Figure 1. Illustration of potential bronchoscopic findings secondary to vascular anomalies, reprinted with permission.1 LMB indicates left main bronchus; RBI, right bronchus intermedius; RMB, right main bronchus.
Figure 2. Complete anterior mid-tracheal compression due to innominate artery.
Figure 3. Right anterior and posterior distal tracheal compression due to double aortic arch.
Figure 4. Diagnostic algorithm for a child with possible vascular anomaly. Short-segment compression is defined as 33% or less of the tracheal length; long-segment compression, more than 33% of the tracheal length. CTA indicates computed tomography with angiography of the neck and chest; DLB, direct laryngoscopy with bronchoscopy; GERD, gastroesophageal reflux disorder; and MRI, magnetic resonance imaging.
Rogers DJ, Cunnane MB, Hartnick CJ. Vascular Compression of the AirwayEstablishing a Functional Diagnostic Algorithm. JAMA Otolaryngol Head Neck Surg. 2013;139(6):586-591. doi:10.1001/jamaoto.2013.3214
Author Affiliations: Departments of Pediatric Otolaryngology (Drs Rogers and Hartnick) and Pediatric Neuroradiology (Dr Cunnane), Massachusetts Eye and Ear Infirmary, Boston; Brigham and Women's Hospital (Dr Cunnane), Boston; and Massachusetts General Hospital (Dr Cunnane), Boston.
Importance Pediatric imaging carries the risk of radiation exposure. Children frequently undergo computed tomography with angiography (CTA) for findings on bronchoscopy with limited knowledge regarding the necessity of such imaging.
Objective To report our experience with all pediatric patients at our institution over an 8-year period with airway symptoms warranting bronchoscopy followed by CTA for potential vascular anomaly. Goals were to report the percentage of positive findings seen on CTA leading to surgery; discuss relative radiation exposure risk and sedation risk for additional radiologic studies; and propose a functional diagnostic algorithm.
Design, Setting, and Participants Retrospective chart review of 42 children aged 2 months to 11 years with tracheomalacia who underwent CTA between 2004 and 2012 in our tertiary aerodigestive center.
Interventions Bronchoscopy and CTA.
Main Outcomes and Measures Presence of vascular anomaly and need for thoracic surgery.
Results Of these 42 children, 21 (50%) had a vascular anomaly identified on CTA. Of these 21, 17 (81%) had innominate artery compression; 1 (5%) had double aortic arch; 1 (5%) had right aortic arch; 3 (14%) had bronchial compression by pulmonary artery; and 1 (5%) had dextrocardia with duplicated vena cava. Six (29%) of these 21 had clinical symptoms and CTA findings requiring thoracic surgery. The most common symptoms in children requiring thoracic surgery were cough, cyanosis, and stridor.
Conclusions and Relevance Deciding when to obtain imaging for bronchoscopic findings suggestive of vascular compression remains challenging. A diagnostic algorithm is proposed as a means to provide the best clinical care while weighing risks of additional radiation exposure vs sedation and exposure to general anesthesia.
Vascular compression of the airway represents a potentially life-threatening cause of extrinsic tracheomalacia. Patients often present similarly to those with intrinsic tracheomalacia, and findings may be subtle on operative bronchoscopy. Symptoms may include stridor, cyanosis, recurrent bronchopulmonary infections, failure to thrive, and chronic cough. Determining who should undergo computed tomography (CT) with angiography (CTA), tracheal fluoroscopy, or magnetic resonance imaging (MRI) remains a challenging task.
Vascular anomalies typically cause pulsatile compression of the airway in characteristic locations (Figure 1).1 Innominate artery compression usually presents as anterior mid-tracheal compression (Figure 2). A double aortic arch compresses the right anterior and posterior distal trachea (Figure 3). A pulmonary artery sling usually causes compression of the right anterior distal trachea and right mainstem bronchus. During bronchoscopy, physicians are often faced with different severities of tracheomalacia. Some patients have only minimal compression of the trachea, while others may have complete collapse. Patients also have collapse of different lengths of the trachea. Deciding who requires further workup is problematic.
