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Amoakon JP, Lee J, Liyanage P, Arora K, Karlstaedt A, Mylavarapu G, Amin R, Naren AP. Defective CFTR modulates mechanosensitive channels TRPV4 and PIEZO1 and drives endothelial barrier failure. iScience 2024; 27:110703. [PMID: 39252977 PMCID: PMC11382128 DOI: 10.1016/j.isci.2024.110703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2024] [Revised: 06/25/2024] [Accepted: 08/06/2024] [Indexed: 09/11/2024] Open
Abstract
Cystic fibrosis (CF) is a genetic disease caused by a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Despite reports of CFTR expression on endothelial cells, pulmonary vascular perturbations, and perfusion deficits in CF patients, the mechanism of pulmonary vascular disease in CF remains unclear. Here, our pilot study of 40 CF patients reveals a loss of small pulmonary blood vessels in patients with severe lung disease. Using a vessel-on-a-chip model, we establish a shear-stress-dependent mechanism of endothelial barrier failure in CF involving TRPV4, a mechanosensitive channel. Furthermore, we demonstrate that CFTR deficiency downregulates the function of PIEZO1, another mechanosensitive channel involved in angiogenesis and wound repair, and exacerbates loss of small pulmonary blood vessel. We also show that CFTR directly interacts with PIEZO1 and enhances its function. Our study identifies key cellular targets to mitigate loss of small pulmonary blood vessels in CF.
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Affiliation(s)
- Jean-Pierre Amoakon
- Department of Systems Biology and Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Division of Pulmonary Medicine and Critical Care, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Jesun Lee
- Division of Pulmonary Medicine and Critical Care, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Pramodha Liyanage
- Division of Pulmonary Medicine and Critical Care, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Kavisha Arora
- Division of Pulmonary Medicine and Critical Care, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Anja Karlstaedt
- Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Goutham Mylavarapu
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Raouf Amin
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Anjaparavanda P Naren
- Department of Systems Biology and Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Division of Pulmonary Medicine and Critical Care, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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Amoakon JP, Mylavarapu G, Amin RS, Naren AP. Pulmonary Vascular Dysfunctions in Cystic Fibrosis. Physiology (Bethesda) 2024; 39:0. [PMID: 38501963 PMCID: PMC11368519 DOI: 10.1152/physiol.00024.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/26/2024] [Accepted: 03/14/2024] [Indexed: 03/20/2024] Open
Abstract
Cystic fibrosis (CF) is an inherited disorder caused by a deleterious mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Given that the CFTR protein is a chloride channel expressed on a variety of cells throughout the human body, mutations in this gene impact several organs, particularly the lungs. For this very reason, research regarding CF disease and CFTR function has historically focused on the lung airway epithelium. Nevertheless, it was discovered more than two decades ago that CFTR is also expressed and functional on endothelial cells. Despite the great strides that have been made in understanding the role of CFTR in the airway epithelium, the role of CFTR in the endothelium remains unclear. Considering that the airway epithelium and endothelium work in tandem to allow gas exchange, it becomes very crucial to understand how a defective CFTR protein can impact the pulmonary vasculature and overall lung function. Fortunately, more recent research has been dedicated to elucidating the role of CFTR in the endothelium. As a result, several vascular dysfunctions associated with CF disease have come to light. Here, we summarize the current knowledge on pulmonary vascular dysfunctions in CF and discuss applicable therapies.
