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Year : 2018  |  Volume : 11  |  Issue : 5  |  Page : 427-429  

Tracheal buckling: A bizarre but normal finding in chest radiograph of a sick preterm infant

1 Department of Neonatology, KK Women's and Children's Hospital, Singapore
2 Department of Neonatology, KK Women's and Children's Hospital; Yong Loo Lin School of Medicine, National University of Singapore, Singapore
3 Department of Neonatology, KK Women's and Children's Hospital; Yong Loo Lin School of Medicine, National University of Singapore; Duke–NUS Graduate Medical School; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore

Date of Web Publication5-Sep-2018

Correspondence Address:
Suresh Chandran
Department of Neonatology, KK Women's and Children's Hospital, 100 Bukit Timah Road
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mjdrdypu.MJDRDYPU_239_17

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Lateral deviation or buckling of the tracheal air column just above the thoracic inlet is infrequently observed on frontal chest X-rays of infants and young children. Tracheal buckling can cause unnecessary concern and alarm to neonatal and pediatric intensivists when dealing with critically ill infants. We report a case of preterm female infant, who was born at 25 weeks of gestation and required intubation at birth and surfactant administration. She was extubated to continuous positive airway pressure support at 5 h of life. On day 24 of life, she had increasing respiratory distress and X-ray of the chest was done. The X-ray showed a significant right lateral deviation of the trachea, raising the concern of mediastinal mass effect or right upper lobe collapse to the attending neonatologist. However, the radiologist diagnosed the lateral deviation of the trachea as benign tracheal buckling. The infant was intubated and ventilated. Two weeks later, a postextubation chest X-ray showed normal trachea.

Keywords: Tracheal air column, tracheal buckling, tracheal deviation

How to cite this article:
Krishnan G S, Joseph M G, Rajadurai VS, Chandran S. Tracheal buckling: A bizarre but normal finding in chest radiograph of a sick preterm infant. Med J DY Patil Vidyapeeth 2018;11:427-9

How to cite this URL:
Krishnan G S, Joseph M G, Rajadurai VS, Chandran S. Tracheal buckling: A bizarre but normal finding in chest radiograph of a sick preterm infant. Med J DY Patil Vidyapeeth [serial online] 2018 [cited 2020 Nov 30];11:427-9. Available from: https://www.mjdrdypv.org/text.asp?2018/11/5/427/240380

  Introduction Top

Lateral deviation or buckling of the trachea is seldom observed in chest X-rays of infants and young children.[1] The buckling of the tracheal air column is noted at or just above the thoracic inlet. The buckling of the trachea can be challenging to the intensivist caring for the critically ill preterm infants. We report here a preterm infant, developing progressively increasing respiratory distress on day 24 of life with a chest X-ray that showed hazy lung fields and tracheal buckling.

  Case Report Top

The preterm female infant was born at 25 weeks of gestation. She had poor respiratory effort at birth and required intubation and a dose of surfactant. She was extubated to continuous positive airway pressure (CPAP) support at 5 h of life. She remained stable till day 19 of life when she developed respiratory distress due to a hemodynamically significant patent ductus arteriosus (PDA). She was reintubated, and a medical closure of PDA was successfully done. Following extubation to CPAP on day 23 of life, she developed increasing respiratory distress within 24 h and needed a higher oxygen requirement. On cardiac evaluation, her PDA was closed, but her chest X-ray was increasingly hazy with a right lateral tracheal deviation [Figure 1]a. Although there was no stridor or clinical features of upper-airway obstruction, the unfamiliar chest X-ray finding of right lateral tracheal deviation puzzled the neonatal medical team. She was reintubated due to acute clinical deterioration and was stabilized with moderate ventilator settings.
Figure 1: (a) Chest X-ray showing tracheal buckling to the right. (b) The trachea in this chest X-ray shows only normal right-sided deviation compared to (a)

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The radiologist who reviewed the chest X-ray found the trachea to have a right lateral deviation in expiratory phase and diagnosed it as benign tracheal buckling, circumventing the need for further investigations. The thymus was not visible and the aortic knuckle was to the left. No other mass was visible in the lung fields. Her echocardiogram was also unremarkable. Two weeks later, she was extubated and a repeat chest radiograph showed a normal tracheal air column [Figure 1]b. Her clinical deterioration was due to early chronic lung disease, unrelated to the tracheal buckling.

  Discussion Top

Unexpected chest radiographic findings in extremely critically ill preterm infants can be alarming to neonatologists in intensive care areas.

We have searched extensively through the medical literature, but very limited publications in the 1970s discussed this issue in reputed radiology journals.[1] Buckling of the tracheal air column at or just above the thoracic inlet is rarely observed on anteroposterior chest X-rays of infants and younger children up to 5 years of age during expiration.[1] This phenomenon is familiar to pediatric radiologists, but can be perplexing to neonatologists and pediatricians, leading to unnecessary further imaging studies.

