Airway hyperreactivity in children with sickle cell disease

The impact of obstructive sleep apnea in children with sickle cell disease and asthma

INTRODUCTION

Asthma and obstructive sleep apnea (OSA) are chronic diseases that disproportionately affect children with sickle cell disease (SCD). The literature describes the negative impact that both conditions have on children with SCD separately; however, the effect of OSA on asthmatic children with OSA is less specific. We hypothesized that the presence of OSA in children with SCD and asthma is associated with specific hematologic markers, worse clinical outcomes, and greater healthcare utilization.

METHODS

We retrospectively evaluated children with both SCD and asthma who underwent polysomnography (PSG). We assessed their demographic information, PSG data, hematologic indices, and healthcare utilization based on the concurrent presence of OSA.

RESULTS

Fifty-nine percent of the cohort had OSA with a lower oxygen saturation (SpO2 ) nadir (87% vs. 93%, p < 0.001) and a lower median daytime SpO2 (96.5% vs. 98.5%, p < 0.05); those with OSA were more likely to have the hemoglobin SS genotype (86% vs. 46.5%, p = 0.03). Additionally, those with OSA had a higher mean corpuscular volume (87 vs. 77.2 fL, p = 0.03) and reticulocyte count (10.1% vs. 5.5%, p < 0.01). There was no difference in asthma severity or healthcare utilization between those with OSA and those without OSA.

DISCUSSION

Overall, children with SCD and asthma might be at increased risk for developing OSA, and screening for sleep-disordered breathing should be incorporated as part of their routine care.

The Role of Inflammation in The Cellular and Molecular Mechanisms of Cardiopulmonary Complications of Sickle Cell Disease

Cardiopulmonary complications remain the major cause of mortality despite newer therapies and improvements in the lifespan of patients with sickle cell disease (SCD). Inflammation has been identified as a major risk modifier in the pathogenesis of SCD-associated cardiopulmonary complications in recent mechanistic and observational studies. In this review, we discuss recent cellular and molecular mechanisms of cardiopulmonary complications in SCD and summarize the most recent evidence from clinical and laboratory studies. We emphasize the role of inflammation in the onset and progression of these complications to better understand the underlying pathobiological processes. We also discuss future basic and translational research in addressing questions about the complex role of inflammation in the development of SCD cardiopulmonary complications, which may lead to promising therapies and reduce morbidity and mortality in this vulnerable population.

Inhaled bronchodilators for acute chest syndrome in people with sickle cell disease

BACKGROUND

Bronchodilators are used to treat bronchial hyper-responsiveness in asthma. Bronchial hyper-responsiveness may be a component of acute chest syndrome in people with sickle cell disease. Therefore, bronchodilators may be useful in the treatment of acute chest syndrome. This is an update of a previously published Cochrane Review.

OBJECTIVES

The aim of the review is to determine whether the use of inhaled, short-acting bronchodilators for acute chest syndrome reduces morbidity and mortality in people with sickle cell disease and to assess whether this treatment causes adverse effects.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches, handsearches of relevant journals and abstract books of conference proceedings. Additional searches were carried out on MEDLINE (1966 to 2004) and Embase (1981 to 2004) and ongoing trial registries (28 September 2022). Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 25 July 2022.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials. Trials using quasi-randomisation methods will be included in future updates of this review if there is sufficient evidence that the treatment and control groups are similar at baseline.

DATA COLLECTION AND ANALYSIS

We found no trials investigating the use of bronchodilators for acute chest syndrome in people with sickle cell disease.

MAIN RESULTS

We found no trials investigating the use of bronchodilators for acute chest syndrome in people with sickle cell disease.

AUTHORS' CONCLUSIONS

If bronchial hyper-responsiveness is an important component of some episodes of acute chest syndrome in people with sickle cell disease, the use of inhaled bronchodilators may be indicated. There is need for a well-designed, adequately-powered randomised controlled trial to assess the benefits and risks of the addition of inhaled bronchodilators to established therapies for acute chest syndrome in people with sickle cell disease.

Benefit of pulmonary subspecialty care for children with sickle cell disease and asthma

OBJECTIVE

Asthma is a recognized comorbidity in children with sickle cell disease (SCD). It increases the risk of acute chest syndrome (ACS), vaso-occlusive episodes, and early mortality. We aim to determine whether evaluation and management of children with SCD and asthma by a pulmonologist reduce rate of asthma exacerbation and ACS.

METHODS

The study included 192 patients with SCD (0-21 years) followed at Children's Hospital of Philadelphia Hematology between January 1, 2015, and December 31, 2018, with a diagnosis of asthma, wheeze, or cough. Patients were placed in two groups: those evaluated by a pulmonologist (SCD-A-P) and those not (SCD-A). Rates of emergency department (ED) visits and hospitalizations for asthma exacerbation and ACS were compared between groups and over time.

RESULTS

SCD-A-P patients (n = 70) were predominantly SCD type SS with lower hemoglobin and hematocrit compared to SCD-A patients (n = 122). SCD-A-P started with a higher average rate of hospital visits for asthma exacerbation and ACS per year (2.69 [1.02-4.37]) compared to SCD-A (0.43 [0.24-0.63]), (p < 0.001). For SCD-A-P patients with at least one hospital visit (n = 48), the average rate decreased from 3.93 (1.57-6.29) to 0.85 (0.48-1.23) following pulmonary consultation (p = 0.014) and was comparable to the SCD-A rate by study end.

CONCLUSION

SCD-A-P was mainly SCD type SS and had higher ED/hospitalization rates for asthma exacerbation and ACS compared to SCD-A, but the rates significantly decreased following pulmonology consultation. These findings support the pulmonologist's role in the multidisciplinary care of SCD patients and highlight the need for evidence-based asthma guidelines for children with SCD.

Variation in pulmonary function tests among children with sickle cell anemia: a systematic review and meta-analysis

Introduction

the spectrum of pulmonary complications in sickle cell anemia (SCA) comprises mainly of acute chest syndrome (ACS), pulmonary hypertension (PH) and airway hyper-responsiveness (AHR). This study was conducted to examine the abnormalities in pulmonary function tests (PFTs) seen in children with SCA.

Methods

electronic databases (Cochrane library, PubMed, EMBASE, Scopus, Web of Science) were used as data sources. Two authors independently reviewed studies. All case-control studies with PFT performed in patients with SCA and normal controls were reviewed. Pulmonary functions were assessed with the help of spirometry, lung volume and gas diffusion findings.

Results

nine studies with 788 SCA children and 1101 controls were analyzed. For all studies, the pooled mean difference for forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, peak expiratory flow rate (PEFR), total lung capacity (TLC) and carbon mono-oxide diffusing capacity (DLCO) were -12.67, (95% CI: -15.41,-9.94), -11.69, (95% CI: -14.24, -9.14), -1.90, (95% CI: -4.32, 0.52), -3.36 (95% CI: -6.69, -0.02), -7.35, (95% CI: -14.97, -0.27) and -4.68, (95% CI -20.64, -11.29) respectively. FEV1 and FVC and were the only parameters found to be significantly decreased.