Recent reports have alerted the public to the increased risk of cancer in the pediatric population due to radiation from CT scans.2 A CT scan of the chest is equal to about 400 chest radiographs in an adult but may vary considerably in the pediatric patient. Frush et al3 have encouraged health care providers to follow the ALARA principle (as low as reasonably achievable) as a radiation dose-reduction strategy in the pediatric population. Even if MRI is performed instead of CTA to work up patients with suspected vascular anomalies, patients often need a second general anesthetic, which is not without risks.
The mere presence of a vascular anomaly does not always necessitate thoracic surgery. An anomalous innominate artery may cause few if any symptoms, or it may produce severe tracheal compression with associated symptoms.4 Myer et al5 and others have reviewed absolute and relative criteria for surgery to correct innominate artery compression.6 Complete vascular rings, such as the double aortic arch, and pulmonary artery slings usually require surgical correction.
In light of the varied findings on bronchoscopy and the increased risks associated with CTA and additional general anesthetics, the purpose of this study was to report our experience with all pediatric patients at our institution over a period of 8 years who had tracheomalacia suggestive of vascular ring or sling who underwent CTA and to describe a functional diagnostic algorithm for these children.
The Massachusetts Eye and Ear Infirmary institutional review board approved this study. Included patients were children 18 years or younger who underwent bronchoscopy first for airway symptoms then had a CTA for findings during the bronchoscopy. Exclusion criteria were age older than 18 years, extraluminal or intraluminal mass, retroesophageal subclavian artery, or presence of an additional airway lesion.
Between 2004 and 2012, 48 children had a CTA for suspected vascular anomaly on operative bronchoscopy at our institution. One patient was excluded because of supraglottic stenosis, 1 for subglottic stenosis, 1 for a subglottic hemangioma, 1 for a large subglottic cyst, and 1 for an intraluminal lesion of a bronchus. One patient with a right aberrant subclavian artery was excluded because of the inherent lack of tracheal or bronchial compression associated with this lesion. The resulting total number of patients included in this study was 42.
Symptoms that led to bronchoscopy included severe stridor and only mild laryngomalacia on flexible fiberoptic laryngoscopy, chronic cough unresponsive to empirical reflux and asthma treatment, cyanosis, recurrent bronchopneumonia, and failure to thrive due to aerodigestive symptoms. A CTA was ordered for patients with clinically significant expiratory stridor (where significant was defined as “enough to warrant bronchoscopic evaluation”) with a short-segment tracheomalacic segment more than 50% obstructing with expiration or if there was any degree of short-segment combined anterior and posterior compression (suggestive of complete vascular ring).
Patient age, sex, presence of a syndrome, and presenting symptoms were reviewed in the electronic medical record. Intraoperative photographs from the bronchoscopies were analyzed to determine the length and degree of tracheal or bronchial compression. The CTAs of the patients who had innominate artery compression were assessed. The percentage of tracheal collapse was estimated by dividing the anterior-posterior distance of the trachea under the innominate artery by the anterior-posterior distance of the trachea at approximately the level of the thyroid gland, where the trachea was of normal caliber.
The characteristics of all patients included in this study were reviewed (Table 1). Of the 42 children, 21 (50%) had a vascular anomaly identified on CTA. The distribution of various vascular anomalies was assessed (Table 2). Of the 21 children with a vascular anomaly identified on CTA, innominate artery compression was the most common, occurring in 15 cases (71%). Although there were 3 cases of bronchial compression by a pulmonary artery (14%), none of these was due to an anomalous origin of the left pulmonary artery, which is the strict definition of a pulmonary artery sling.7 Of the 15 patients with innominate artery compression, 4 (27%) required thoracic surgery.