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Affiliation(s)
- Jean-Pierre Amoakon
- Department of Systems Biology and Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States
- Division of Pulmonary Medicine and Critical Care, Cedars-Sinai Medical Center, Los Angeles, California, United States
| | - Goutham Mylavarapu
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
| | - Raouf S Amin
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
| | - Anjaparavanda P Naren
- Department of Systems Biology and Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States
- Division of Pulmonary Medicine and Critical Care, Cedars-Sinai Medical Center, Los Angeles, California, United States
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
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Roussel A, Sage E, Roux A, Guth A, Mellot F, Gravel G. Bronchial artery embolization for hemoptysis in adult patients with cystic fibrosis: a single-center retrospective study. Acta Radiol 2023; 64:1381-1389. [PMID: 36802809 DOI: 10.1177/02841851221126833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Hemoptysis is a severe complication of cystic fibrosis (CF) for which bronchial artery embolization (BAE) is an efficient primary therapeutic option. However, recurrence is more frequent than for other etiologies of hemoptysis. PURPOSE To assess the safety and efficacy of BAE in patients with CF and hemoptysis and predictive factors for recurrent hemoptysis. MATERIAL AND METHODS This retrospective study reviewed all adult patients with CF treated by BAE for hemoptysis in our center from 2004 to 2021. The primary endpoint was the recurrence of hemoptysis after bronchial artery embolization. Secondary endpoints were overall survival and complications. We introduced the vascular burden (VB) defined as the sum of all bronchial artery diameters measured on pre-procedural enhanced computed tomography (CT) scans. RESULTS A total of 48 BAE were performed in 31 patients. A total of 19 recurrences occurred with a median recurrence-free survival of 3.9 years. In univariate analyzes, percentage of unembolized VB (%UVB) (hazard ratio [HR] = 1.034, 95% confidence interval [CI=1.016-1.052; P < 0.001) and %UVB vascularizing the suspected bleeding lung (%UVB-lat) (HR = 1.024, 95% CI=1.012-1.037; P < 0.001) were associated with recurrence. In multivariate analyzes, only %UVB-lat remained significantly associated with recurrence (HR = 1.020, 95% CI=1.002-1.038; P = 0.030). One patient died during follow-up. No complication of grade 3 or higher was reported according to the CIRSE classification system for complications. CONCLUSION When possible, unilateral BAE seems sufficient in patients with CF with hemoptysis even in such a diffuse disease involving both lungs. The efficiency of BAE could be improved by thoroughly targeting all arteries vascularizing the bleeding lung.
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Affiliation(s)
- Alexandre Roussel
- Department of Diagnostic and Interventional Radiology, Foch Hospital, Suresnes, France
| | - Edouard Sage
- Department of Thoracic Surgery, Foch Hospital, Suresnes, France
| | - Antoine Roux
- Department of Pneumology, Foch Hospital, Suresnes, France
| | - Axel Guth
- Department of Diagnostic and Interventional Radiology, Foch Hospital, Suresnes, France
| | - François Mellot
- Department of Diagnostic and Interventional Radiology, Foch Hospital, Suresnes, France
| | - Guillaume Gravel
- Department of Diagnostic and Interventional Radiology, Foch Hospital, Suresnes, France
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Angiographic and histopathological study on bronchial-to-pulmonary vascular anastomoses on explants from patients with cystic fibrosis after bronchial artery embolisation. J Cyst Fibros 2022; 21:1042-1047. [DOI: 10.1016/j.jcf.2022.04.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 04/19/2022] [Accepted: 04/19/2022] [Indexed: 11/21/2022]
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Dohna M, Renz DM, Stehling F, Dohna-Schwake C, Sutharsan S, Neurohr C, Wirtz H, Eickmeier O, Grosse-Onnebrink J, Sauerbrey A, Soditt V, Poplawska K, Wacker F, Montag MJ. Coil embolisation for massive haemoptysis in cystic fibrosis. BMJ Open Respir Res 2021; 8:8/1/e000985. [PMID: 34385150 PMCID: PMC8362706 DOI: 10.1136/bmjresp-2021-000985] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 07/26/2021] [Indexed: 12/01/2022] Open
Abstract
Introduction Massive haemoptysis is a life-threatening event in advanced cystic fibrosis (CF) lung disease with bronchial artery embolisation (BAE) as standard of care treatment. The aim of our study was to scrutinise short-term and long-term outcomes of patients with CF and haemoptysis after BAE using coils. Methods We carried out a retrospective cohort study of 34 adult patients treated for massive haemoptysis with super selective bronchial artery coil embolisation (ssBACE) between January 2008 and February 2015. Embolisation protocol was restricted to the culprit vessel(s) and three lobes maximum. Demographic data, functional end-expiratory volume in 1 s in % predicted (FEV1% pred.) and body mass index before and after ssBACE, sputum colonisation, procedural data, time to transplant and time to death were documented. Results Patients treated with ssBACE showed significant improvement of FEV1% pred. after embolisation (p=0.004) with 72.8% alive 5 years post-ssBACE. Mean age of the patients was 29.9 years (±7.7). Mean FEV1% pred. was 45.7% (±20.1). Median survival to follow-up was 75 months (0–125). Severe complication rate was 0%, recanalisation rate 8.8% and 5-year-reintervention rate 58.8%. Chronic infection with Pseudomonas aeruginosa was found in 79.4%, Staphylococcus areus in 50% and Aspergillus fumigatus in 47.1%. Discussion ssBACE is a safe and effective treatment for massive haemoptysis in patients with CF with good results for controlling haemostasis and excellent short-term and long-term survival, especially in severely affected patients with FEV<40% pred. We think the data of our study support the use of coils and a protocol of careful and prudent embolisation.
