Ann Otol 85: 1976
ACQUIRED AND CONGENITAL SUBGLOTTIC STENOSIS IN THE INFANT JAMES MICHAEL
H.
STEVENS,
L.
PARKIN,
MD
MD
AUGUST
L.
J UNG,
MD
SALT LAKE CITY, UTAH
SUMMARY - During the calendar year of 1974, the Intermountain Newborn Intensive Care Center at the University of Utah Medical Center had 603 admissions. A representative group of 293 charts were reviewed which indicated that 44% of these children were intubated from hours to weeks. The overall mortality rate for the 293 children was 29%. Eighteen of the 603 children were diagnosed as having subglottic stenosis. Fifteen of these children appeared to have acquired subglottic stenosis secondary to endotracheal intubation. Three ehildren had congenital subglottic stenosis. Tracheostomy was necessary in the management of 15 patients. Ten of the 18 patients have survived and two of these patients still have tracheostomy tubes in place. The survival and thickness of the stenotic area are inversely proportional to the birth weight and the duration ofIntubation. Endoscopic excision, dilatation and stenting were techniques utilized in the treatment of these stenotic lesions. The extubation technique utilized is described. The factors involved in the production of acquired subglottic stenosis are presented along with suggestions to decrease the incidence of this problem in the intubated child.
Assisted ventilation with various respirator machines and techniques has become a common practice in the care of the newborn with respiratory dysfunction. Maintenance of a closed system is necessary for the performance of such ventilatory assistance. The indwelling endotracheal tube is usually the initial technique by which this closed system is achieved. Much attention in recent years has been focused on the problems associated with such intubation. This paper reviews the experience with a group of newborn patients who demonstrated narrowing of the subglottic airway as seen in a newborn intensive care unit. The relationship of endotracheal intubation in the etiology and treatment of this problem will he discussed. METHODS AND MATERIALS
During the calendar year of 1974, 18 infants with subglottic stenosis were evaluated and treated in the Intermountain Newborn Inten-
sive Care Center (INICC) at the University of Utah Medical Center. The experience with these infants was reviewed retrospectively and forms the basis for this clinical study. The total number of children admitted during this period was 603. The charts of 293 consecutive admissions from July 1 to December 31, 1974, were studied to determine incidence of endotracheal intubation, development of subglottic stenosis and mortality in this group of newborns. All patients with a diagnosis of subglottic stenosis have now had a one to two-year follow-up. The infants who otherwise were patients of the Newborn Intensive Care Center received follow-up only until their death or discharge from the IN ICC. In all infants receiving closed system ventilatory assistance, endotracheal intubation was performed by pediatric house staff and specialized INICC nurses. Uneuffed, Murphy type endotracheal tubes were utilized. Tubes were not reused. The tubes were changed on an average of every three to five days or more frequently if secretions were copious, thick, or obstructive. All tracheobronchial endoscopies and tracheostomies were performed by the otolaryngology service under the direct supervision of the authors.
From the Department of Surgery, Division of Otolaryngology, and the Department of Pediatrics, University of Utah College of Medicine, Salt Lake City, Utah. Presented at the meeting of the American Broncho-Esophagological Association Palm Beach, Florida, April 27-28, 1976. ' 573
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574
PARKIN E1' AL. TABLE I
TABLE III
INTUBAnON, TRACHEOSTOMY AND MORTALITY IN 293 CONSECUTIVE NEWBORN INTENSIVE CARE PATIENTS
INCIDENCE OF SUBGLOTTIC STENOSIS
Intubated Tracheostomy Expired No. of patients Total patients Percent
Number Total patients Percent
18
3
15
603
603
3%
0.5%
603 2.5%
128
7
86
293 44%
293 2.4%
293
RESULTS
29%
The review of charts from 293 consecutive patients admitted to the INICC revealed an overall mortality of 86 or 29% (Table I). The number of patients who required endotracheal intubation was 128 of these 293 or 44%. Of the 128 intubated patients, 62 died, giving a 48% mortality rate among the intubated infants (Table II). Deaths occurred in 24 patients who were not intubated. It would be expected that the death rate would be higher in the intubated patients as they were generally the more seriously ill. Subglottic stenosis was diagnosed in 10 of the 128 intubated patients. The stenosis was considered to be congenital in three patients and acquired in seven patients. No subglottic stenosis was diagnosed in the nonintubated group of patients. Tracheostomy was necessary in seven patients. The subglottic stenosis was managed without tracheostomy in three patients. The incidence of acquired subglottic stenosis in this total group of 293 patients was 2.4%. The incidence of acquired subglottic stenosis in the intubated group was 5%. During the entire year of 1974, acquired subglottic stenosis was diagnosed in 15 of 603 patients for an incidence of 2.5% (Table III). Congenital subglottic stenosis was diagnosed in three of 603 patients for an incidence of 0.5%. All three of these patients received endotracheal intubation during their initial airway management. One of these patients required tracheostomy and was successfully extubated. The other two patients were managed without tracheostomy. All three patients are alive and well with good airway function.
