Epithelial changes in the trachea of children

The effects of suctioning techniques on the distal tracheal mucosa in intubated low birth weight infants

Microscopic pathology of the distal trachea at autopsy was retrospectively reviewed in 51 low birth weight infants (less than 1250 g). Twenty-six patients from 1977 who had nasal and/or orotracheal intubation and who underwent suctioning with uncontrolled deep suctioning technique were compared to 25 patients from 1980 who had orotracheal intubation with suctioning to the tube tip only. Clinical diagnoses, duration of intubation and number of intubations were correlated to degree of distal tracheal injury: absent (normal epithelium), mild (focal epithelial loss), moderate (diffuse epithelial loss/some inflammation), or severe (submucosal ulceration/squamous metaplasia). From 1977 to 1980 the mortality rate, mean gestational age and mean birth weight all decreased by 20% (P less than 0.05), 1.1 week (P less than 0.05) and 118 g (P less than 0.01) in both autopsied and non-autopsied infants. In 1977, 15 of 26 autopsies (58%) revealed mild (6), moderate (5) or severe (4) pathology. The mean duration of intubation was 71.3, 11.8, and 265 h. respectively. No history of intubation was obtained in two patients with mild injury. No significant tracheal pathology was seen in 11 patients (42%) in 1977. In 1980, fewer patients, 10 of 24 autopsies (42%), revealed mild (3), moderate (4) or severe (3) pathology. The mean duration of intubation was 19.3, 318.3 and 1391.3 h, respectively. One patient with no history of intubation had mild tracheal injury. No significant tracheal pathology was seen in 15 patients (58%) in 1980. The diagnoses of hyaline membrane disease, anemia, hyperbilirubinemia and coagulation disorder were seen more frequently in patients with moderate and severe tracheal pathology both in 1977 and 1980. Despite factors which should lead to greater tracheal injury--longer duration of intubation, lower birth weights and younger gestational age--less tracheal injury was seen in infants undergoing careful suctioning techniques. Clinical implications for the low birth weight neonate are discussed.

Tracheobronchial abnormalities in infants with bronchopulmonary dysplasia

Twelve preterm infants with bronchopulmonary dysplasia underwent bronchoscopy to determine if airway abnormalities were contributing to persistent pulmonary problems. Indications for bronchoscopy were persistent atelectasis, lobar hyperinflation, or both on chest radiograph (11 patients), unexplained respiratory distress (three patients), and aspiration of tissuelike material from a tracheostomy (one patient). Bronchoscopy revealed abnormalities of the trachea, bronchi, or both in all infants, including partial or near total airway occlusion by abnormal growth of tissue (10 patients); tracheomalacia, bronchomalacia, or both (three patients); and inspissated secretions (two patients). Seven infants died during initial hospitalization. Tracheobronchial abnormalities should be considered as a cause of persistent pulmonary problems in infants with bronchopulmonary dysplasia.

Iatrogenic epithelial change caused by endotracheal intubation of neonates

Tracheae of 20 neonates were obtained at postmortem examination. All neonates had been intubated for between 4 h and 105 days. The tracheal epithelial lining was examined by both light and scanning electron microscopy. Five tracheae which had never been intubated served as controls. All of these showed ciliation throughout their length. Those neonates who had been intubated showed epithelial change which ranged from a simple deciliation to a full stratified squamous epithelium. The degree of change was broadly related to the duration of intubation.

A quantitative comparison of the early histopathological changes from tracheotomy and endotracheal intubation on the distal trachea in fetal lambs

Twenty-four premature fetal lambs underwent tracheotomy (n = 11) or endotracheal intubation (n = 13) for 3-9 h for an unrelated experiment. All were maintained with 100% oxygen on a pressure cycled ventilator. No suctioning was performed. At sacrifice, sections of the distal trachea were studied for histopathological changes in epithelium, submucosa and mucous glands. All changes were confined to the epithelium and were reported as either partial or total epithelial erosion in regards to preservation of the basal cell layer. In tracheotomized and intubated animals, both partial and total erosion were seen as early as 3 and 3.5 h, respectively. In the intubated animals, 13.5% of the cumulative tracheal circumference showed total erosion; 19.8% showed partial erosion. In animals undergoing tracheotomy, 9.6% of the cumulative tracheal circumference had total erosion; 19.1% had partial erosion. Possible etiological factors include oxygen toxicity, lack of humidification, effects of mechanical ventilation and indirect trauma from surgery or intubation. The clinical significance for premature infants is discussed.

