaluated a cohort of patients (N = 29) with haemolytic PNH for elevated pulmonary artery systolic pressure and cardiac function by Doppler-echocardiography. Of the 29 patients, eight were further studied using cardiac magnetic resonance imaging (MRI), as well as two additional patients (number of patients studied using cardiac MRI = 10). Plasma from the first cohort (N = 29) demonstrated intravascular haemolysis associated with a 12-fold increase in median nitric oxide (NO) consumption when compared with healthy volunteers (P < 0·001). Doppler echocardiography demonstrated normal left ventricular function and elevated pulmonary artery systolic pressure in 41% of patients. Cardiac MRI from the second cohort (N = 10) demonstrated depressed right ventricular function in 80% of PNH patients tested, and 60% had findings suggestive of subclinical small pulmonary emboli. Together, these data suggest a high prevalence of haemolysis-associated NO scavenging, Doppler-estimated systolic pulmonary hypertension, and depressed right ventricular function in patients with PNH.

Clinical and electrocardiographic evaluation of sickle-cell anaemia patients with pulmonary hypertension

Pulmonary hypertension is an emerging complication of sickle cell anaemia with associated increased risk of mortality. In order to evaluate the clinical and electrocardiographic findings in adult sickle-cell patients with pulmonary hypertension, a cross sectional study was conducted on sixty two sickle cell anaemia patients and sixty two age and sex matched normal controls. Elevated pulmonary artery pressures (PAP), defined by PAP ≥ 30 mm Hg on echocardiography, was demonstrated in 41.9% of patients with sickle cell anaemia and in 3.2% of the controls; χ² = 26.571, P < 0.001. Right ventricular hypertrophy, increased P-wave duration, QTc interval, and QTc dispersion were significantly associated with pulmonary hypertension. Significant correlation was found between mean PAP and (1) Frequency of crisis (Spearman correlation = 0.320; P = 0.011), (2) body mass index (Pearson's correlation = −0.297; P = 0.019), and (3) QTc interval (Pearson's correlation 0.261; P = 0.040). Pulmonary hypertension in adult sickle anaemia patients is associated with electrocardiographic evidence of right ventricular hypertrophy, and correlates significantly with frequency of vaso-occlusive crisis, and QTc interval. The observations by this study tend to suggest that these parameters could be useful for early detection and prevention of pulmonary hypertension in patients with sickle cell anaemia.

Intensive care unit management of patients with severe pulmonary hypertension and right heart failure

Despite advances in medical therapies, pulmonary arterial hypertension (PAH) continues to cause significant morbidity and mortality. Although the right ventricle (RV) can adapt to an increase in afterload, progression of the pulmonary vasculopathy that characterizes PAH causes many patients to develop progressive right ventricular failure. Furthermore, acute right ventricular decompensation may develop from disorders that lead to either an acute increase in cardiac demand, such as sepsis, or to an increase in ventricular afterload, including interruptions in medical therapy, arrhythmia, or pulmonary embolism. The poor reserve of the right ventricle, RV ischemia, and adverse right ventricular influence on left ventricular filling may lead to a global reduction in oxygen delivery and multiorgan failure. There is a paucity of data to guide clinicians caring for acute right heart failure in PAH. Treatment recommendations are frequently based on animal models of acute right heart failure or case series in humans with other causes of pulmonary hypertension. Successful treatment often requires that invasive hemodynamics be used to monitor the effect of strategies that are based primarily on biological plausibility. Herein we have developed an approach based on the current understanding of RV failure in PAH and have attempted to develop a treatment paradigm based on physiological principles and available evidence.

Allogeneic cellular and autologous stem cell therapy for sickle cell disease: 'whom, when and how'

Sickle cell disease (SCD) is an autosomal recessive inherited hematological disorder characterized by chronic hemolysis and vaso-occlusion, resulting in multiorgan dysfunction and premature death. The only known curative therapy for patients with severe SCD is myeloablative conditioning and allo-SCT from HLA-matched sibling donors. In this state of the art review, we discuss current and future considerations including patient selection/eligibility, intensity of conditioning regimens, allogeneic graft sources, graft manipulation, mixed donor chimerism, organ function and stability and autologous gene correction stem cell strategies. Recent novel approaches to promote mixed donor chimerism have included the use of matched unrelated adult donors, umbilical cord blood donors, haploidentical familial donors and the utilization of nonmyeloablative, such as reduced intensity and reduced toxicity conditioning regimens. Future strategies will include gene therapy and autologous gene correction stem cell designs. Prospects are bright for novel stem and cellular approaches for patients with severe SCD, and we are currently at the end of the beginning for utilizing cellular therapeutics for the curative treatment of this chronic and debilitating condition.