The tracheostomies were done over an endotracheal tube or bronchoscope. Horizontal skin incisions were utilized and the tracheal incision performed was either a lazy "H" or an inferiorly based anterior tracheal wall Hap incorporating two adjacent tracheal rings. During the first three days, a gauze or net tracheostomy dressing was used to allow the escape of free air around the tube. This is important in the prevention of subcutaneous cervical emphysema and pneumomediastinum. The first tracheostomy tube change was accomplished at 48 to 72 hours. Silk or nylon traction sutures ( 5-0) were placed in the trachea at the time of tracheostomy to facilitate the initial tube change. These traction sutures were removed at the first or second tube change. The tracheostomy tubes were then changed at three-day intervals. Franklin or Shiley pediatric tracheostomy tubes were utilized in all patients. Extubation techniques will be covered in the discussion section. The INICC services a large geographic area. The majority of patients referred to the INICC have respiratory distress syndromes with or without other associated congenital problems. Those patients being transferred from other medical facilities are transported by a specialized air-transport team equipped to provide ventilatory as well as other supportive care while in transit. TABLE II TRACHEOSTOMY, ACQUIRED SUBGLOTTIC STENOSIS AND MORTALITY IN INTUBATED INFANTS
Acquired Subglottic Tracheostomy Stenosis Expired No. of patients Total intubated patients Percent
All Cases Congenital Acquired of Stenosis Stenosis Stenosis
7
7
62
128 5%
128 5%
128 48%
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SUBGLOTTIC STENOSIS
575
TABLE IV SUBGLOTTIC STENOSIS Female
9
9
15
Tracheostomy Extubated Yes No 5
3
15
7
II
Tracheostomy Yes No
Stenosis Etiology Acquired Congenital
Stenosis Type Thick n.«
Sex Male
Expired No Yes
10
The remainder of the results will be from the evaluation of the 18 patients with diagnosed subglottic stenosis managed in 1974 (Tables IV and V). Of the 18 patients, nine were male and nine were female. Acquired stenosis was present in 15 patients. All 18 patients had endotracheal tube placement and 16 patients required respirators. Tracheostomy was required in the management of 15 patients. The type of stenosis was considered thin if the length of subglottic involvement was less than 4 mm. If greater than 4 mm, the stenosis was typed as thick. Thin stenosis was seen in 7 patients and thick stenosis was seen in 11 patients. All congenital subglottic stenoses were of the thin type. Death occurred in eight patients. Five of these patients were discharged from the INICC with tracheostomies in place
Alive Without Trach
With Trach
10
8
3
2
8
and died at home or at other medical facilities. The tracheostomy was probably a factor in one death. This patient developed tracheal granulomata below the tracheostomy site near the carina. These were periodically removed endoscopically. The patient died at home with a pulmonary infection and at autopsy there was compromise of the right main stem bronchus by the granuloma. All other children died because of their underlying illnesses. None of the expired children were extubated prior to death. Sixteen of the 18 patients were premature by weight or gestation time or both. Respiratory distress syndrome was present as hyaline membrane disease, Wilson-Mikity syndrome or bronchopulmonary dysplasia in 16 patients. Significant cardiovascular disease was also seen in 12 patients with patent
TABLE V SUMMARY OF 18 SUBGLOTTIC STENOSIS PATIENTS RS IC Birth weight in kilograms Days of intubation Acquired or congenital stenosis Thick or thin stenosis Tracheostomy Tracheostomy extubation Survival
sc JJ
AD BE BF PM BF IP GI MK AH MM SV GS BW HT
1.2 2.8 .96 1.1 2.3 1.0 2.3 2.4 .68 2.5 2.7 1.9 1.7 1.1 .93 .74 2.0 .93 60
10 56 31 36 20
A
A
A
A
A
A
6
10 45
7
3
4
24 29 34 29 10 41
C
A
C
C
A
A
A
A
A
A
A
A
Tn Tk Tk Tk Tk Tk Tn Tn Tk Tn Tn Tn Tk Tk Tk Tk Tn Tk
+ + + + + + + +
+ +
,
+
T
+ +
+ + + ++ + + + + + + + +
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-+
+ +
576
PARKIN ET AL.
ductus arteriosus and congestive heart failure being most common. One patient had a bilateral vocal cord paralysis of uncertain etiology. He was intubated for 10 days and subsequently underwent tracheostomy with spontaneous improvement in vocal cord function. Extubation was accomplished but repeat tracheostomy was necessary because of progressive airway obstruction. Endoscopy at the time of repeat tracheostomy revealed a thick subglottic stenosis. The mothers of six newborns had significant health problems at the time of delivery. Two mothers had sepsis, one was a heroin addict, and two had severe diabetes. Of the two diabetic mothers, one had polyhydramnios. These five newborns were premature and developed acquired subglottic stenosis. The sixth mother had myasthenia gravis in poor control. Her daughter had immediate airway distress at birth and was intubated. A peculiarity of the larynx was noted and the child was referred to the INICC. The endotracheal tube was removed three days later and an anterior glottic web was excised. In addition, a posterior and lateral subglottic thin weblike stenosis was discovered which had been partially avulsed by the endotracheal tube. The glottic web and the subglottic stenosis were excised and a nasotracheal tube placed. Extubation was accomplished but in the ensuing 72 hours the patient developed inspiratory stridor and repeat endoscopy was performed, revealing subglottic and glottic granuloma which were excised. Tracheostomy was performed. A soft stent was fashioned and secured in the larynx. The stent was removed and the child extubated ten days later with no additional airway problems. Five patients were diagnosed as having subglottic stenosis three days to 12 weeks following the removal of the endotracheal tube. All five of these patients had thin subglottic stenosis and were intubated ten days or less. Two of these patients were diagnosed as having congenital subglottic stenosis. The stenotic area was dilated in one
TABLE VI BIRTH WEIGHT RELATED TO STENOSIS TYPE AND SURVIVAL
Birth Wt. in No. of Survival Stenosis Type Kilograms Patients Alive Dead Thick Thin
0.5-1.0 1.0-1.5 1.5-2.0 2.0-2.5
>
2.5 Total
1 2 I 3 3 10
5 4 2 4 3 18
4 2 1 1 0 8
5 3 1 1 1 11
0 1 1 3 2 7
patient and excised in the second. Tracheostomy was not required in either patient. The other three patients were thought to have acquired stenosis. Two of these patients required tracheostomy. The stenotic area was excised in the third patient without tracheostomy. All five of these patients were discharged from the INICC with good airway function. The prognosis for survival was poorer and the incidence of thick subglottic stenosis was greater as the time of intubation increased and the birth weight of the child decreased. The correlation of birth weight and intubation time with survival and stenosis type are seen in Tables VI and VII. In addition to the subglottic narrowing, 11 of the patients had vocal cord abnormalities at the time of tracheostomy. The most common glottic finding was posterior intubation granuloTABLE VII DURATION OF ENDOTRACHEAL INTUBATION RELATED TO STENOSIS TYPE AND SURVIVAL
Duration of Intubation No. of Survival Stenosis Type in Days Patients Alive Dead Thick Thin
49 Total
4 4 5 2 3 18
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4 3 1 0 2 10
0 1 4 2 1 8
0 2 5 2 2 11
4 2 0 0 1 7
577
SUBGLOTTIC STENOSIS
mas. One vocal cord laceration was seen and vocal cord ulcerations were also noted. As mentioned above, two patients had congenital vocal cord pathologies, i.e., bilateral vocal cord paralysis and an anterior glottic web. Of the seven patients with thin type subglottic stenosis, all were discharged with good airway function and all are living. Three of these patients did not require tracheostomy. The stenotic area was endoscopically excised in three patients and dilated in four. Eleven patients had thick stenosis and only one of these patients has been extubated after serial dilatations over a IS-month period. This patient was extubated at seven months of age but required repeat tracheostomy three weeks later because of progressive stridor. He was re-extubated at 21 months of age and has done well for three months since then. Two of these 11 patients are alive with the tracheostomy in place. Both of these patients have undergone repeated dilatations and seem to be near final extubation. Eight patients with thick stenosis died with their tracheostomies in place. Extubation was accomplished in the tracheostomized child by first endoscopically confirming the presence of an anatomically patent airway. The tracheostomy tube was removed at the time of endoscopy and a nasotracheal tube was reinserted for 24 to 48 hours. Six hours prior to removal of the endotracheal tube, the child was given intramuscular Decadronw" 0.25 mg/kg. One half of the initial Decadron® dose was then repeated every six hours for 24 to 48 hours. The patients also received IPPB with racemic epinephrine every two to four hours. The patient's heart rate, respiratory rate, and blood gases were all monitored. Our experience has found this to be the best decannulation technique. Two of the 15 patients who underwent tracheostomy developed complications related to the tracheostomy placement. One patient was accident-
ally extubated 24 hours after her tracheostomy. The tube was reinserted and the patient received assisted ventilation. She failed to improve and an otolaryngology resident was called in who discovered that the tracheostomy tube had been replaced paratracheal. The tube was reinserted into the trachea with immediate respiratory improvement. Bilateral subcutaneous cervical emphysema and pneumomediastinum were diagnosed and managed uneventfully. The second patient developed tracheal granulomas below the level of the tracheostomy requiring repeated endoscopic excision. These were probably a contributing factor in the patient's subsequent death with a respiratory infection. DISCUSSION
As the skills of the neonatologist increase and improved techniques become available to him, an increased survival of the more critically ill and smaller premature children will be achieved. Obvious factors in the reduction of mortality in the newborn child with respiratory distress syndromes are the efficiency and skills of the pediatric intensive care transport team. The air transport service which is operational at the University of Utah Medical Center makes possible the safe transport of critically ill newborns from rural areas to the Intermountain Newborn Intensive Care Center. A high percentage of these newborns require assisted ventilation, many utilizing a closed system with an endotracheal or tracheostomy tube. Subglottic stenosis carries a much more serious prognosis for the surgical re-establishment of normal airway function. Unlike tracheal stenosis where excision and end-to-end anastomosis have provided satisfactory results in a large percentage of patients, the surgical control of subglottic stenosis has been less satisfactory. Many patients, particularly those with the thick type subglottic stenosis, will be discharged from the hospital with a tracheostomy
"Merck Sharp and Dohme, West Point, PA.
