Upper airway obstruction in children (2009)

Poiseuille’s law is central to the understanding and management of all airway obstructions in children, with the clinical impact of even a small reduction in radius being compounded by the inverse relationship of the resistance to the radius to the power 4. Indeed deterioration from a ‘mild’ obstruction to life threatening airway compromise may be heralded by slight decrease in airway diameter (Figure 1). Successful outcome in all cases of childhood airway obstruction is dependant upon the efficient cooperation between suitably experienced otolaryngologists, anesthetists, and intensivists. Illustration of the increase in airway resistance with decrease in airway diameter. The aim of this article is to discuss the presentation, assessment, and management of the common causes of childhood airway obstruction as seen in a tertiary level unit. Traditionally, airway management often comprised tracheostomy insertion, but the development of endoscopic techniques has superseded this in an ever increasing proportion of cases. Treatment strategies and principles will be highlighted and placed in context with results reported in the literature. Laryngomalacia is the commonest cause of congenital stridor. The presenting symptom is usually inspiratory stridor commencing within the first 2 weeks of life, exacerbated by feeding, agitation, and lying in the supine position. The airway obstruction results from collapse of supraglottic structures on inspiration. The etiology is not fully understood, but the condition is consistently associated with certain anatomical abnormalities, namely short aryepiglottic folds, redundant arytenoid mucosa prolapsing into the glottis and a long curled epiglottis (Figure 2). Surgical management of the condition is largely based on correction of these anatomical anomalies. The natural history of the inspiratory stridor is to often worsen initially for 6–9 months, before gradually improving, with most children being free of symptoms by 18–24 months (1). In the absence of atypical symptoms (e.g. cyanosis, altered cry, choking with feeds), which could suggest an alternative diagnosis or the presence of synchronous lesions elsewhere in the airway, the condition may be diagnosed by awake flexible fibreoptic laryngoscopy (FFL) in the outpatient department. Laryngomalacia can be classified into three types dependant on site of the abnormality (1). Type 1 is due to prolapse of redundant arytenoid mucosa into the glottis. Type 2 is a result of short aryepiglottic folds and Type 3 is characterized by collapse of the epiglottis posteriorly over the glottis. It is our departmental policy to perform rigid endoscopy in the following circumstances: (i) severe progressive symptoms; (ii) atypical symptoms; (iii) FFL inconclusive; and (iv) clinical or fibreoptic suspicion of a synchronous airway lesion (SAL). The possibility of an SAL has lead some authors to advocate rigid endoscopy in all cases of suspected laryngomalacia (2). However, although the rate of SALs in the literature is significant (20–30%) (1, 3, 4) the impact upon outcome and time to symptom resolution has been shown to be negligible (3, 4). Laryngomalacia, like vocal cord palsy (VCP), is a dynamic condition and therefore, if formal airway assessment is indicated, it should be performed under general anesthesia with the child breathing spontaneously. Supraglottic collapse is most obvious during the ‘waking phase’ at the end of the procedure. Supraglottic collapse in laryngomalacia. The majority of children will not require surgical intervention, with the remaining 5–10% requiring some form of surgical treatment (1, 4). Surgical options include division of the aryepiglottic folds to ‘open’ the constricted supraglottis (Figure 3), resection of the redundant mucosa and suspension of the prolapsing epiglottis to uncover the laryngeal introitus (5,6). Rates of complete resolution of stridor of over 80% have been reported following aryepiglottoplasty (6,7). A degree of gastro-esophageal reflux disease (GERD) is often associated with laryngomalacia and all children should therefore receive anti-reflux medication (3). The exact relationship is not fully understood (1), with GERD possibly reflecting changes in airway and intrathoracic pressures in response to the airway obstruction, as opposed to being a causal factor. A neurological form of the condition exists and may be seen in children with neurological or neuromuscular conditions, such as cerebral palsy. In such cases, surgical intervention should be approached with caution and it may be most appropriate to manage severe airway collapse with a tracheostomy. ‘Cold steel’ aryepiglottoplasty in laryngomalacia. Vocal cord palsy is a relatively common cause of airway obstruction in children that may be idiopathic, iatrogenic, as a result of a neurological abnormality or birth trauma (8,9). Unilateral VCP presents with stridor, breathy cry (or voice) and feeding difficulties from birth or following surgical procedures in the thorax. The symptoms are often relatively mild and resolution of symptoms can usually be expected as compensation from the contra-lateral vocal cord ensues over a period of months. FFL in the awake child is often all that is required to diagnose the problem in the absence of other symptoms. Radiological assessment is also important in both unilateral and bilateral VCP in order to diagnose associated central nervous system (e.g. Arnold-Chiari malformation) (10,11) and