Diffuse necrotizing tracheobronchitis: An acute and chronic disease

Diffuse Necrotizing Tracheobronchitis: An Acute and Chronic Disease By Steven Z. Rubin, Cynthia L. Trevenen, and I. Mitchell Ottawa, Ontario, Canada 9 Necrotizing tracheobronchitis (NTB) is characterized by acute episodes of airway obstruction, hypercarbia, and lack of chest movement in mechanically ventilated neonates. Emergency bronchoscopic removal of necrotic tissue is essential for survival. Although postmortem lesions extend into smaller bronchi, survivors have not demonstrated residual tracheobronchial abnormalities. T w o infants w e r e treated successfully for NTB but succumbed to diffuse tracheobronchial strictures with progressive pulmonary hyperinflation. A third neonate with esophageal atresia and left pulmonary agenesis developed NTB. Despite initial postbronchoscopic improvement, the infant died at age 6 weeks with diffuse obstructing NTB. All three infants required endotracheal intubation and mechanical ventilation. High-frequency jet ventilation was not used. Tracheal cultures for fungi, bacteria and viruses w e r e negative. Successful treatment of NTB may be followed acutely by recurrence of NTB and chronically by diffuse tracheobronchial strictures and emphysema. 9 1988 by Grune & Stratton, Inc. INDEX WORDS: obstruction.

Necrotizing

tracheobronchitis;

airway

B S T R U C T I O N of the major airways in ventilated infants by debris comprising thick homogeneous basophilic material lined on the luminal aspect by necrotic epithelium has been termed necrotizing tracheobronchitis (NTB). 1 The source of the luminal obstruction is thought to be detached necrotic mucosa admixed with mucus. 1 Kirpalani, et al 2 stressed that a clinical diagnosis of N T B should be made in mechanically ventilated infants with airway obstruction characterized by hypercarbia, lack of chest movement and difficulty with ventilation. Immediate bronchoscopy with removal of the intraluminal obstruction is the treatment of choice. Dramatic response has been noted in those infants with a localized obstruction. Long term

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From the Department of Pediatric Surgery, Children's Hospital of Eastern Ontario, Ottawa; the Departments of Clinical Laboratory Medicine and Pulmonary Medicine, Alberta Children's Hospital, Calgary. Presented at the 20th Annual Meeting of the Pacific Association of Pediatric Surgeons, Seattle and Rosario, WA, April 26 to May 1, 1987. Address reprint requests to Steven Z. Rubin, MD, Department of Surgery, Children's Hospital of Eastern Ontario, 401 Smyth Rd, Ottawa, Ontario K I H 81,1, Canada. 9 1988 by Grune & Stratton, Inc. 0022-3468/88/2305-0021 $03.00/0

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survival without apparent chronic respiratory disease has been reported. 3 When N T B is diffuse resuscitation has been unsuccessful. 2 We describe three infants with diffuse N T B responding satisfactorily to bronchoscopic removal of intraluminal debris. Diffuse tracheobronchial narrowing seen in two infants as an apparent sequela to N T B has not been previously reported. MATERIALS AND METHODS Three patients in the neonatal intensive care unit (NICU) were diagnosed with NTB. Two of the patients had been admitted with severe hyaline membrane disease and required prolonged mechanical ventilation with increased inspiratory oxygen concentrations (FIO2). They survived multiple episodes of NTB in the first 2 months of life, but developed diffuse airway narrowing extending from the distal trachea into the distal bronchi. Both children succumbed at age 12 months. The third infant had multiple congenital anomalies including left pulmonary agenesis, esophageal atresia and distal tracheoesophageal fistula. Having survived (1) severe neonatal respiratory distress, (2) insertion of a gastrostomy tube, (3) ligation of tracheoesophageal fistula, and (4) two general anaesthetics she developed NTB at eight days of age. Bronchoscopy and aspiration of a plug of necrotic tissue and mucus produced a dramatic improvement. A further episode of NTB ten days later was managed similarly. The tracheal aspirate grew Staph aureus and intravenous Cloxacillin was started. Septic arthritis of the knee due to Candida albicans was treated with intravenous Amphotericin B. Her condition was stable for a 2-week period but the reappearance of NTB diffusely involving the trachea and bronchi resulted in the baby's demise over a 24-hour period despite multiple bronchoscopic attempts to clear the airway. The ventilators used were an infant Bird Mark 8 (Bird Corp, Palm Springs, CA), Sechrist model IV-100 (Sechrist Industries Incorporated, Annaheim, CA), and a Bourns Bear Cub infant ventilator (Bear Medical Systems, Riverside, CA). Inspired gases were warmed to 31~ and humidified using an in-line Concha Therm 3 (Respiratory Care Incorporated, Arlington Heights, IL) humidifier. The ventilator rate varied from 40 to 80 per minute. High frequency ventilation was not used. Peak inspiratory and positive end expiratory pressure with a range of 20 to 40 and 3 to 10 cm water pressure respectively were used. Inspiratory to expiratory ratio ranged from 1 to 1.5:1. All tubing used was sterile. Infants were orally or nasally intubated with uncuffed Portex (Portex Incorporated, Scarborough, Ontario) tubes (ETT) with the end positioned midtracheally. ETT toilet was accomplished by instillation of 0.2 mL saline every four hours followed by suctioning with a soft suction catheter. Aspirates were sent daily for bacteriology. Bronchoscopy was performed in the NICU at the bedside without general anaesthesia. A fiberoptic rigid ventilating pediatric bronchoscope (Storz GMBH and Co, Tuttlingen, West Germany) was used. Obstructing intraluminal material removed from the trachea and major bronchi was sent for histology and bacteriologic culture.