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578
PARKIN ET AL.
tube in place. Fearon and Cotton reviewed their experience with 25 consecutive cases of severe subglottic stenosis in children and reported a 24% mortality rate among children with tracheostomy in place.', These authors presented a surgical approach to the correction of this problem which appears to have promise. Endotracheal intubation with assisted ventilation has become a more frequent occurrence as evidenced by the 44% of patients admitted to the INICC experiencing this procedure. Endotracheal intubation has been promoted as a replacement for tracheostomy in acute inflammatory disease of the upper airway in ehildren.v-' Injuries to the supraglottic, glottic, and subglottic laryngeal area as well as tracheal injuries have been described from acute as well as long-term endotracheal intubation.s-" Since it is apparent that prolonged endotracheal intubation can cause permanent airway damage with subglottic stenosis being a difficult pathological entity to manage, the question then becomes what constitutes prolonged intubation. There is no consensus of opinion on this matter. Recommendations for tracheostomy as a replacement of endotracheal intubation in children range from six days to never.v" Komorn et al10 emphasized that laryngotracheal damage can occur at the time of intubation as well as during the presence of the tube in the airway. Hence the skill and technique utilized in initial intubation and at subsequent tube changes are very important. Mucosal ulceration with exposure of the cartilaginous framework and secondary infection resulting in cicatrix formation are probably basic in the etiology of subglottic stenosis. Utilization of endotracheal tubes which are too large can lead to pressure necrosis of the mucosa and cartilage exposure.'> Tube shape as well as tube size have been suggested as an important factor in the production of laryngotracheal injury." Another important factor is the piston action developed by the respirator attached to the endotracheal or tracheostomy tube. Humidification is an important factor.
TABLE VIII FACTORS IN THE PRODUCTION OF LARYNGOTRACHEAL DAMAGE 1. 2. 3. 4. 5. 6. 7. 8. 9.
Physical trauma during intubation Endotracheal tube size Endotracheal tube shape Humidification Piston action of respirator Physiologic activity of larynx and trachea Infection Underlying systemic disease Duration of intubation
One author (JLP) was called to see an infant in severe respiratory distress with a pCO z of 124 and marked cyanosis. The child had an endotracheal tube in place. The humidifier apparatus had malfunctioned for an unknown period of time leaving the child with no supplemental humidity. Bronchoscopy was performed and a heavy fibrinous pseudomembrane of the entire tracheobronchial tree was encountered. Brisk lavage and removal of the majority of the visible pseudomembrane was accomplished. The child had rapid improvement in her respiratory status and blood gases with eventual uneventful recovery. This experience re-emphasized the importance of constant humidity in the assisted ventilation situations. The duration of endotracheal intubation is an important but inconstant factor. Joshi et al5 reviewed 172 infants with respiratory distress syndrome and demonstrated severe lesions in 15.8% of their cases. They correlated the severity of the changes with the duration of intubation. Our results also support this concept as our more severe thick subglottic stenoses were seen in the cases of more prolonged intubation. Ferlic,? however, reported prolonged intubation in infants without significant laryngotracheal injury. Table VIn outlines the important factors in the production of laryngotracheal injury during assisted ventilation. Prevention of laryngotracheal damage results from conscientious efforts to con-
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SUBGLOTTIC STENOSIS
trol the factors mentioned in Table VIII. When dealing with the premature infant with respiratory distress it is not often possible to use the ne~t smaller size endotracheal tube. It IS advisable in these infants to use a 0.5 mm smaller tube than a tube that fits too snugly. Hengerer et al6 suggested a modification of tube shape to prevent laryngeal injury. This suggestion would possibly help if the tube could be secured so that no physiologic motion of the larynx or transmitted motion of the respirator occurred. It would seem that transmitted motion would transform a triangular shaped tube into a laryngotracheal Hoto-Hooter's with an increased damage risk. With any tube it is important to attach the respirator in such a way as to minimize transmitted motion. Adequate humidification is extremely important in prevention of crusting and tube occlusion by visc~us secretions. Periodic tracheal lavage WIth normal saline has also been found to be a helpful additional therapy. The determination of prolonged intubation in an individual patient is difficult. Endoscopy has been performed at three to five weeks of intubation and if subglottic ulcerations or narrowing is encountered, tracheostomy is advised. Subglottic narrowing is difficult to assess as the endotracheal tube acts as a stent and the subglottic area needs to be observed for narrowing over several minutes after removal of the endotracheal tube. If no evidence of severe laryngotracheal damage is present, the endotracheal tube is replaced. This method is not foolproof. We have recently seen two patients; one had large vocal cord granulomas and unilateral subglottic ulcerations, and the other child had concentric thin subglottic narrowing. Both children were extubated prior to tracheostomy. The child with vocal cord granulomas was subjected to endoscopy two weeks later without evidence of subglottic stenosis and with marked reduction in the granulomas. The other child has not been endoseeped since extubation but functions well without a tube five weeks later.: Definite criteria for prolonged intuba-
579
tion are difficult to define. Two of the 15 patients tracheostomized in this study developed tracheostomy related complications. If !racheostomy is performed, prevention of complications is very important. A higher complication rate has been reported in pediatric relative to adult tracheostomies.P The pediatric tracheostomy should be performed with an endotracheal tube or bronchoscope in place to give the trachea rigidity ~n? facilitate identification. This also mmimizes the amount of dissection necessary. The tracheal incision has been shown to be an important factor. We now utilize mainly an inverted U tracheal flap incision as described by Lulenski.l" Tracheal traction ties are routinely placed at the time of tracheostomy to facilitate replacement of the tracheostomy tube if accidentally dislodged prior to the establishment of a mature tracheocutaneous fistula. It is also important during this time not to use an occlusive tracheal dressing. There is frequently an air leak around the tracheostomy tube and if an occlusive dressing is present this air is forced into the cervical or thoracic tissue to cause cervical emphysema or pneumothorax or pneunomediastinum. As with the endotracheal tube, the tracheostomy tube should be attached to the respirator in such a way as to diminish transmitted respirator motion. In the premature infant, the standard pediatric tracheostomy tubes are too long. Radiographs should be obtained to assess tube length and shortening of the standard tube is frequently necessary. If accidental extubation occurs, a small suction catheter can be threaded into the trachea and used as a guide for the replacement of the tracheostomy tube, which is slid over the catheter followed by removal of the catheter when the tracheostomy tube is in place. What is the best technique for the treatment of subglottic stenosis when it is encountered in the infant? We have had best results with endoscopic excision or serial dilatations of the thin type stenosis. However, with the thick
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PARKIN ET AL.
