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Hypoxic Pulmonary Vasoconstriction Does Not Explain All Regional Perfusion Redistribution in Asthma.

Hypoxic Pulmonary Vasoconstriction Does Not Explain All Regional Perfusion Redistribution in Asthma.

Am J Respir Crit Care Med. 2017 Jun 23;:

Authors: Kelly VJ, Hibbert KA, Kohli P, Kone M, Greenblatt EE, Venegas JG, Winkler T, Harris RS

Abstract
RATIONALE: Regional hypoventilation in bronchoconstricted asthmatics is spatially associated with reduced perfusion, which is proposed to result from Hypoxic Pulmonary Vasoconstriction (HPV). Our study aimed to determine the role of HPV in the regional perfusion redistribution in bronchoconstricted asthmatics.
METHODS: Eight asthmatics completed PET-CT lung imaging at baseline and after bronchoconstriction, breathing either Room Air or 80% Oxygen (80%O2, separate days). Relative perfusion, specific ventilation (sV), and gas fraction (Fgas) in the 25% of the lung with the lowest specific ventilation (sVlow) and the remaining lung (sVhigh) were quantified and compared.
RESULTS: In the sVlow region, bronchoconstriction caused a significant decrease in sV under both Room Air and 80%O2 conditions (mean±SD baseline vs. bronchoconstriction: 1.02±0.20vs.0.35±0.19 and 1.03±0.20vs.0.32±0.16, P<0.05, respectively). In the sVlow region, relative perfusion decreased after bronchoconstriction under Room Air conditions and, also, to a lesser degree under 80%O2 conditions (1.02±0.19vs.0.72±0.08, P<0.001 and 1.08±0.19vs.0.91±0.12, P<0.05). Fgas increased after bronchoconstriction under Room Air conditions only (0.99±0.04vs.1.00±0.02, P<0.05). sVlow sub-region analysis indicated that some of the reduction in relative perfusion following bronchoconstriction under 80%O2 conditions occurred due to presence of regional hypoxia. However, relative perfusion was also significantly reduced in sVlow sub-regions that were hyperoxic under 80%O2 conditions.
CONCLUSIONS: Hypoxic pulmonary vasoconstriction is not the only mechanism that contributes to perfusion redistribution in bronchoconstricted asthmatics suggesting that another, non-hypoxia mechanism, also contributes. We propose that this non-hypoxia mechanism may be either direct mechanical interactions and/or, unidentified inter-cellular signalling between constricted airways, the parenchyma and the surrounding vasculature.

PMID: 28644040 [PubMed - as supplied by publisher]




Examining the Effect of Residual Amikacin on Sputum Culture for Nontuberculous Mycobacteria.

Examining the Effect of Residual Amikacin on Sputum Culture for Nontuberculous Mycobacteria.

Am J Respir Crit Care Med. 2017 Jun 23;:

Authors: Eagle G, Brown K, Floto RA

PMID: 28644036 [PubMed - as supplied by publisher]




Reply to Epithelial Mesenchymal Transition (EMT): A Necessary New Therapeutic Target in COPD?
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Reply to Epithelial Mesenchymal Transition (EMT): A Necessary New Therapeutic Target in COPD?

Am J Respir Crit Care Med. 2017 Jun 22;:

Authors: Yang J, Shaykhiev R

PMID: 28640654 [PubMed - as supplied by publisher]




Epithelial Mesenchymal Transition (EMT): A Necessary New Therapeutic Target in COPD?
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Epithelial Mesenchymal Transition (EMT): A Necessary New Therapeutic Target in COPD?

Am J Respir Crit Care Med. 2017 Jun 22;:

Authors: Sohal SS, Eapen MS, Ward C, Walters EH

PMID: 28640653 [PubMed - as supplied by publisher]




Exposure Interaction - A Life-long Phenomenon with Relevance to Chronic Obstructive Pulmonary Disease.
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Exposure Interaction - A Life-long Phenomenon with Relevance to Chronic Obstructive Pulmonary Disease.

Am J Respir Crit Care Med. 2017 Jun 22;:

Authors: Vestbo J, Lange P

PMID: 28640650 [PubMed - as supplied by publisher]




Asthma Attacks in Children: Does Blocking IgE Reduce Rhinoviral Infections?
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Asthma Attacks in Children: Does Blocking IgE Reduce Rhinoviral Infections?

Am J Respir Crit Care Med. 2017 Jun 22;:

Authors: Saglani S, Bush A

PMID: 28640649 [PubMed - as supplied by publisher]




Extracellular Vesicle Transfer from Mesenchymal Stromal Cells Modulates Macrophage Function in Acute Lung Injury: Basic Science and Clinical Implications.
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Extracellular Vesicle Transfer from Mesenchymal Stromal Cells Modulates Macrophage Function in Acute Lung Injury: Basic Science and Clinical Implications.

Am J Respir Crit Care Med. 2017 Jun 22;:

Authors: Matthay MA

PMID: 28640648 [PubMed - as supplied by publisher]




OSA and Diabetic Mellitus - SEEING Beyond Glycemic Control.
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OSA and Diabetic Mellitus - SEEING Beyond Glycemic Control.

Am J Respir Crit Care Med. 2017 Jun 22;:

Authors: Ip MSM, Wong D

PMID: 28640643 [PubMed - as supplied by publisher]