Pulmonary complications of sickle cell disease

The pulmonary complications of sickle cell disease are a major cause of morbidity and mortality in affected patients. The acute chest syndrome (ACS) is a leading cause of death in patients with sickle cell disease and has a multifactorial etiology. Hydroxyurea (HU), stem cell transplantation (SCT) and chronic transfusions are known to prevent the recurrence of ACS. Careful management of patients admitted for pain crises and surgery including use of incentive spirometry is critical in preventing this complication. Pulmonary hypertension is well known to be associated with sickle cell disease and patients with pulmonary hypertension have increased mortality. Asthma is also commonly seen in patients with sickle cell disease and is associated with a more complicated course. Chronic lung disease develops in a significant proportion of patients with sickle cell disease.

Echocardiographic markers of elevated pulmonary pressure and left ventricular diastolic dysfunction are associated with exercise intolerance in adults and adolescents with homozygous sickle cell anemia in the United States and United Kingdom

BACKGROUND

Noninvasively assessed pulmonary pressure elevations and left ventricular (LV) diastolic dysfunction are associated with increased mortality in adults with sickle cell disease, but their relationship to exercise intolerance has not been evaluated prospectively.

METHODS AND RESULTS

Echocardiography, 6-minute walk distance, hemolytic rate, and serum concentrations of ferritin and erythropoietin were evaluated in a cohort of 483 subjects with homozygous hemoglobin S in the U.S. and U.K. Walk-Treatment of Pulmonary Hypertension and Sickle Cell Disease with Sildenafil Therapy (Walk-PHaSST) study. Tricuspid regurgitation velocity, which reflects systolic pulmonary artery pressure, was 2.7 to <3.0 m/s (mean±SD, 2.8±0.1) in 26% of the subjects and ≥3.0 m/s (mean±SD, 3.4±0.4) in 11%. The LV lateral E/e' ratio, which has been shown to reflect LV filling pressure in other conditions but has not been studied in sickle cell disease, was significantly higher in the groups with tricuspid regurgitation velocity ≥2.7 m/s. Increased hemolysis (P<0.0001), LV lateral E/e' ratio (P=0.0001), blood urea nitrogen (P=0.0002), and erythropoietin (P=0.002) were independently associated with an increased tricuspid regurgitation velocity. Furthermore, female sex (P<0.0001), older age (P<0.0001), LV lateral E/e' ratio (P=0.014), and tricuspid regurgitation velocity (P=0.019) were independent predictors of a shorter 6-minute walk distance.

CONCLUSIONS

Echocardiography-estimated elevated pulmonary artery systolic pressure and LV lateral E/e' ratio were independently associated with poor exercise capacity in a large cohort of patients with sickle cell anemia. Controlled trials investigating whether strategies to prevent or delay pulmonary hypertension and/or LV diastolic dysfunction will improve exercise capacity and long-term outcomes in sickle cell anemia should be considered. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00492531.

Elevated tricuspid regurgitation velocity and decline in exercise capacity over 22 months of follow up in children and adolescents with sickle cell anemia

BACKGROUND

While in adults with sickle cell disease an elevation of tricuspid regurgitation velocity is associated with increased mortality, the importance of this finding in children has not been established. The role of intravascular hemolysis in the development of this complication is controversial.

DESIGN AND METHODS

We conducted a prospective, longitudinal, multi-center study of 160 individuals aged 3-20 years with hemoglobin SS, performing baseline and follow-up determinations of clinical markers, six-minute walk distance less than tricuspid regurgitation velocity and E/Etdi ratio by echocardiography.

