Related Experiment Video
Updated: Aug 4, 2026
09:54
A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
Cardiovascular changes during deep breath-hold dives in a pressure chamber
M Ferrigno1, G Ferretti, A Ellis
1Center for Research and Education in Special Environments, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14214, USA. mferrigno@bics.bwh.harvard.edu
Journal of Applied Physiology (Bethesda, Md. : 1985)
|October 24, 1997
Summary
Elite breath-hold divers experienced significant bradycardia and decreased cardiac output in cool water. This diving response, while animal-like, showed less perfect human adaptation with arrhythmias and severe hypertension.
Area of Science:
- Physiology
- Human adaptation
- Diving science
Background:
- Elite breath-hold diving elicits physiological responses.
- Understanding human adaptation to extreme environments is crucial.
Purpose of the Study:
- To investigate physiological responses during deep breath-hold dives.
- To compare responses in thermoneutral versus cool water.
Main Methods:
- Recorded electrocardiogram, cardiac output, and blood lactate.
- Performed invasive arterial blood pressure monitoring in two divers.
- Utilized a pressure chamber for dives to 40-55 meters.
Main Results:
- Cool water intensified bradycardia (20-30 bpm) and reduced cardiac output (<3 L/min).
- Arrhythmias were more frequent in cool water dives.
- Significant hypertension (up to 290/150 mmHg) occurred due to vasoconstriction, leading to anaerobic metabolism and increased blood lactate.
Conclusions:
- Human breath-hold diving response mimics animal responses but with notable differences.
- Arrhythmias and severe hypertension suggest imperfect human adaptation to deep diving stress.
More Related Videos
Related Concept Videos
01:24Factors Affecting Respiration
Respiration is a crucial physiological function involving exchanging oxygen (O2) and carbon dioxide (CO2) between an organism and its environment. Various factors can impact this essential process:
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:
01:30Alterations 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...
01:17Other Factors Affecting Respiration Centers
Breathing is primarily an involuntary activity regulated by the brainstem respiratory centers. However, it can also be consciously controlled, allowing us to hold our breath or take deeper breaths when needed. This voluntary control is facilitated by the cerebral motor cortex, which bypasses the medullary centers to stimulate the respiratory muscles directly.
However, the ability to hold one's breath voluntarily is not limitless. When the CO2 concentration in the blood reaches a critical level,...
However, the ability to hold one's breath voluntarily is not limitless. When the CO2 concentration in the blood reaches a critical level,...
01:25Hyperpnea and Hyperventilation
Hyperventilation refers to a higher-than-normal rate and depth of breathing, often associated with anxiety attacks. This excessive breathing surpasses the body's need to expel CO2, leading to a condition known as hypocapnia - an unusually low level of carbon dioxide in the blood. Hypocapnia can constrict cerebral blood vessels, reducing blood flow to the brain, which may result in dizziness or fainting. Early signs include tingling and muscle spasms in the hands and face, caused by falling...