Clinical analysis of bronchoscope diagnosis and treatment for airway foreign body removal in pediatric patients

Foreign body (FB) refers to FB in the larynx, trachea and bronchi, which is more frequent in infants and children less than 3 years old, upper respiratory tract obstruction can occur if treatment is not on time, and it can endanger life of the child in severe cases [1]. Early and accurate diagnosis and early removal of airway FB can significantly reduce airway complications. With the wide spread application and technological development of flexible bronchoscopes, various effective methods were adopted for different FB using flexible bronchoscopes. In the past 3 years, we have used flexible bronchoscopes, combining with foreign body forceps, mesh basket, cryosurgery, laser and balloon etc., successfully removed FB in the airway of 628 children, and reported as follows.

Airway FB is the most common respiratory emergency in children. The foreign body aspiration in the airway is usually divided into three stages [2]. The first stage is the sudden impact of the FB into the airway, leading to acute cough, stridor, respiratory distress and cyanosis. This period is the most dangerous. If the foreign body is trapped in the glottis and airway, it may cause suffocation and even death. The patient usually progresses to an asymptomatic stage, followed by airway FBs that are trapped in a fixed position in the tracheobronchial tree, and the airway reflex gradually weakens over time. The third stage involves complications secondary to chronic airway FB, manifested as infections, such as recurrent pneumonia, chronic cough, unilateral wheezing, or asthma-like symptoms. Further delay in the diagnosis of airway FB may lead to bronchiectasis and permanent damage to lung tissue. Therefore, the children with recurrent cough, wheezing, hemoptysis, lung inflammation and other unknown causes after repeated anti-inflammatory treatments should be highly vigilant for airway FB, and bronchoscopy should be performed as soon as possible to confirm the diagnosis and treatment.

Studies reported that rigid bronchoscopy was used as the gold standard for diagnosis and treatment of FB in the airway [3]. The rigid bronchoscopy can maintain effective mechanical ventilation through the breathing circuit without retaining general anesthesia, while exploring the airway to determine the location of foreign bodies, and can enter the bronchial segment of the leaf segment, so that the airway forms a straight channel, which is convenient for rigid bronchoscopy. The foreign body forceps linear forceps can improve the success rate of foreign body removal, especially for foreign bodies with irregular shapes such as bones, pen caps, peanuts, etc., with large volume and incarceration resistance. In this study, 2 cases with pen caps, 1 case with walnut kernels and 1 case with plastic foreign bodies were foreign bodies with large volume and incarceration resistance, so the flexible bronchoscope combined with the rigid endoscope was required to be used together. Another case of fruit core-like foreign body was incarcerated in the subglottic airway, and the location was special, and it was difficult to remove with the rigid endoscope or the flexible bronchoscope alone. Because the foreign body is too large to damage the glottis, it also avoids the residual foreign body in the distal airway. Since the rigid bronchoscope can be fixed at a certain position in the bronchus to form a straight airway, the inner diameter of the segmental bronchus in children under 2 years old is about 2–5 mm, but with the deepening of the location of the foreign body, especially the foreign body in the bronchus below the lung segment, rigid bronchial The scope can only be selected with 3.0 inner diameter (inner diameter 4.3 mm, outer diameter 5.0 mm), narrow tube,smallvisual range, there is the blindness during clamping, so it is easy to push the foreign body into the deeper position or bite the bronchus by wrong forceps. Ridge leading to local oozing. In recent years, the flexible bronchoscopy has been widely used in clinical operation, as it is more safe. With skilled operation by physicians, the flexible bronchoscopy can be conducted under local anesthesia and sedation. Will repeatedly rub the vocal cords to avoid severe edema in the glottis. A small amount of sedation can be tolerated well, and the bronchi or upper lobe bronchi, including subsegmental bronchi, that are not easily visible on rigid bronchoscopy can be clearly seen, usually up to grade 6 or 7. The rigid bronchoscope is limited by the equipment and cannot be used for patients with cervical spine, mandible or head abnormalities, because the neck is not suitable for extension and mandibular fixation; it is also not suitable for foreign bodies in the peripheral airways, especially those in the upper lungs. At the same time, the operation of rigid bronchoscopy is more difficulty, and the qualified personnel is limited, which also impact the application. Furthermore, the flexible bronchoscope can locally flush the inflammatory site during the process of clamping the bronchial foreign body, and if necessary, can remove the abnormally proliferated granulation tissue, thereby helping the absorption, discharge and recovery of local inflammatory exudates. The airway is unobstructed, the disease duration was shortened, and the complications was reduced. Due to the continuous stimulation of the bronchi by exogenous bronchial foreign bodies, the bronchial mucosa is prone to granulation tissue hyperplasia, which can further lead to complications such as atelectasis, bronchiectasis, pneumonia, etc., such as secondary bronchiectasis, which are often local, and non-full lung diffuse, so after flexible bronchoscope treatment, foreign body stimulation can be removed as soon as possible, which may reduce complications, reduce further invasive treatment operations, and prevent surgical treatment maximum. In this study, the complication rate during and after flexible bronchoscopy in children with airway foreign bodies was 19.6%, and there were no deaths due to FB and treatment. This is consistent with many reports in the literature [4‐6]. Therefore, flexible bronchoscopy has become a commonly used method for removing FB in the airway of children.