Conclusion

sickle cell anemia was associated with lower FEV1 and FVC, thus, supporting the role of routine monitoring for the progression of lung function decline in children with SCA with ACS. We recommend routine screening and lung function monitoring for early recognition of pulmonary function decline.

Lung clearance index in children with sickle cell disease

INTRODUCTION

The lung clearance index (LCI) derived from the multiple breath washout test (MBW), is both feasible and sensitive to early lung disease detection in young children with cystic fibrosis and asthma. The utility of LCI has not been studied in children with sickle cell disease (SCD). We hypothesized that children with SCD, with or without asthma or airway hyperreactivity (AHR), would have an elevated LCI compared to healthy controls.

METHODS

Children with SCD from a single center between the ages of 6 and 18 years were studied at baseline health and completed MBW, spirometry, plethysmography and blood was drawn for serum markers. Results were compared to healthy controls of similar race, age, and gender.

RESULTS

Healthy controls (n = 35) had a significantly higher daytime oxygen saturation level, weight and body mass index but not height compared to participants with SCD (n = 34). Total lung capacity (TLC) z-scores were significantly higher in the healthy controls compared to those with SCD (0.87 [1.13] vs. 0.02 [1.27]; p = .005) while differences in forced expiratory volume in 1 s z-scores approached significance (0.26 [0.97] vs. -0.22 [1.09]; p = .055). There was no significant difference in LCI between the healthy controls compared to participants with SCD (7.29 [0.72] vs. 7.40 [0.69]; p = .514).

CONCLUSION

LCI did not differentiate SCD from healthy controls in children between the ages of 6 and 18 years at baseline health. TLC may be an important pulmonary function measure to follow longitudinally in the pediatric SCD population.

Pulmonary Manifestations of Hematologic and Oncologic Diseases in Children

Pulmonary complications are common in children with hematologic or oncologic diseases, and many experience long-term effects even after the primary disease has been cured. This article reviews pulmonary complications in children with cancer, after hematopoietic stem cell transplant, and caused by sickle cell disease and discusses their management.

The Worst Things in Life are Free: The Role of Free Heme in Sickle Cell Disease

Hemolysis is a pathological feature of several diseases of diverse etiology such as hereditary anemias, malaria, and sepsis. A major complication of hemolysis involves the release of large quantities of hemoglobin into the blood circulation and the subsequent generation of harmful metabolites like labile heme. Protective mechanisms like haptoglobin-hemoglobin and hemopexin-heme binding, and heme oxygenase-1 enzymatic degradation of heme limit the toxicity of the hemolysis-related molecules. The capacity of these protective systems is exceeded in hemolytic diseases, resulting in high residual levels of hemolysis products in the circulation, which pose a great oxidative and proinflammatory risk. Sickle cell disease (SCD) features a prominent hemolytic anemia which impacts the phenotypic variability and disease severity. Not only is circulating heme a potent oxidative molecule, but it can act as an erythrocytic danger-associated molecular pattern (eDAMP) molecule which contributes to a proinflammatory state, promoting sickle complications such as vaso-occlusion and acute lung injury. Exposure to extracellular heme in SCD can also augment the expression of placental growth factor (PlGF) and interleukin-6 (IL-6), with important consequences to enthothelin-1 (ET-1) secretion and pulmonary hypertension, and potentially the development of renal and cardiac dysfunction. This review focuses on heme-induced mechanisms that are implicated in disease pathways, mainly in SCD. A special emphasis is given to heme-induced PlGF and IL-6 related mechanisms and their role in SCD disease progression.

Current perspectives of sickle cell disease in Nigeria: changing the narratives

Introduction: Sickle cell disease (SCD) is an inherited blood disorder characterized by clinical heterogeneity that may be influenced by environmental factors, ethnicity, race, social and economic factors as well as genetic and epigenetic factors. Areas covered: The present review was carried out to provide a comprehensive assessment of the current burden of SCD and treatments available for persons with SCD in Nigeria with the aim of identifying surveillance and treatment gaps, informing to guide the planning and implementation of better crisis prevention measures for SCD patients and set an agenda for new areas of SCD research in the country. This review assessed medical, biomedical and genetic studies on SCD patients in Nigeria and other endemic countries of the world. Expert opinion: Integration of hydroxyurea therapy into the management of SCD and surveillance via new-born screening (NBS) for early detection and management will improve the survival of persons with SCD in Nigeria. However, it will be important to carry out pilot studies, initiate strategic advocacy initiatives to educate the people about NBS benefits, develop collaborations between potential stakeholders and design sustainable financing scheme.

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.

Sickle Cell Disease: Monitoring, Current Treatment, and Therapeutics Under Development

Screening and early detection of organ injury, as well as expanded use of red cell transfusion and hydroxyurea in children have changed best practices for clinical care in sickle cell disease. The current standard of care for children with sickle cell disease is discussed through a review of screening recommendations, disease monitoring, and approach to treatment. Novel pharmacologic agents under investigation in clinical trials are also reviewed.

Bronchodilator Use for Acute Chest Syndrome Among Large Pediatric Hospitals in North America

The utility of bronchodilators to treat acute chest syndrome (ACS) in patients with sickle cell disease is unknown. Our objectives were to examine the variability in bronchodilator use for ACS among pediatric hospitals contributing to a large database and to examine the relationship between bronchodilator use and length of stay (LOS) and mortality. Between 2005 and 2011, bronchodilators were used during 6812/11 328 hospitalizations (60.1%) and use varied from 0.0% to 97.0% (median = 46.0%, interquartile range = 37.0% to 74.0%). Median LOS was 4 days, and interquartile range was 2 to 6 days. Bronchodilator use was associated with a 13.2% increase in LOS (95% confidence interval = 9.2% to 17.3%, P < .001). However, in the subgroup with asthma, bronchodilator use was associated with a 17.9% decrease in LOS (95% confidence interval = 1.7% to 31.4%, P = .03). There is wide variability in bronchodilator use for ACS, and it has variable association with LOS, depending on comorbid asthma. Prospective trials are needed to evaluate bronchodilators for ACS.

Pathophysiology of Sickle Cell Disease

Since the discovery of sickle cell disease (SCD) in 1910, enormous strides have been made in the elucidation of the pathogenesis of its protean complications, which has inspired recent advances in targeted molecular therapies. In SCD, a single amino acid substitution in the β-globin chain leads to polymerization of mutant hemoglobin S, impairing erythrocyte rheology and survival. Clinically, erythrocyte abnormalities in SCD manifest in hemolytic anemia and cycles of microvascular vaso-occlusion leading to end-organ ischemia-reperfusion injury and infarction. Vaso-occlusive events and intravascular hemolysis promote inflammation and redox instability that lead to progressive small- and large-vessel vasculopathy. Based on current evidence, the pathobiology of SCD is considered to be a vicious cycle of four major processes, all the subject of active study and novel therapeutic targeting: ( a) hemoglobin S polymerization, ( b) impaired biorheology and increased adhesion-mediated vaso-occlusion, ( c) hemolysis-mediated endothelial dysfunction, and ( d) concerted activation of sterile inflammation (Toll-like receptor 4- and inflammasome-dependent innate immune pathways). These molecular, cellular, and biophysical processes synergize to promote acute and chronic pain and end-organ injury and failure in SCD. This review provides an exhaustive overview of the current understanding of the molecular pathophysiology of SCD, how this pathophysiology contributes to complications of the central nervous and cardiopulmonary systems, and how this knowledge is being harnessed to develop current and potential therapies.