cardiovascular abnormalities (12). Supportive treatment alone is often sufficient in unilateral VCP, with feeding via a nasogastric tube until the child develops a ‘safe’ swallow and possibly chest physiotherapy until an adequate cough is obtained. Bilateral VCP presents a far greater clinical challenge and can cause potentially life-threatening airway obstruction. Dysphonia is not usually found in bilateral VCP (8,11). Tracheostomy insertion may be required in the emergency situation to safeguard the airway. Tracheostomy may be necessary in approximately half of cases of bilateral VCP (8). Magnetic resonance imaging of the brain in cases of bilateral VCP is mandatory in order to exclude an Arnold-Chiari malformation with hydrocephalus (10). Diagnosis is once more by rigid airway endoscopy, under general anesthesia with spontaneous ventilation, and cord mobility is best assessed during the waking phase. Care should be taken to also assess passive vocal cord movements in order to diagnose cord immobility due to crico-arytenoid fixation (9), complicating prolonged intubation or intubation injury to the larynx. Vocal cord mobility may return to some degree in patients with VCP. Spontaneous recovery rates of up to 70% are reported (8) and therefore an interval of at least a year should be given before an airway widening procedure is undertaken, with CO2 laser being the treatment modality of choice (9,11). Ultimately the aim of surgical treatment is to provide an adequate airway, facilitating tracheostomy decannulation where present, while safeguarding the best possible voice quality (9). Laser arytenoidectomy has been shown to meet both of these criteria in a study of six children from the Great Ormond Street Hospital, in London (9). The improvement in airway was sufficient to facilitate decannulation in the four children with tracheostomies preoperatively (9). A CO2 laser is used to widen the airway by resecting the vocal process and part of the body of arytenoid cartilage on one side, paying attention not to damage the membranous anterior 2/3 of the vocal cord (Figure 4). Improvement in vocal cord function in idiopathic bilateral VCP can occur up to approximately 10 years of age and therefore in such cases an endoscopic airway widening procedure should be delayed until the teenage years (8,13). Airway enlargement by laser arytenoidectomy in bilateral vocal cord palsy. E, epiglottis; VF, vocal fold; VP, vocal process of arytenoid cartilage; MP, muscular process of arytenoids cartilage; AEF, aryepiglottic fold. Recurrent respiratory papillomatosis is a benign condition, of viral etiology, characterized by recurrent proliferations of squamous papillomata within the airway, anywhere from lips to lungs. The viral pathogen is most commonly Human Papilloma Virus types 6 and 11. Proliferations involving the larynx may present with childhood hoarseness and symptoms of progressive airway obstruction (Figure 5). Involvement of the tracheobronchial tree will also lead to airway obstruction and usually presents a more significant management problem. The recurrent nature of this condition often necessitates multiple surgical procedures. Laryngeal recurrent respiratory papillomatosis involving the glottis. The current management philosophy is toward a more conservative approach, aimed at ameliorating airway symptoms while limiting subsequent scarring of the larynx. Younger age at diagnosis has been shown to be a negative prognostic factor for remission (14). Surgical debulking is the treatment of choice and several modalities have been used, including ‘cold steel’, microdebrider, CO2 laser and radiofrequency ablation (15,16). The use of adjuvant medical treatments, such as intralesional cidofovir remains controversial (17,18). CO2 laser treatment of laryngeal papillomata has largely been superseded by other techniques, such as the microdebrider, due to the increased risk of fibrosis and scarring subsequently impacting on the airway and voice quality. Wherever possible the procedure should be undertaken with the child breathing spontaneously, without endotracheal intubation in order to limit the chance of distal seeding of the papilloma. Microdebrider and radiofrequency ablation wands are now available designed to allow access to the larynx and trachea as far distally as the carina (16). Subglottic cysts are a rare, but increasingly encountered, cause of stridor in children, representing 7% of the airway pathologies identified at direct laryngotracheobronchoscopy (DLTB) over a 2 year period, at our unit (19). All of the children with subglottic cysts in this study had been intubated in the neonatal period. Importantly, the same study also identified a median delay of 4.25 months to the onset of symptoms (range 1–13 months) (1). Their anatomical location means that the stridor is characteristically biphasic in nature. The etiology of subglottic cysts is thought to be mucosal damage from endotracheal intubation, especially in ex-premature children. The length of intubation is not necessarily critical to cyst formation with children identified following intubation for a single day (19,20). Concurrent subglottic stenosis (SGS) should also be considered (19,20) and may on occasion necessitate tracheostomy insertion. The exact relationship between subglottic cysts and SGS is not known, with both either representing the consequences of the same subglottic trauma, or cysts resulting from the additional risk of mucosal trauma in SGS, even