The trachea is long compared to the short neck and rib cage in infants and hence tends to buckle in expiration. Although the exact cause of lateral tracheal deviation is unclear, a few causes have been speculated.[1] During expiration, the alveoli collapse, leaving a diffuse opacity in the chest radiograph. The distal trachea moves up and down during the phases of respiration, causing the trachea to buckle in expiration, due to the relative fixation of trachea at the thoracic inlet.[2] During expiration, lax retropharyngeal tissues cause crowding of the trachea [3] and soft-tissue thickness increases,[4] leading to buckling. In most cases, the prevertebral soft tissues are minimally thick for only 0.2 s during inspiration. Hence, it is important to obtain a good inspiratory film, which can be challenging, especially in preterm sick infants.[5]

A correlation has been described between the direction of tracheal buckling and the side of the aortic arch. During embryological development of the trachea and the aortic arch, the heart exerts a tractional force on the aortic arch, causing it to assume a more medial position in the superior thoracic aperture. This causes displacement of the lower cervical and thoracic trachea to the right (opposite side of the arch).[6] To the left of the aortic arch, two major arteries, left common carotid and left subclavian, arise, whereas only innominate artery arise from the right of the arch, and this might contribute to tracheal buckling due to close contact of these vessels to trachea within the restricted space of superior mediastinum. In addition, the position of the thymus can also contribute to the displacement of the trachea to the right. Normally, the right lobe of the thymus lies more laterally and inferiorly than the left lobe, and this can cause deviation of the trachea to the right.[1]

Cervical Prolongation of the thymus is common in infants, and this has also been speculated to contribute to dextrolateral deviation of the trachea.[1] As the thymus is relatively larger in infancy and decreases in size after 2 years of life, it could explain why the observation of tracheal buckling in children above 2 years is markedly lower than that in infancy.

Although the incidental observation of tracheal buckling may not have clinical significance on the infant, it is important to recognize it as a normal phenomenon while managing the critically ill preterm neonates and infants. However, if the tracheal buckling is constant even with the neck fully extended and in inspiration, it is important to re-evaluate the infant for underlying pathologies that may cause extrinsic compression such as vascular anomalies, tumors, enlarged thyroid, lymph nodes, and tension pneumothorax.[7],[8]

  Conclusion Top

Tracheal buckling in an extremely sick preterm infant's chest X-ray could be worrying to the caring physician if unaware of this normal airway appearance. It is important to bear in mind that tracheal buckling may be a normal phenomenon in infants and children up to 5 years of age.


The authors would like to acknowledge Associate Professor Teo Eu- Leong Harvey James, Department of diagnostic radiology, KK Women's and Children's Hospital, Singapore, for his contributions in reporting the two chest X-rays included in this report.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Chang LW, Lee FA, Gwinn JL. Normal lateral deviation of the trachea in infants and children. Am J Roentgenol Radium Ther Nucl Med 1970;109:247-51.  Back to cited text no. 1
D'Alessandro MP. Normal Chest, Expiratory With Tracheal Buckling. Virtual Pediatric Hospital: A Pediatric Digital Library™. Iowa City (IA): Donna M. D'Alessandro; c1992-2007. Available from: http://www.virtualpediatrichospital.org/providers/PAP/ChestDiseases/ANormChestExpTraBu.shtml. [Last revised on 2006 Jul 20; Last accessed on 2007 Feb 20].  Back to cited text no. 2
Hay PD Jr. The neck. In: Case JT, editor. Annals of Roentgenology. Vol. 9. New York: Paul B Hoeber Inc.; 1930. p. 22-8, 82-93.  Back to cited text no. 3
Brenner GH. Variatons in the depth of the cervical prevertebral tissues in normal infants studied by cinefluography. Am J Roentgenol 1964;91:573-7.  Back to cited text no. 4
Berger PE, Kuhns LR, Poznanski AK. A simple technique for eliminating tracheal buckling on lateral neck roentgenograms. Pediatr Radiol 1974;2:69-71.  Back to cited text no. 5
Congdon ED. Transformation of the aortic arch system during the development of the human embryo. Contrib Embryol 1922;14:47-110.  Back to cited text no. 6
Swischuk LE. Anterior tracheal indentation in infancy and early childhood: Normal or abnormal? Am J Roentgenol Radium Ther Nucl Med 1971;112:12-7.  Back to cited text no. 7
Poppel MH, Jacobson HG. Tracheal buckling; differential roentgen sign. JAMA Arch Otolaryngol 1953;57:44-50.  Back to cited text no. 8


  [Figure 1]

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1 Tracheal Buckling in a Young Child
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