RESULTS

At baseline, 14.1% had tricuspid regurgitation velocity of 2.60 m/sec or over, which suggests elevated systolic pulmonary artery pressure, and 7.7% had increased E/Etdi, which suggests elevated left ventricular filling pressure. Over a median of 22 months, baseline elevation in tricuspid regurgitation velocity was associated with an estimated 4.4-fold increase in the odds of a 10% or more decline in age-standardized six-minute-walk distance (P = 0.015). During this interval, baseline values above the median for a hemolytic component derived from four markers of hemolysis were associated with a 9.0-fold increase in the odds of the new onset of elevated tricuspid regurgitation velocity (P = 0.008) and baseline E/Etdi elevation was associated with an estimated 6.1-fold increase in the odds (P = 0.039). In pathway analysis, higher baseline hemolytic component and E/Etdi predicted elevated tricuspid regurgitation velocity at both baseline and follow up, and these elevations in turn predicted decline in six-minute-walk distance.

CONCLUSIONS

Further studies should define the long-term risks of elevated tricuspid regurgitation velocity in childhood and identify potential interventions to prevent increased pulmonary artery pressure and preserve function.

The critical roles of platelet activation and reduced NO bioavailability in fatal pulmonary arterial hypertension in a murine hemolysis model

Pulmonary arterial hypertension (PAH) is suspected to be a strong mortality determinant of hemolytic disorders. However, direct contribution of acute intravascular hemolysis to fatal PAH has not been investigated. The roles of nitric oxide (NO) insufficiency and platelet activation in hemolysis-associated fatal PAH have been suspected but not been experimentally studied. We recently generated a unique intravascular hemolysis mouse model in which the membrane toxin, intermedilysin (ILY), exclusively lyses the erythrocytes of transgenically expressing human CD59 mice (ThCD59(RBC)), thereby inducing ILY-dose-dependent massive hemolysis. Using this murine hemolysis model, we found that the acute increase in pulmonary arterial pressure leading to right ventricle failure caused sudden death. Reduced NO bioavailability and massive platelet activation/aggregation leading to the formation of massive thrombosis specifically in the pulmonary microvasculature played the critical roles in pathogenesis of acute hemolysis-associated fatal PAH. Therapeutic interventions enhancing NO bioactivity or inhibiting platelet activation prevented sudden death or prolonged survival time via the suppression of the acute increase in pulmonary arterial pressure and improvement of right ventricle function. These findings further highlight the importance of the inhibition of platelet activation and the enhancement of NO bioavailability for the treatment and prevention of hemolysis-associated (fatal) PAH.

Pulmonary hypertension and nitric oxide depletion in sickle cell disease

During the past decade a large body of experimental and clinical studies has focused on the hypothesis that nitric oxide (NO) depletion by plasma hemoglobin in the microcirculation plays a central role in the pathogenesis of many manifestations of sickle cell disease (SCD), particularly pulmonary hypertension. We have carefully examined those studies and believe that the conclusions drawn from them are not adequately supported by the data. We agree that NO depletion may well play a role in the pathophysiology of other hemolytic states such as paroxysmal nocturnal hemoglobinuria, in which plasma hemoglobin concentrations are often at least an order of magnitude greater than in SCD. Accordingly, we conclude that clinical trials in SCD designed to increase the bioavailability of NO or association studies in which SCD clinical manifestations are related to plasma hemoglobin via its surrogates should be viewed with caution.

A short course of prednisone in the management of acute chest syndrome of sickle cell disease

BACKGROUND

A short course of dexamethasone therapy may attenuate the course of acute chest syndrome (ACS) of sickle cell disease, but it also increases the risk of early readmission after discharge. Over several years at our institution, an "asthma regimen" of prednisone [2 mg/kg/d (max 80 mg) in 2 divided doses for 5 days] has increasingly been used to treat moderate-to-severe ACS.

METHODS

Review of medical records identified 63 patients hospitalized 78 times with ACS over a 2-year period. The clinical course of patients who received prednisone was compared with that of those who did not, particularly to assess the frequency of early (within 2 weeks) readmission after discharge.

RESULTS

Eight (15.1%) of the 53 children receiving prednisone and 2 (8%) of the 25 who did not were readmitted within 2 weeks (P=0.33), usually for treatment of pain. Patients with moderate-to-severe ACS were more likely to receive prednisone. There was no difference in the duration of stay or the need for blood transfusion between the 2 groups; 21.8% of all the patients received blood.

CONCLUSION

A short course of prednisone did not significantly increase readmission rate after discharge. Larger prospective studies are needed to confirm safety and to establish efficacy.