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Affiliation(s)
- Martha Dohna
- Pediatric Radiology, Hannover Medical School, Hannover, Germany
| | | | - Florian Stehling
- Department of Pediatric Pulmonology and Sleep Medicine, University Hospital Essen, Essen, Germany
| | | | | | - Claus Neurohr
- Robert-Bosch-Krankenhaus Klinik Schillerhohe, Gerlingen, Germany
| | - Hubert Wirtz
- Department of Respiratory Medicine, University Hospital Leipzig, Leipzig, Germany
| | - Olaf Eickmeier
- Department of Pneumology, Hospital of the Goethe University Frankfurt, Frankfurt am Main, Germany
| | | | | | - Volker Soditt
- Pediatrics, Stadtisches Klinikum Solingen, Solingen, Germany
| | - Krystyna Poplawska
- Pediatrics, Johannes Gutenberg University Hospital Mainz, Mainz, Germany
| | - Frank Wacker
- Radiology, Hannover Medical School, Hannover, Germany
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Monroe EJ, Pierce DB, Ingraham CR, Johnson GE, Shivaram GM, Valji K. An Interventionalist's Guide to Hemoptysis in Cystic Fibrosis. Radiographics 2018. [PMID: 29528824 DOI: 10.1148/rg.2018170122] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Massive hemoptysis occurs in a minority of patients with cystic fibrosis, with an annual incidence of 1%. Although rare, massive hemoptysis can be a severe and potentially fatal complication of this disease. Beyond the acute life-threatening event, hemoptysis in patients with cystic fibrosis has been associated with faster decline in lung function, accelerated need for lung transplant, and increased mortality. The bronchial arteries are the culprit vessels in over 90% of cases of hemoptysis. This normally quiescent vascular system undergoes remarkable hypertrophy, collateralization, and angiogenesis before the onset of hemoptysis, introducing numerous pitfalls for the interventionalist. However, in experienced hands, bronchial artery embolization is a safe and potentially lifesaving therapy. Preprocedural noninvasive imaging, specifically computed tomographic angiography, has been repeatedly validated for helping to localize the likely site of bleeding, characterizing pertinent arterial anatomy, and promoting efficient and effective intervention; it has been recommended for all stable patients with hemoptysis. Success in the angiographic suite requires a thorough understanding of normal and variant bronchial arterial anatomy, appropriate patient selection, and a meticulous embolization technique. A meticulous approach to imaging and intervention, conscientious of both visualized and nonvisualized collateral pathways and nontarget vessels, can minimize potentially devastating complications. This review summarizes the current literature, modern procedural techniques, and emerging controversies, serving to guide an evolving approach to management of patients with cystic fibrosis and hemoptysis. ©RSNA, 2018.