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.

Airway inflammation in sickle cell disease-A translational perspective

Asthma and sickle cell disease (SCD) are common chronic conditions in children of African ancestry that are characterized by cough, wheeze, and obstructive patterns on pulmonary function. Pulmonary function testing in children with SCD has estimated a prevalence of obstructive lung disease ranging from 13% to 57%, and airway hyper-responsiveness of up to 77%, independent of a diagnosis of asthma. Asthma co-existing with SCD is associated with increased risk of acute chest syndrome (ACS), respiratory symptoms, pain episodes, and death. However, there are inherent differences in the pathophysiology of SCD and asthma. While classic allergic asthma in the general population is associated with a T-helper 2 cell (Th-2 cells) pattern of cell inflammation, increased IgE levels and often positive allergy testing, inflammation in SCD is associated with different inflammatory pathways, involving neutrophilic and monocytic pathways, which have been explored to a limited extent in mouse models and with a dearth of human studies. The current review summarizes the existent literature on sickle cell related airway inflammation and its cross roads with allergic asthma-related inflammation, and discusses the importance of further elucidating and understanding these common and divergent inflammatory pathways in human studies to facilitate development of targeted therapy for children with SCD and pulmonary morbidity.

Asthma Screening in Pediatric Sickle Cell Disease: A Clinic-Based Program Using Questionnaires and Spirometry

A clinician diagnosis of asthma is associated with increased morbidity and mortality in people with sickle cell disease (SCD). We hypothesized that a screening program would help identify children with asthma needing referral to pulmonary clinic. We conducted a single-center project to screen patients with SCD for asthma using a previously validated questionnaire (Breathmobile) and for pulmonary function abnormalities with portable spirometry. Participants with a positive questionnaire and/or abnormal spirometry were referred to pediatric pulmonary clinic. We evaluated clinical associations with abnormal spirometry and questionnaire responses. Of the 157 participants, 58 (37%) had a positive asthma screening questionnaire. Interpretable spirometry was available for 105 (83% of those eligible) and of these, 35 (34%) had abnormal results. The asthma questionnaire was 87.5% sensitive [95% confidence interval (CI) 74.8-95.3] and 85.3% specific (95% CI 77.3-91.4) to detect a clinician diagnosis of asthma. Participants with positive questionnaires were older (mean age 12.2 vs. 9.9 years, P = 0.012). Spirometry identified 16 additional participants who had normal asthma questionnaires. Seventy-four participants (47%) were referred to pediatric pulmonary clinic and 25 (34%) of these participants scheduled clinic appointments; however, only 13 (52%) were evaluated in pulmonary clinic. Clinic-based asthma screening and spirometry frequently identified individuals with asthma and pulmonary function abnormalities. Only 22% of those referred were eventually seen in pulmonary clinic. The impact of improved screening and treatment on the pulmonary morbidity in SCD needs to be defined and is an area for future investigation. In addition, case management or multidisciplinary clinics may enhance future screening programs.

Acute Chest Syndrome in Children with Sickle Cell Disease

Acute chest syndrome (ACS) is a frequent cause of acute lung disease in children with sickle cell disease (SCD). Patients may present with ACS or may develop this complication during the course of a hospitalization for acute vaso-occlusive crises (VOC). ACS is associated with prolonged hospitalization, increased risk of respiratory failure, and the potential for developing chronic lung disease. ACS in SCD is defined as the presence of fever and/or new respiratory symptoms accompanied by the presence of a new pulmonary infiltrate on chest X-ray. The spectrum of clinical manifestations can range from mild respiratory illness to acute respiratory distress syndrome. The presence of severe hypoxemia is a useful predictor of severity and outcome. The etiology of ACS is often multifactorial. One of the proposed mechanisms involves increased adhesion of sickle red cells to pulmonary microvasculature in the presence of hypoxia. Other commonly associated etiologies include infection, pulmonary fat embolism, and infarction. Infection is a common cause in children, whereas adults usually present with pain crises. Several risk factors have been identified in children to be associated with increased incidence of ACS. These include younger age, severe SCD genotypes (SS or Sβ⁰ thalassemia), lower fetal hemoglobin concentrations, higher steady-state hemoglobin levels, higher steady-state white blood cell counts, history of asthma, and tobacco smoke exposure. Opiate overdose and resulting hypoventilation can also trigger ACS. Prompt diagnosis and management with intravenous fluids, analgesics, aggressive incentive spirometry, supplemental oxygen or respiratory support, antibiotics, and transfusion therapy, are key to the prevention of clinical deterioration. Bronchodilators should be considered if there is history of asthma or in the presence of acute bronchospasm. Treatment with hydroxyurea should be considered for prevention of recurrent episodes. This review evaluates the etiology, pathophysiology, risk factors, clinical presentation of ACS, and preventive and treatment strategies for effective management of ACS.

Placental growth factor: What hematologists need to know

Although first identified in placenta, the angiogenic factor known as placental growth factor (PlGF) can be widely expressed in ischemic or damaged tissues. Recent studies have indicated that PlGF is a relevant factor in the pathobiology of blood diseases including hemoglobinopathies and hematologic malignancies. Therapies for such blood diseases may one day be based upon these and ongoing investigations into the role of PlGF in sickle cell disease, acute and chronic leukemias, and complications related to hematopoietic cell transplantation. In this review, we summarize recent studies regarding the potential role of PlGF in blood disorders and suggest avenues for future research.

Inhaled bronchodilators for acute chest syndrome in people with sickle cell disease

BACKGROUND

Bronchodilators are used to treat bronchial hyper-responsiveness in asthma. Bronchial hyper-responsiveness may be a component of acute chest syndrome in people with sickle cell disease. Therefore, bronchodilators may be useful in the treatment of acute chest syndrome. This is an update of a previously published Cochrane Review.

OBJECTIVES

To assess the benefits and risks associated with the use of bronchodilators in people with acute chest syndrome.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearches of relevant journals and abstract books of conference proceedings. Additional searches were carried out on MEDLINE (1966 to 2002) and Embase (1981 to 2002).Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 11 July 2016.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials. Trials using quasi-randomisation methods will be included in future updates of this review if there is sufficient evidence that the treatment and control groups are similar at baseline.

DATA COLLECTION AND ANALYSIS

We found no trials investigating the use of bronchodilators for acute chest syndrome in people with sickle cell disease.

MAIN RESULTS

We found no trials investigating the use of bronchodilators for acute chest syndrome in people with sickle cell disease.