Six (29%) of the 21 children with a vascular anomaly on CTA had clinical symptoms and CTA findings requiring thoracic surgery. Patient symptoms and findings on bronchoscopy and CTA were analyzed for the patients who required thoracic surgery (Table 3). Of these 6 children, 4 (67%) had innominate artery compression; 1 (17%) had a double aortic arch; and 1 (17%) had a right aortic arch. All of the patients were 15 months or younger. Four of the patients were boys, and the other 2 were girls. The most common presenting symptom in patients who needed thoracic surgery for a vascular anomaly was cough, which occurred in all patients. Cyanosis and stridor were the next most frequent symptoms, both occurring in 5 patients (83%). Two patients (33%) had recurrent bronchopneumonia. Only 1 patient (17%) demonstrated failure to thrive.
All 4 of the children with innominate artery compression who required thoracic surgery had greater than 70% short-segment anterior compression of the mid-trachea on bronchoscopy (Figure 2). Short-segment compression was defined by the senior author (C.J.H.) as involvement of one-third or less of the tracheal length and long-segment as more than one-third of the tracheal length. All of these children had chronic cough, cyanosis, and stridor. Only 1 (25%) of the 4 children had failure to thrive. None of these children had recurrent bronchopulmonary infections.
The degree of tracheal compression on CTA in the patients with innominate artery compression was defined as mild (33% or less), moderate (>33% to 67%), or severe (>67%). All of the children in the present study had moderate or severe compression of the anterior trachea by the innominate artery on CTA.
Due to the intimate relationship of the thoracic vasculature with the trachea and bronchi, any variation in this anatomy may produce compression of the airway. Stridor, particularly during expiration, occurs due to higher intrathoracic pressure than atmospheric pressure, which causes narrowing of the airway.8 Any narrowing, whether from intrinsic tracheal or bronchial weakness or from external compression, may cause stridor. Tracheal compression also impairs mucociliary clearance, which may lead to recurrent bronchopneumonia and chronic cough.4 The tracheal compression may be severe enough to completely collapse the airway and cause cyanosis or death spells.8- 10 In general, complete vascular rings and pulmonary artery slings present earlier in life because they are tighter and produce more compression.10,11 Roesler et al12 showed that 96% of children with vascular anomalies present by age 6 months, but 25% of children had at least a 6-month delay from symptom onset to surgical intervention. In our population, the most common presenting symptom in all the children with a vascular anomaly and in those who required thoracic surgery was chronic cough. Cyanosis and stridor were the next most common symptoms. Few of the children in our study had recurrent bronchopneumonia, and even fewer presented with failure to thrive. Shah et al13 reviewed 64 cases of vascular rings and found the most common presenting symptoms to be stridor, recurrent bronchopneumonia, and cough.
Innominate artery compression was the most common vascular anomaly, which was found in 15 of our patients. Compression of a bronchus by a pulmonary artery was found in 3 patients, double aortic arch in 1 patient, right aortic arch in 1 patient, and dextrocardia with duplicate vena cava in 1 patient. More importantly, of the 6 children who required surgery, 4 (67%) had innominate artery compression; 1 (17%) had a double aortic arch; and 1 (17%) had a right aortic arch. Erwin et al14 also found innominate artery compression to be the most common vascular anomaly requiring thoracic surgery, followed by double aortic arch. This is in contrast to other studies evaluating vascular anomalies that required thoracic surgery. McLaughlin et al10 found the double aortic arch to be the most common vascular anomaly in patients who required thoracic surgery, occurring in 54%, followed by right aortic arch in 31%, anomalous innominate artery in 9%, left aortic arch variants in 3%, and finally pulmonary artery sling in 3%. Shah et al13 found the top 2 most common vascular rings requiring thoracic surgery to be double aortic arch and right aortic arch.
