Airway Physiology

2019 ◽  
Author(s):  
Gilbert S Tang
Keyword(s):  
Airway Resistance ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Work Of Breathing ◽  
Lung Compliance ◽  
Flow Volume ◽  
Carbon Dioxide Transport ◽  
Basic Principles ◽  
Pulmonary Vasoconstriction ◽  
Volume Measurements ◽  
Airway Physiology

An understanding of airway physiology is important for the anesthesiologist, tasked with supporting the patient's respiratory functions which are altered in the conduct of anesthesia and surgery, or which may be abnormal due to co-existing disease. Airflow and airway resistance, lung compliance, spirometric values, flow-volume measurements, work of breathing, ventilation-perfusion matching, and oxygen-carbon dioxide transport are some of the basic principles. Clinical application of physiology allows the anesthesiologist to anticipate and manage changes that may occur when anesthetizing the patient, altering position or manipulating the airway. This review contains 5 tables, and 25 references. Keywords: Ohm’s law, laminar vs turbulent flow, Reynold’s number, Heliox, Bernoulli’s principle, compliance vs elasticity, Law of Laplace, spirometry, dead space, hypoxic pulmonary vasoconstriction

The Respiratory System

2019 ◽  
Author(s):  
Zerlina Wong ◽  
Michael Nurok
Keyword(s):  
Carbon Dioxide ◽  
Respiratory System ◽  
Airway Resistance ◽  
Respiratory Mechanics ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Lung Compliance ◽  
The Body ◽  
Elastic Recoil ◽  
Carbon Dioxide Transport ◽  
Pulmonary Vasoconstriction

The pulmonary system is crucial for survival. Managing respiratory mechanics and airway requires a sophisticated understanding of pulmonary physiology. This chapter discusses the ways in which oxygen is brought into the body and carbon dioxide is expelled and reviews the principles of respiratory mechanics, including lung compliance, airway resistance, chemoreceptor and mechanoreceptor control of ventilation, hypoxic pulmonary vasoconstriction, distribution of perfusion, and other properties that affect oxygen and carbon dioxide transport. The respiratory system exists in a state of equilibrium, where the inward elastic recoil of the lungs is balanced with the outward elastic recoil of the chest wall. Airway resistance and compliance are important factors that affect ventilation and air movement. This chapter reviews the role that chemoreceptors and mechanoreceptors have on controlling ventilation, as well as the effects that hypercarbia and hypoxemia have on pulmonary and cerebral circulation, and the Bohr and Haldane effects that elucidate understanding of the hemoglobin dissociation curve. These principles all inform the care of patients who require mechanical ventilation, as we endeavor to support them through their surgery or intensive care stay. This review contains 7 figures and 38 references. Key Words: apneic oxygenation, Bohr effect, chemoreceptors, compliance, Haldane effect, hypoxic pulmonary vasoconstriction, resistance, respiratory mechanics, ventilation-perfusion

scholarly journals To the informative value of flow-volume curve in forced expiration

2008 ◽  
pp. 91-97 ◽  
Author(s):  
G. A. Lyubimov ◽  
I. M. Skobeleva ◽  
G. M. Sakharova ◽  
A. V. Suvorov
Keyword(s):  
Airway Resistance ◽  
Lung Compliance ◽  
Forced Expiration ◽  
Flow Volume ◽  
Functional Tests ◽  
Lung Volumes ◽  
Volume Curve ◽  
Quitting Smoking ◽  
Flow Volume Curve ◽  
Airway Walls

This report introduces a mathematical model of forced expiration to analyze pulmonary function. Results of 3-year lung function monitoring of an ex-smoker have been shown in the paper. Actual values of lung volumes and airway resistance were used for modeling. The computerized data were compared to the flow-volume curve parameters and lung volumes measured during the forced expiration. Weak correlation between the "flow-volume" curve parameters and the time after quitting smoking together with significant change in the lung volumes and the airway resistance seen in the study could be due to some processes which have not been followed in this study (lung compliance, airway resistance at forced expiration, and elastic properties of airway walls).The results demonstrated that mathematical models could increase informative value of pulmonary functional tests. In addition, the model could emphasize additional functional tests for better diagnostic usefulness of functional investigations.

Vascular adaptations to hypoxia: molecular and cellular mechanisms regulating vascular tone

2007 ◽  
Vol 43 ◽  
pp. 105-120 ◽  
Author(s):  
Michael L. Paffett ◽  
Benjimen R. Walker
Keyword(s):  
Vascular Tone ◽  
Cellular Proliferation ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Hypoxia Inducible Factor ◽  
Systemic Circulation ◽  
Cellular Mechanisms ◽  
Hypoxia Inducible Factor 1 ◽  
Pulmonary Vasoconstriction ◽  
Adaptive Mechanisms ◽  
Adaptive Processes

Several molecular and cellular adaptive mechanisms to hypoxia exist within the vasculature. Many of these processes involve oxygen sensing which is transduced into mediators of vasoconstriction in the pulmonary circulation and vasodilation in the systemic circulation. A variety of oxygen-responsive pathways, such as HIF (hypoxia-inducible factor)-1 and HOs (haem oxygenases), contribute to the overall adaptive process during hypoxia and are currently an area of intense research. Generation of ROS (reactive oxygen species) may also differentially regulate vascular tone in these circulations. Potential candidates underlying the divergent responses between the systemic and pulmonary circulations may include Nox (NADPH oxidase)-derived ROS and mitochondrial-derived ROS. In addition to alterations in ROS production governing vascular tone in the hypoxic setting, other vascular adaptations are likely to be involved. HPV (hypoxic pulmonary vasoconstriction) and CH (chronic hypoxia)-induced alterations in cellular proliferation, ionic conductances and changes in the contractile apparatus sensitivity to calcium, all occur as adaptive processes within the vasculature.

Hypoxic Pulmonary Vasoconstriction and Chronic Lung Disease

2013 ◽  
Vol 12 (3) ◽  
pp. 135-144 ◽  
Author(s):  
Erik R. Swenson
Keyword(s):  
Pulmonary Hypertension ◽  
Lung Disease ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
World Health ◽  
Disease States ◽  
Pulmonary Vasoconstriction ◽  
Local Ventilation ◽  
Pulmonary Vascular Endothelium ◽  
Health And Disease ◽  
Health Organization

Hypoxic vasoconstriction in the lung is a unique and fundamental characteristic of the pulmonary circulation. It functions in health and disease states to better preserve ventilation-perfusion matching by diverting blood flow to better ventilated regions when local ventilation is compromised. As more areas of lung become hypoxic either with high altitude or global lung disease, then hypoxic pulmonary vasoconstriction (HPV) becomes less effective in ventilation-perfusion matching and can lead to pulmonary hypertension. HPV is intrinsic to the vascular smooth muscle and its mechanisms remain poorly understood. In addition, the pulmonary vascular endothelium, red cells, lung innervation, and numerous circulating vasoactive agents also affect the strength of HPV. This review will discuss the pathophysiology of HPV and address its role in pulmonary hypertension associated with World Health Organization Group 3 diseases. When sustained beyond many hours, HPV may initiate pulmonary vascular remodeling and lead to more fixed and less oxygen-responsive pulmonary hypertension if the hypoxic stimulus is maintained.

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