AUTHORS' CONCLUSIONS

If bronchial hyper-responsiveness is an important component of some episodes of acute chest syndrome in people with sickle cell disease, the use of inhaled bronchodilators may be indicated. There is need for a well-designed, adequately-powered randomised controlled trial to assess the benefits and risks of the addition of inhaled bronchodilators to established therapies for acute chest syndrome in people with sickle cell disease.

Higher prevalence of wheezing and lower FEV1 and FVC percent predicted in adults with sickle cell anaemia: A cross-sectional study

BACKGROUND AND OBJECTIVE

Respiratory symptoms including wheezing are common in adults with sickle cell anaemia (SCA), even in the absence of asthma. However, the prevalence of spirometry changes and respiratory symptoms in adults with SCA is unknown.

METHODS

Using a cross-sectional study design, we tested the hypothesis that adults with SCA (cases) would have higher rates of lower airway obstruction and wheezing than those without SCA (controls) using the American Thoracic Society Division of Lung Diseases' questionnaire. Patients were adults with SCA aged between 18 and 65 years. Controls were consecutive unselected individuals without SCA who presented to an outpatient general medicine clinic.

RESULTS

We enrolled 150 adults with SCA and 287 consecutive controls without SCA. The median age was 23.0 and 27.0 years for adults with and without SCA, respectively. Cases were more likely to report cough without a cold (35.0% vs 18.6%, P < 0.001), lower forced expiratory volume in 1 s (FEV₁ ) % predicted (70.1% vs 82.1%, P = 0.001) and lower forced vital capacity (FVC) % predicted (67.4% vs 74.9%, P = 0.001) than controls. In the multivariable model, wheezing was significantly associated with SCA status (OR = 1.69, 95% CI = 1.08-2.65, P = 0.024). Similarly, FEV₁ % predicted was significantly associated with SCA status and wheezing (P = 0.001 for both).

CONCLUSION

Adults with SCA experience a higher rate of wheezing and impaired respiratory functions compared with controls from the same region.

Airway hyperreactivity is frequent in non-asthmatic children with sickle cell disease

BACKGROUND

Asthma is associated with poorer outcomes in sickle cell disease (SCD). Whether AHR can exist in SCD as a distinct entity, separate and independent of asthma, is unknown.

AIMS

Our goal was to elucidate the prevalence of AHR, as measured by a methacholine challenge test (MCT), in children with SCD who did not have concomitant asthma or any recent history of acute chest syndrome (ACS). To determine if AHR was associated with asthma-like symptoms, we compared the results of the MCT to a validated asthma questionnaire. We also examined if a correlation between AHR and inflammatory markers exists.

METHODS

AHR was identified with a positive MCT defined as a provocation concentration (PC20 ) < 4 mg/ml. The children and/or their parents completed the ISAAC (International Study of Asthma and Allergies in Children) questionnaire. We obtained blood, urine, and exhaled breath condensate samples. We measured cysteinyl leukotriene levels in urine and exhaled breath condensate via enzyme immunoassay.

RESULTS

Twenty-nine of forty children (72.5%) had a positive MCT. Nine (31.0%) also reported asthma-like symptoms on questionnaire. Inflammatory markers did not correlate with AHR. Among MCT positive subjects, those on hydroxyurea had significantly less severe AHR as quantified by PC20 (P = 0.014).

CONCLUSIONS

In children with SCD, there is a high prevalence of AHR that is not associated with asthma-like symptoms. AHR may be a distinct entity in children with SCD, existing in the absence of concomitant asthma. Hydroxyurea therapy might lessen the severity of AHR in affected individuals. Pediatr Pulmonol. 2016; 51:950-957. © 2015 Wiley Periodicals, Inc.

Pulmonary Function Tests in Sickle Cell Disease

OBJECTIVE

To determine pulmonary function abnormalities in children with Sickle Cell Disease (SCD) from Western India.

METHODS

In this cross sectional study conducted at Surat, Gujarat, India; equal number of age and gender matched children i.e., 99 in the age group of 6-18 y was recruited in case (children with SCD) and control (non-SCD healthy children) groups respectively. Weight, height, body mass index (BMI) and hemoglobin (Hb) were assessed as baseline characteristics and spirometry was performed to assess the pulmonary function.

RESULTS

The two groups of children were comparable in the baseline characteristics such as weight, height and BMI, however mean hemoglobin was significantly low in SCD as compared to healthy controls [9.1 ± 1.52 vs. 11.4 ± 1.04 (p=0.001)]. Mean (% predicted) Forced expiratory volume in 1 s (FEV1) (86.79 ± 11.6 vs. 94.3 ± 16.1) and FVC (84.4 ± 11.5 vs. 91.75 ± 15.2) values were significantly low (p < 0.001) in cases.

CONCLUSIONS

The present study revealed that the difference of pulmonary function tests between sickle cell patients and normal age matched controls were statistically significant but this difference was not clinically significant.

Acute Chest Syndrome in Sickle Cell Disease: Pathophysiology and Management

Acute chest syndrome (ACS) is defined as the development of a new pulmonary infiltrate and respiratory symptoms in a patient with sickle cell disease (SCD). One of the most serious complications of SCD, ACS is the leading cause of mortality in patients with SCD. ACS is age dependent, with children having milder disease that often is infectious. Adults often have more severe disease, with pulmonary fat embolism secondary to preceding long bone infarction frequently as a contributing factor. Rapid diagnosis and a high index of suspicion are crucial since this syndrome may have a high mortality rate. A high white blood cell count and a felling hemoglobin tend to be associated with this illness. Patients are often febrile, but may not have positive blood or sputum cultures. Appropriate therapy includes judicious fluids, close attention to respiratory care, antibiotics, and transfusion therapy. Use of the drug, hydroxyurea, has been shown to decrease the incidence of ACS. Patients with repeated episodes are at risk for the development of chronic lung disease and pulmonary hypertension. New treatment strategies such as inhibitors of cytokines and pulmonary vasodilators such as nitric oxide may reduce the high mortality of ACS.

The intersection between asthma and acute chest syndrome in children with sickle-cell anaemia

Acute chest syndrome is a frequent cause of acute lung disease in children with sickle-cell disease. Asthma is common in children with sickle-cell disease and is associated with increased incidence of vaso-occlusive pain events, acute chest syndrome episodes, and earlier death. Risk factors for asthma exacerbation and an acute chest syndrome episode are similar, and both can present with shortness of breath, chest pain, cough, and wheezing. Despite overlapping risk factors and symptoms, an acute exacerbation of asthma or an episode of acute chest syndrome are two distinct entities that need disease-specific management strategies. Although understanding has increased about asthma as a comorbidity in sickle-cell disease and its effects on morbidity, substantial gaps remain in knowledge about best management.

