Pediatric airway endoscopy

Abstract

Ashoke Kumar Basu In 1806 Bozzini, the father of airway endoscopy, created an instrument which enabled doctors to see into the airway of patients. Airway endoscopy involves introduction of an instrument into the air passage of a patient while he is breathing spontaneously or is under controlled ventilation. The airway is illuminated, enabling the surgeon to look for any abnormality under magnification and to perform any procedure both in the upper and lower air passages. Today, endoscopes are of two types, viz., flexible and rigid. Both are fibro-optic endoscopes which became available to the medical fraternity in the 70s. In India the pediatric rigid bronchoscope became available in the mid 80s and the flexible ones became available a few years later. Before this, pediatric airway endoscopy was considered to be unsafe. However, the introduction of rigid ventilating bronchoscope with Hopkins’ rod-lens system and miniaturization of flexible bronchoscopes transformed the scenario. The flexible pediatric bronchoscope has the advantage of 180° mobility of its distal end. The size of its outer diameter varies from 3.9 mm to 1.8 mm. It has one or two working channels of varying dimensions for suction, irrigation, or instrumentation. The 1.8 mm size flexible bronchoscope can be used in premature infants (of more than 1 kg body weight) but these bronchoscopes do not have any working channels. Flexible endoscopes can be used in a patient who is awake and is breathing spontaneously for diagnostic purposes, for irrigation and giving lavage as well as for performing biopsies. Since the working channels are narrow, these instruments cannot suck out thick tenacious secretions. They are also unsuitable for the extraction of foreign bodies. The advantage of a flexible bronchoscope is that it can be used as a bedside procedure in a neonatal intensive care unit (NICU) setup without general anesthesia. As flexible endoscopy is performed on an unsecure airway while the patient is breathing spontaneously, the procedure must be completed within 40-45 sec to avoid hypoxia. If the procedure must be prolonged, attempts are made to supplement the oxygen supply through the working channel. In older children, the flexible endoscope can be introduced through the endotracheal tube attached to a side arm for ventilation. The rigid pediatric bronchoscope has a rod-lens telescope. A side channel allows ventilation through the sheath while an instrument port allows concurrent irrigation and suction. The scopes are of various sizes (from 2.5 to 7) and lengths (from 23 cm to 30 cm). The outer diameter of the sheath is usually a little bigger than the number of the sheath. The 3.5 scope is the most suitable scope for inspection, irrigation, biopsy, and removal of foreign bodies in both infants and older children. The 3.5 size scope is available in a longer length, which can easily be negotiated into the bronchi of older children. Optical forceps for grasping foreign bodies or taking biopsies have in-built channels to carry the rod telescope. This enables the surgeon to perform the procedure inside the airway under vision. Rigid bronchoscopy is always performed under general anesthesia in the operation theater with intensive monitoring. Various foreign body forceps are available for the removal of different types of foreign bodies. Rigid bronchoscopy can be performed for a longer period of time and in the event of an episode of hypoxia, the telescope can be easily retracted allowing unhindered ventilation through the rigid bronchoscope sheath in place. Telescopes of various inclinations (such as 30° and 70°) are used to inspect upper lobe bronchi of both the sides. But with the rigid bronchoscope, it is difficult to cannulate the upper lobe bronchi of either side. However, a rigid bronchoscope can also be used to inflate a collapsed segment of the lung in a controlled manner. Bronchoscopy is indicated in patients of stridor, unresolving and recurring pneumonitis, persistent atelectasis, persistent cough, tracheoesophageal fistula (both congenital and acquired), airway trauma and tumor, and suspicion of foreign body. Endoscopy should be avoided in patients suffering from cardiovascular instability and in case of active bleeding in the airway. In my experience of over three decades, I have performed over 750 pediatric airway endoscopies. I have dealt with cases of laryngo-tracheomalacia, external airway compression, agenesis of the lungs, congenital or acquired fistulae of the trachea and bronchus, unresolved pneumonitis or collapse, and foreign body of the airway. More than 85% of the patients had suspected foreign body in the air passage. They presented with history of one or more of the following clinical findings: Choking, wheezing, stridor, recurring pneumonitis, chest retraction, mediastinal shift, reduced air entry, and surgical emphysema. Some of them had failed bronchoscopy elsewhere. Removal of foreign body becomes difficult if a vegetable foreign body is old as the object becomes friable. Some of the vegetable foreign bodies such as cardamom have multiple seeds inside them. Extra care must be taken while grasping such an object so that the seeds do not burst out of the pod and scatter into the airway. Seeds absorb moisture from the lungs and over a period of time swell and become bigger, making grasping and extraction difficult. Foreign bodies, which are metallic or have a chemical coating cause ulcer and bleeding, which in turn makes extraction difficult and also prolongs postoperative recovery. Foreign bodies, which obstruct the airway completely cause collection of pus distally and their removal may lead to spillage of pus into other parts of the airway. Plastic foreign bodies with holes or ones that are conically shaped (such as parts of a ballpoint pen) tend to slip during extraction and are difficult to be removed. After removal of foreign bodies, patients usually get better quickly. However, they need to be monitored (for at least 24 h) as intensively as they are monitored during the procedure. Performing a bronchoscopy requires skill on the part of the surgeon, an expert anesthesiologist, as well as good infrastructure and well-coordinated support staff. It is well-rewarding; the success rate is very high and with the infrastructural support provided by corporate hospitals today, a challenge that young pediatric surgeons can take up.