IMAGES IN PULMONARY, CRITICAL CARE, SLEEP MEDICINE AND THE SCIENCES Central Airway Narrowing during an Acute Asthma Attack Daniel Gorbett1, Subha Ghosh2, Christina Boutsicaris3, Karen Wood1, and Ulysses J. Magalang1 1 Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, 2Department of Radiology, and 3College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio
Figure 1. L = left; R = right.
Author Contributions: Concept and design: D.G. and U.J.M.; drafting the manuscript for important intellectual content: D.G., C.B., K.W., and U.J.M.; review of images and creation of virtual bronchoscopic image: S.G.; review of manuscript: D.G., S.G., C.B., K.W., and U.J.M.; final approval of manuscript: D.G., S.G., C.B., K.W., and U.J.M. Am J Respir Crit Care Med Vol 190, Iss 6, pp e20–e21, Sep 15, 2014 Copyright © 2014 by the American Thoracic Society DOI: 10.1164/rccm.201309-1600IM Internet address: www.atsjournals.org
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American Journal of Respiratory and Critical Care Medicine Volume 190 Number 6 | September 15 2014
IMAGES IN PULMONARY, CRITICAL CARE, SLEEP MEDICINE AND THE SCIENCES A 47-year-old female was admitted to the intensive care unit with acute respiratory failure due to status asthmaticus requiring mechanical ventilation. She had bilateral wheezing on examination, and there was a marked difference between the peak inspiratory and the plateau airway pressure on an inspiratory pause maneuver during mechanical ventilation (settings: assist control mode, tidal volume of 420 ml, respiratory rate of 18/min, positive end-expiratory pressure of 5 cm H2O, and FIO2 of 0.50). On the first hospital day, a computed tomography (CT) pulmonary angiogram was performed because of a previous history of deep venous thrombosis. The patient was heavily sedated, without evident ventilator dyssynchrony, and with minimal respiratory effort at the time of the clinical CT acquisition. The images were not timed to the phase of the respiratory cycle. This showed severe narrowing of both mainstem bronchi (Figure 1A, black arrow). A virtual bronchoscopy three-dimensional reconstruction (3D Flythrough Aquarius iNtuition; TeraRecon, Foster City, CA) of the CT images is shown in Figure 1B. Review of the patient’s medical records showed that a CT scan of the chest (not shown) obtained 4 months earlier did not show evidence of airway narrowing. A repeat CT scan of the chest, also done while under heavy sedation, several days later at a time of clinical improvement (Figure 1C) showed no airway narrowing (red arrow). Bronchoscopy (Figure 1D) showed the same findings without excessive airway narrowing during expiration. These images, in addition to the results of the prior CT of the chest, revealed that compression of the central airways during the acute asthma attack was unlikely due to tracheobronchomalacia, which is known to mimic or complicate asthma (1, 2). The site of airway obstruction in asthma is located in the small airways but may involve the large airways in some patients (3, 4). Although the exact mechanism of the central airway obstruction in this patient is unclear, one possibility is that the narrowing of the small airways during an acute asthma attack can manifest in such a way as to result in the dynamic compression of the central airways. For example, severe peripheral airway narrowing could increase the pressure drop across the small airways during expiration, resulting in low upstream airway pressure, and create an environment that may promote central airway collapse. In addition, compliance of the central airways may be increased due to deposition of bronchodilator therapy in the central airways, making them more susceptible to compression (5). n Author disclosures are available with the text of this article at www.atsjournals.org.
References 1. Solomon DA, Fanta CH, Levy BD, Loscalzo J. Clinical problemsolving: whistling in the dark. N Engl J Med 2012;366: 1725–1730. 2. Baroni RH, Feller-Kopman D, Nishino M, Hatabu H, Loring SH, Ernst A, Boiselle PM. Tracheobronchomalacia: comparison between endexpiratory and dynamic expiratory CT for evaluation of central airway collapse. Radiology 2005;235:635–641.
3. Despas PJ, Leroux M, Macklem PT. Site of airway obstruction in asthma as determined by measuring maximal expiratory flow breathing air and a helium-oxygen mixture. J Clin Invest 1972;51:3235–3243. 4. Campana L, Kenyon J, Zhalehdoust-Sani S, Tzeng YS, Sun Y, Albert M, Lutchen KR. Probing airway conditions governing ventilation defects in asthma via hyperpolarized MRI image functional modeling. J Appl Physiol (1985) 2009;106:1293–1300. 5. Cazzola M, Page CP, Calzetta L, Matera MG. Pharmacology and therapeutics of bronchodilators. Pharmacol Rev 2012;64:450–504.
