Foreign bodies in the airways: a meta-analysis of published papers.

Background: Very recently, some attempts have been made to start a systematic collection of foreign bodies (FB) in view of using them to characterize the risk of chocking in terms of size, shape and consistency of the FB. However, most of the epidemiologic evidence on foreign bodies in children comes from single-center retrospective studies, without any systematic geographical and temporal coverage. This paper is aimed at providing an estimate of the distribution of foreign body's injuries in children according to gender, age, type of FB, site of obstruction, clinical presentation, diagnostic/therapeutic procedures, complications, as emerging from a meta-analytic review of published papers.

Methods: A free text search on PubMed database ((foreign bodies) OR (foreign body)) AND ((aspiration) OR (airways) OR (tracheobronchial) OR (nasal) OR (inhalation) OR (obstruction) OR (choking) OR (inhaled) OR (aspirations) OR (nose) OR (throat) OR (asphyxiation)) AND ((children) OR (child)) finalized to identify all English written articles referring to foreign body inhalation over a 30 years period (1978-2008) was performed. The target of the analysis has been defined as the proportion of injuries as reported in the studies, stratified according to children demographic characteristics, type of FB, site of obstruction. The pooled proportions of FB were calculated using the DerSimonian and Laird approach.

Results: 1699 papers were retrieved and 1063 were judged pertinent; 214 English written case series were identified, among them 174 articles were available and have been included in the analysis. Airway foreign body most commonly occurs in young children, almost 20% of children who have inhaled foreign bodies being between 0 and 3 years of age. Organic FB, particularly nuts, are the most documented objects while, among inorganic FBs, the greatest pooled proportion has been recorded for magnets, which can be particularly destructive in each location. Non specific symptoms or a complete absence of symptoms are not unusual, justifying mistaken or delayed diagnosis. Acute and chronic complications seem to occur in almost 15% of patients.

Conclusions: Even if an enormous heterogeneity among primary studies seems to exist and even if the absence of variables standardized definitions across case series, including class age definition and symptoms and signs descriptions, seriously impairs studies comparability, our results testify the relevant morbidity associated with foreign body inhalation in children, stressing the importance of preventive measures.