Acute Asthma Exacerbations in Childhood
Acute Asthma Exacerbations in Childhood
Asthma is a heterogeneous disease more appropriately seen as a syndrome rather than a single pathologic entity. Although it can remain quiescent for extended time periods, the inflammatory and remodeling processes affect the bronchial milieu and predispose to acute and occasionally severe clinical manifestations. The complexity underlying these episodes is enhanced during childhood, an era of ongoing alterations and maturation of key biological systems. In this review, the authors focus on such sudden-onset events, emphasizing on their diversity on the basis of the numerous asthma phenotypes.
Asthma is the most common respiratory chronic disease of childhood: its prevalence has been rising in the western world for the last three decades, up to the point to currently affect a proportion of children as high as 10% in the USA. It is a heterogeneous condition expressed through a plethora of phenotypes that mirror diverse, not fully characterized underlying mechanisms. From this perspective, the definition of asthma as a syndrome rather than a single entity would do justice to the multitude of immunologic, mechanistic and structural factors that orchestrate its pathogenesis. These multiple facets of asthma, perplex both characterization of the disease and the streamlining of efficient treatment measures. Furthermore, the inherent difficulty in illustrating pediatric asthma mechanics (owing to continuously ongoing maturation processes and considerable overlap between diverse phenotypes), further impedes our understanding of the disease in this age group. Asthma exacerbations, for example, are sudden-onset, episodic deteriorations of preexisting disease, and a key cause for anxiety and impaired quality of life in this particularly susceptible age group. Although the clinical manifestations of a severe asthma exacerbation are fairly obvious, they are not specific; moreover, pediatric patients demonstrating more subtle symptoms could pose a diagnostic challenge. Indeed, they commonly present with various nonpathognomonic complaints, including wheezing, cough and respiratory distress. Such a clinical picture could very well fit other pathologic entities that do not warrant treatment on an emergency basis, including respiratory tract infections, laryngomalacia/tracheomalacia, primary ciliary dyskenisia, vocal-cord dysfunction, structural abnormalities of the upper and lower airway, mechanical obstruction, cystic fibrosis, bronchiolitis, acute wheeze and post-bronchiolitis wheeze. Nevertheless, in contrast to many of these conditions, a severe asthma exacerbation has the potential to rapidly culminate in life-threatening respiratory compromise. Indeed, notwithstanding the last decade's advances in our knowledge of asthma pathophysiology, acute exacerbations remain a source of considerable morbidity for patients and financial burden for healthcare systems. Efficient prevention of acute asthma attacks depends on factors such as severity, control of the underlying disease and the definition used for exacerbations. In effect, the lack of objective criteria and of a uniformly accepted definition for an asthma exacerbation impedes our efforts to prevent such events. Therefore, a concise characterization of what is essentially an abrupt and severe worsening of asthma symptoms is of importance. Accordingly, acute asthma exacerbations have been defined as 'episodes of progressive shortness of breath, cough, wheezing and chest tightness presented individually or in combination'. Nevertheless, this definition cannot clearly discriminate exacerbations from transient episodes of inadequate asthma control. Therefore, a definition of asthma exacerbations on the basis of their severity was pursued. In this context, severe incidents were characterized in an American Thoracic Society and European Respiratory Society joint consensus statement as events that urge for immediate action on the part of the patient and physician to prevent a serious outcome, such as hospitalization or death. They should also require systemic corticosteroid administration for at least 3 days. The American Thoracic Society/European Respiratory Society consensus statement also defined moderate asthma exacerbations as "events requiring a temporary change in treatment and entailing at least one of the following for a minimum of 2 days: increased rescue bronchodilator use and lung function deterioration not requiring systematic corticosteroid administration, or an ED visit." On the other hand, mild exacerbations are essentially indiscriminable from single episodes of transient loss of control, being close to the patient's normal range of symptom variation.
Therefore, a long sought-after adequate definition of abrupt 'asthma attacks', a concise categorization of clinically relevant disease and the streamlining of appropriate treatment measures are rendered of importance. Nevertheless, this can be demanding, taking into account the diversity of the disease. A recent pediatric asthma International Consensus (ICON), attempted to establish a basis for clinical evaluation, by defining exacerbations as, "acute or sub-acute episodes of progressive increase in asthma symptoms, associated with airflow obstruction".