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Figure 1. L = left; R = right.
Author Contributions: Concept and design: D.G. and U.J.M.; drafting the manuscript for important intellectual content: D.G., C.B., K.W., and U.J.M.; review of images and creation of virtual bronchoscopic image: S.G.; review of manuscript: D.G., S.G., C.B., K.W., and U.J.M.; final approval of manuscript: D.G., S.G., C.B., K.W., and U.J.M. Am J Respir Crit Care Med Vol 190, Iss 6, pp e20–e21, Sep 15, 2014 Copyright © 2014 by the American Thoracic Society DOI: 10.1164/rccm.201309-1600IM Internet address: www.atsjournals.org
e20
American Journal of Respiratory and Critical Care Medicine Volume 190 Number 6 | September 15 2014
IMAGES IN PULMONARY, CRITICAL CARE, SLEEP MEDICINE AND THE SCIENCES A 47-year-old female was admitted to the intensive care unit with acute respiratory failure due to status asthmaticus requiring mechanical ventilation. She had bilateral wheezing on examination, and there was a marked difference between the peak inspiratory and the plateau airway pressure on an inspiratory pause maneuver during mechanical ventilation (settings: assist control mode, tidal volume of 420 ml, respiratory rate of 18/min, positive end-expiratory pressure of 5 cm H2O, and FIO2 of 0.50). On the first hospital day, a computed tomography (CT) pulmonary angiogram was performed because of a previous history of deep venous thrombosis. The patient was heavily sedated, without evident ventilator dyssynchrony, and with minimal respiratory effort at the time of the clinical CT acquisition. The images were not timed to the phase of the respiratory cycle. This showed severe narrowing of both mainstem bronchi (Figure 1A, black arrow). A virtual bronchoscopy three-dimensional reconstruction (3D Flythrough Aquarius iNtuition; TeraRecon, Foster City, CA) of the CT images is shown in Figure 1B. Review of the patient’s medical records showed that a CT scan of the chest (not shown) obtained 4 months earlier did not show evidence of airway narrowing. A repeat CT scan of the chest, also done while under heavy sedation, several days later at a time of clinical improvement (Figure 1C) showed no airway narrowing (red arrow). Bronchoscopy (Figure 1D) showed the same findings without excessive airway narrowing during expiration. These images, in addition to the results of the prior CT of the chest, revealed that compression of the central airways during the acute asthma attack was unlikely due to tracheobronchomalacia, which is known to mimic or complicate asthma (1, 2). The site of airway obstruction in asthma is located in the small airways but may involve the large airways in some patients (3, 4). Although the exact mechanism of the central airway obstruction in this patient is unclear, one possibility is that the narrowing of the small airways during an acute asthma attack can manifest in such a way as to result in the dynamic compression of the central airways. For example, severe peripheral airway narrowing could increase the pressure drop across the small airways during expiration, resulting in low upstream airway pressure, and create an environment that may promote central airway collapse. In addition, compliance of the central airways may be increased due to deposition of bronchodilator therapy in the central airways, making them more susceptible to compression (5). n Author disclosures are available with the text of this article at www.atsjournals.org.
References 1. Solomon DA, Fanta CH, Levy BD, Loscalzo J. Clinical problemsolving: whistling in the dark. N Engl J Med 2012;366: 1725–1730. 2. Baroni RH, Feller-Kopman D, Nishino M, Hatabu H, Loring SH, Ernst A, Boiselle PM. Tracheobronchomalacia: comparison between endexpiratory and dynamic expiratory CT for evaluation of central airway collapse. Radiology 2005;235:635–641.
3. Despas PJ, Leroux M, Macklem PT. Site of airway obstruction in asthma as determined by measuring maximal expiratory flow breathing air and a helium-oxygen mixture. J Clin Invest 1972;51:3235–3243. 4. Campana L, Kenyon J, Zhalehdoust-Sani S, Tzeng YS, Sun Y, Albert M, Lutchen KR. Probing airway conditions governing ventilation defects in asthma via hyperpolarized MRI image functional modeling. J Appl Physiol (1985) 2009;106:1293–1300. 5. Cazzola M, Page CP, Calzetta L, Matera MG. Pharmacology and therapeutics of bronchodilators. Pharmacol Rev 2012;64:450–504.
Images in Pulmonary, Critical Care, Sleep Medicine and the Sciences
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