stenosis, excision endoscopically has not been successful. Serial dilatations have been moderately successful. Intralesion steroid injections do not seem to add much benefit in our experience. An endolaryngeal stent was successfully utilized in the treatment of one patient with congenital glottic and subglottic stenosis where simple excision did not solve the problem. We have not utilized open surgical procedures in the young children of this series. Fearon and Cotton have reported promising results with the surgical treatment of subglottic stenosis and noted no effect on the developing larynx of the monkey subjected to their procedure.t-lv'" Prolonged endotracheal intubation with siliconized endotracheal tubes has also been reported as a successful way to treat subglottic stenosis.1 6 •17 We have not had experience with this technique. The extubation or decannulation technique which we utilize has previously been described under the Results section. The endotracheal tube is utilized as a temporary stent for extubation. 18 •19 Systemic steroids are given prior to and following decannulation to decrease laryngotracheal edema.s" Posi-
tive pressure ventilating assistance by mask with recemic epinephrine is also used following extubation to decrease laryngotracheal edema." Attempted decannulation is always preceded by endoscopic assessment of the anatomic patency of the airway. This technique has been most satisfactory in our experience. Decannulation should be performed as early as possible because prolonged tracheostomy may affect the growth and development of the laryngotracheal airway.P CONCLUSION
Subglottic stenosis is a serious management problem in the infant. Prevention should be attempted by diminishing the factors leading to its production. The duration of intubation is an important factor but is inconstant in its effect and difficult to individualize. Thin subglottic stenosis should be excised and/or dilated with establishment of airway function. Thick subglottic stenosis is more difficult to treat. Serial dilatations and tracheostomy are currently being used pending the success of reported surgical correction techniques.
REFERENCES 1. Fearon B, Cotton R: Surgical correction of subglottic stenosis in infants and children. Ann Otol Rhinol Laryngol 83:428-431, 1974 2. Tos M: Nasotracheal intubation instead of tracheostomy in acute epiglottitis in children. Acta Otolaryngol (Stockh) 75:382-383, 1973 3. Heldtander P, Lee P: Treatment of acute epiglottitis in children by long-term intubation. Acta Otolaryngol (Stock) 75 :379381, 1973 4. Schuller DE, Berek HG: The safety of intubation in croup and epiglottitis: an eight year follow-up. Laryngoscope 85:33-46, 1975 5. Joshi VV, Mandavia SG, Stem L, et al: Acute lesions induced by endotracheal intubation. Am J Dis Child 124:646-649, 1972 6. Hengerer AS, Strome M, Jaffe BF: Injuries to the neonatal larynx from long-term endotracheal tube intubation and suggested tube modification for prevention. Ann Otol Rhinol Laryngol 84:764-770, 1975 7. Ferlic RM: Tracheostomy or endotracheal intubation. Ann Otol Rhinol Laryngol 83:739-743, 1974 8. Lindholm CD: Prolonged endotracheal
intubation. Acta Anesthesiol Scand (Suppl) 33, 1969 9. Johnsen S: What is prolonged intubation. Acta Otolaryngol (Stockh) 75 :377 -378, 1973 10. Komom RM, Smith CP, Erwin JR: Acute laryngeal injury with short term endotracheal anesthesia. Laryngoscope 83: 683-690, 1973 11. Strome E, Ferguson CF: Multiple postintubation complications. Ann Otol Rhinol Laryngol 83:432-438, 1974 12. Chew JY, Cantrell RW: Tracheostomy: complications and their management. Arch Otolaryngol 96:538-545, 1972 13. Lulenski GC, Batsakis JG: Tracheal incision as a contributing factor to tracheal stenosis. Ann Otol Rhinol Laryngol 84:781786,1975 14. Fearon B, Cotton R: Subglottic stenosis in infants and children: the clinical problem and experimental correction. Can J Otolaryngol 1:281-289, 1972 15. Fearon B, Cotton R: Surgical correction of subglottic stenosis of the larynx. Ann Otol Rhinol Laryngo181:1-6, 1972
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SUBGLOTTIC STENOSIS
16. Bos CE, Berkovits RNP, Struben WH: Wider application of prolonged nasotracheal intubation. J Laryngol Otol 87 :263-279, 1973 17. Andersen HC, Elbrond 0, Geisen 0: Treatment of tracheal stenosis. J Laryngol OtoI88:615-624, 1974 18. Greenberg LM, Davenport HT, Shimo G: Method for difficult decannulations in children. Arch Otolaryngol 81 :72-76, 1965 19. Crysdale WS: Nasotracheal intubation in management of delayed decannulation. Ann
581
Otol Rhinol Laryngol 83:802-809, 1974 20. Biller HF, Bone RC, Harvey JE, et al, Laryngeal edema: an experimental study. Laryngoscope 70:1084-1087, 1970 21. Jordan WS, Graves CL, Elwyn RA: New therapy for postintubation laryngeal edema and tracheitis in children. JAMA 212: 585-588, 1970 22. Freeland AP, Wright JLW, Ardan GM: Developmental influences of infant tracheostomy. J Laryngol Otol 88 :927 -936, 1974
REPRINTs-James L. Parkin, MD, Division of Otolaryngology, University of Utah College of Medicine, Salt Lake City, UT 84112.
ESSAY CONTEST The American Cleft Palate Education Foundation, Inc. announces its annual essay contest for high school students, lay persons, graduate students and novice professionals. Winners will receive cash and a plaque. For information contact: Dr. Curtis Weiss, Essay Contest Committee Chairman, University of Nevada, Department of Speech Pathology and Audiology, Reno 89557, telephone (702) 784-4887.