In this study, the airway FB removal with the flexible bronchoscope were mainly edible plant FB, which may be related to the immature swallowing mechanism of the child [7]. The success rate of the flexible bronchoscope for removing FB was different in the studies Tang et al. used flexible bronchoscope to remove FB from the airway of 1027 children with a success rate of 91.3% [8]. Rodrigues et al. reported that the success rate of using 33 cases of flexible bronchoscope to remove FB was 82.5% [9]. In this study, 628 cases of FBs were removed with the flexible bronchoscope, and the success rate of removal was 99.2%. Under normal circumstances, the flexible bronchoscope treatment port can smoothly grasp a part of the airway FB through the foreign body forceps, and some FBs due to the abnormal size, texture, and shape, or due to the long period in the airway, the surrounding granulation tissue proliferation is obvious or even the FB is completely wrapped, and it is difficult to remove the foreign body smoothly with foreign body forceps. For the removal of airway FB of different natures, the flexible bronchoscope can be used alone or in combination with foreign body forceps, net baskets, freezing, balloons, lasers and other technologies. For a small number of intractable airway FB, when there is a risk of massive hemoptysis, airway perforation, etc., surgical intervention is ultimately required [10, 11]. The 628 cases of airway FBs in this group were successfully removed except 5 cases with rigid bronchoscopy and 123 cases had mild side effects, which were all improved after treatment. There were no major hemoptysis, dyspnea, pneumothorax and other conditions caused. The experience is summarized as follows: (1) For FB that have the short retention time and are particularly small, non-sharp FB can be directly adsorbed on the end of the bronchial lens by negative pressure and slowly moved out of the airway with the bronchoscope. (2) FB with irregular shapes, relatively rough surfaces, and movable FB can be fine-tuned to the appropriate gripping position with foreign body forceps. The clamps are slowly moved out of the airway with the bronchoscope. (3) Smooth, spherical or elliptical, fragile and movable FB. The foreign body can be taken out by freezing or mesh basket. (4) The incarcerated foreign body can be taken out by forceps, and the balloon will slowly pass through the gap between the airway and the foreign body, enter the distal end of the foreign body, expand and pull and cause the foreign body to loosen. Use forceps or mesh basket to take out the remaining FB (5) The foreign body that is wrapped and covered by granulation tissue can be removed by laser, freezing or electrocoagulation to clean the surrounding granulation tissue, and then the foreign body clamp or mesh basket is used to take out the foreign body.

In summary, for those who have repeated coughing, wheezing, and recurrent respiratory symptoms after anti-inflammatory treatment, the foreign body is highly suspected, and the bronchoscopy should be performed as soon as possible. For airway foreign bodies of different natures, the bronchoscopy should be combined with appropriate bronchoscopy based on the type, location, size, firmness of incarceration, and granulation encapsulation, which can not only improve the removal rate of airway foreign bodies, but also can shorten the operation duration and reduce the occurrence of complications.