Abstract and Introduction
Abstract
Asthma is a heterogeneous disease more appropriately seen as a syndrome rather than a single pathologic entity. Although it can remain quiescent for extended time periods, the inflammatory and remodeling processes affect the bronchial milieu and predispose to acute and occasionally severe clinical manifestations. The complexity underlying these episodes is enhanced during childhood, an era of ongoing alterations and maturation of key biological systems. In this review, the authors focus on such sudden-onset events, emphasizing on their diversity on the basis of the numerous asthma phenotypes.
Introduction
Asthma is the most common respiratory chronic disease of childhood: its prevalence has been rising in the western world for the last three decades, up to the point to currently affect a proportion of children as high as 10% in the USA. It is a heterogeneous condition expressed through a plethora of phenotypes that mirror diverse, not fully characterized underlying mechanisms. From this perspective, the definition of asthma as a syndrome rather than a single entity would do justice to the multitude of immunologic, mechanistic and structural factors that orchestrate its pathogenesis. These multiple facets of asthma, perplex both characterization of the disease and the streamlining of efficient treatment measures. Furthermore, the inherent difficulty in illustrating pediatric asthma mechanics (owing to continuously ongoing maturation processes and considerable overlap between diverse phenotypes), further impedes our understanding of the disease in this age group. Asthma exacerbations, for example, are sudden-onset, episodic deteriorations of preexisting disease, and a key cause for anxiety and impaired quality of life in this particularly susceptible age group. Although the clinical manifestations of a severe asthma exacerbation are fairly obvious, they are not specific; moreover, pediatric patients demonstrating more subtle symptoms could pose a diagnostic challenge. Indeed, they commonly present with various nonpathognomonic complaints, including wheezing, cough and respiratory distress. Such a clinical picture could very well fit other pathologic entities that do not warrant treatment on an emergency basis, including respiratory tract infections, laryngomalacia/tracheomalacia, primary ciliary dyskenisia, vocal-cord dysfunction, structural abnormalities of the upper and lower airway, mechanical obstruction, cystic fibrosis, bronchiolitis, acute wheeze and post-bronchiolitis wheeze. Nevertheless, in contrast to many of these conditions, a severe asthma exacerbation has the potential to rapidly culminate in life-threatening respiratory compromise. Indeed, notwithstanding the last decade's advances in our knowledge of asthma pathophysiology, acute exacerbations remain a source of considerable morbidity for patients and financial burden for healthcare systems. Efficient prevention of acute asthma attacks depends on factors such as severity, control of the underlying disease and the definition used for exacerbations. In effect, the lack of objective criteria and of a uniformly accepted definition for an asthma exacerbation impedes our efforts to prevent such events. Therefore, a concise characterization of what is essentially an abrupt and severe worsening of asthma symptoms is of importance. Accordingly, acute asthma exacerbations have been defined as 'episodes of progressive shortness of breath, cough, wheezing and chest tightness presented individually or in combination'. Nevertheless, this definition cannot clearly discriminate exacerbations from transient episodes of inadequate asthma control. Therefore, a definition of asthma exacerbations on the basis of their severity was pursued. In this context, severe incidents were characterized in an American Thoracic Society and European Respiratory Society joint consensus statement as events that urge for immediate action on the part of the patient and physician to prevent a serious outcome, such as hospitalization or death. They should also require systemic corticosteroid administration for at least 3 days. The American Thoracic Society/European Respiratory Society consensus statement also defined moderate asthma exacerbations as "events requiring a temporary change in treatment and entailing at least one of the following for a minimum of 2 days: increased rescue bronchodilator use and lung function deterioration not requiring systematic corticosteroid administration, or an ED visit." On the other hand, mild exacerbations are essentially indiscriminable from single episodes of transient loss of control, being close to the patient's normal range of symptom variation.
Therefore, a long sought-after adequate definition of abrupt 'asthma attacks', a concise categorization of clinically relevant disease and the streamlining of appropriate treatment measures are rendered of importance. Nevertheless, this can be demanding, taking into account the diversity of the disease. A recent pediatric asthma International Consensus (ICON), attempted to establish a basis for clinical evaluation, by defining exacerbations as, "acute or sub-acute episodes of progressive increase in asthma symptoms, associated with airflow obstruction".