Our findings showed that in a pediatric Chinese population, FB aspiration is more common in children under 3 years of age, with a peak incidence between 1 and 2 years, and the peanuts were the most commonly inhaled objects, findings in agreement with previously published literature. In children up to 2 years, FBs were more frequently found in the left bronchus, whereas in children aged 2 and older FBs were more frequently found in the right bronchus. The clinical presentation varied upon the type, size, location of the airway FB, with the most common symptoms being coughing, wheezing, and decreased air entry.
Age and gender distribution
In our study FB aspiration was most frequently observed in boys, consistent with previous studies. We do report, however, a slightly higher ratio, of 2.6:1 in comparison with previous reports of a male to female ratio of 2:1 (15-18). Of note, we noticed that FB aspiration did not occur in girls older than 4 years of age. The fact that the majority of FBs aspirations affects boys could be explained by their likely more impulsive nature and adventurous games. Contrary to this trend, however, several studies reported a similar incidence of FB in both genders (19,20).
In agreement with previous literature, the vast majority (92%) of the patients were under 3 years of age, with the highest incidence (69%) of FB aspiration occurring in children 1 to 2 years old (15,21-24). The increased incidence at this young age has been attributed to several factors: 1) chewing objects as stage of normal oral development; 2) incomplete development of posterior teeth (molars) and, consequently, the food placed in the mouth is not adequately chewed; 3) engagement in various activities such as playing, running, crying, or laughing, while having various objects or food in the mouth, increasing the possibility of making a forced air inspiration; 4) anatomic particularities of the larynx during childhood, that is positioned high; and 5) inadequate control of deglutition (16,18,25). In addition, parents’ inattention or thumping children for acts of naughtiness during eating seem to be contributory (26).
Time lag from inhalation to treatment
The time between FB aspiration and extraction ranged from less than 1 hour to several months. Consistent with other reports (15,19,21,27), in this study, almost a quarter of presentations to hospital were within 24 hours and over 90 % within 1 month. When FB aspiration is suspected, immediate hospital admission is necessary, because a FB may suddenly dislodge from the original location, and obstruct another vital part of the airway, that could lead to death (28). Typical signs of a chronic FB inhalation are fever, purulent bronchitis, and bronchopneumonia that may be followed a pulmonary abscess (29). In this study, delay in the diagnosis of FB aspiration longer than 1 month occurred in 7% of children, which led to a considerable incidence of complications among these, such as pneumonia (40%) and pleural effusion (13%). The key to reaching an earlier diagnosis lies in a detailed history to identify risk factors, a thorough examination that elicits important signs, and supportive X-ray findings. However, the diagnosis of FB aspiration is frequently delayed, because the child is asymptomatic, there are no definitive findings at physical examination, and neither clinical symptoms nor radiological findings are sufficiently specific and sensitive to demonstrate the presence of a FB in the bronchial tree.
Symptoms and signs
Clinical features depend on the type, location, and size of the FB, as well as the duration and degree of obstruction (30). FBs lodged in the proximal airways such as trachea and main bronchus are probably more prone to be acutely symptomatic than FBs located in peripheral airways. In our patients, the most frequent symptoms were cough, followed by reduced breath sounds, and wheezing, in agreement with previous reports (19,22,23,31). Overall, although all the clinical symptoms reported have a high positive predictive value for FB aspiration, all also have a relative low specificity (17,18). It should be noted that despite having a FB in the bronchial tree, a small percent (1%) of children in our study were completely asymptomatic. It was reported that even as many as 30% of the patients with FB aspiration have normal physical examinations (30,32). Thus, the absence of clinical symptoms with a positive history for FB aspiration cannot exclude the presence of a FB in the airway in a young child.
To improve diagnostic accuracy above history and physical examination alone, imaging plays a key role in the initial evaluation and follow-up of possible FB aspiration. However, the value of chest radiography in making a diagnosis remains controversial. In our study, more than one-third (38%) of the patients with laryngotracheal or bronchial FBs showed normal x-ray findings. It has been reported that the percentage of patients with FB aspiration having normal chest x-ray in other retrospective studies ranged from a low of 10% (33) to a high of 46% (18). The relative high percentage of normal x-ray findings may be related to the fact that most of the FBs were radiolucent organic objects. In our study, the common abnormal x-ray findings in the patients with bronchial FBs were mediastinal shift, obstructive emphysema, and pneumonia. Similarly, previous studies reported as most common x-ray findings mediastinal shift (19,34), air trapping (35,36), and atelectasis (37). However, it should be kept in mind that these signs are not pathognomonic, and, as a result, chest radiography alone is neither sufficiently sensitive nor specific enough method for diagnosis of FB aspiration. If history and clinical findings suggest FB aspiration, a normal chest x-ray should never deter the physician from carrying out a bronchoscopy.
The most suitable technique for removing an FB in children remains controversial. Although previous studies recommended rigid bronchoscopy for extraction of FBs in children (15,16,19,20,28,31), recent studies have demonstrated the effectiveness of flexible bronchoscopy (17,18,38-40). In contrast with rigid techniques, flexible bronchoscopy offers several advantages such as the possibility to reach higher order of subsegmental bronchi and be conducted with local anesthesia, with the child under deep sedation. (38,41). The ready availability in most medical centers and the development of new pediatric flexible scopes with working channels combined with increased expertise and skills of the operators led to increased used of flexible bronchoscopy in children. (41).
At our institution, we prefer flexible bronchoscopy using local anesthesia. Transient hypoxia and tachypnea during the procedure were noted in this series although they were rare. In all cases they were immediately alleviated by oxygen supplementation or prompt ending of the procedure. It should be noted that proper training and experience is crucial to optimizing the outcome and minimizing the risk of complications in tracheobronchial FB removal. With one exception, no severe complications such as cardiac arrest, large hematorrhea, and anesthetic events occurred in our cohort. A small percentage of the patients underwent rigid bronchoscopy due to the special location of the FBs (near epiglottis or glottis) and the special feature of the FBs (obstructing airways completely and leaving no space for basket forceps to reach or having a very smooth surface to be clipped by biopsy forceps). The endoscopic procedures failed to remove the FBs which were located in the basal segment of the lower lobe in 4 patients (2%), and these patients underwent surgery for removal of the FBs.
Whereas in adults the inhaled FBs most commonly lodge in the right bronchus due to anatomy of the right and left tracheobronchial angles (42), in children, the preference of FBs location is controversial, with some studies reporting higher frequency of the FB either in the right bronchus (19,24,31,33), or in the left bronchus (9,29,43), whereas some other studies found an approximately even distribution (23,30,44). In our study, in children younger than 2 years the FBs were more frequently found in the left bronchus, but in children aged 2 and older the FBs were more frequently found in the right bronchus. The preference for FB to lodge in the left bronchus in children younger than 2 years is not clear, it might be explained by the particular anatomical changes of the bronchial tree during the playing times such as those described by Van et al. (42). Another explanation might be that in young children the left main bronchus has almost the same diameter as the right one and is not ramified at the same acute angle as in adults (45).
Type of foreign bodies
Our findings are in agreement with those presented by previous authors that 71% to 98% of the inhaled FBs are organic in nature (15,16,18,19,24). In our study, the vast majority of the FBs were food items. Among these, most frequently FBs encountered were peanuts, followed by watermelon and sunflower seeds, consistent with previous domestic studies (19,38,46). However, plastic objects (toys) were not a frequent cause of FB aspiration in our study but they represented more than 10% of those identified in the developed world (47). The nature of inhaled FBs varies among countries and is largely dependent on cultural, social, and economic factors that include parental attitudes and eating habits (11).