with an age-appropriate endotracheal tube. Again an unobstructed view of the operative site is achieved under general anesthesia with the patient breathing spontaneously. The cysts may be marsupialized using laryngeal micro-instruments, CO2 laser or a microdebrider (19) (Figure 6a,b). Despite adequate initial treatment cysts may recur in up to 50% of cases (19–21) and therefore interval reassessment should be performed 6–8 weeks later. Supraglottic cysts are even rarer and are treated by marsupilization (Figure 7). (a) Preoperatively subglottic cyst. (b) Postmarsupilization of the subglottic cyst. Supraglottic cyst. A subglottic hemangioma is a vascular anomaly resulting from endothelial hyperplasia (22). It is usually characterized by the onset of biphasic stridor within the first 6 weeks to 6 months of age. Initially the hemangioma continues to enlarge (proliferative phase) for up to 1 year (23) with resultant progression of symptoms of airway obstruction. However, the tumor eventually enters a period of regression (involution phase) with gradual resolution of symptoms over a 2–5 year period. The exact etiology of the condition is not understood (22). The diagnostic pathway begins with ascertaining the exact nature and onset of the stridor and physical examination may reveal a cutaneous hemangioma in association with a subglottic hemangioma in approximately half of cases (24). Airway endoscopy with spontaneous ventilation is mandatory for all cases of biphasic stridor, as discussed earlier, and will demonstrate a compressible subglottic swelling, often found posteriorly on the left side, that may blanch in response to topical epinephrine. Following diagnosis various treatment options are available dependant upon the age of the child, the degree of subglottic narrowing, distribution of the hemangiomatous tissue within the subglottis and the presence of co-morbidities. The principal ‘nonsurgical’ treatment is corticosteroids, delivered either systemically or intra-lesionally. ‘Surgical’ options comprise either, excision of the abnormal tissue (CO2 laser excision or an open approach with submucosal resection) or bypassing the developing airway narrowing while awaiting the natural regression of the lesion (tracheostomy). Each modality has pros and cons, and in practice more than one modality is often employed. Systemic and intralesional steroids have both been reported to successfully treat subglottic hemangiomas. Meeuwis et al. reported six children successfully treated with intralesional corticosteroid injection and intubation, avoiding tracheostomy over an average follow-up period of 3.3 years. The average total duration of intubation was however 19 days (7–36) (24). Systemic corticosteroids alone may be successful in a third of patients, providing the airway narrowing is not circumferential and does not exceed 50% (22). Systemic complications resulting from prolonged corticosteroid usage, such as growth retardation and Cushing syndrome, are well recognized (22,24) and the involvement of a pediatric endocrinologist is essential if a prolonged course is anticipated. Laser vaporization has also been reported to be successful but is associated with a risk of iatrogenic SGS (25). Open surgical excision has been demonstrated to provide a ‘one stop’ treatment in noncircumferential subglottic hemangiomas (26) (Figure 8a,b). Successful outcome, in terms of avoiding tracheostomy insertion or decannulation of existing tracheostomy, has been reported in over 90% of cases (26). An anterior cartilage graft may also be required if there are concerns about the development of a SGS (26). Although tracheostomy will protect the airway until the tumor involutes, it is itself associated with significant potential complications, including accidental decannulation or tube obstruction with the risk of cerebral hypoxia and death. The author’s protocol for the management of subglottic hemangiomas is illustrated in Figure 9. (a) Right subglottic hemangioma. (b) Rigid endoscopy following open excision of the right subglottic hemangioma seen in Fig. 8a. A protocol for the management of subglottic hemangioma. Laryngeal clefts result from failure of either the posterior cricoid lamina or the septum between the trachea and esophagus to develop, and are a rare cause of childhood airway symptoms. The anomaly usually presents with a combination of stridor, feeding difficulty, choking episodes, recurrent chest infections and possibly cyanotic episodes. The range and severity of symptoms vary with the extent of the communication between the airway and esophagus. Laryngeal clefts may be found in association with Opitz–Frias and Pallister–Hall syndromes (27). The gold standard investigation is suspension laryngoscopy under general anesthesia and spontaneous ventilation, with palpation of the inter-arytenoid notch and examination of the tracheobronchial tree (28). The most commonly used classification system is that described by Benjamin and Inglis, whereby each cleft is classified into one of four catergories dependant upon the length of the cleft in relation to the cricoid cartilage and the sternal notch (29) (Figure 10). Posterior view of the airway illustrating the Benjamin and Inglis classification of laryngeal clefts (Benjamin 1989). A, arytenoid cartilages; CC, cricoid cartilage; TC, tracheal cartilage; C, clavicle. Type 1 clefts can be managed conservatively in most cases, with endoscopic suture repair of the cleft reserved for those children who remain