Pediatr Radiol (1997) 27: 276–280  Springer-Verlag 1997

Tain Lee S. K. Lee

Received: 11 October 1995 Accepted: 10 March 1996

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T. Lee ( ) Department of Radiology, Taichung Veterans General Hospital, 160, Taichung Kang Road Section 3, Taichung, Taiwan, ROC T. Lee ⋅ S. K. Lee Department of Radiology, Taichung Veterans General Hospital, Taiwan, ROC

Upper airway obstruction in infants and children: evaluation by tracheobronchography with a non-ionic contrast agent

Abstract The clinical benefits of tracheobronchograms using nonionic contrast medium were evaluated prospectively in ten infants and children with suspected airway obstruction who could not be weaned from endotracheal intubation and were in incubators. All patients were examined unsedated. The contrast agent was injected via the intubation tube, pumped with an Ambu-bag (Manual Resuscitator, Formosa-CJ Health Business Corporation, Tai-

wan), and then a chest radiograph was obtained immediately in both anteroposterior and lateral views using portable equipment. Imaging results were correct in eight of ten cases as judged from bronchoscopic, surgical, and clinical data. No complications occurred during or after these examinations. This method provides an easy, safe, and helpful technique for diagnosis of the airway in nonsedated infants and children whose condition is critical.

Introduction

Materials and methods

There are a number of imaging modalities for evaluating the upper airway. However, as most sick infants and children depend on ventilation control, it is a challenge to evaluate them effectively without harming their ventilation. A rough estimate of the airway is helpful for prompt diagnosis and treatment. Radiography is of little help in such conditions. Techniques such as ultrafast CT, three-dimensional CT, and even MRI have better resolution than conventional radiography. However, they are not available in every hospital, and sedation may be necessary during the examination. Tracheobronchography using a low-osmolar, non-ionic contrast agent could be a good alternative, as it is quite flexible and visualizes the airway sufficiently to point the way to the next step. We present our experience with this modified tracheobronchography with a non-ionic contrast agent, which has proved helpful in giving our clinical colleagues the necessary information to plan further management.

Ten patients with clinically suspected upper airway obstruction were studied with non-ionic contrast agent tracheobronchography. Their ages, sex distribution, and clinical findings are summarized in Table 1. All patients had endotracheal intubation or a tracheotomy tube when tracheobronchography was performed. First of all, we withdrew the intubation tube to as proximal a point as possible, then 1 cc Iopamiro 200 (Brass, Italy) as contrast agent was injected via the tube and pumped by an Ambu-bag (Manual Resuscitator, Formosa-CJ Health Business Corporation, Taiwan), immediately after which a chest radiograph was made in both anteroposterior and lateral views using portable equipment. After that we normally used the suction from the intubation tube to remove the contrast agent and a follow-up chest radiograph was taken 4–6 h later which allowed us to evaluate the patient’s chest condition. The trachea was measured in these films: the criterion for tracheal stenosis was a diameter of the trachea smaller than that of the upper trachea, in which the endotracheal tube was positioned. All patients underwent bronchoscopy, and one had surgical confirmation of the extent of stenosis.

Results A summary of the clinical data, tracheobronchograms, bronchoscopy, and follow-up is given in Table 1. A total

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Table 1 Summary of clinical, tracheobronchographic, bronchoscopic, and surgical findings (AAD against advice discharge, ASD atrial septal defect, F/U follow-up, OPD outpatients department, PDA patent ductus arteriosus, SOB shortness of breath, S/P status post) Case Age/sex

Clinical findings

Tracheobronchogram

Bronchoscopic or surgical findings

Follow-up

(1) No abnormal findings on bronchoscopy (2) Open lung biopsy: bronchiolitis obliterans Collapse of tracheal tree, tracheal ring undetectable, tracheomalacia considered Diffuse small caliber of trachea, bronchi

