The Role of RIB Infarcts in the Acute Chest Syndrome of Sickle Cell Diseases

Acute chest syndrome of sickle cell disease: genetics, risk factors, prognosis and management

IntroductionSickle cell disease, one of the world's most prevalent Mendelian disorders, is a chronic hemolytic anemia punctuated by acute vasoocclusive events. Both hemolysis and vasoocclusion lead to irreversible organ damage and failure. Among the many sub-phenotypes of sickle cell disease is the acute chest syndrome (ACS) characterized by combinations of chest pain, cough, dyspnea, fever, abnormal lung exam, leukocytosis, hypoxia, and new radiographic opacities. ACS is a major cause of morbidity and mortality.Area coveredWe briefly review the diagnosis, epidemiology, etiology, and current treatments for ACS and focus on understanding and estimating the risks for developing this complication, how prognosis and outcomes might be improved and the genetic elements that might impact the risk of ACS.Expert opinionThe clinical heterogeneity of ACS has hindered our understanding of risk stratification. Lacking controlled clinical trials most treatment is based on expert opinion. Fetal hemoglobin levels and coexistent α thalassemia affect the incidence of ACS; other genetic associations are tenuous. Transfusions, whose use not innocuous, should be targeted to the severity and likelihood of ACS progression. Stable, non-hypoxic patients with favorable hematologic and radiographic findings usually do not need transfusion; severe progressive ACS is best managed with exchange transfusion.

Therapeutic approach to pediatric patients with acute chest syndrome: national multicenter survey of non invasive ventilation (NIV) and transfusion

BACKGROUND

Intensive care units (ICUs) have seen a spike in the use of noninvasive ventilation (NIV) for many medical conditions. We sought to investigate the attitudes and clinical practice regarding the management of acute chest syndrome (ACS) with a focus on NIV in pediatric ICUs.

METHOD

Members of the French Group for Pediatric Intensive Care Emergencies (GFRUP) were asked to complete an online survey on physicians' attitudes toward children with ACS admitted to the PICU during 2015.

RESULTS

The survey was answered by teams from 17 PICUs (240 beds). In total, 15 centers (88%) had a local transfusion unit and 14 (82%) worked in connection with a sickle cell disease (SCD) reference center. During 2015, 360 patients with SCD were managed (median: 7 per center; 21) of whom 137 (38%) for an ACS (median: 4 ACS per center; 8). The median length of PICU stay for ACS was 5 days (3.1). Among the 137 patients who presented with ACS, 73 (53%) received simple blood transfusion and 16 (12%) received exchange transfusion. For patients who required noninvasive ventilatory support, NIV with bilevel pressure (BiPAP) was the most frequent method (n = 68, 50%), followed by continuous positive airway pressure (CPAP) (n = 23, 17%) and high-flow oxygen (n = 21, 15%). The proportion of patients on BiPAP was up to 71% in the centers most frequently managing ACS patients.

CONCLUSION

BiPAP is commonly used in PICUs for SCD patients with ACS, especially in trained centers. Future physiological studies and randomized controlled trials might help to choose the best ventilatory support 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.

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.

Integrating Fat Embolism Syndrome Scoring Indices in Sickle Cell Disease: A Practice Management Review

Fat embolism syndrome (FES) has been described in the literature as a rare complication of sickle cell disease (SCD). A review article published in 2005 reported 24 cases of FES associated with SCD. In many cases, a definitive diagnosis of FES in SCD is made on autopsy because of the lack of early recognition and the paucity of sensitive and specific testing for this syndrome. Patients with FES usually have a fulminant, rapidly deteriorating clinical course with mortality occurring within the first 24 hours. We postulate that FES is not well recognized in SCD and that FES scores are useful diagnostic tools in patients with SCD. We queried the electronic medical records with the diagnostic codes for SCD with acute chest syndrome (ACS), pulmonary embolism, or acute respiratory distress syndrome admitted to our hospital from 2008 to 2016 to identify patients suspected of having FES. In addition, we performed an extensive literature review to evaluate the management practice of pediatric patients with FES and SCD from 1966 to 2016. Six patients met our selection criteria from the hospital records, and 4 case reports from the literature search were also included. We applied the Gurd and Wilson criteria and the Schonfeld Fat Embolism Index to identify patients who met the criteria for FES. Nine patients fulfilled Gurd and Wilson criteria, and 9 patients who were evaluable met the Schonfeld criteria for FES. A rapidly deteriorating clinical course in a patient with SCD presenting with ACS or severe vaso-occlusive crisis should trigger a high index of suspicion for FES. Gurd and Wilson criteria or the Schonfeld Fat Embolism Index are useful diagnostic tools for FES in SCD.