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Affiliation(s)
- Eric J Monroe
- From the Department of Radiology, University of Washington, Seattle, Wash (E.J.M., D.B.P., C.R.I., G.E.J., G.M.S., K.V.); and Department of Radiology, Seattle Children's Hospital, 4800 Sand Point Way NE, MA.7.220-Radiology, Seattle, WA 98105 (E.J.M., G.M.S.)
| | - David B Pierce
- From the Department of Radiology, University of Washington, Seattle, Wash (E.J.M., D.B.P., C.R.I., G.E.J., G.M.S., K.V.); and Department of Radiology, Seattle Children's Hospital, 4800 Sand Point Way NE, MA.7.220-Radiology, Seattle, WA 98105 (E.J.M., G.M.S.)
| | - Christopher R Ingraham
- From the Department of Radiology, University of Washington, Seattle, Wash (E.J.M., D.B.P., C.R.I., G.E.J., G.M.S., K.V.); and Department of Radiology, Seattle Children's Hospital, 4800 Sand Point Way NE, MA.7.220-Radiology, Seattle, WA 98105 (E.J.M., G.M.S.)
| | - Guy E Johnson
- From the Department of Radiology, University of Washington, Seattle, Wash (E.J.M., D.B.P., C.R.I., G.E.J., G.M.S., K.V.); and Department of Radiology, Seattle Children's Hospital, 4800 Sand Point Way NE, MA.7.220-Radiology, Seattle, WA 98105 (E.J.M., G.M.S.)
| | - Giridhar M Shivaram
- From the Department of Radiology, University of Washington, Seattle, Wash (E.J.M., D.B.P., C.R.I., G.E.J., G.M.S., K.V.); and Department of Radiology, Seattle Children's Hospital, 4800 Sand Point Way NE, MA.7.220-Radiology, Seattle, WA 98105 (E.J.M., G.M.S.)
| | - Karim Valji
- From the Department of Radiology, University of Washington, Seattle, Wash (E.J.M., D.B.P., C.R.I., G.E.J., G.M.S., K.V.); and Department of Radiology, Seattle Children's Hospital, 4800 Sand Point Way NE, MA.7.220-Radiology, Seattle, WA 98105 (E.J.M., G.M.S.)
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7
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Somayaji R, Ramos KJ, Kapnadak SG, Aitken ML, Goss CH. Common clinical features of CF (respiratory disease and exocrine pancreatic insufficiency). Presse Med 2017; 46:e109-e124. [PMID: 28554722 DOI: 10.1016/j.lpm.2017.03.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/06/2017] [Accepted: 03/29/2017] [Indexed: 12/17/2022] Open
Abstract
First described as a disease of the pancreas, cystic fibrosis is a genetically inherited progressive disease affecting multiple organ systems. Pulmonary and pancreatic involvement is common in individuals with cystic fibrosis, and the former is attributable to most of the mortality that occurs with the condition. This chapter provides an overview of a clinical approach to the pulmonary and pancreatic manifestations of cystic fibrosis.
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Affiliation(s)
- Ranjani Somayaji
- University of Calgary, Department of Medicine, Calgary, AB, Canada
| | - Kathleen J Ramos
- University of Washington, Department of Medicine, Division of Pulmonary and Critical Care Medicine, Seattle, WA, USA
| | - Siddhartha G Kapnadak
- University of Washington, Department of Medicine, Division of Pulmonary and Critical Care Medicine, Seattle, WA, USA
| | - Moira L Aitken
- University of Washington, Department of Medicine, Division of Pulmonary and Critical Care Medicine, Seattle, WA, USA
| | - Christopher H Goss
- University of Washington, Department of Medicine, Division of Pulmonary and Critical Care Medicine, Seattle, WA, USA; University of Washington, Department of Pediatrics, Division of Pediatric Pulmonology, Seattle, WA, USA; Seattle Children's Research Institute, Cystic Fibrosis Foundation Therapeutics Development Network Coordinating Center, Seattle, WA, USA.
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8
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Town JA, Monroe EJ, Aitken ML. Deaths Related to Bronchial Arterial Embolization in Patients With Cystic Fibrosis: Three Cases and an Institutional Review. Chest 2017; 150:e93-e98. [PMID: 27719829 DOI: 10.1016/j.chest.2016.03.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 01/27/2016] [Accepted: 03/02/2016] [Indexed: 10/20/2022] Open
Abstract
Cystic fibrosis (CF) patients are at risk for life-threatening hemoptysis, sometimes necessitating bronchial arterial embolization (BAE). Spinal artery embolization and pulmonary infarction are commonly cited procedural risks, yet respiratory failure and death are underappreciated. We conducted a retrospective institutional review of our outcomes after BAE for hemoptysis in CF and present three cases highlighting this complication. From 2007 to 2015, 12 patients underwent 17 BAE procedures for hemoptysis at our institution. Three patients experienced respiratory failure and died within 3 months of BAE. Nonsurvivors had significantly lower baseline FEV1 values than survivors (21.8% vs 52.6%, P < .05). BAE as a treatment for life-threatening hemoptysis may precipitate respiratory failure in end-stage CF and should accelerate the evaluation for lung transplantation. Institutions should reevaluate their BAE practices to ensure preservation of the bronchial circulation, which contributes to gas exchange in these patients.