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ACQUIRED AND CONGENITAL SUBGLOTTIC STENOSIS IN THE INFANT JAMES MICHAEL
H.
STEVENS,
L.
PARKIN,
MD
MD
AUGUST
L.
J UNG,
MD
SALT LAKE CITY, UTAH
SUMMARY - During the calendar year of 1974, the Intermountain Newborn Intensive Care Center at the University of Utah Medical Center had 603 admissions. A representative group of 293 charts were reviewed which indicated that 44% of these children were intubated from hours to weeks. The overall mortality rate for the 293 children was 29%. Eighteen of the 603 children were diagnosed as having subglottic stenosis. Fifteen of these children appeared to have acquired subglottic stenosis secondary to endotracheal intubation. Three ehildren had congenital subglottic stenosis. Tracheostomy was necessary in the management of 15 patients. Ten of the 18 patients have survived and two of these patients still have tracheostomy tubes in place. The survival and thickness of the stenotic area are inversely proportional to the birth weight and the duration ofIntubation. Endoscopic excision, dilatation and stenting were techniques utilized in the treatment of these stenotic lesions. The extubation technique utilized is described. The factors involved in the production of acquired subglottic stenosis are presented along with suggestions to decrease the incidence of this problem in the intubated child.
Assisted ventilation with various respirator machines and techniques has become a common practice in the care of the newborn with respiratory dysfunction. Maintenance of a closed system is necessary for the performance of such ventilatory assistance. The indwelling endotracheal tube is usually the initial technique by which this closed system is achieved. Much attention in recent years has been focused on the problems associated with such intubation. This paper reviews the experience with a group of newborn patients who demonstrated narrowing of the subglottic airway as seen in a newborn intensive care unit. The relationship of endotracheal intubation in the etiology and treatment of this problem will he discussed. METHODS AND MATERIALS
During the calendar year of 1974, 18 infants with subglottic stenosis were evaluated and treated in the Intermountain Newborn Inten-
sive Care Center (INICC) at the University of Utah Medical Center. The experience with these infants was reviewed retrospectively and forms the basis for this clinical study. The total number of children admitted during this period was 603. The charts of 293 consecutive admissions from July 1 to December 31, 1974, were studied to determine incidence of endotracheal intubation, development of subglottic stenosis and mortality in this group of newborns. All patients with a diagnosis of subglottic stenosis have now had a one to two-year follow-up. The infants who otherwise were patients of the Newborn Intensive Care Center received follow-up only until their death or discharge from the IN ICC. In all infants receiving closed system ventilatory assistance, endotracheal intubation was performed by pediatric house staff and specialized INICC nurses. Uneuffed, Murphy type endotracheal tubes were utilized. Tubes were not reused. The tubes were changed on an average of every three to five days or more frequently if secretions were copious, thick, or obstructive. All tracheobronchial endoscopies and tracheostomies were performed by the otolaryngology service under the direct supervision of the authors.
From the Department of Surgery, Division of Otolaryngology, and the Department of Pediatrics, University of Utah College of Medicine, Salt Lake City, Utah. Presented at the meeting of the American Broncho-Esophagological Association Palm Beach, Florida, April 27-28, 1976. ' 573
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PARKIN E1' AL. TABLE I
TABLE III
INTUBAnON, TRACHEOSTOMY AND MORTALITY IN 293 CONSECUTIVE NEWBORN INTENSIVE CARE PATIENTS
INCIDENCE OF SUBGLOTTIC STENOSIS
Intubated Tracheostomy Expired No. of patients Total patients Percent
Number Total patients Percent
18
3
15
603
603
3%
0.5%
603 2.5%
128
7
86
293 44%
293 2.4%
293
RESULTS
29%
The review of charts from 293 consecutive patients admitted to the INICC revealed an overall mortality of 86 or 29% (Table I). The number of patients who required endotracheal intubation was 128 of these 293 or 44%. Of the 128 intubated patients, 62 died, giving a 48% mortality rate among the intubated infants (Table II). Deaths occurred in 24 patients who were not intubated. It would be expected that the death rate would be higher in the intubated patients as they were generally the more seriously ill. Subglottic stenosis was diagnosed in 10 of the 128 intubated patients. The stenosis was considered to be congenital in three patients and acquired in seven patients. No subglottic stenosis was diagnosed in the nonintubated group of patients. Tracheostomy was necessary in seven patients. The subglottic stenosis was managed without tracheostomy in three patients. The incidence of acquired subglottic stenosis in this total group of 293 patients was 2.4%. The incidence of acquired subglottic stenosis in the intubated group was 5%. During the entire year of 1974, acquired subglottic stenosis was diagnosed in 15 of 603 patients for an incidence of 2.5% (Table III). Congenital subglottic stenosis was diagnosed in three of 603 patients for an incidence of 0.5%. All three of these patients received endotracheal intubation during their initial airway management. One of these patients required tracheostomy and was successfully extubated. The other two patients were managed without tracheostomy. All three patients are alive and well with good airway function.
