Airway sensors play an important role in control of breathing. Recently, it was found that pulmonary slowly adapting stretch receptors (SARs) cease after a brief excitation following sodium pump blockade by ouabain. This deactivation can be explained by overexcitation. If this is true, mechanical stimulation of the SARs should also lead to a deactivation. In this study, we recorded unit activity of the SARs in anesthetized, open-chest, and mechanically ventilated rabbits and examined their responses to lung inflation at different constant pressures. Forty-seven of 137 units had a clear deactivation during the lung inflation. The deactivation threshold varied from unit to unit. For a given unit, the higher the inflation pressure, the sooner the deactivation occurs. For example, the SARs deactivated at 3.0 +/- 0.3 and 4.8 +/- 0.4 s when the lungs were inflated to constant pressures of 30 and 20 cmH(2)O, respectively (n = 25, P < 0.0001). The units usually ceased after a brief intense discharge. In some units, their activity shifted to a lower level, indicating a pacemaker switching. Our results support the notion that SARs deactivate due to overexcitation.
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http://dx.doi.org/10.1152/japplphysiol.01286.2006 | DOI Listing |
Crit Care
January 2025
Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, ON, Canada.
Background: In patients with acute hypoxemic respiratory failure (AHRF) under mechanical ventilation, the change in pressure slope during a low-flow insufflation indicates a global airway opening pressure (AOP) needed to reopen closed airways and may be used for titration of positive end-expiratory pressure.
Objectives: To understand 1) if airways open homogeneously inside the lungs or significant regional AOP variations exist; 2) whether the pattern of the pressure slope change during low-flow insufflation can indicate the presence of regional AOP variations.
Methods: Using electrical impedance tomography, we recorded low-flow insufflation maneuvers (< 10 L/min) starting from end-expiratory positive pressure 0-5 cmHO.
BMJ Open
December 2024
Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
Introduction: Global healthcare expenditures are rising, driven largely by increased spending in both high- and low-income countries with hospitalisation as a primary contributor. Respiratory diseases, particularly lung cancer, pose significant public health and economic challenges with thoracic surgery as the standard curative treatment. Complications post resection, such as arrhythmias, infections and respiratory failure, result in substantial healthcare costs and resource demands.
View Article and Find Full Text PDFPLoS Comput Biol
January 2025
Department of Mechanical Engineering, University of California Riverside, Riverside, California, United States of America.
Respiratory diseases represent a significant healthcare burden, as evidenced by the devastating impact of COVID-19. Biophysical models offer the possibility to anticipate system behavior and provide insights into physiological functions, advancements which are comparatively and notably nascent when it comes to pulmonary mechanics research. In this context, an Inverse Finite Element Analysis (IFEA) pipeline is developed to construct the first continuously ventilated three-dimensional structurally representative pulmonary model informed by both organ- and tissue-level breathing experiments from a cadaveric human lung.
View Article and Find Full Text PDFJ Proteome Res
January 2025
School of Pharmacy, Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States.
() utilizes heme as an iron source from the host during infection. Biliverdin beta and delta (BVIXβ and BVIXδ) are generated by HemO, specific to , while biliverdin alpha is generated from the bacterial BphO system and by mammalian heme oxygenases. Here, we have developed and characterized a quantitative LC-MS/MS assay for the separation of three endogenous isomers, BVIXα, BVIXβ, and BVIXδ.
View Article and Find Full Text PDFMultimed Man Cardiothorac Surg
January 2025
Respiratory Disease Center, Kyoto Katsura Hospital, Kyoto, Japan.
The plane running between two adjacent pulmonary segments consists of a very thin layer of connective tissue through which the pulmonary vein also runs. To perform an anatomically correct segmentectomy, this segmental plane needs to be divided. Before the operation, the locations of vessels and bronchi are confirmed by three-dimensional computed tomography.
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