Journal of Pediatric Surgery, Vol 23, No 5 (May), 1988: pp 476-477

NECROTIZlNG TRACHEOBRONCHITIS

DISCUSSION

N T B is an iatrogenic lesion of the tracheobronchial tree. The postmortem incidence of N T B varies from 20% to 44% of neonates dying in the N I C U : The reported number of infants diagnosed with N T B and treated by bronchoscopy continues to increase. An initial survival of two of eight patients 2 was followed by the bronchoscopic salvage of ten of 15 babies: Many infants required multiple bronchoscopies to clear the airway. The incidence of N T B may be decreased by careful humidification of inspired gases, avoidance of high temperature, and minimal use of high flow ventilation. Neither the type of ventilator nor the chemical nature of the E T T appear to cause N T B ) '2 Infective agents have not been incriminated in the etiology: Nevertheless, careful placement of the ETT, avoidance of unnecessary trauma and sterility of instrumentation are essential in airway care and may prevent secondary damage to the airway. The factors that influence survival are primarily an ability to make the diagnosis and successful bronchoscopic extraction of the obstructing debris. There appear to be two anatomical forms of the disease. 2 The localized type usually occurs a few centimeters distal to the end of the E T T and often follows high frequency jet ventilation. 5 Here bronchoscopic removal of the obstruction is immediately successful and although temporary localized narrowing has occurred no longterm sequelae in survivors have been described. The diffuse type, on the other hand, has not been previously associated with salvage by immediate bronchoscopy and is well described in autopsy specimens. A signifi-

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cant improvement in ventilation was seen after bronchoscopic removal of N T B debris in the three infants herein reported. Acute episodes of airway obstruction due to N T B may be recurrent. In our patients the time interval between such events varied from a few hours to ten days. Repeated urgent bronchoscopies m a y be needed to obtain adequate ventilation in the infants. Tracheal wall pathology including obstructed dilated mucus glands, granulomata and submucosal fibrosis have been suggested as different temporal points in the natural history of NTB. 2 Recurrent episodes of N T B m a y indicate a more severe insult to the tracheobronchial wall with a greater probability of fibrosis. The diffuse stricturing of the tracheobronchial tree seen in two of the infants described may be the first documentation of the natural history of diffuse N T B surviving the neonatal period. Long-term followup in such infants surviving diffuse or recurrent episodes of N T B is required. REFERENCES

1. Metlay LA, MacPherson TA, Doshi N, et al: A new iatrogenous lesion in newborns requiring assisted ventilation. New Engl J Med 309:111-112, 1983 (letter) 2. Kirpalani H, Higa T, Perlman M, et al: Diagnosisand therapy of necrotizing tracheobronchitis in ventilated neonates. Crit Care Med 13:792-797, 1985 3. Mimouni F, Ballard JL, Ballard ET, et al: Necrotizing tracheobronchitis: Case report. Pediatrics 77:366-368, 1986 4. Pietsch JB, Nagaraj HS, Groff DB, et al: Necrotizing tracheobronchitis: A new indication for emergency bronchoscopy in the neonate. J Pediatr Surg 20:391-393, 1985 5. Boros SJ, Mammel MC, Lewallen PK, et al: Necrotizing tracheobronchitis: A complication of high frequency ventilation. J Pediatr 109:95-100, 1986