The tracheostomies were done over an endotracheal tube or bronchoscope. Horizontal skin incisions were utilized and the tracheal incision performed was either a lazy "H" or an inferiorly based anterior tracheal wall Hap incorporating two adjacent tracheal rings. During the first three days, a gauze or net tracheostomy dressing was used to allow the escape of free air around the tube. This is important in the prevention of subcutaneous cervical emphysema and pneumomediastinum. The first tracheostomy tube change was accomplished at 48 to 72 hours. Silk or nylon traction sutures ( 5-0) were placed in the trachea at the time of tracheostomy to facilitate the initial tube change. These traction sutures were removed at the first or second tube change. The tracheostomy tubes were then changed at three-day intervals. Franklin or Shiley pediatric tracheostomy tubes were utilized in all patients. Extubation techniques will be covered in the discussion section. The INICC services a large geographic area. The majority of patients referred to the INICC have respiratory distress syndromes with or without other associated congenital problems. Those patients being transferred from other medical facilities are transported by a specialized air-transport team equipped to provide ventilatory as well as other supportive care while in transit. TABLE II TRACHEOSTOMY, ACQUIRED SUBGLOTTIC STENOSIS AND MORTALITY IN INTUBATED INFANTS
Acquired Subglottic Tracheostomy Stenosis Expired No. of patients Total intubated patients Percent
All Cases Congenital Acquired of Stenosis Stenosis Stenosis
7
7
62
128 5%
128 5%
128 48%
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SUBGLOTTIC STENOSIS
575
TABLE IV SUBGLOTTIC STENOSIS Female
9
9
15
Tracheostomy Extubated Yes No 5
3
15
7
II
Tracheostomy Yes No
Stenosis Etiology Acquired Congenital
Stenosis Type Thick n.«
Sex Male
Expired No Yes
10
The remainder of the results will be from the evaluation of the 18 patients with diagnosed subglottic stenosis managed in 1974 (Tables IV and V). Of the 18 patients, nine were male and nine were female. Acquired stenosis was present in 15 patients. All 18 patients had endotracheal tube placement and 16 patients required respirators. Tracheostomy was required in the management of 15 patients. The type of stenosis was considered thin if the length of subglottic involvement was less than 4 mm. If greater than 4 mm, the stenosis was typed as thick. Thin stenosis was seen in 7 patients and thick stenosis was seen in 11 patients. All congenital subglottic stenoses were of the thin type. Death occurred in eight patients. Five of these patients were discharged from the INICC with tracheostomies in place
Alive Without Trach
With Trach
10
8
3
2
8
and died at home or at other medical facilities. The tracheostomy was probably a factor in one death. This patient developed tracheal granulomata below the tracheostomy site near the carina. These were periodically removed endoscopically. The patient died at home with a pulmonary infection and at autopsy there was compromise of the right main stem bronchus by the granuloma. All other children died because of their underlying illnesses. None of the expired children were extubated prior to death. Sixteen of the 18 patients were premature by weight or gestation time or both. Respiratory distress syndrome was present as hyaline membrane disease, Wilson-Mikity syndrome or bronchopulmonary dysplasia in 16 patients. Significant cardiovascular disease was also seen in 12 patients with patent
TABLE V SUMMARY OF 18 SUBGLOTTIC STENOSIS PATIENTS RS IC Birth weight in kilograms Days of intubation Acquired or congenital stenosis Thick or thin stenosis Tracheostomy Tracheostomy extubation Survival
sc JJ
AD BE BF PM BF IP GI MK AH MM SV GS BW HT
1.2 2.8 .96 1.1 2.3 1.0 2.3 2.4 .68 2.5 2.7 1.9 1.7 1.1 .93 .74 2.0 .93 60
10 56 31 36 20
A
A
A
A
A
A
6
10 45
7
3
4
24 29 34 29 10 41
C
A
C
C
A
A
A
A
A
A
A
A
Tn Tk Tk Tk Tk Tk Tn Tn Tk Tn Tn Tn Tk Tk Tk Tk Tn Tk
+ + + + + + + +
+ +
,
+
T
+ +
+ + + ++ + + + + + + + +
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-+
+ +
576
PARKIN ET AL.
ductus arteriosus and congestive heart failure being most common. One patient had a bilateral vocal cord paralysis of uncertain etiology. He was intubated for 10 days and subsequently underwent tracheostomy with spontaneous improvement in vocal cord function. Extubation was accomplished but repeat tracheostomy was necessary because of progressive airway obstruction. Endoscopy at the time of repeat tracheostomy revealed a thick subglottic stenosis. The mothers of six newborns had significant health problems at the time of delivery. Two mothers had sepsis, one was a heroin addict, and two had severe diabetes. Of the two diabetic mothers, one had polyhydramnios. These five newborns were premature and developed acquired subglottic stenosis. The sixth mother had myasthenia gravis in poor control. Her daughter had immediate airway distress at birth and was intubated. A peculiarity of the larynx was noted and the child was referred to the INICC. The endotracheal tube was removed three days later and an anterior glottic web was excised. In addition, a posterior and lateral subglottic thin weblike stenosis was discovered which had been partially avulsed by the endotracheal tube. The glottic web and the subglottic stenosis were excised and a nasotracheal tube placed. Extubation was accomplished but in the ensuing 72 hours the patient developed inspiratory stridor and repeat endoscopy was performed, revealing subglottic and glottic granuloma which were excised. Tracheostomy was performed. A soft stent was fashioned and secured in the larynx. The stent was removed and the child extubated ten days later with no additional airway problems. Five patients were diagnosed as having subglottic stenosis three days to 12 weeks following the removal of the endotracheal tube. All five of these patients had thin subglottic stenosis and were intubated ten days or less. Two of these patients were diagnosed as having congenital subglottic stenosis. The stenotic area was dilated in one
TABLE VI BIRTH WEIGHT RELATED TO STENOSIS TYPE AND SURVIVAL
Birth Wt. in No. of Survival Stenosis Type Kilograms Patients Alive Dead Thick Thin
0.5-1.0 1.0-1.5 1.5-2.0 2.0-2.5
>
2.5 Total
1 2 I 3 3 10
5 4 2 4 3 18
4 2 1 1 0 8
5 3 1 1 1 11
0 1 1 3 2 7
patient and excised in the second. Tracheostomy was not required in either patient. The other three patients were thought to have acquired stenosis. Two of these patients required tracheostomy. The stenotic area was excised in the third patient without tracheostomy. All five of these patients were discharged from the INICC with good airway function. The prognosis for survival was poorer and the incidence of thick subglottic stenosis was greater as the time of intubation increased and the birth weight of the child decreased. The correlation of birth weight and intubation time with survival and stenosis type are seen in Tables VI and VII. In addition to the subglottic narrowing, 11 of the patients had vocal cord abnormalities at the time of tracheostomy. The most common glottic finding was posterior intubation granuloTABLE VII DURATION OF ENDOTRACHEAL INTUBATION RELATED TO STENOSIS TYPE AND SURVIVAL
Duration of Intubation No. of Survival Stenosis Type in Days Patients Alive Dead Thick Thin
49 Total
4 4 5 2 3 18
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4 3 1 0 2 10
0 1 4 2 1 8
0 2 5 2 2 11
4 2 0 0 1 7
577
SUBGLOTTIC STENOSIS
mas. One vocal cord laceration was seen and vocal cord ulcerations were also noted. As mentioned above, two patients had congenital vocal cord pathologies, i.e., bilateral vocal cord paralysis and an anterior glottic web. Of the seven patients with thin type subglottic stenosis, all were discharged with good airway function and all are living. Three of these patients did not require tracheostomy. The stenotic area was endoscopically excised in three patients and dilated in four. Eleven patients had thick stenosis and only one of these patients has been extubated after serial dilatations over a IS-month period. This patient was extubated at seven months of age but required repeat tracheostomy three weeks later because of progressive stridor. He was re-extubated at 21 months of age and has done well for three months since then. Two of these 11 patients are alive with the tracheostomy in place. Both of these patients have undergone repeated dilatations and seem to be near final extubation. Eight patients with thick stenosis died with their tracheostomies in place. Extubation was accomplished in the tracheostomized child by first endoscopically confirming the presence of an anatomically patent airway. The tracheostomy tube was removed at the time of endoscopy and a nasotracheal tube was reinserted for 24 to 48 hours. Six hours prior to removal of the endotracheal tube, the child was given intramuscular Decadronw" 0.25 mg/kg. One half of the initial Decadron® dose was then repeated every six hours for 24 to 48 hours. The patients also received IPPB with racemic epinephrine every two to four hours. The patient's heart rate, respiratory rate, and blood gases were all monitored. Our experience has found this to be the best decannulation technique. Two of the 15 patients who underwent tracheostomy developed complications related to the tracheostomy placement. One patient was accident-
ally extubated 24 hours after her tracheostomy. The tube was reinserted and the patient received assisted ventilation. She failed to improve and an otolaryngology resident was called in who discovered that the tracheostomy tube had been replaced paratracheal. The tube was reinserted into the trachea with immediate respiratory improvement. Bilateral subcutaneous cervical emphysema and pneumomediastinum were diagnosed and managed uneventfully. The second patient developed tracheal granulomas below the level of the tracheostomy requiring repeated endoscopic excision. These were probably a contributing factor in the patient's subsequent death with a respiratory infection. DISCUSSION
As the skills of the neonatologist increase and improved techniques become available to him, an increased survival of the more critically ill and smaller premature children will be achieved. Obvious factors in the reduction of mortality in the newborn child with respiratory distress syndromes are the efficiency and skills of the pediatric intensive care transport team. The air transport service which is operational at the University of Utah Medical Center makes possible the safe transport of critically ill newborns from rural areas to the Intermountain Newborn Intensive Care Center. A high percentage of these newborns require assisted ventilation, many utilizing a closed system with an endotracheal or tracheostomy tube. Subglottic stenosis carries a much more serious prognosis for the surgical re-establishment of normal airway function. Unlike tracheal stenosis where excision and end-to-end anastomosis have provided satisfactory results in a large percentage of patients, the surgical control of subglottic stenosis has been less satisfactory. Many patients, particularly those with the thick type subglottic stenosis, will be discharged from the hospital with a tracheostomy
"Merck Sharp and Dohme, West Point, PA.