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Affiliation(s)
- James A Town
- Division of Pulmonary and Critical Care, Department of Medicine, University of Washington, Seattle, WA.
| | - Eric J Monroe
- Department of Radiology, Seattle Childrens, Seattle, WA
| | - Moira L Aitken
- Division of Pulmonary and Critical Care, Department of Medicine, University of Washington, Seattle, WA
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9
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Robertson HT. Dead space: the physiology of wasted ventilation. Eur Respir J 2014; 45:1704-16. [PMID: 25395032 DOI: 10.1183/09031936.00137614] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Accepted: 09/29/2014] [Indexed: 11/05/2022]
Abstract
An elevated physiological dead space, calculated from measurements of arterial CO2 and mixed expired CO2, has proven to be a useful clinical marker of prognosis both for patients with acute respiratory distress syndrome and for patients with severe heart failure. Although a frequently cited explanation for an elevated dead space measurement has been the development of alveolar regions receiving no perfusion, evidence for this mechanism is lacking in both of these disease settings. For the range of physiological abnormalities associated with an increased physiological dead space measurement, increased alveolar ventilation/perfusion ratio (V'A/Q') heterogeneity has been the most important pathophysiological mechanism. Depending on the disease condition, additional mechanisms that can contribute to an elevated physiological dead space measurement include shunt, a substantial increase in overall V'A/Q' ratio, diffusion impairment, and ventilation delivered to unperfused alveolar spaces.
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Affiliation(s)
- H Thomas Robertson
- Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, WA, USA
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10
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Gade J, Greisen G, Larsen IK, Bibby BM, Olsen PS. Tissue hypoxaemia causes oedema, inflammation and fibrosis in porcine bronchial transsection. SCAND CARDIOVASC J 2012; 46:286-94. [PMID: 22607392 DOI: 10.3109/14017431.2012.695086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVES Bronchial artery revascularization in lung transplantation is disputed. This study examined the physiological consequences of porcine bronchial transsection and reanastomosis with and without bronchial artery blood supply with relation to lung transplantation. DESIGN Translational, controlled animal study. Twelve pigs were operated through a left lateral thoracotomy. The left bronchus was transsected and reanastomosed. In the control group (n = 6), the bronchial arteries were preserved and in the study group (n = 6) they were severed. Bronchial mucosa blood flow (BMBF) was measured with laser-Doppler velocimetry and bronchial mucosa haemoglobin saturation and concentration with diffuse reflectance spectrophotometry. Measurements were made preoperatively, postoperatively and after 1 week. RESULTS In the study group, left postoperative BMBF was significantly lower than preoperatively (115 vs. 210 PU/s, p = 0.0001) and lower than in the control group (115 vs. 205 PU/s, p = 0.002). Repeated measurement ANOVA showed a significant treatment effect depending on time (p = 0.0034). The left mucosal haemoglobin saturation in the study group was significantly reduced postoperatively, 92% versus 61%, with a treatment effect depending on time (p = 0.0080). The reduction in left/right ratio of the mucosal haemoglobin concentration 1 week postoperatively in the study group was insignificant. CONCLUSION Bronchial transsection and reanastomosis without bronchial artery blood supply was followed by significant decrease in mucosal blood flow and saturation postoperatively, and also in tissue haemoglobin concentration at section, and provides a physiologic explanation of histological changes.
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Affiliation(s)
- John Gade
- Department of Cardiothoracic Surgery RT, Rigshospitalet, Copenhagen University Hospital, Denmark.