Squamous epithelium in the subglottic region of paediatric larynges

A macroscopic staining method was used to display and measure the extent of squamous epithelium in the subglottis of stillborn babies and of babies less than 3 months old. Squamous epithelium was found to be present in some babies without a previous history of intubation (3 of 8) and in some stillborn babies (3 of 11). Squamous epithelium in the subglottic space of the human is thus present at birth.

[Structural disorders of the human tracheal mucosa: incidence, sex distribution and topography]

The trachea in 148 patients investigated with respect to incidence and topographic properties of squamous metaplasia, basal-cell hyperplasia, and goblet-cell hyperplasia (randomized study including 88 men and 60 women). Each trachea was examined histologically at 41 defined locations. In men, the percentage of squamous metaplasia is 9.6%, of basal-cell hyperplasia 14.9%, and of goblet-cell hyperplasia 7.1% (all locations concerned without regard to topography). In women, the corresponding figures are only 4.2% (squamous metaplasia), 9.5% (basal-cell hyperplasia), and 3.9% (goblet-cell hyperplasia). The topographic centers of textural changes of the tracheal mucosa in both men and women are the same. The site of predilection of goblet-cell hyperplasia is the lower and the middle third of the trachea. The preferential areas of squamous metaplasia are the upper and the lower third of the trachea. Basal-cell hyperplasia is mostly seen in the upper third of the trachea close to the cricoid, as well as in the entire anterior and posterior walls of the remaining parts of the trachea.

Recurrent lobar atelectasis due to acquired bronchial stenosis in neonates

Bronchial obstruction by granulation tissue caused atelectasis in ten infants who required frequent suctioning and mechanical ventilation for more than 20 days. The endotracheal suctioning had been performed with a No. 6 or No. 8 French catheter with multiple end and side holes at the tip. Bronchoscopic examination revealed nodular and polypoid granulation at the level of the carina and bronchus, more often on the right side. In five infants, atelectasis was treated with gentle, less frequent suctioning and vigorous pulmonary toilet. Two of these infants died of severe atelectasis and chronic lung disease. Five infants underwent excision or cauterization of granulation tissue. Histopathologic examination of this tissue disclosed inflammation, fibrosis, and squamous metaplasia in each of the five specimens. Eight of the ten infants are alive without symptoms, the oldest being 27 months. Prevention may require critical analysis of suction techniques and the catheter tips employed. Whistle tip catheters should be avoided. Mild obstructive lesions can be managed by gentle and less frequent suctioning and aggressive pulmonary care, but severe obstruction, as determined by a compromise of the lumen of greater than 20%, may require excision or cauterization.

Squamous metaplasia of the tracheal epithelium in children

Thirty-seven (1-6%) tracheas from 2170 children showed squamous metaplasia. (Cases with tracheo-oesophageal fistula and congenital heart disease were excluded). The metaplasia extended into the bronchi in 15 cases. Features of pulmonary retention were present in seven cases. Respiratory infection, probably viral, seemed to be the most significant causative factor in 20 children, including those with cystic fibrosis. Tracheal instrumentation was a possible factor in 11 cases but oxygen therapy alone did not seem important. The metaplasia was almost certainly congenital in one child and probably in two others but no stillborn infants showed metaplasia. In many children the metaplasia seemed to be due to a combination of factors.

Mucosal changes in the trachea and main bronchi of newborn infants after naso-tracheal intubation

Permanent sequelae of nasotracheal intubation are uncommon, but acute ulceration and squamous metaplasia occur. Histological sections from the trachea and main bronchi were examined in 12 infants. A nasotracheal tube had been inserted during the first two weeks of life of these infants and had been in place for more than one week. In four cases the patient died some time (7 to 108 days) after extubation. Similar sections from patients who were not intubated, intubated only for attempted resuscitation, or intubated for several hours were studied for comparison. The sections were classified according to the degree of mucosal loss and metaplasia, and the extent of the lesions was estimated. Squamous change was seen in most sections from all 12 patients with the exception of one who died 57 days after extubation. Some respiratory epithelium was seen in all patients. In the eight patients who died while intubated, the changes were more marked in the right main bronchus than the left in seven, and more marked in the lower trachea than the upper in five. In the two patients intubated for several hours, in addition to mucosal loss, early metaplasia was seen. It is suggested that mucosal loss is replaced by the squamous metaplasia, and that trauma caused by suction catheters in the lower trachea and right main bronchus is more extensive than that due to the endotracheal tube itself.