Related Experiment Video
Updated: Jun 16, 2026
08:34
Investigation into Deep Breathing through Measurement of Ventilatory Parameters and Observation of Breathing Patterns
Published on: September 16, 2019
Arterial blood gas changes in progressively deeper breath-hold dives
Thomas K M Scott1, Xavier C E Vrijdag2, Hanna van Waart2
1Department of Anaesthesia, Fiona Stanley Hospital, Perth, Murdoch, Australia.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|June 15, 2026
Summary
Breath-hold diving causes arterial gas spikes due to lung compression. The greatest effects on partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2) occurred at 40m, not at deeper depths.
Area of Science:
- Physiology
- Diving Medicine
- Sports Science
Background:
- Breath-hold diving to depths exceeding 60m may cause physiological changes.
- Lung compression at depth can alter arterial blood gases, potentially contributing to narcosis-like symptoms.
Purpose of the Study:
- To investigate the magnitude of arterial gas spikes during deep breath-hold dives.
- To determine the relationship between dive depth and changes in arterial oxygen and carbon dioxide levels.
Main Methods:
- Three elite breath-hold divers were studied during dives to 20, 40, 60, and 80m.
- Arterial blood samples were collected at depth via radial artery catheters.
- PaO2 and PaCO2 levels were measured before and during dives.
Main Results:
- The greatest increase in arterial oxygen (PaO2) was observed at 40m.
- Arterial carbon dioxide (PaCO2) levels plateaued at 40m and 60m before increasing at 80m.
- Compression effects on arterial gases appeared maximal at 40m, aligning with Boyle's Law predictions for lung volume reduction.
Conclusions:
- The peak effect of lung compression on arterial gases occurs at approximately 40m depth.
- Beyond 40m, metabolic processes become the primary drivers of PaO2 decrease and PaCO2 increase.
- These findings offer insights into physiological responses during extreme breath-hold diving.
Related Concept Videos
01:30Alterations in Respiration II
There are numerous types of normal and abnormal respiration. Based on ventilatory movements, breathing patterns are classified as regular, deep, or shallow. Examples include Biot's breathing, Cheyne-Stokes respiration, Kussmaul's breathing, hyperventilation, and hypoventilation. Each pattern is clinically significant and aids in evaluating patients.
In Biot's breathing, the respiratory rate and depth are irregular, alternating between periods of deep gasping and apnea. Common causes include...
In Biot's breathing, the respiratory rate and depth are irregular, alternating between periods of deep gasping and apnea. Common causes include...
01:31Chemical Factors Affecting Respiration Centers
Chemical factors such as changing CO2, O2, and H+ levels in arterial blood play a critical role in influencing respiration depth and rates. These variations are detected by chemoreceptors—specialized sensors located in two primary body areas. Central chemoreceptors are found throughout the brain stem, including the ventrolateral medulla, while peripheral chemoreceptors are located in the aortic arch and carotid arteries.
CO2 has a potent influence on respiration and is strictly regulated. Under...
CO2 has a potent influence on respiration and is strictly regulated. Under...
01:29Assessment of Ventilation II: Respiratory Depth and Rhythm
Respiratory Depth
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:
01:17Assessment of Diffusion and Perfusion
Understanding and evaluating diffusion and perfusion is critical in assessing a patient's respiratory and circulatory health. These processes play key roles in maintaining the body's internal environment, ensuring that tissues receive adequate oxygen while waste products are efficiently removed.
The Role of Diffusion in Respiration
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. In the respiratory system, this principle...
The Role of Diffusion in Respiration
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. In the respiratory system, this principle...
01:23Acute Respiratory Failure-IV
Respiratory failure can manifest suddenly or gradually, characterized by a rapid decline in PaO2 and a rapid rise in PaCO2. This situation indicates a severe respiratory problem that may quickly become a life-threatening emergency. One of the early signs of hypoxemic Acute Respiratory Failure (ARF) is a change in mental status due to the brain's sensitivity to oxygen levels and changes in acid-base balance. Symptoms such as restlessness, confusion, and agitation suggest inadequate oxygen...
01:26Blood Studies I: ABG and VBG
Blood studies are critical in the medical field, enabling healthcare professionals to assess a patient's health status accurately. This page will focus on two significant blood studies: Arterial Blood Gas (ABG) and Venous Blood Gas (VBG).
Arterial Blood Gas (ABG)
Arterial Blood Gas (ABG) studies are crucial for assessing the lungs' ability to supply oxygen and remove carbon dioxide, reflecting the patient's ventilation status. They also help understand the kidneys' capacity to reabsorb or...
Arterial Blood Gas (ABG)
Arterial Blood Gas (ABG) studies are crucial for assessing the lungs' ability to supply oxygen and remove carbon dioxide, reflecting the patient's ventilation status. They also help understand the kidneys' capacity to reabsorb or...