Acquired subglottic stenosis in neonates

Risk Factors Associated With the Development of Acquired Airway Disease After Congenital Heart Surgery: A Retrospective Cohort Study

Objective. In this single-center, retrospective review, we sought to determine the risk factors associated with the development of severe acquired airway disease (AAD; vocal cord paralysis [VCP] or subglottic stenosis [SGS]) in pediatric patients who had undergone surgery for congenital heart disease (CHD) with cardiopulmonary bypass. All patients who required surgical treatment for CHD using cardiopulmonary bypass at our institution between 2010 and 2015 were reviewed. We defined severe AAD as either clinically significant VCP, SGS, or both, requiring consultation with the otolaryngology (ENT) service for evaluation. The disease was classified as severe because it led to difficulty with intubation or failure to wean mechanical ventilation. This airway disease was not present or was clinically insignificant prior to congenital heart surgery. Results. Over a 5-year period (August 2010 to December 2015), 1395 patients were evaluated. Of these, 25 (1.8%) had significant AAD. Age was the only statistically significant independent predictor of AAD ( P < .001). Those with AAD were younger—3 versus 8 months—and had longer intubation time: 5 (2-18) versus 2 days (1-5). Of those who developed AAD, most (22/25) required some form of additional surgical procedure for its evaluation or management. Only 3 of the 25 patients with severe AAD required tracheostomy. Conclusions. Children who undergo congenital heart surgery with cardiopulmonary bypass are at risk for developing AAD, most often because of SGS or VCP. AAD can lead to failed extubation in the postoperative setting as well as difficult intubation during subsequent anesthetics. Although it often requires surgical treatment, it responds well to therapy and rarely requires tracheostomy.

Subglottic injury: a clinically relevant animal model

OBJECTIVES/HYPOTHESIS

To develop a clinically aligned, reproducible model for subglottic injury.

STUDY DESIGN

Prospective randomized control pilot study.

METHODS

Juvenile (3-month-old) New Zealand White rabbits underwent intubation with a 3-cm length of an endotracheal tube that was chosen so that there would be no air leak below 20 cm of water. This tube was one or two sizes above the appropriate tube for the animal. It was held in situ with a suture placed at the trachea and secured over a button in the neck for a period of 1 week. Animals were sacrificed 1 week postextubation, and larynges were harvested. A range of histological techniques and gross morphology were utilized to examine the injury caused at the level of the subglottis. Unintubated animals constituted controlled specimens.

RESULTS

Intubated animals demonstrated considerable histopathology including evidence of ulceration, inflammation, granulation tissue, perichondritis, and chondritis when compared with control animals. Morphometric analysis demonstrated a significant increase in lamina propria thickness (P = .0013), mucosal thickness (P ≤ .0001), and in goblet cell areal density (P = .014). Analysis of mucin types found a significant decrease in acidic (P = .0001) mucin coinciding with a significant increase in mixed mucin types (P = .0013).

CONCLUSIONS

Our model provides a reliable and reproducible technique for acute/subacute injury to the subglottis secondary to intubation, which is consistent with previous histological findings of early changes associated with acquired subglottic stenosis (SGS). Future uses of this model could include the examination of current adjunctive therapies and their effects on limiting progression to SGS.

Nasal mask positive pressure ventilation in paediatric patients with type II respiratory failure

We report our experience with nasal mask ventilation in children and adolescents with type II respiratory failure admitted to the paediatric intensive care unit (PICU) over an 18-month period. Seven patients were treated with nasal mask ventilation during part of their PICU stay. All showed significant improvement in arterial pH, PaCO2, and PaO2/FiO2 from presentation to discharge, although at discharge PaCO2 and PaO2/FiO2 fell outside of the normal range. Complications occurred in four patients. When compared to 11 patients with type II respiratory failure not treated with nasal mask ventilation, the nasal mask ventilation group had a similar PICU length of stay and incidence of complications. We conclude that nasal mask ventilation may be useful in maintaining near normal alveolar ventilation in selected children with type II respiratory failure and that a prospective study of this technique is indicated.

Localized tracheomalacia as a complication of the Cole tracheal tube

The Cole tracheal tube is designed for use in neonates. Subglottic stenosis is a recognized complication of prolonged use of the tube. We report a case of tracheomalacia as a further complication of prolonged use of the tube. A 4-month-old infant with a history of repeated failed extubation and multiple medical problems was found to have an unusual region of severe inspiratory collapse localized to the upper 1 cm of the trachea. This was felt to be the result of pressure from the shoulder of the Cole tube which had been used for prolonged intubation. A tracheostomy was performed to bypass the collapse, but the infant subsequently died due to other medical problems.

Microbial flora of the subglottis in intubated pediatric patients

Infection of the intubated subglottis is felt to be one of the many factors involved in the pathogenesis of acquired cicatricial subglottic stenosis. The precise role of infection is unclear and the microbial flora has not been established. An analysis of subglottic culture material, from 22 intubated pediatric patients undergoing tracheotomy, has been performed to establish the nature of the subglottic microbial flora. Fifty-nine isolates were found, including 19 types of organisms. The number of isolates per patient ranged from one to eight, with an average of 2.7 isolates per patient. The most common isolates in the 22 patients were alpha-hemolytic Streptococcus viridans (17 isolates-77%), Neisseria sp. (6 isolates-27%), Pseudomonas sp. (5 isolates-22%), and coagulase negative Staphylococcus sp. (5 isolates-22%). This data indicates that colonization of the subglottis in intubated pediatric patients is polymicrobial in nature. alpha-Hemolytic Streptococcus viridans and Neisseria sp. were most common, with a shift in cultured flora towards Pseudomonas sp. in patients intubated for more than 10 days. In view of this, antimicrobial therapy may be of benefit in preventing acquired cicatricial subglottic stenosis.