New strategies for the treatment of pulmonary hypertension in sickle cell disease : the rationale for arginine therapy

Nitric oxide (NO) is inactivated in sickle cell disease (SCD), while bioavailability of arginine, the substrate for NO synthesis, is diminished. Impaired NO bioavailability represents the central feature of endothelial dysfunction, and is a key factor in the pathophysiology of SCD. Inactivation of NO correlates with the hemolytic rate and is associated with erythrocyte release of cell-free hemoglobin and arginase during hemolysis. Accelerated consumption of NO is enhanced further by the inflammatory environment of oxidative stress that exists in SCD. Based upon its critical role in mediating vasodilation and cell growth, decreased NO bioavailability has also been implicated in the pathogenesis of pulmonary arterial hypertension (PHT). Secondary PHT is a common life-threatening complication of SCD that also occurs in most hereditary and chronic hemolytic disorders. Aberrant arginine metabolism contributes to endothelial dysfunction and PHT 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 PHT. Decompartmentalization of hemoglobin into plasma consumes endothelial NO and thus drives a metabolic requirement for arginine, whose bioavailability is further limited by arginase activity. New treatments aimed at maximizing both arginine and NO bioavailability through arginase inhibition, suppression of hemolytic rate, or oral arginine supplementation may represent novel therapeutic strategies.

Preschool Wheezing Phenotypes

Wheezing in preschool children is very common, with a wide differential diagnosis. It is essential to be sure of the exact sound that parents are describing; the term ‘wheeze‘ is often applied to non-specific sounds. Structural airway disease such as vascular ring should be considered. Thereafter we propose that umbrella terms for preschool wheeze should be abandoned in favour of ‘Hargreave phenotyping’, in which the presence and extent of the components of infection, inflammation, variable airflow obstruction, and fixed airflow obstruction are determined as far as is possible, rather than using a general umbrella term such as ‘asthma’. The justification for this approach is that it leads to a logical approach to treatment in the disparate airway diseases presenting in the preschool years, and should hopefully prevent over-treatment with inhaled corticosteroids. If, despite this approach, doubt remains as to the nature of the airway disease, then a therapeutic trial of treatment is permissible, but it should be for a short defined period only. In any event, such children should be reviewed regularly to see if treatments need to be changed.

Inflammatory targets of therapy in sickle cell disease

Sickle cell disease (SCD) is a monogenic globin disorder characterized by the production of a structurally abnormal hemoglobin (Hb) variant Hb S, which causes severe hemolytic anemia, episodic painful vaso-occlusion, and ultimately end-organ damage. The primary disease pathophysiology is intracellular Hb S polymerization and consequent sickling of erythrocytes. It has become evident for more than several decades that a more complex disease process contributes to the myriad of clinical complications seen in patients with SCD with inflammation playing a central role. Drugs targeting specific inflammatory pathways therefore offer an attractive therapeutic strategy to ameliorate many of the clinical events in SCD. In addition, they are useful tools to dissect the molecular and cellular mechanisms that promote individual clinical events and for developing improved therapeutics to address more challenging clinical dilemmas such as refractoriness to opioids or hyperalgesia. Here, we discuss the prospect of targeting multiple inflammatory pathways implicated in the pathogenesis of SCD with a focus on new therapeutics, striving to link the actions of the anti-inflammatory agents to a defined pathobiology, and specific clinical manifestations of SCD. We also review the anti-inflammatory attributes and the cognate inflammatory targets of hydroxyurea, the only Food and Drug Administration-approved drug for SCD.

Placenta growth factor augments airway hyperresponsiveness via leukotrienes and IL-13

Airway hyperresponsiveness (AHR) affects 55%-77% of children with sickle cell disease (SCD) and occurs even in the absence of asthma. While asthma increases SCD morbidity and mortality, the mechanisms underlying the high AHR prevalence in a hemoglobinopathy remain unknown. We hypothesized that placenta growth factor (PlGF), an erythroblast-secreted factor that is elevated in SCD, mediates AHR. In allergen-exposed mice, loss of Plgf dampened AHR, reduced inflammation and eosinophilia, and decreased expression of the Th2 cytokine IL-13 and the leukotriene-synthesizing enzymes 5-lipoxygenase and leukotriene-C4-synthase. Plgf-/- mice treated with leukotrienes phenocopied the WT response to allergen exposure; conversely, anti-PlGF Ab administration in WT animals blunted the AHR. Notably, Th2-mediated STAT6 activation further increased PlGF expression from lung epithelium, eosinophils, and macrophages, creating a PlGF/leukotriene/Th2-response positive feedback loop. Similarly, we found that the Th2 response in asthma patients is associated with increased expression of PlGF and its downstream genes in respiratory epithelial cells. In an SCD mouse model, we observed increased AHR and higher leukotriene levels that were abrogated by anti-PlGF Ab or the 5-lipoxygenase inhibitor zileuton. Overall, our findings indicate that PlGF exacerbates AHR and uniquely links the leukotriene and Th2 pathways in asthma. These data also suggest that zileuton and anti-PlGF Ab could be promising therapies to reduce pulmonary morbidity in SCD.

Sickle cell disease: wheeze or asthma?

Sickle cell disease (SCD) is the most common life-limiting genetic disease among African Americans, affecting more than 100,000 people in the United States. Respiratory disorders in patients with sickle cell disease have been associated with increased morbidity and mortality. Associations between asthma and pain, acute chest syndrome (ACS), and even death have long been reported. More recently wheezing, even in the absence of an asthma diagnosis, has gained attention as a possible marker of SCD severity. Several challenges exist with regards to making the diagnosis of asthma in patients with SCD, including the high prevalence of wheezing, evidence of airway obstruction on pulmonary function testing, and/or airway hyperresponsiveness among patients with SCD. These features often occur in isolation, in the absence of other clinical criteria necessary for an asthma diagnosis. In this review we will summarize: 1) Our current understanding of the epidemiology of asthma, wheezing, airway obstruction, and airway responsiveness among patients with SCD; 2) The evidence supporting associations with SCD morbidity; 3) Our understanding of the pathophysiology of airway inflammation in SCD; 4) Current approaches to diagnosis and management of asthma in SCD; and 5) Future directions.

The sickle cell mouse lung: proinflammatory and primed for allergic inflammation

Comorbid asthma in sickle cell disease (SCD) confers higher rates of vaso-occlusive pain and mortality, yet the physiological link between these two distinct diseases remains puzzling. We used a mouse model of SCD to study pulmonary immunology and physiology before and after the induction of allergic airway disease (AAD). SCD mice were sensitized with ovalbumin (OVA) and aluminum hydroxide by the intraperitoneal route followed by daily, nose-only OVA-aerosol challenge to induce AAD. The lungs of naive SCD mice showed signs of inflammatory and immune processes: (1) histologic and cytochemical evidence of airway inflammation compared with naive wild-type mice; (2) bronchoalveolar lavage (BAL) fluid contained increased total lymphocytes, %CD8+ T cells, granulocyte-colony stimulating factor, interleukin 5 (IL-5), IL-7, and chemokine (C-X-C motif) ligand (CXCL)1; and (3) lung tissue and hilar lymph node (HLN) had increased CD4+, CD8+, and regulatory T (Treg) cells. Furthermore, SCD mice at AAD demonstrated significant changes compared with the naive state: (1) BAL fluid with increased %CD4+ T cells and Treg cells, lower %CD8+ T cells, and decreased interferon gamma, CXCL10, chemokine (C-C motif) ligand 2, and IL-17; (2) serum with increased OVA-specific immunoglobulin E, IL-6, and IL-13, and decreased IL-1α and CXCL10; (3) no increase in Treg cells in the lung tissue or HLN; and (4) hyporesponsiveness to methacholine challenge. In conclusion, SCD mice have an altered immunologic pulmonary milieu and physiological responsiveness. These findings suggest that the clinical phenotype of AAD in SCD mice differs from that of wild-type mice and that individuals with SCD may also have a unique, divergent phenotype perhaps amenable to a different therapeutic approach.

