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Related Concept Videos

Pulmonary Function Tests01:25

Pulmonary Function Tests

Pulmonary Function Tests (PFTs)
Pulmonary Function Tests are crucial diagnostic tools for assessing respiratory function, particularly in patients with chronic respiratory disorders. They comprehensively evaluate lung volumes, ventilatory function, breathing mechanics, diffusion, and gas exchange. These tests help diagnose pulmonary diseases and play a significant role in monitoring disease progression, evaluating disability, and assessing response to therapy.
PFTs involve using a spirometer, a...
Chronic Obstructive Pulmonary Disease-II: Pathophysiology01:20

Chronic Obstructive Pulmonary Disease-II: Pathophysiology

Chronic Obstructive Pulmonary Disease (COPD) pathophysiology is intricate and multifaceted, involving a complex interplay of physiological processes. Understanding these mechanisms is crucial for effectively managing and treating COPD. Here is an in-depth look at the critical elements in the pathophysiology of COPD:
Chronic Inflammation
External and Internal Respiration01:24

External and Internal Respiration

External respiration occurs in the lungs, and it is the first step in the journey of oxygen inside the body. When we inhale, oxygen enters our lungs and diffuses across the thin alveolar membrane. The alveoli are tiny, air-filled sacs that provide a vast surface area for gas exchange. Oxygen in the alveoli has a higher partial pressure (105 mmHg) than in the adjacent pulmonary capillaries (40 mmHg), establishing a pressure gradient. As a result, oxygen molecules move from the alveoli into the...
Chronic Obstructive Pulmonary Disease-IV: Assessement and Diagnostic Studies01:27

Chronic Obstructive Pulmonary Disease-IV: Assessement and Diagnostic Studies

Assessing and diagnosing Chronic Obstructive Pulmonary Disease (COPD) involves a detailed approach that includes a comprehensive review of medical history, physical examination, and a variety of diagnostic tests. This thorough evaluation is essential to ensure an accurate diagnosis and guide effective management strategies.
Medical History
Chronic Obstructive Pulmonary Disease01:24

Chronic Obstructive Pulmonary Disease

COPD is defined as a heterogeneous lung condition marked by persistent respiratory symptoms such as dyspnea, cough, and sputum production, caused by abnormalities in the airways that cause airflow obstruction.
Smoking is a primary risk factor for COPD, with over 80% of patients having a history of it. Patients typically experience progressive dyspnea or labored breathing, frequent coughing, and recurrent pulmonary infections. Many eventually succumb to respiratory failure, characterized by...
Lung Capacity01:47

Lung Capacity

The air in the lungs is measured in volumes and capacities. Lung volume measures reflect the amount of air taken in, released, or left over after a lung function, like a single inhalation. Lung capacity measures are sums of two or more lung volume measures.

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Related Experiment Video

Updated: Jul 2, 2026

Dual Test Gas Pulmonary Diffusing Capacity Measurement During Exercise in Humans Using the Single-Breath Method
08:44

Dual Test Gas Pulmonary Diffusing Capacity Measurement During Exercise in Humans Using the Single-Breath Method

Published on: February 2, 2024

Pulmonary diffusing capacity for nitric oxide during exercise in morbid obesity.

Gerald S Zavorsky1, Do J Kim, Elspeth R McGregor

  • 1Department of Obstetrics, Gynecology, and Women's Health, School of Medicine, Saint Louis University, Saint Mary's Health Center, Saint Louis, Missouri, USA. zavorsky@slu.edu

Obesity (Silver Spring, Md.)
|September 6, 2008
PubMed
Summary

Morbidly obese individuals show increased pulmonary diffusion capacity relative to lung size during exercise. This suggests their lungs adapt differently to physical exertion compared to non-obese individuals.

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Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise
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Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise

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Last Updated: Jul 2, 2026

Dual Test Gas Pulmonary Diffusing Capacity Measurement During Exercise in Humans Using the Single-Breath Method
08:44

Dual Test Gas Pulmonary Diffusing Capacity Measurement During Exercise in Humans Using the Single-Breath Method

Published on: February 2, 2024

Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise
07:09

Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise

Published on: February 20, 2017

Area of Science:

  • Pulmonary physiology
  • Exercise science
  • Obesity research

Background:

  • Morbid obesity can impact respiratory function, particularly during physical activity.
  • Pulmonary diffusing capacity is a key measure of gas exchange efficiency.

Purpose of the Study:

  • To investigate pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) during exercise in morbidly obese individuals.
  • To compare these measures between morbidly obese subjects and non-obese controls.

Main Methods:

  • Ten morbidly obese and nine non-obese subjects underwent two exercise testing sessions.
  • Pulmonary diffusion was assessed using single-breath maneuvers during incremental exercise.
  • Measurements included DLNO, DLCO, pulmonary capillary blood volume, heart rate, and oxygen consumption (VO2).

Main Results:

  • When normalized to alveolar volume (VA), DLNO, DLCO, and pulmonary capillary blood volume were higher in the obese group (P <= 0.06).
  • The relationship between VO2 and pulmonary diffusion measures, irrespective of normalization to VA, did not differ between groups (P > 0.10).
  • Obese individuals exhibited a greater increase in pulmonary diffusion per unit increase in VA during exercise.

Conclusions:

  • Morbidly obese individuals demonstrate enhanced pulmonary diffusion relative to alveolar volume during exercise.
  • This adaptation may be linked to a smaller increase in alveolar volume per unit increase in oxygen consumption in obese subjects.
  • Findings highlight unique pulmonary responses to exercise in morbid obesity.