Formal reintubation for incipient neonatal subglottic stenosis

In a small prospective series of 10 children who presented with incipient subglottic stenosis following neonatal intubation a protocol of formal reintubation for two weeks, with sedation, enabled six of the children to avoid tracheostomy or other forms of surgery and in the remaining four it is unlikely that the trial of reintubation made the degree of laryngeal and subglottic damage worse.

Tracheostomy: acute and long-term mortality and morbidity in very low birth weight premature infants

Thirty-six very low birth weight premature infants (VLBW-PT) born at 24 to 32 weeks gestation and with birth weights 635 to 1,360 g who had tracheostomies performed for acquired subglottic stenosis or for prolonged mechanical ventilation were followed in relation to acute and long-term mortality and morbidity. Mortality due to the tracheostomy occurred in 4 patients (11%); mortality from all other causes was 25%. Death after hospital discharge was associated with the nonuse of prescribed cardiorespiratory monitors. Complications < 1 week postsurgery occurred in 31% of infants and complications > or = 1 week postsurgery occurred in 64% of infants. Fifty percent of infants required tracheostomy for > 2 years and/or extensive reconstructive surgery of the airway. Parents should be counselled that VLBW-PT infants with a tracheostomy may require extended medical and home care. An effective home care program requires parental training in tracheostomy care, the use of ancillary equipment, and infant cardiopulmonary resuscitation.

Endoscopic balloon dilatation of acquired airway stenosis in newborn infants: a promising treatment

Acquired stenosis of the trachea or bronchus in newborn infants is a possible complication of perinatal intubation and mechanical ventilation. Although the exact pathophysiology is unknown, stenosis formation seems to be initiated by pressure necrosis. Prematurity is thought to be an important risk factor for acquired airway stenosis. Management of stenotic lesions may be conservative, surgical, or endoscopic. Four patients were treated with endoscopic balloon dilatation with satisfactory results. Endoscopic balloon dilatation is the method of choice in most newborn infants with acquired bronchial or tracheal stenosis.

Subglottic ulceration and healing following endotracheal intubation in the neonate: a morphometric study

In neonates, acquired subglottic stenosis is the most serious long-term complication of endotracheal intubation and is due primarily to posttraumatic fibrosis of the infant larynx. We have examined 78 larynges, 75 of which were intubated, from infants ranging in gestation from 22 to 40 weeks, and who survived from a few hours to up to 300 days. Each larynx was morphometrically assessed for the extent of acute injury, indicated by the percentage of epithelial loss, and healing, indicated by the percentage of a subglottic ulcer covered by metaplastic squamous epithelium. Results show that acute injury is almost invariable, and up to 100% of the subglottic epithelium may be lost within a few hours of intubation, but that progression of injury is relatively short-lived. Ulcer healing starts after a few days, rapidly progresses from day 10, and in the majority of cases is complete after 30 days. This study suggests that long-standing acute injury in the subglottis is the exception rather than the rule, even with the endotracheal tube remaining in place.

Long term pathological sequelae of neonatal endotracheal intubation

In neonates, acquired subglottic stenosis (SGS) is the most serious long term complication of endotracheal intubation. In this case report, we describe the pathological changes in the larynx of a child who died two years after successful treatment, involving corrective surgery, for neonatally acquired SGS. Stenosis, due to dense fibrous connective tissue, was still present at death. However, there was evidence that there had been growth of the laryngeal cartilages. Disruption of the laryngeal cartilages was present anteriorly due to the antecedent surgery but major cricoid cartilage injury secondary to intubation was not seen. The crico-arytenoid joints demonstrated ankylosis and to this was attributed the abnormal quality of voice noted in the child at follow-up. The pathological changes are considered in relation to the pathology of endotracheal intubation and pathogenesis of acquired subglottic stenosis.

Subglottic stenosis in children: a conservative approach

Subglottic stenosis may be either congenital or acquired and is one of the commonest causes of acute and chronic airways obstruction in neonates and infants. Most acquired stenoses result from perinatal intubation. The management of these lesions remains controversial, particularly regarding the timing of surgical intervention. At Alder Hey Children's Hospital a series of 33 patients with subglottic stenosis have been reviewed. A conservative approach, employing long-term tracheotomy as the mainstay of treatment, has achieved a success rate of 72.7%, and only 3 patients have so far needed corrective surgery (9%), of which 1 has been decannulated to date. One patient (3%) died of bronchopulmonary dysplasia. We believe that, where close follow-up is possible, a conservative approach is the method of choice.

Management of subglottic stenosis: experience from two centres

The incidence of subglottic stenosis in children has risen rapidly in the last 20 years as more advanced techniques enable younger preterm neonates to survive. There has been a similar rise in the number of different surgical methods devised to alleviate the stenosis; success has been claimed for each technique. The importance of normal laryngeal growth throughout an often protracted period of surgical intervention may, however, have been underestimated. This study analyses the data from two units in London over the last five years and assesses retrospectively the benefit of different surgical approaches.