Hematopoietic stem cell transplantation for hemoglobinopathies: current practice and emerging trends

Despite improvements in the management of thalassemia major and sickle cell disease, treatment complications are frequent and life expectancy remains diminished for these patients. Hematopoietic stem cell transplantation (HSCT) is the only curative option currently available. Existing results for HSCT in patients with hemoglobinopathy are excellent and still improving. New conditioning regimens are being used to reduce treatment-related toxicity and new donor pools accessed to increase the number of patients who can undergo HSCT.

Vasculopathy in sickle cell disease: Biology, pathophysiology, genetics, translational medicine, and new research directions

Sickle cell disease has been very well characterized as a single amino acid molecular disorder of hemoglobin leading to its pathological polymerization, with resulting red cell rigidity that causes poor microvascular blood flow, with consequent tissue ischemia and infarction. More recently, an independent spectrum of pathophysiology of blood vessel function has been demonstrated, involving abnormal vascular tone and activated, adhesive endothelium. These vasculopathic abnormalities are attributable to pathways involving hemolysis-associated defects in nitric oxide bioavailability, oxidative stress, ischemia-reperfusion injury, hemostatic activation, leukocytes and platelets. Vasculopathy of sickle cell disease has been implicated in the development of pulmonary hypertension, stroke, leg ulceration and priapism, particularly associated with hemolytic severity, and reported also in other severe hemolytic disorders. This vasculopathy might also play a role in other chronic organ dysfunction in patients with sickle cell disease. These pathways present novel targets for pharmacologic intervention, and several clinical trials are already under way. The authors present their perspectives of a workshop held at the National Institutes of Health in August 2008 on vasculopathy in sickle cell disease, along with meritorious future scientific questions on the topic of vascular complications of sickle cell disease.

Diagnosis and assessment of pulmonary arterial hypertension

The diagnosis and assessment of pulmonary arterial hypertension is a rapidly evolving area, with changes occurring in the definition of the disease, screening and diagnostic techniques, and staging and follow-up assessment. The definition of pulmonary hypertension has been simplified, and is now based on currently available evidence. There has been substantial progress in advancing the imaging techniques and biomarkers used to screen patients for the disease and to follow up their response to therapy. The importance of accurate assessment of right ventricular function in following up the clinical course and response to therapy is more fully appreciated. As new therapies are developed for pulmonary arterial hypertension, screening, prompt diagnosis, and accurate assessment of disease severity become increasingly important. A clear definition of pulmonary hypertension and the development of a rational approach to diagnostic assessment and follow-up using both conventional and new tools will be essential to deriving maximal benefit from our expanding therapeutic armamentarium.

Sickle cell disease in North Europe

The numbers of patients with sickle cell disease in Northern Europe are steadily increasing due to migration, leading to a need for improved healthcare services for these patients. We outline the role of neonatal and antenatal screening programmes in the diagnosis of sickle cell disease, clinical aspects of care and the therapeutic options available. The clinical areas discussed in detail are pain management, the management of stroke and other neurological complications and the management of pulmonary and splenic complications. The role of hydroxyurea, blood transfusion and bone marrow transplantation are also discussed.

Doppler-defined pulmonary hypertension and the risk of death in children with sickle cell disease followed for a mean of three years

Pulmonary hypertension (PH) is associated with increased mortality in adults with sickle cell disease (SCD), but its prognostic significance in children is unknown. Eighty-eight children with SCD were followed after echocardiographic screening for PH. After a mean follow-up of 3 years, all 18 subjects with PH were alive. In our children, as in adults with SCD, PH was associated with increased haemolysis. In contrast, our subjects with PH did not have overt systemic disease observed in adults. PH may be a manifestation of progressive organ damage from chronic haemolysis and systemic vasculopathy that ultimately leads to early death in adulthood.