Crises in Sickle Cell Disease

In spite of significant strides in the treatment of sickle cell disease (SCD), SCD crises are still responsible for high morbidity and early mortality. While most patients initially seek care in the acute setting for a seemingly uncomplicated pain episode (pain crisis or vaso-occlusive crisis), this initial event is the primary risk factor for potentially life-threatening complications. The pathophysiological basis of these illnesses is end-organ ischemia and infarction combined with the downstream effects of hemolysis that results from red blood cell sickling. These pathological changes can occur acutely and lead to a dramatic clinical presentation, but are frequently superimposed over a milieu of chronic vasculopathy, immune dysregulation, and decreased functional reserve. In the lungs, acute chest syndrome is a particularly ominous lung injury syndrome with a complex pathogenesis and potentially devastating sequelae, but all organ systems can be affected. It is, therefore, critical to understand the SCD patients' susceptibility to acute complications and their risk factors so that they can be recognized promptly and managed effectively. Blood transfusions remain the mainstay of therapy for all severe acute crises. Recommendations and indications for the safest and most efficient implementation of transfusion strategies in the critical care setting are therefore presented and discussed, together with their pitfalls and potential future therapeutic alternatives. In particular, the importance of extended phenotypic red blood cell matching cannot be overemphasized, due to the high prevalence of severe complications from red cell alloimmunization in SCD.

The Acute Chest Syndrome in Cameroonian children living with sickle cell disease

Background

Although sub-Saharan Africa (SSA) is particularly affected by sickle cell disease (SCD), there is dearth of research on this topic in the region, specifically targeting the magnitude of SCD-related complications. We therefore conducted this study to determine the burden of acute chest syndrome (ACS) and describe its clinical and therapeutic aspects among SCD children in Cameroon, a SSA country.

Methods

This was a retrospective study carried-out from September 2013 to June 2014 at the SCD unit of the Mother and Child Centre of the Chantal Biya Foundation, a pediatric reference centre in Yaoundé, Cameroon. We enrolled all SCD children with confirmed diagnosis of ACS, and recorded their clinical presentation at admission along with their evolution during hospitalization.

Results

Twenty one cases of ACS were identified during the study period, from 338 hospitalizations of children with SCD. Ages ranged from 11 months to 16 years with a mean (standard deviation) of 5.5 (3.4) years, and a male/female sex ratio of 3.2/1. We noticed relatively low levels of HbF, from 6.4 to 21.9 % with a mean of 14.6 % (6.0 %). The three main symptoms at admission were fever (90.5 %), cough (81 %) and chest pains (28.6 %). Two patients (9.5 %) developed ACS 2 days after admission. The mean values of leukocytes, neutrophils, serum CRP, serum LDH and hemoglobin were respectively 32479.4 (17862.3)/mm³, 23476 (11543.7)/mm³, 228.2 (132.6) mg/l, 3452.3 (2916.3) IU/l and 6.5 (1.2) g/dl. The main localizations of radiological alveolar consolidations were the lower lobes (90.5 %). Treatment associated broad-spectrum antibiotics (100 %), hydration (100 %), analgesics (43.2 %), whole blood transfusion (66.7 %), and oxygen supplementation (33.3 %). Blood transfusion significantly improved hemoglobin level (p = 0.039). The duration of hospitalization, the mean of which was 6.8 (3.1) days, was influenced by none of the tested variables (all p values > 0.05).

Conclusion

ACS is frequent among SCD children in our milieu. Its etiologies seem to be multifactorial. Patients’ parents should be educated to recognize early signs and symptoms of the disease, and consult rapidly. Additionally, clinicians must be trained to diagnose ACS, and manage it promptly and efficiently to avoid its related catastrophic consequences.

Bone involvement in sickle cell disease

Bone involvement is the commonest clinical manifestation of sickle cell disease both in the acute setting such as painful vaso-occlusive crises, and as a source of chronic, progressive disability such as avascular necrosis. Management of these problems is often difficult because of the diagnostic imprecision of most laboratory and imaging investigations and because of the lack of evidence for most surgical procedures in sickle cell disease. This review first discusses the acute problems related to bone involvement in sickle cell disease, with particular reference to differentiating infection from infarction, and then describes the long-term effects of sickle cell disease on bone mineral density, growth, and chronic bone and joint damage.

Sickle cell diseases: current therapeutic options and potential pitfalls in preventive therapy for transcranial Doppler abnormalities

Sickle cell disease is an important and common hemoglobinopathy that is highly prevalent worldwide. Recent clinical research has clarified the natural history, and newer, exciting therapeutic maneuvers have been developed, including stem cell transplantation, a curative, albeit toxic strategy. There is a need for early identification of a severe disease profile so that these newer therapeutic interventions can be offered before severe organ damage occurs. Investigative methodologic research by radiologists to discover early organ damage can be important to successful planning of treatment protocols. Stroke is one complication, which, if diagnosed early, can be satisfactorily managed with more aggressive therapy. The advent of transcranial Doppler and MRI have greatly increased the ability to detect early CNS disease.