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PARKIN ET AL.
tube in place. Fearon and Cotton reviewed their experience with 25 consecutive cases of severe subglottic stenosis in children and reported a 24% mortality rate among children with tracheostomy in place.', These authors presented a surgical approach to the correction of this problem which appears to have promise. Endotracheal intubation with assisted ventilation has become a more frequent occurrence as evidenced by the 44% of patients admitted to the INICC experiencing this procedure. Endotracheal intubation has been promoted as a replacement for tracheostomy in acute inflammatory disease of the upper airway in ehildren.v-' Injuries to the supraglottic, glottic, and subglottic laryngeal area as well as tracheal injuries have been described from acute as well as long-term endotracheal intubation.s-" Since it is apparent that prolonged endotracheal intubation can cause permanent airway damage with subglottic stenosis being a difficult pathological entity to manage, the question then becomes what constitutes prolonged intubation. There is no consensus of opinion on this matter. Recommendations for tracheostomy as a replacement of endotracheal intubation in children range from six days to never.v" Komorn et al10 emphasized that laryngotracheal damage can occur at the time of intubation as well as during the presence of the tube in the airway. Hence the skill and technique utilized in initial intubation and at subsequent tube changes are very important. Mucosal ulceration with exposure of the cartilaginous framework and secondary infection resulting in cicatrix formation are probably basic in the etiology of subglottic stenosis. Utilization of endotracheal tubes which are too large can lead to pressure necrosis of the mucosa and cartilage exposure.'> Tube shape as well as tube size have been suggested as an important factor in the production of laryngotracheal injury." Another important factor is the piston action developed by the respirator attached to the endotracheal or tracheostomy tube. Humidification is an important factor.
TABLE VIII FACTORS IN THE PRODUCTION OF LARYNGOTRACHEAL DAMAGE 1. 2. 3. 4. 5. 6. 7. 8. 9.
Physical trauma during intubation Endotracheal tube size Endotracheal tube shape Humidification Piston action of respirator Physiologic activity of larynx and trachea Infection Underlying systemic disease Duration of intubation
One author (JLP) was called to see an infant in severe respiratory distress with a pCO z of 124 and marked cyanosis. The child had an endotracheal tube in place. The humidifier apparatus had malfunctioned for an unknown period of time leaving the child with no supplemental humidity. Bronchoscopy was performed and a heavy fibrinous pseudomembrane of the entire tracheobronchial tree was encountered. Brisk lavage and removal of the majority of the visible pseudomembrane was accomplished. The child had rapid improvement in her respiratory status and blood gases with eventual uneventful recovery. This experience re-emphasized the importance of constant humidity in the assisted ventilation situations. The duration of endotracheal intubation is an important but inconstant factor. Joshi et al5 reviewed 172 infants with respiratory distress syndrome and demonstrated severe lesions in 15.8% of their cases. They correlated the severity of the changes with the duration of intubation. Our results also support this concept as our more severe thick subglottic stenoses were seen in the cases of more prolonged intubation. Ferlic,? however, reported prolonged intubation in infants without significant laryngotracheal injury. Table VIn outlines the important factors in the production of laryngotracheal injury during assisted ventilation. Prevention of laryngotracheal damage results from conscientious efforts to con-
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SUBGLOTTIC STENOSIS
trol the factors mentioned in Table VIII. When dealing with the premature infant with respiratory distress it is not often possible to use the ne~t smaller size endotracheal tube. It IS advisable in these infants to use a 0.5 mm smaller tube than a tube that fits too snugly. Hengerer et al6 suggested a modification of tube shape to prevent laryngeal injury. This suggestion would possibly help if the tube could be secured so that no physiologic motion of the larynx or transmitted motion of the respirator occurred. It would seem that transmitted motion would transform a triangular shaped tube into a laryngotracheal Hoto-Hooter's with an increased damage risk. With any tube it is important to attach the respirator in such a way as to minimize transmitted motion. Adequate humidification is extremely important in prevention of crusting and tube occlusion by visc~us secretions. Periodic tracheal lavage WIth normal saline has also been found to be a helpful additional therapy. The determination of prolonged intubation in an individual patient is difficult. Endoscopy has been performed at three to five weeks of intubation and if subglottic ulcerations or narrowing is encountered, tracheostomy is advised. Subglottic narrowing is difficult to assess as the endotracheal tube acts as a stent and the subglottic area needs to be observed for narrowing over several minutes after removal of the endotracheal tube. If no evidence of severe laryngotracheal damage is present, the endotracheal tube is replaced. This method is not foolproof. We have recently seen two patients; one had large vocal cord granulomas and unilateral subglottic ulcerations, and the other child had concentric thin subglottic narrowing. Both children were extubated prior to tracheostomy. The child with vocal cord granulomas was subjected to endoscopy two weeks later without evidence of subglottic stenosis and with marked reduction in the granulomas. The other child has not been endoseeped since extubation but functions well without a tube five weeks later.: Definite criteria for prolonged intuba-
579
tion are difficult to define. Two of the 15 patients tracheostomized in this study developed tracheostomy related complications. If !racheostomy is performed, prevention of complications is very important. A higher complication rate has been reported in pediatric relative to adult tracheostomies.P The pediatric tracheostomy should be performed with an endotracheal tube or bronchoscope in place to give the trachea rigidity ~n? facilitate identification. This also mmimizes the amount of dissection necessary. The tracheal incision has been shown to be an important factor. We now utilize mainly an inverted U tracheal flap incision as described by Lulenski.l" Tracheal traction ties are routinely placed at the time of tracheostomy to facilitate replacement of the tracheostomy tube if accidentally dislodged prior to the establishment of a mature tracheocutaneous fistula. It is also important during this time not to use an occlusive tracheal dressing. There is frequently an air leak around the tracheostomy tube and if an occlusive dressing is present this air is forced into the cervical or thoracic tissue to cause cervical emphysema or pneumothorax or pneunomediastinum. As with the endotracheal tube, the tracheostomy tube should be attached to the respirator in such a way as to diminish transmitted respirator motion. In the premature infant, the standard pediatric tracheostomy tubes are too long. Radiographs should be obtained to assess tube length and shortening of the standard tube is frequently necessary. If accidental extubation occurs, a small suction catheter can be threaded into the trachea and used as a guide for the replacement of the tracheostomy tube, which is slid over the catheter followed by removal of the catheter when the tracheostomy tube is in place. What is the best technique for the treatment of subglottic stenosis when it is encountered in the infant? We have had best results with endoscopic excision or serial dilatations of the thin type stenosis. However, with the thick
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PARKIN ET AL.