Tricuspid regurgitant jet velocity elevation and its relationship to lung function in pediatric sickle cell disease

Concerns about the morbidity and mortality associated with tricuspid regurgitant jet velocity (TRJV) elevation, which may indicate pulmonary hypertension (PHT), in adults with sickle cell disease (SCD) have prompted growing interest in screening the pediatric sickle cell population. The goals of our study were to estimate the prevalence of TRJV elevation and determine its relationship to pulmonary function in children and young adults with SCD at baseline. Seventy-eight subjects (10-24 years old) with SCD underwent prospective screening by Doppler echocardiogram (ECHO), complete lung function evaluation, and laboratory testing as part of standard care at steady state. Tricuspid regurgitation was quantifiable in 68/78 (87%) subjects and peak TRJV was > or =2.5 m/sec in 26/78 (33.3%) evaluated. The frequency of obstruction, restriction, or abnormal gas exchange found on lung function evaluation was not significantly different in subjects with and without TRJV elevation. However, significant inverse correlations were observed between TRJV and both % predicted forced vital capacity (FVC) (r = -0.29, P = 0.022) and oxygen saturation (r = -0.26, P = 0.036). When compared to subjects without TRJV elevation, subjects with TRJV elevation had significantly lower % predicted forced expiratory volume in 1 sec (FEV(1)) (78.9 +/- 14.4 vs. 86.6 +/- 13.0%, P = 0.023), FVC (82.8 +/- 14.1 vs. 90.7 +/- 12.9%, P = 0.017), and oxygen saturation (95.8 +/- 3.2 vs. 97.5 +/- 2.4%, P = 0.016). We found that the combination of low hemoglobin and low % predicted FVC best predicted TRJV elevation (chi(2) = 17.05, P = 0.001) in our cohort, correctly identifying 70% of cases and resulting in positive and negative predictive values of 60 and 74%, respectively. We conclude that in this young population with SCD, TRJV elevation that is not significantly associated with abnormal lung function is common at baseline.

Nitric oxide and arginine dysregulation: a novel pathway to pulmonary hypertension in hemolytic disorders

Secondary pulmonary hypertension (PH) is emerging as one of the leading causes of mortality and morbidity in patients with hemolytic anemias such as sickle cell disease (SCD) and thalassemia. Impaired nitric oxide (NO) bioavailability represents the central feature of endothelial dysfunction, and is a major factor in the pathophysiology of PH. Inactivation of NO correlates with hemolytic rate and is associated with the erythrocyte release of cell-free hemoglobin, which consumes NO directly, and the simultaneous release of the arginine-metabolizing enzyme arginase, which limits bioavailability of the NO synthase substrate arginine during the process of intravascular hemolysis. Rapid consumption of NO is accelerated by oxygen radicals that exists in both SCD and thalassemia. A dysregulation of arginine metabolism contributes to endothelial dysfunction and PH in SCD, and is strongly associated with prospective patient mortality. The central mechanism responsible for this metabolic disorder is enhanced arginine turnover, occurring secondary to enhanced plasma arginase activity. This is consistent with a growing appreciation of the role of excessive arginase activity in human diseases, including asthma and pulmonary arterial hypertension. New treatments aimed at improving arginine and NO bioavailability through arginase inhibition, suppression of hemolytic rate, oral arginine supplementation, or use of NO donors represent potential therapeutic strategies for this common pulmonary complication of hemolytic disorders.

A prospective appraisal of pulmonary hypertension in children with sickle cell disease

OBJECTIVES

Pulmonary hypertension (PHT) is a life-threatening complication of sickle cell disease that occurs in 20% to 40% of adults. Measurement of maximal tricuspid regurgitant jet velocity (TRV) by echocardiography provides a noninvasive screening tool; TRV values > or =2.5 m/s are correlated with PHT and increased mortality. Our objective was to estimate the prevalence of PHT in our pediatric sickle cell population and its possible association with various clinical and laboratory findings, including obstructive sleep apnea and/or pulmonary dysfunction.

STUDY DESIGN

Eligible children had measurement of the TRV. Clinical data were collected, including detailed history with a standardized sleep apnea questionnaire; those with suggestive histories had polysomonography. Pulmonary function was assessed using whole body plethysmography.

RESULTS

Of 48 subjects (79% homozygous sickle cell anemia; median age 12 y; 11 receiving chronic transfusion) enrolled in the study, 4 (8.3%) had TRV >2.5 m/s; all had homozygous sickle cell anemia and 1 was receiving hydroxyurea after 3 years of transfusion for secondary stroke prevention. Subjects with elevated TRV had higher indirect bilirubin levels; we found no association between elevated TRV and obstructive apnea or pulmonary function abnormalities.

CONCLUSIONS

Elevation of TRV was relatively uncommon in our pediatric patients as compared with prevalence reported in adults and may be associated with increased hemolysis. There was no association with obstructive sleep apnea or abnormal pulmonary function.