Application of an Asthma Screening Questionnaire in Children with Sickle Cell Disease

Objective: Asthma in sickle cell disease (SCD) patients is associated with elevated morbidity and mortality. Early detection and initiation of treatment may therefore lead to improved outcome. Utility of an asthma screening questionnaire to identify obstructive airway disease and physician diagnosed asthma in children with SCD at an outpatient setting as an effective, easy-to-administer screening tool has not previously been evaluated in this population. Methods: A previously validated asthma screening questionnaire and spirometry were prospectively administered to 41 SCD children at a routine clinic visit. Results: Prevalence of obstructive airway was 51.2% (n = 21) and physician diagnosis of asthma 33.3% (n = 13). Sensitivity (40%) and specificity (75%) of the questionnaire was poor in detecting obstructive airway disease, but sensitivity (77%), specificity (100%), positive predictive value (100%), and negative predictive value (90%) were high in detecting physician diagnosis of asthma. Conclusion: An asthma screening questionnaire could be a useful tool in identifying at-risk SCD children who may benefit from further management.

Genetic diminution of circulating prothrombin ameliorates multiorgan pathologies in sickle cell disease mice

Sickle cell disease (SCD) results in vascular occlusions, chronic hemolytic anemia, and cumulative organ damage. A conspicuous feature of SCD is chronic inflammation and coagulation system activation. Thrombin (factor IIa [FIIa]) is both a central protease in hemostasis and a key modifier of inflammatory processes. To explore the hypothesis that reduced prothrombin (factor II [FII]) levels in SCD will limit vaso-occlusion, vasculopathy, and inflammation, we used 2 strategies to suppress FII in SCD mice. Weekly administration of FII antisense oligonucleotide "gapmer" to Berkeley SCD mice to selectively reduce circulating FII levels to ∼10% of normal for 15 weeks significantly diminished early mortality. More comprehensive, long-term comparative studies were done using mice with genetic diminution of circulating FII. Here, cohorts of FII(lox/-) mice (constitutively carrying ∼10% normal FII) and FII(WT) mice were tracked in parallel for a year following the imposition of SCD via hematopoietic stem cell transplantation. This genetically imposed suppression of FII levels resulted in an impressive reduction in inflammation (reduction in leukocytosis, thrombocytosis, and circulating interleukin-6 levels), reduced endothelial cell dysfunction (reduced endothelial activation and circulating soluble vascular cell adhesion molecule), and a significant improvement in SCD-associated end-organ damage (nephropathy, pulmonary hypertension, pulmonary inflammation, liver function, inflammatory infiltration, and microinfarctions). Notably, all of these benefits were achieved with a relatively modest 1.25-fold increase in prothrombin times, and in the absence of hemorrhagic complications. Taken together, these data establish that prothrombin is a powerful modifier of SCD-induced end-organ damage, and present a novel therapeutic target to ameliorate SCD pathologies.

Wheezing is common in children with sickle cell disease when compared with controls

In children with sickle cell disease (SCD), wheezing may occur in the absence of asthma. However, the prevalence of wheezing in children with SCD when compared with children without SCD (controls) in the same setting is unknown. Using a case-control study design, we tested the hypothesis that children with SCD would have a higher rate of wheezing than those without SCD. We enrolled 163 children with SCD (cases) and 96 children without SCD (controls) from a community hospital in Nigeria. Parent reports of respiratory symptoms were identified based on responses to questions taken from the American Thoracic Society Division of Lung Diseases' Questionnaire. The median age was 8.5 years for children with SCD and 7.7 years for controls. Cases were more likely than controls to report wheezing both with colds (17.3% vs. 2.1%, P<0.01) and without colds (4.9% vs. 0%, P=0.03). Cases had 9.8 times greater odds of wheezing (95% confidence interval, 2.3-42.2). In the multivariable model, the only variable associated with wheezing was SCD status (odds ratio=18.7, 95% confidence interval, 2.5-142; P=0.005). Children with SCD experience a significantly higher rate of wheezing when compared with children of similar age without SCD.

Inhaled bronchodilators for acute chest syndrome in people with sickle cell disease

BACKGROUND

Bronchodilators are used to treat bronchial hyper-responsiveness in asthma. Bronchial hyper-responsiveness may be a component of acute chest syndrome in people with sickle cell disease. Therefore, bronchodilators may be useful in the treatment of acute chest syndrome.

OBJECTIVES

To assess the benefits and risks associated with the use of bronchodilators in people with acute chest syndrome.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearches of relevant journals and abstract books of conference proceedings. Additional searches were carried out on MEDLINE (1966 to 2002) and Embase (1981 to 2002).Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 17 March 2014.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials. Trials using quasi-randomisation methods will be included in future updates of this review if there is sufficient evidence that the treatment and control groups are similar at baseline.

DATA COLLECTION AND ANALYSIS

We found no trials investigating the use of bronchodilators for acute chest syndrome in people with sickle cell disease.

MAIN RESULTS

We found no trials investigating the use of bronchodilators for acute chest syndrome in people with sickle cell disease.

AUTHORS' CONCLUSIONS

If bronchial hyper-responsiveness is an important component of some episodes of acute chest syndrome in people with sickle cell disease, the use of inhaled bronchodilators may be indicated. There is need for a well-designed, adequately-powered randomised controlled trial to assess the benefits and risks of the addition of inhaled bronchodilators to established therapies for acute chest syndrome in people with sickle cell disease.

Obstructive sleep apnea and sickle cell anemia

OBJECTIVE

To ascertain the prevalence of and risk factors for obstructive sleep apnea syndrome (OSAS) in children with sickle cell anemia (SCA).

METHODS

Cross-sectional baseline data were analyzed from the Sleep and Asthma Cohort Study, a multicenter prospective study designed to evaluate the contribution of sleep and breathing abnormalities to SCA-related morbidity in children ages 4 to 18 years, unselected for OSAS symptoms or asthma. Multivariable logistic regression assessed the relationships between OSAS status on the basis of overnight in-laboratory polysomnography and putative risk factors obtained from questionnaires and direct measurements.

RESULTS

Participants included 243 children with a median age of 10 years; 50% were boys, 99% were of African heritage, and 95% were homozygous for β(S) hemoglobin. OSAS, defined by obstructive apnea hypopnea indices, was present in 100 (41%) or 25 (10%) children at cutpoints of ≥1 or ≥5, respectively. In univariate analyses, OSAS was associated with higher levels of habitual snoring, lower waking pulse oxygen saturation (Spo2), reduced lung function, less caretaker education, and non-preterm birth. Lower sleep-related Spo2 metrics were also associated with higher obstructive apnea hypopnea indices. In multivariable analyses, habitual snoring and lower waking Spo2 remained risk factors for OSAS in children with SCA.