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11
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McCullagh A, Rosenthal M, Wanner A, Hurtado A, Padley S, Bush A. The bronchial circulation--worth a closer look: a review of the relationship between the bronchial vasculature and airway inflammation. Pediatr Pulmonol 2010; 45:1-13. [PMID: 20025051 DOI: 10.1002/ppul.21135] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Until recently, the bronchial circulation has been relatively ignored in the research and clinical arenas, perhaps because of its small volume and seeming dispensability relative to the pulmonary circulation. Although the bronchial circulation only receives around 1% of the cardiac output in health, it serves functions that are critical to maintaining airway and lung function. The bronchial circulation also plays an important role in many lung and airway diseases; through its ability to increase in size, the bronchial circulation is able to provide lung parenchymal perfusion when the pulmonary circulation is compromised, and more recently the role of the bronchial circulation in the pathogenesis of inflammatory airway disease has been explored. Due to the anatomic variability and small volume of the bronchial circulation, much of the research to date has necessitated the use of animal models and invasive procedures. More recently, non-invasive techniques for measuring bronchial blood flow in the mucosal microvascular network have been developed and offer a new avenue for the study of this circulation in humans. In conjunction with molecular research, measurement of airway blood flow (Q(aw)) may help elucidate the role of the bronchial circulation in inflammatory airway disease and become a useful tool for monitoring therapy.
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Affiliation(s)
- Angela McCullagh
- Department of Paediatric Respiratory Medicine, Royal Brompton Hospital, London, UK
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12
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Abstract
Measuring soluble gas in the exhaled breath is a non-invasive technique used to estimate levels of respiratory, solvent, and metabolic gases. The interpretation of these measurements is based on the assumption that the measured gases exchange in the alveoli. While the respiratory gases have a low blood-solubility and exchange in the alveoli, high blood-soluble gases exchange in the airways. The effect of airway gas exchange on the interpretation of these exhaled breath measurements can be significant. We describe airway gas exchange in relation to exhaled measurements of soluble gases that exchange in the alveoli. The mechanisms of airway gas exchange are reviewed and criteria for determining if a gas exchanges in the airways are provided. The effects of diffusion, perfusion, temperature and breathing maneuver on airway gas exchange and on measurement of exhaled soluble gas are discussed. A method for estimating the impact of airway gas exchange on exhaled breath measurements is presented. We recommend that investigators should carefully control the inspired air conditions and type of exhalation maneuver used in a breath test. Additionally, care should be taken when interpreting breath tests from subjects with pulmonary disease.
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Affiliation(s)
- Joseph C Anderson
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Box 356522, University of Washington, Seattle, Washington 98195-6522, USA.
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13
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Schimmel C, Bernard SL, Anderson JC, Polissar NL, Lakshminarayan S, Hlastala MP. Soluble gas exchange in the pulmonary airways of sheep. J Appl Physiol (1985) 2004; 97:1702-8. [PMID: 15220303 DOI: 10.1152/japplphysiol.01272.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We studied the airway gas exchange properties of five inert gases with different blood solubilities in the lungs of anesthetized sheep. Animals were ventilated through a bifurcated endobronchial tube to allow independent ventilation and collection of exhaled gases from each lung. An aortic pouch at the origin of the bronchial artery was created to control perfusion and enable infusion of a solution of inert gases into the bronchial circulation. Occlusion of the left pulmonary artery prevented pulmonary perfusion of that lung so that gas exchange occurred predominantly via the bronchial circulation. Excretion from the bronchial circulation (defined as the partial pressure of gas in exhaled gas divided by the partial pressure of gas in bronchial arterial blood) increased with increasing gas solubility (ranging from a mean of 4.2 x 10(-5) for SF6 to 4.8 x 10(-2) for ether) and increasing bronchial blood flow. Excretion was inversely affected by molecular weight (MW), demonstrating a dependence on diffusion. Excretions of the higher MW gases, halothane (MW = 194) and SF6 (MW = 146), were depressed relative to excretion of the lower MW gases ethane, cyclopropane, and ether (MW = 30, 42, 74, respectively). All results were consistent with previous studies of gas exchange in the isolated in situ trachea.
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Affiliation(s)
- Carmel Schimmel
- Department of Medicine, University of Washington, Seattle 98195-6522, USA
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