stenosis, excision endoscopically has not been successful. Serial dilatations have been moderately successful. Intralesion steroid injections do not seem to add much benefit in our experience. An endolaryngeal stent was successfully utilized in the treatment of one patient with congenital glottic and subglottic stenosis where simple excision did not solve the problem. We have not utilized open surgical procedures in the young children of this series. Fearon and Cotton have reported promising results with the surgical treatment of subglottic stenosis and noted no effect on the developing larynx of the monkey subjected to their procedure.t-lv'" Prolonged endotracheal intubation with siliconized endotracheal tubes has also been reported as a successful way to treat subglottic stenosis.1 6 •17 We have not had experience with this technique. The extubation or decannulation technique which we utilize has previously been described under the Results section. The endotracheal tube is utilized as a temporary stent for extubation. 18 •19 Systemic steroids are given prior to and following decannulation to decrease laryngotracheal edema.s" Posi-
tive pressure ventilating assistance by mask with recemic epinephrine is also used following extubation to decrease laryngotracheal edema." Attempted decannulation is always preceded by endoscopic assessment of the anatomic patency of the airway. This technique has been most satisfactory in our experience. Decannulation should be performed as early as possible because prolonged tracheostomy may affect the growth and development of the laryngotracheal airway.P CONCLUSION
Subglottic stenosis is a serious management problem in the infant. Prevention should be attempted by diminishing the factors leading to its production. The duration of intubation is an important factor but is inconstant in its effect and difficult to individualize. Thin subglottic stenosis should be excised and/or dilated with establishment of airway function. Thick subglottic stenosis is more difficult to treat. Serial dilatations and tracheostomy are currently being used pending the success of reported surgical correction techniques.
REFERENCES 1. Fearon B, Cotton R: Surgical correction of subglottic stenosis in infants and children. Ann Otol Rhinol Laryngol 83:428-431, 1974 2. Tos M: Nasotracheal intubation instead of tracheostomy in acute epiglottitis in children. Acta Otolaryngol (Stockh) 75:382-383, 1973 3. Heldtander P, Lee P: Treatment of acute epiglottitis in children by long-term intubation. Acta Otolaryngol (Stock) 75 :379381, 1973 4. Schuller DE, Berek HG: The safety of intubation in croup and epiglottitis: an eight year follow-up. Laryngoscope 85:33-46, 1975 5. Joshi VV, Mandavia SG, Stem L, et al: Acute lesions induced by endotracheal intubation. Am J Dis Child 124:646-649, 1972 6. Hengerer AS, Strome M, Jaffe BF: Injuries to the neonatal larynx from long-term endotracheal tube intubation and suggested tube modification for prevention. Ann Otol Rhinol Laryngol 84:764-770, 1975 7. Ferlic RM: Tracheostomy or endotracheal intubation. Ann Otol Rhinol Laryngol 83:739-743, 1974 8. Lindholm CD: Prolonged endotracheal
intubation. Acta Anesthesiol Scand (Suppl) 33, 1969 9. Johnsen S: What is prolonged intubation. Acta Otolaryngol (Stockh) 75 :377 -378, 1973 10. Komom RM, Smith CP, Erwin JR: Acute laryngeal injury with short term endotracheal anesthesia. Laryngoscope 83: 683-690, 1973 11. Strome E, Ferguson CF: Multiple postintubation complications. Ann Otol Rhinol Laryngol 83:432-438, 1974 12. Chew JY, Cantrell RW: Tracheostomy: complications and their management. Arch Otolaryngol 96:538-545, 1972 13. Lulenski GC, Batsakis JG: Tracheal incision as a contributing factor to tracheal stenosis. Ann Otol Rhinol Laryngol 84:781786,1975 14. Fearon B, Cotton R: Subglottic stenosis in infants and children: the clinical problem and experimental correction. Can J Otolaryngol 1:281-289, 1972 15. Fearon B, Cotton R: Surgical correction of subglottic stenosis of the larynx. Ann Otol Rhinol Laryngo181:1-6, 1972
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SUBGLOTTIC STENOSIS
16. Bos CE, Berkovits RNP, Struben WH: Wider application of prolonged nasotracheal intubation. J Laryngol Otol 87 :263-279, 1973 17. Andersen HC, Elbrond 0, Geisen 0: Treatment of tracheal stenosis. J Laryngol OtoI88:615-624, 1974 18. Greenberg LM, Davenport HT, Shimo G: Method for difficult decannulations in children. Arch Otolaryngol 81 :72-76, 1965 19. Crysdale WS: Nasotracheal intubation in management of delayed decannulation. Ann
581
Otol Rhinol Laryngol 83:802-809, 1974 20. Biller HF, Bone RC, Harvey JE, et al, Laryngeal edema: an experimental study. Laryngoscope 70:1084-1087, 1970 21. Jordan WS, Graves CL, Elwyn RA: New therapy for postintubation laryngeal edema and tracheitis in children. JAMA 212: 585-588, 1970 22. Freeland AP, Wright JLW, Ardan GM: Developmental influences of infant tracheostomy. J Laryngol Otol 88 :927 -936, 1974
REPRINTs-James L. Parkin, MD, Division of Otolaryngology, University of Utah College of Medicine, Salt Lake City, UT 84112.
ESSAY CONTEST The American Cleft Palate Education Foundation, Inc. announces its annual essay contest for high school students, lay persons, graduate students and novice professionals. Winners will receive cash and a plaque. For information contact: Dr. Curtis Weiss, Essay Contest Committee Chairman, University of Nevada, Department of Speech Pathology and Audiology, Reno 89557, telephone (702) 784-4887.
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