CONCLUSIONS

The prevalence of OSAS in children with SCA is higher than in the general pediatric population. Habitual snoring and lower waking Spo2 values, data easily obtained in routine care, were the strongest OSAS risk factors. Because OSAS is a treatable condition with adverse health outcomes, greater efforts are needed to screen, diagnose, and treat OSAS in this high-risk, vulnerable population.

Airways obstruction and pulmonary capillary blood volume in children with sickle cell disease

OBJECTIVES AND WORKING HYPOTHESIS

Airways obstruction occurs in young children with sickle cell disease (SCD). Our aim was to test the hypothesis that increased pulmonary capillary blood volume at least in part explained the increased airways obstruction as this would inform which therapy might be most appropriate to treat the airway obstruction.

STUDY DESIGN

Observational study.

PATIENT-SUBJECT SELECTION

Twenty-five SCD children and 25 ethnic origin matched controls were recruited.

METHODOLOGY

Respiratory system resistance, using impulse oscillometry at 5 Hz (R5 %pred), pulmonary capillary blood volume (Vc), alveolar volume (VA), and spirometry were assessed before and after bronchodilator (ipratropium bromide). Lung volume measurements were also made.

RESULTS

The SCD children compared to the controls had a higher R5 %pred before (median 133 (range 88-181)% vs. 102 (83-184)%, P = 0.0046) and after (105 (79-150)% vs. 91 (64-147)%, P = 0.0489) bronchodilator and their median Vc/VA (ml/L) was higher before (26 (18-38) vs. 18 (14-28) P < 0.0001) and after (26 (19-41) vs. 18 (13-27) P < 0.0001) bronchodilator. There were similar decreases in R5 %pred post-bronchodilator in the two groups, but no significant changes in Vc/VA in either group. Vc/VA correlated significantly with R5 %pred in the SCD children only.

CONCLUSIONS

Increased pulmonary capillary blood volume contributes to the increased airways obstruction in children with SCD, hence, bronchodilators may be of limited benefit in reducing their airways obstruction.

Respiratory syncytial virus and seasonal influenza cause similar illnesses in children with sickle cell disease

BACKGROUND

Respiratory syncytial virus (RSV) is a cause of acute chest syndrome (ACS) in sickle cell disease (SCD), but its clinical course and acute complications have not been well characterized. We compared RSV to seasonal influenza infections in children with SCD.

PROCEDURE

We defined cases as laboratory-confirmed RSV or seasonal influenza infection in inpatients and outpatients <18 years of age with SCD from 1 September 1993 to 30 June 2011. We used Fisher's exact test to compare proportions, Student's t-test or Wilcoxon rank-sum test to compare continuous variables, and logistic regression to evaluate associations.

RESULTS

We identified 64 children with RSV and 91 with seasonal influenza. Clinical symptoms, including fever, cough, and rhinorrhea were similar for RSV and influenza, as were complications, including ACS and treatments for SCD. In a multivariable logistic regression model, older age (OR 1.2 per year, 95% CI [1.02-1.5], P = 0.04), increased white blood cell count at presentation (OR 1.1 per 1,000/μl increase, 95% CI [1.03-1.3], P = 0.008), and a history of asthma (OR 7, 95% [CI 1.3-37], P = 0.03) were independently associated with increased risk of ACS in children with RSV. The hospitalization rate for children with SCD and RSV (40 per 1,000 <5 years and 63 per 1,000 <2 years) greatly exceeds the general population (3 in 1,000 <5 years).

CONCLUSIONS

We conclude that RSV infection is often associated with ACS and similar in severity to influenza infection in febrile children with SCD.

Abnormal pulmonary function and associated risk factors in children and adolescents with sickle cell anemia

Obstructive and restrictive pulmonary changes develop in children with sickle cell disease, but reports conflict as to the type of change that predominates. We prospectively performed spirometry, plethysmography, and lung diffusing capacity in 146 children aged 7 to 20 years with hemoglobin SS or Sβ(0)-thalassemia. Nineteen percent of the patients had obstructive physiology as defined according to guidelines of the American Thoracic Society. In addition, 9% had restrictive physiology and 11% had abnormal but not categorized physiology. Increasing age, patient-reported or family-reported history of asthma or wheezing, and higher lactate dehydrogenase concentration were independent predictors of obstruction as reflected in lower forced expiratory volume in the first second/forced vital capacity. In conclusion, abnormal pulmonary function, most often obstructive, is common in children with hemoglobin SS and Sβ(0)-thalassemia. Full pulmonary function testing should be performed in children with hemoglobin SS or Sβ(0)-thalassemia, especially with history of asthma or wheezing and accentuated elevations in hemolytic markers.

Wheezing symptoms and parental asthma are associated with a physician diagnosis of asthma in children with sickle cell anemia

OBJECTIVE

To identify factors associated with asthma associated with increased sickle cell anemia (SCA).

STUDY DESIGN

Children with SCA (N = 187; mean age 9.6 years, 48% male) were classified as having "asthma" based on parent report of physician diagnosis plus prescription of asthma medication (n = 53) or "no asthma" based on the absence of these features (n = 134). Pain and acute chest syndrome (ACS) events were collected prospectively.

RESULTS

Multiple variable logistic regression model identified 3 factors associated with asthma: parent with asthma (P = .006), wheezing causing shortness of breath (P = .001), and wheezing after exercise (P < .001). When ≥2 features were present, model sensitivity was 100%. When none of the features were present, model sensitivity was 0%. When only 1 feature was present, model sensitivity was also 0%, and presence of ≥2 of positive allergy skin tests, airway obstruction on spirometry, and bronchodilator responsiveness did not improve clinical utility. ACS incident rates were significantly higher in individuals with asthma than in those without asthma (incident rate ratio 2.21, CI 1.31-3.76), but pain rates were not (incident rate ratio 1.28, CI 0.78-2.10).

CONCLUSIONS

For children with SCA, having a parent with asthma and specific wheezing symptoms are the best features to distinguish those with and without parent report of a physician diagnosis of asthma and to identify those at higher risk for ACS events. The value of treatment for asthma in the prevention of SCA morbidity needs to be studied.

Hypoxemia in sickle cell disease: significance and management

Hypoxemia is common in SCD and likely exacerbates SCD vasculopathy. Pulse oximeter correlation with arterial oxygen tension in patients with SCD may at times be poor and arterial blood gas confirmation is required in hypoxic patients. Supplemental oxygen should be administered for the correction of hypoxemia, which if untreated creates a risk of multi-organ failure. Transfusion and hydroxyurea can improve oxygen delivery to tissues and organs. The role of supplemental oxygen therapy in preventing or reversing SCD vasculopathy is controversial. Nitric oxide therapy for VOC pain has not fulfilled promise to date. On the other hand, lung distension (CPAP, incentive spirometry, PEP therapy) are promising treatments requiring further study.