symptomatic conservative repair is by suspension with a tube and spontaneous The management of a cleft into the 4) between and and is by a The management of clefts 2 and 3), to the remains controversial with some an open approach via an anterior to the described for the endoscopic approach is with the aim of avoiding both a period of intubation, the for a tracheostomy and the possibility of the laryngeal (Figure (a) and (b) Type 3 laryngeal cleft before and endoscopic suture and have reported the successful endoscopic treatment of four children with Type 3 with of at a follow-up of months. Each child subsequently had a but a mild degree of (27). et following a reported the successful endoscopic treatment of six patients with Type with Type and one with Type with laryngeal In the same study of open to have been successful from the of feeding without (28). Subglottic stenosis (SGS) continues to present a significant airway management problem. SGS may be congenital (e.g. or (e.g. laryngeal The presenting of the condition are stridor recurrent failure to and recurrent respiratory infections SGS is diagnosed by with the child breathing and the airway using endotracheal of increasing diameter. The system described by and is used to the degree of stenosis and in treatment 1 does not exceed 50% stenosis and 2 is obstruction (Figure In 3 the stenosis is and is in (Figure and 2 Subglottic and 3 subglottic The for airway is whereby a cartilage from either the or the is into a in order to a (Figure will also require a posterior graft into a posterior cricoid to the patient should have compromise or respiratory and should not be In a a tracheostomy is not in to safeguard the airway and the is for approximately 6 A is performed to the and assess the airway. upon the outcome of the airway and subsequent the patient is between months the A tracheostomy is not used in a and the child is left intubated with an age-appropriate endotracheal tube for days both and safeguarding the airway. Although will vary a is usually performed to the child, and an interval dependant upon the condition of the larynx. All patients receive GERD to the negative impact of on mucosal with anterior cartilage graft for subglottic 1 SGS may be managed conservatively in especially in congenital cases where of the airway with growth of the child can be anticipated. 2 and 3 SGS usually surgical intervention with cartilage and in order to sufficient airway SGS necessitates either or resection rates of are reported for with rates being for and are characterized by airway collapse during and are due to of the (Figure The condition usually presents within the first months of life and possible biphasic stridor, recurrent cyanotic episodes, and cough and recurrent infections are to be of of and result airway is classified to the etiology into and although the exact are not fully In the tracheal are considered to be of and this may be associated with or as a result of prolonged endotracheal results from upon the airway or can be found in association with is usually with resolution of symptoms by 2 years of age The severity of symptoms is dependant upon the extent of airway involvement and collapse and may be compounded by airway such as laryngeal clefts and respiratory abnormalities, such as may be found in association with certain syndromes such as Airway under general anesthesia with spontaneous ventilation is the of but dependant upon the cause (e.g. vascular additional will be The cardiovascular of the child is critical the and nature include chest physiotherapy and of the with either airway or airway Surgical options are dependant upon and include to from an and Tracheostomy may be to the airway, while awaiting natural resolution of the especially a significant length of the trachea is A protocol for the investigation and management of is given in Figure resulting from vascular A protocol for the management of on in children. to the larynx are to earlier, endotracheal intubation is in the etiology of subglottic cysts and intubation may result in progressive of the to of the arytenoid and cricoid with formation injury is often in the context of direct examination of the airway is Laryngeal injury may also be suspected airway symptoms following successful In such the severity and progression of will the of formal airway with spontaneous ventilation is the investigation of choice and may demonstrate changes to the such as vocal cord and mucosal (Figure It is of critical to of and in the of cartilage and circumferential risk the development of SGS and will often require tracheostomy insertion in order to the such as GERD and should also be managed weeks may without facilitating subglottic scarring may be treated with using an (a) injury to the larynx (b) injury to the larynx vocal cord and Rigid endoscopy remains the investigation for and dynamic childhood airway of the breathing child under general anesthesia is essential if dynamic airway such as VCP and are to be tracheostomy remains an important treatment modality it is associated with significant and In children the rate to the tracheostomy has been reported to be as as the of surgical techniques, greater will be placed on the to adequate often without endotracheal intubation, in the of increasingly significant airway obstruction. to from the Illustration at the The authors have of airway obstruction. are not for the or of by the than should be to the for the The is not for the or of by the than should be to the for the