Discharged; symptoms improved; regular F/U in OPD

Associated findings

1

17 Months/F

Respiratory distress

Normal

2

6 Months/F

Normal

3

8 Months/M

Progressive SOB with respiratory distress Respiratory distress

4

3 Months/F

Dyspnea lasting days

Localized stenosis just below tracheostomy tube

Circumferential stenosis, diameter of the narrowing trachea about 1.5 mm on bronchoscopy; tracheoplasty

Died

5

6 Months/F

SOB and fever

2 Months/M

7

2 Months/F

Cough off and on for 1 month, progressive Remained dependent on ventilator after ligation procedure for PDA

Tracheal narrowing below the tracheostomy tube, distal extent not determined Normal caliber of trachea

Died of acute respiratory failure

6

Diffuse narrowing of trachea and bilateral main bronchi No tracheobronchial narrowing No tracheobronchial narrowing

8

3 Days/M

SOB and retraction, respiratory distress after birth

No tracheobronchial narrowing

Bronchoscopy showed no abnormal findings

AAD; MRI of brain showed cortical atrophy and medullary hypoplasia

9

2 Days/F

SOB and noisy breath sounds

No abnormal finding

Newborn/M

Progressive respiratory distress after esophageal operation

Relative narrowing of lower trachea and main bronchi

Bronchoscopy showed no indentation or stenosis, suspected laryngomalacia Bronchoscopy revealed mild stenosis of trachea, tracheal stenosis considered

Discharged; symptoms improved; F/U in OPD Transferred to PDA, S/P, closure another institution of fistula and endto-end esophageal anastomosis for type D esophageal atresia

10

Narrowing from endotracheal tube to bronchi

Bronchoscopy revealed mild tracheomalacia

of ten non-ionic contrast agent tracheobronchograms were obtained in the ten patients in the study. Bronchoscopy was performed subsequently in all ten patients. This was most useful for confirming the presence of complete cartilaginous tracheal rings, as well as determining the length and severity of stenosis. Four cases of tracheal stenosis suspected by tracheobronchography were proved by subsequent bronchoscopy (Figs. 1, 2). One of these four patients later underwent tracheoplasty, but three of them died later in the hospital be-

In OPD

Died

Large PDA and congestive heart failure, S/P Congenital heart disease (PDA, ASD), hemivertebrae, rib deformity with scoliosis, right hand ectrodactyly, etc.

Discharged; symptoms, improved; F/U in OPD Died of brain atrophy and respiratory failure

cause of respiratory failure. Two patients had normal tracheobronchograms, but tracheomalacia was found with bronchoscopy in the patient who had had an operation for patent ductus arteriosus earlier. Tracheomalacia is a condition in which a segment of trachea collapses by 50 % or more of its maximal cross-sectional area [1], prior to intubation or surgical repair. One case of laryngomalacia, or infantile larynx, was proved by laryngoscopy, also in a patient with a normal tracheobronchogram; this condition is often associated with ex-

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a

Fig. 1 Case 4. a A tracheobronchogram in anteroposterior (AP) projection shows a localized tracheal stenosis (arrowheads) just below the endotracheal tube. b A lateral tracheobronchogram showing the localized stenosis (arrowheads) in the same position as in Fig. 1 a. The tracheal stenosis was confirmed by bronchoscopy and the patient underwent tracheoplasty. c An AP chest film taken on the following day using portable equipment shows no residual contrast agent in the hyperinflated lungs

cessive infolding of the aryepiglottic fold during inspiration [1]. Of the remaining three patients with normal tracheobronchograms, one underwent open lung biopsy and bronchiolitis obliterans was diagnosed. After short hospitalization she was discharged with improved symptoms and followed up in the outpatients department. In the second patient, pneumonia with respiratory failure was diagnosed. He was discharged after the symptoms improved. The third patient underwent an MRI study of the brain which showed cortical atrophy and medullary hypoplasia. The symptoms of upper airway obstruction could be due to central apnea.

