Congenital airway malacia is one of the few causes of irreversible airways obstruction in children, but the incidence in the general population is unknown. Severe airway malacia or malacia associated with specific syndromes is usually recognized and diagnosed early in infancy, but information about clinical features of children with primary malacia, often diagnosed only later in childhood, is scarce.
We analyzed all flexible bronchoscopies performed between 1997 and 2004 in the Sophia Children's Hospital, summarized clinical features of children with primary airway malacia, estimated the incidence of primary airway malacia, and calculated the predictive value of a clinical diagnosis of airway malacia by pediatric pulmonologists.
In a total of 512 bronchoscopies, airway malacia was diagnosed in 160 children (94 males) at a median age of 4.0 years (range, 0 to 17 years). Airway malacia was classified as primary in 136 children and secondary in 24 children. The incidence of primary airway malacia was estimated to be at least 1 in 2,100. When pediatric pulmonologists expected to find airway malacia (based on symptoms, history, and lung function) prior to bronchoscopy, this was correct in 74% of the cases. In 52% of the airway malacia diagnoses, the diagnosis was not suspected prior to bronchoscopy. Presenting clinical features of children with airway malacia were variable and atypical, showing considerable overlap with features of allergic asthma. Peak expiratory flow was more reduced than FEV(1).
Primary airway malacia is not rare in the general population, with an estimated incidence of at least 1 in 2,100 children. Airway malacia is difficult to recognize based on clinical features that show overlap with those of more common pulmonary diseases. We recommend bronchoscopy in patients with impaired exercise tolerance, recurrent lower airways infection, and therapy-resistant, irreversible, and/or atypical asthma to rule out airway malacia.
"If signaling in any of these pathways goes awry, a structurally weak trachea develops, giving rise to potentially fatal airway collapse during respiration. This pathology is known as primary tracheomalacia (for reviews see (Boogaard et al., 2005; Carden et al., 2005; McNamara and Crabbe, 2004)). FGF signaling plays multiple essential roles in growth plate chondrogenesis (reviewed in (Ornitz and Marie, 2002)) and in the trachea, yet its ectopic activation in the trachea results in poor deposition of extracellular matrix (Eswarakumar et al., 2004; Sala et al., 2011). "
[Show abstract][Hide abstract] ABSTRACT: The specific program that enables the stereotypic differentiation of specialized cartilages, including the trachea, is intrinsically distinct from the program that gives rise to growth plate hypertrophic chondrocytes. For example, Snail1 is an effector of FGF signaling in growth plate pre-hypertrophic chondrocytes, but it derails the normal program of permanent chondrocytes, repressing the transcription of Aggrecan and Collagen type 2a1 (Col2a1). Here we show that miRNA activity is essential for normal trachea development and that miR-125b and miR-30a/c keep Snail1 at low levels, thus enabling full functional differentiation of Col2a1 tracheal chondrocytes. Specific inhibition of miR-125b and miR-30a/c in chondrocytes or Dicer1 knockout in the trachea, de-repress Snail1. As a consequence, the transcription of Aggrecan and Col2a1 is hampered and extracellular matrix deposition is decreased. Our data reveals a new miRNA pathway that is safekeeping the specific genetic program of differentiated and matrix-producing tracheal chondrocytes from acquisition of unwanted signals. This pathway may improve understanding of human primary tracheomalacia and improve protocols for cartilage tissue engineering.
"Tracheomalacia describes weakness of the walls of the trachea and it may result in lifethreatening episodes and/or recurrent hospitalizations for lower airway infections (Austin and Ali, 2003; Boogaard et al., 2005; Carden et al., 2005; McNamara and Crabbe, 2004). It can be an isolated idiopathic anomaly or associated with EA-TEF, primary defects of cartilage synthesis (e.g., dyschondroplasia), cartilage degeneration due to trauma (e.g., longterm tracheal intubation), or extrinsic compressive lesions such as vascular rings or tumors (Berdon, 2000). "
[Show abstract][Hide abstract] ABSTRACT: Developmental lung biology is a field that has the potential for significant human impact: lung disease at the extremes of age continues to cause major morbidity and mortality worldwide. Understanding how the lung develops holds the promise that investigators can use this knowledge to aid lung repair and regeneration. In the decade since the "molecular embryology" of the lung was first comprehensively reviewed, new challenges have emerged-and it is on these that we focus the current review. Firstly, there is a critical need to understand the progenitor cell biology of the lung in order to exploit the potential of stem cells for the treatment of lung disease. Secondly, the current familiar descriptions of lung morphogenesis governed by growth and transcription factors need to be elaborated upon with the reinclusion and reconsideration of other factors, such as mechanics, in lung growth. Thirdly, efforts to parse the finer detail of lung bud signaling may need to be combined with broader consideration of overarching mechanisms that may be therapeutically easier to target: in this arena, we advance the proposal that looking at the lung in general (and branching in particular) in terms of clocks may yield unexpected benefits.
Current Topics in Developmental Biology 01/2010; 90:73-158. DOI:10.1016/S0070-2153(10)90003-3 · 4.68 Impact Factor
"Boogaard-2005 reported incidence of primary airway malacia to be at least 1 in 2100 infants. The presenting clinical features of children with airway malacia are variable, with overlapping features of allergic asthma4.The problem is structural abnormality and immaturity of tracheal rings allowing collapse of the trachea. Diffuse malacia of airway of congenital origin improves by age of 6-12 months. "
[Show abstract][Hide abstract] ABSTRACT: SUMMARY: In infants & children variety of conditions and syndromes are associated with difficult Airway. Anaesthetic management becomes a challenge if it remains unrecognized until induction and sometimes results in disaster, leading to oropharyngeal trauma, laryngeal oedema, cardiovascular & neurological complications. A 4-month-old child with multiple congenital anomalies was posted for cataract extraction for early and better development of vision. He had history of post birth respiratory distress, difficulty in feeding, breath holding with delayed mile stones. He was treated as for Juvenile asthma. This child was induced with inhalation anaesthesia. There was difficulty in laryngoscopic intubation and could pass much smaller size of the tube than predicted. He developed post operative stridor and desaturation. The problems which we faced during the anaesthetic management and during postoperative period are discussed with this case.
Indian journal of anaesthesia 12/2009; 53(6):683-7.
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