Recent reports of the dangers of radiation from imaging in the pediatric population have forced health care providers to reevaluate the use of CT. Boone et al,15 on behalf of the American Association of Physicists in Medicine (AAPM), determined that CT scans in the pediatric population may result in up to 2.79 times the radiation dose of that in adults, depending on the type of CT scanner used and the size of the child.15 Frush et al3 and Brody et al16 have demonstrated the need for health care providers to follow the ALARA principle as a dose-reduction strategy in the pediatric population. Many centers use MRI to evaluate for potential vascular anomalies,14,17 which represents an attractive alternative to CTA, especially if it can be performed under the same general anesthetic, because it involves no radiation. However, at our center, children are unable to go directly from their bronchoscopy to get an MRI under the same general anesthetic, but they may be transported directly for a CTA. This means scheduling a separate sedation and/or general anesthetic for a longer radiologic examination, often in children with a tenuous airway. Additional general anesthetics in these children are not without risk. Girshin et al18 found that the mortality rate for general anesthesia performed on children in the MRI suite was 1 in 3900, which is approximately twice the rate for general anesthesia performed in the operating room. Aside from the obvious risks of airway obstruction, studies have shown that exposure to anesthetics in young children may lead to behavioral disturbances and learning disabilities.19,20
The clinical presentation of a child with a vascular anomaly causing extrinsic tracheomalacia may be quite similar to that of a child with intrinsic tracheomalacia. These children will usually undergo operative bronchoscopy at some point owing to the severity of their symptoms, and this is the clinical decision point where the surgeon must determine whether to further image the child. One must remember that the decision to image for a potential vascular anomaly must be based on both the clinical symptoms and the findings on bronchoscopy. For example, 1 of the children in our study was found to have a right aortic arch on CTA, which required thoracic surgery, but the patient had not developed stridor and cyanosis by presentation. In addition, children may be quite symptomatic and have severe tracheal compression on bronchoscopy, but the CTA may underestimate the severity of innominate artery compression. Moës et al21 stressed that the decision for surgery should be based on the severity of symptoms and not just the degree of airway compression.21 Some CTAs must be performed while the patient is intubated or by using a laryngeal mask airway with positive-pressure ventilation, which likely stents the trachea open. Also, the CTA must catch the images in the expiratory phase to fully evaluate the amount of extrinsic compression. Although effort is made to image the trachea during expiration, a second acquisition of images to ensure the patient was indeed in the expiration phase is unlikely due to radiation risks.
Another important concern when evaluating children for potential vascular anomalies is knowing who would need thoracic surgery should a vascular anomaly be found. All complete vascular rings and pulmonary artery slings undergo thoracic surgery. For innominate artery compression and other partial vascular rings, many children may be observed carefully owing to the self-limiting nature of these anomalies. However, some patients will require thoracic surgery to correct the vascular anomaly. Mustard et al,6 in 1969, described their indications for thoracic surgery as reflex apnea and recurrent bronchopulmonary infections. In 1971, MacDonald et al22 divided surgical criteria into absolute and relative criteria while adding failure of medical management, greater than 50% tracheal compression, and associated airway or lung abnormalities to the existing criteria. Myer et al5 reviewed absolute and relative criteria for thoracic surgery in 1989. Absolute criteria included reflex apnea, failure of medical management of severe respiratory distress after 48 hours, and prolonged intubation. Relative criteria were recurrent tracheobronchitis or bronchopneumonia; exercise intolerance; significant dysphagia or failure to thrive; and coexistence of subglottic stenosis, asthma, cystic fibrosis, or prior tracheoesophageal fistula repair.
We developed a diagnostic algorithm to provide the best clinical care while weighing the risks of additional radiation vs additional sedation and exposure to general anesthesia (Figure 4). When a child presents with symptoms concerning for airway obstruction severe enough to warrant further workup, first a thorough history is taken and physical examination performed followed by flexible laryngoscopy to assess for laryngomalacia, vocal fold mobility, and other lesions. If the child demonstrates severe stridor and only mild laryngomalacia, recurrent bronchopneumonia despite adequate antibiotic treatment, or failure to thrive due to aerodigestive symptoms, or if endoscopy is needed to evaluate recalcitrant asthma and/or reflux, then operative bronchoscopy is performed.