Longitudinal follow up of elevated pulmonary artery pressures in children with sickle cell disease

Elevated pulmonary artery pressures (PAP) occur in approximately 30% of children with sickle cell disease. In adults, pulmonary hypertension is significantly associated with mortality. There are no data on the long term significance in children. Nineteen children with SS/Sbeta(0) thalassaemia had elevated PAP, defined as tricuspid regurgitant jet velocity (TRV) > or =2.5 m/s on screening echocardiograms. They were prospectively followed for 23 months (range 19-31 months). Patients with initial TRV > or = 3 or TRV > or = 2.5 m/s on repeat echocardiogram had cardiopulmonary evaluation and were offered treatment with hydroxyurea. Associated conditions like asthma and obstructive sleep apnea were treated. 18/19 patients had follow-up echocardiograms. These showed normalization of TRV in 8 patients. Risk factors associated with persistent elevation were higher TRV on initial echocardiogram (P = 0.01), lower haemoglobin (P = 0.003) and lower oxygen saturation (P = 0.03). Five patients with persistently elevated PAP were treated with hydroxyurea. Mean right ventricular pressure dropped from 40.16 to 29.26 (P = 0.017) after 3-6 months and to 23.6 mmHg (P = 0.002) after 9-12 months on treatment. In conclusion (i) At borderline elevation of TRV there is intrapatient variability and echocardiograms should be repeated for confirmation. (ii) Elevated PAP are reversible in children with early detection and treatment with hydroxyurea.

Delayed adverse vascular events after splenectomy in hereditary spherocytosis

BACKGROUND

It is probable that the variety and frequency of delayed adverse vascular events after splenectomy are underappreciated. Splenectomy is performed for a wide variety of conditions, and delayed postsplenectomy hazards are not often studied.

OBJECTIVE

To estimate the relative risk of adverse vascular events in members of hereditary spherocytosis families who have or have not had a splenectomy.

METHODS

Members of families in which hereditary spherocytosis exists were systematically questioned about adverse vascular events.

RESULTS

The cumulative incidence of arterial and venous events at age 70 years was greater in persons who had undergone a splenectomy for spherocytosis (arterial, 22% females, 32% males; venous, 20% females, 19% males) than in affected persons who did not undergo splenectomy (arterial, 3% females, 2% males; venous, 6% females, 4% males) or non-affected family members (arterial, 10% females, 17% males; venous, 4% females, 12% males). Affected subjects who undergo splenectomy are at greatly increased risk of arterial events as compared to affected subjects who do not undergo splenectomy [arterial, hazard ratio (HR) 7.2, 95% confidence interval (CI) 2.8-17.2; venous, HR 3.3, 95% CI 1.1-9.8].

CONCLUSION

There is a significant, long-lasting, increased risk of adverse arterial and venous thromboembolic events after splenectomy performed for hereditary spherocytosis. A review of the literature indicates that this is also true when splenectomy is performed for several other indications.

Resolution of chronic hypoxemia in pediatric sickle cell patients after treatment with hydroxyurea

Chronic hypoxemia is a common manifestation among patients with sickle cell anemia (SCA) who develop chronic lung disease. We report the beneficial effect of hydroxyurea on chronic hypoxemia in three pediatric patients with SCA and recurrent episodes of acute chest syndrome (ACS). All three patients improved rapidly after they were treated with hydroxyurea despite having additional risk factors for hypoxemia. A prospective trial is warranted to assess whether there is a therapeutic effect from the use of hydroxyurea in pediatric SCA patients with chronic hypoxemia.

Symptomatic pulmonary hypertension in a child with sickle cell disease

Pulmonary hypertension is a survival-limiting complication in adults with homozygous sickle cell disease (SS), but little is known about the development, course, or best treatment of pulmonary hypertension in children with SS. We report the clinical course and treatment of a child with SS-associated, hemolysis-driven pulmonary hypertension.

Pulmonary hypertension associated with sickle cell disease: pathophysiology and rationale for treatment

Approximately one third of patients with sickle cell disease (SCD) have pulmonary hypertension (PH), which increases their risk of death. Endothelin (ET)-1 is elevated in SCD and appears to play a key role in many of the pathologic processes in this disease, including PH, suggesting that endothelin receptor antagonists such as bosentan may be effective in treating patients with SCD, particularly those with PH. Other possible treatments include sildenafil, epoprostenol, and oral arginine. Data from controlled clinical trials are needed to establish the most effective treatment of patients with PH associated with SCD.