Lung function in sickle cell disease

Although some of the most severe complications of Sickle Cell Disease (SCD) tend to be acute and severe (e.g. acute chest syndrome, stroke etc.), the chronic ones can be equally debilitating. Prominent among them is the effect that the disease has on lung growth and function. For many years the traditional teaching has been that SCD is associated with the development of a restrictive lung defect. However, there is increasing evidence that this is not a universal finding and that at least during childhood and adolescence, the majority of the patients have a normal or obstructive pattern of lung function. The following article reviews the current knowledge on the effects of SCD on lung growth and function. Special emphasis is given to the controversies among the published articles in the literature and discusses possible causes for these discrepancies.

Reduced forced expiratory flow but not increased exhaled nitric oxide or airway responsiveness to methacholine characterises paediatric sickle cell airway disease

BACKGROUND

Asthma and airway hyper-responsiveness are reportedly more common in children with sickle cell disease (SCD).

AIM

To determine airway responsiveness, airway inflammation and clinical features of asthma in SCD.

METHODS

A prospective, single-centre study of 50 SCD children without overt pulmonary vascular disease and 50 controls. Exhaled nitric oxide (FeNO) and total serum IgE were measured and spirometry and methacholine challenge were performed. The methacholine dose-response slope (DRS) was calculated.

RESULTS

Doctor diagnosis of asthma was made in 7 (14%) SCD versus 12 (24%) control subjects (p=0.203). FeNO levels were similar in SCD and controls (p=0.250), and were higher in those with atopy and an asthma diagnosis (OR 4.33, 95% CI 1.7 to 11.1; p<0.05). zFEV1 (p=0.002) and zFEV1/FVC (p=0.003) but not zFVC (p=0.098) were lower in SCD versus controls. DRS was higher in those with asthma (p=0.006) but not in SCD versus controls (p=0.403). DRS correlated with FeNO and blood eosinophil count in controls but not SCD. In SCD, DRS was higher in those admitted to hospital with respiratory symptoms (n=27) versus those never admitted (n=23) (p=0.046). DRS was similar in those with at least one acute chest syndrome episode (n=12) versus those with none (n=35) (p=0.247).

CONCLUSIONS

SCD children have airflow obstruction despite having minimal evidence of pulmonary vascular disease. Airflow obstruction is not associated with increased methacholine sensitivity or eosinophilic inflammation, at least as judged by FeNO. Airflow obstruction in SCD does not appear to be related to childhood eosinophilic asthma, but its pathophysiology remains ill understood.

Wheezing in children with sickle cell disease

PURPOSE OF REVIEW

The purpose of this article is to provide a comprehensive review of wheezing in sickle cell disease (SCD), including epidemiology, pathophysiology, associations between wheezing and SCD morbidity and finally the clinical approach to evaluation and management of individuals with SCD who wheeze.

RECENT FINDINGS

Wheezing is common in SCD and in some individuals represents an intrinsic component of SCD-related lung disease rather than asthma. Emerging data suggest that, regardless of the cause, individuals with SCD and with recurrent wheezing are at increased risk for subsequent morbidity and premature mortality. We believe individuals who acutely wheeze and have respiratory symptoms should be managed with a beta agonist and short-term treatment of oral steroids, typically less than 3 days to attenuate rebound vaso-occlusive disease. For those who wheeze and have a history or examination associated with atopy, we consider asthma treatment and monitoring per National Heart, Lung and Blood Institute asthma guidelines.

SUMMARY

Wheezing in SCD should be treated aggressively both in the acute setting and with controller medications. Prospective SCD-specific clinical trials will be necessary to address whether anti-inflammatory asthma therapies (leukotriene antagonists, inhaled corticosteroids) can safely mitigate the sequelae of wheezing in SCD.

Asthma management in sickle cell disease

Asthma is a common comorbid factor in sickle cell disease (SCD). However, the incidence of asthma in SCD is much higher than expected compared to rates in the general population. Whether "asthma" in SCD is purely related to genetic and environmental factors or rather is the consequence of the underlying hemolytic and inflammatory state is a topic of recent debate. Regardless of the etiology, hypoxemia induced by bronchoconstriction and inflammation associated with asthma exacerbations will contribute to a cycle of sickling and subsequent complications of SCD. Recent studies confirm that asthma predisposes to complications of SCD such as pain crises, acute chest syndrome, and stroke and is associated with increased mortality. Early recognition and aggressive standard of care management of asthma may prevent serious pulmonary complications and reduce mortality. However, data regarding the management of asthma in SCD is very limited. Clinical trials are needed to evaluate the effectiveness of current asthma therapy in patients with SCD and coincident asthma, while mechanistic studies are needed to delineate the underlying pathophysiology.

Pulmonary function abnormalities and asthma are prevalent in children with sickle cell disease and are associated with acute chest syndrome

Pulmonary diseases form major sources of morbidity and mortality in children with sickle cell disease (SCD). The objective of the study was to determine the prevalence of lung function abnormalities and asthma and their association with acute chest syndrome (ACS) in children with SCD. This was a cross-sectional retrospective study of 127 children with SCD; we collected information regarding ACS and asthma and pulmonary function test (PFT) data. Based on PFT results, the patients were assigned to one pattern of lung function [normal, obstructive lung disease (OLD), restrictive lung disease (RLD)]. Statistical analyses included Pearson correlation, prevalence odds ratio (POR), cross-tabulation, and multiple binary logistic regression. OLD was noted in 35% and RLD in 23% of the patients, with the remainder exhibiting a normal PFT pattern. Forty-six percent of patients had asthma, 64% of whom had a history of ACS. OLD (r = .244, P = .008, POR = 2.8) and asthma (r = .395, P < .001, POR = 5.4) were significantly associated with a history of ACS. There was a negative correlation between having normal PFT data and a history of ACS (r = -.289, P = .002, POR = .3). Asthma and pulmonary function abnormalities are prevalent in children with SCD, with OLD being more common than RLD. There is an association between asthma, OLD, and ACS, however causality cannot be proven due to the study design. We stress the importance of actively investigating for a clinical diagnosis of asthma in all patients with SCD and suggest that PFT data may help detect patients at lower risk for ACS.

Outcome and challenges of kidney transplant in patients with sickle cell disease

Sickle cell nephropathy is a common presentation in patients with sickle cell disease. End-stage kidney disease is the most severe presentation of sickle cell nephropathy in terms of morbidity and mortality. Sickle cell disease patients with end-stage kidney disease are amenable to renal replacement therapy including kidney transplant. Kidney transplant in these patients has been associated with variable outcome with recent studies reporting short- and long-term outcomes comparable to that of patients with HbAA. Sickle cell disease patients are predisposed to various haematological, cardiorespiratory, and immunological challenges. These challenges have the potential to limit, delay, or prevent kidney transplant in patients with sickle cell disease. There are few reports on the outcome and challenges of kidney transplant in this group of patients. The aim of this review is to highlight the outcome and challenges of kidney transplant in patients with sickle cell disease.