If the tracheal compression or collapse is short-segment type involving 33% or less of the tracheal length (as defined by the senior author C.J.H.), this is suggestive of extrinsic compression. It would seem that external compression by the caliber of a large blood vessel would result in a short length (≤33%) of trachea being compressed and that intrinsic tracheomalacia would involve more of the trachea (>33%). In addition, if the compression involves the right anterior and posterior tracheal walls or mainstem bronchus (fishmouth deformity), this may be from a double aortic arch, other complete vascular ring, or even a pulmonary artery sling and should be imaged. Symptoms are less important in these patients because a complete vascular ring will eventually require surgery. In the remainder of the short-segment tracheal compression group, if greater than 50% anterior or posterior tracheal compression is found, the child should undergo a CTA or MRI. We believe that if the collapse is greater than 50%, these patients are more likely to have severe symptoms (possibly requiring surgery).
If the tracheal compression or collapse is less than 50%, the patient's symptoms become more important in the workup. In patients with less than 50% collapse, we place more emphasis on symptoms to ensure we do not miss a vascular ring or sling in these patients. If the primary symptoms are chronic cough, cyanosis, and stridor as seen in our patients with vascular anomalies that required thoracic surgery, these patients should undergo a CTA or MRI. If these symptoms are not present, one should treat other causes first, before considering additional imaging. Likewise, if the tracheal compression is long-segment type, involving greater than 33% of the tracheal length (as defined by the senior author C.J.H.), these patients should also be treated for other causes before further imaging. If patients are still quite symptomatic despite appropriate treatment, one should consider a CTA or MRI because vascular anomalies may compress a longer length of trachea than is actually in contact with the vessel.17 If patients continue to improve after treating other causes, they should not be imaged.
Our study has a few limitations. It is a retrospective review, so bias was difficult to completely exclude. Although 42 children who underwent CTAs for suspected vascular anomalies were included in this study, only 6 required thoracic surgery. Moreover, we were only able to evaluate children who were determined to need bronchoscopy and a CTA, introducing selection bias of the senior author (C.J.H.), who made the determination. Due to the radiation and anesthesia risks in children, it is unfeasible to image every child who has findings suggestive of a vascular anomaly on bronchoscopy. Likewise, more self-limiting partial vascular rings, such as an aberrant innominate artery, may be found, which may not necessitate thoracic surgery.
In conclusion, children with vascular anomalies causing extrinsic compression of the airway often present similarly to those with intrinsic tracheomalacia. In light of recent well-documented concerns regarding increased cancer risk associated with CT and the risks of additional general anesthetics, one must determine the appropriate patient for additional imaging. Clinical symptoms and findings on bronchoscopy may predict who is likely to have a vascular anomaly or who may need thoracic surgery to correct it. We developed a diagnostic algorithm in an attempt to provide the best clinical care while weighing the risks of additional radiation vs additional sedation and exposure to general anesthesia.
Correspondence: Christopher J. Hartnick, MD, MS Epi, Department of Pediatric Otolaryngology, Massachusetts Eye and Ear Infirmary, 243 Charles St, Boston, MA 02114 (Christopher_Hartnick@meei.harvard.edu).
Submitted for Publication: February 8, 2013; final revision received March 19, 2013; accepted April 11, 2013.
Author Contributions: Dr Hartnick had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Rogers, Cunnane, and Hartnick. Acquisition of data: Rogers, Cunnane, and Hartnick. Analysis and interpretation of data: Rogers, Cunnane, and Hartnick. Drafting of the manuscript: Rogers. Critical revision of the manuscript for important intellectual content: Rogers, Cunnane, and Hartnick. Administrative, technical, and material support: Rogers, Cunnane, and Hartnick. Study supervision: Hartnick.
Conflict of Interest Disclosures: None reported.