Prevalence and risk factors of elevated pulmonary artery pressures in children with sickle cell disease

OBJECTIVES

The objectives of this study were (1) to determine the prevalence and risk factors of elevated pulmonary artery pressures in children with homozygous SS or Sbeta(0) thalassemia using Doppler echocardiography and (2) to determine a correlation between abnormal transcranial Doppler examinations and elevated pulmonary artery pressures.

METHODS

Screening echocardiograms were prospectively performed during an annual comprehensive clinic visit on children who were older than 6 years and had homozygous SS or Sbeta(0) thalassemia. Detailed history, examination, and laboratory tests were done, and transcranial Doppler examinations were obtained in children 2 to 14 years of age. Pulmonary hypertension was defined as pulmonary artery systolic pressure of at least 30 mmHg corresponding to a peak tricuspid regurgitant jet velocity of > or = 2.5 m/second. Mild pulmonary hypertension was defined as tricuspid regurgitant jet velocity > or = 2.5 to 2.9 m/second. Moderate pulmonary hypertension was defined as tricuspid regurgitant jet velocity > or = 3 m/second. Patients with pulmonary stenosis or right outflow obstruction were excluded. Characteristics were compared between patients with mild, moderate, and no pulmonary hypertension using 1-way analysis of variance for continuous variable and Fisher's exact test for categorical variables.

RESULTS

Of the 75 patients who had homozygous SS/Sbeta(0) thalassemia and were older than 6 years, echocardiograms were obtained for 62 (82.6%). Thirty percent (19 of 62) of patients had elevated tricuspid regurgitant jet velocity > or = 2.5 m/second. One third of these patients had tricuspid regurgitant jet velocity > or = 3 m/second. All patients with elevated tricuspid regurgitant jet velocity had SS disease. A high reticulocyte count, low oxygen saturation, and a high platelet count were significantly associated with elevated pulmonary artery pressures. There was no difference in age, gender, history of acute chest syndrome, hydroxyurea therapy, chronic blood transfusion, stroke, hemoglobin, and bilirubin between patients with and without elevated pulmonary artery pressures. A total of 47% patients with elevated tricuspid regurgitant jet velocity and 57% without elevated tricuspid regurgitant jet velocity had screening transcranial Doppler examinations. Transcranial Doppler examinations were normal for all patients.

CONCLUSIONS

High pulmonary artery pressures do occur in children with sickle cell disease. Screening by echocardiography can lead to early detection and intervention that may potentially reverse this disease process. There was no correlation between elevated pulmonary artery pressures and abnormal transcranial Doppler examination in our study.

Quality of sleep and pulmonary function in clinically stable adolescents with sickle cell anemia

OBJECTIVE

To evaluate quality of sleep and pulmonary function in clinically stable adolescents with sickle cell anemia (SCA).

METHODS

A cross-sectional descriptive study involving 50 patients with SCA submitted to nocturnal polysomnography and spirometry at the Brasília University Hospital. Anthropometric, polysomnographic and pulmonary function data were analyzed. Patients were divided into two groups according to oxygen saturation by pulse oximetry (SpO2) during rapid eye movement (REM) sleep: SpO2 < 93%; and SpO2 > 93%. Descriptive statistics, Student's t-test, chi-square test and Pearson's correlation coefficient were used.

RESULTS

Mean age was 13.9 +/- 2.5 years. Total sleep time and REM sleep percentage were lower, whereas REM sleep latency, the number of awakenings, movement during sleep, changes in sleep stage, sleep-disordered breathing index and obstructive apnea index were higher. Two patients (4%) did not present REM. There were statistically significant differences between the groups in most of the polysomnographic variables. The SpO2 in REM sleep presented a strong positive correlation with waking SpO2 and with SpO2 in non-REM sleep, whereas it presented a strong negative correlation with the percentage of total sleep time during which SPO2 was < 90%. Mean spirometric values were within normal ranges. Residual volume and the residual volume/total lung capacity/functional residual capacity ratio were elevated.

CONCLUSION

Sleep impairment in clinically stable patients with SCA is probably due to hemoglobin desaturation and not to individual alterations in pulmonary function.