Discussion Severe respiratory distress in infancy can be due to various causes, but the clinical manifestations are seldom diagnostic in themselves and it may be difficult to distinguish pharyngeal and laryngeal disease from tracheal disorder. This remains one of the most challenging

b

c

problems in pediatric diagnosis. The diagnosis is often delayed, although death during transport and preoperative assessment can be prevented if the urgency of treating even apparently mild airway obstruction is recognized. Traditional diagnostic imaging modalities of the upper airway in children, such as plain film radiography, fluoroscopy, and high-kilovolt added-filtration radiography [2], have been used for many years but sometimes they cannot provide satisfactory information for the purpose of surgical planning. In an era of technological advances many new imaging modalities and computer software packages have been developed which can help to evaluate the upper airway in the pediatric group. Brasch et al. used ultrafast CT to evaluate upper airway obstruction in 25 infants and children and were optimistic that ultrafast CT is an accurate diagnostic method without the need for sedation and with relatively low radiation exposure [3]. Brody et al. suggested the use of both cine and high-resolution modes to get the greatest diagnostic accuracy in airway evaluation [4]. Manson

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a

Fig. 2 Case 5. Tracheobronchograms in a AP and b oblique projection show diffuse narrowing of the trachea and bilateral main bronchi (arrowheads). Tracheal stenosis was proved by subsequent bronchoscopy. c An AP chest film taken the following day using portable equipment shows no residual contrast agent in the lungs

and his colleagues used three-dimensional CT for diagnosing congenital tracheal stenosis, which is satisfactory for establishing anatomical orientation with respect to regional mediastinal structures for surgery, although some limitations exist [5]. However, these advanced modern imaging modalities are not available in every hospital and, although we are not ignoring their value, even conventional CT is helpful and has been used effectively in the evaluation of primary and secondary tracheal stenosis [6, 7], as well as of external compression of the trachea by mediastinal conditions, such as pulmonary artery sling [8–11]. In fact, when dealing with an infant with respiratory distress who is often also dependent on endotracheal intubation and ventilation assistance, and when the patient must always be in an incubator, transport to the examination room can be difficult, requiring many pediatricians, nurses and anesthetists. Endoscopic examination of the upper airway obstruction is mandatory to make a diagnosis and plan treatment, but endoscopic assessment is potentially dan-

b

c

gerous, making contrast tracheobronchography more important. Actually, tracheobronchography has been used for a long time for diagnosis of various upper airway disorders but contrast agents such as propyliodone (Dionosil, Glaxo Laboratories, Greenford, Middlesex) have some disadvantages, e. g., difficulty in preparation and administration and compromised pulmonary function [12]. This agent is no longer available, and Iotrolan 300 has been used as an alternative for bronchography [13], although this contrast agent is also not available here now. A low-osmolar non-ionic contrast agent has similar osmolarity to the serum; we used Iopamiro 300 (Schering AG, Berlin) as a contrast agent for tracheobronchography, as described. Infants show signs of slight tachypnea during chest radiography, but their breathing returns to normal quickly. No residual contrast agent could be found on subsequent chest films, but transient pulmonary edema had been seen at other institutions, and mild diuretics were suggested. From our limited experience, we found this method still to have some limitations: (1) it is not a dynamic study technique as it failed

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to find two cases of tracheomalacia. According to the textbook, this disorder is usually accompanied by cardiovascular diseases, so a history of cardiovascular disease in a patient could be of help in diagnosis; maybe we can will be able to solve this problem with fluoroscopic control. (2) The study field is beyond the tip of the intubation tube. Moreover, the upper trachea with indwelling intubation tube must be of a normal caliber

or the tube cannot be positioned. (3) Intrinsic and extrinsic conditions of tracheal disorders cannot be differentiated, but chest sonography or CT can depict most mediastinal problems. We conclude that tracheobronchography using a non-ionic contrast agent is an easy, safe, and effective method for evaluating upper airway obstructions.

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