Related Experiment Video
Updated: Jun 7, 2026
09:54
A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
Oxygen consumption at altitude as a risk factor for altitude decompression sickness
James T Webb1, Larry P Krock, Michael L Gernhardt
1NASA Johnson Space Center, Houston, TX, USA. jtwebb@swbell.net
Aviation, Space, and Environmental Medicine
|November 4, 2010
Summary
Exercise intensity, measured by oxygen consumption (Vo2), significantly correlates with decompression sickness (DCS) risk. Higher Vo2 levels during altitude exposures indicate a greater likelihood of developing DCS.
Area of Science:
- Aerospace Medicine
- Physiology
- Exercise Science
Background:
- The link between exercise and decompression sickness (DCS) has been recognized for decades.
- Quantifying this relationship has been challenging due to the difficulty in isolating exercise as a sole variable.
- A comprehensive DCS database from Brooks City-Base provides extensive physiological data from over 3000 altitude exposures.
Purpose of the Study:
- To measure oxygen consumption (Vo2) during activities undertaken in previous altitude exposures.
- To retrospectively determine the relationship between Vo2, a measure of exercise intensity, and the incidence of DCS.
Main Methods:
- Ground-level activities were designed to replicate standardized exercise protocols used during altitude exposures.
- Oxygen consumption (Vo2) was measured breath-by-breath using a COSMED metabolic system.
- Vo2 data from four activity levels under controlled conditions were analyzed to correlate with observed DCS risk.
Main Results:
- Previous altitude exposures (8992-9144 m for 4 hours after a 1-hour prebreathe) resulted in DCS incidence ranging from 38-86%.
- This study quantified the Vo2 associated with activities during these exposures.
- A strong correlation (0.89) was found between the highest 1-minute Vo2 and DCS incidence.
Conclusions:
- The highest 1-minute Vo2 during altitude exposure is highly correlated with the level of DCS risk.
- Future research with lower activity levels could refine DCS risk modeling.
- Understanding exercise intensity is crucial for mitigating DCS in high-altitude environments.
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:
01:27Oxygen Transport in the Blood
Hemoglobin (Hb) is a crucial molecule in the human body, consisting of four polypeptide chains, each bound to an iron-containing heme group. This unique structure enables hemoglobin to bind to oxygen, with each molecule capable of combining with four molecules of oxygen, leading to rapid and reversible oxygen loading. When fully loaded with oxygen, it is called oxyhemoglobin, while hemoglobin that has released oxygen is called reduced hemoglobin or deoxyhemoglobin. As hemoglobin binds oxygen,...
01:21Acute Respiratory Failure-II
Type I Respiratory Failure, or hypoxemic respiratory failure, occurs when the partial pressure of oxygen (PaO2) in arterial blood falls below 60 mmHg while breathing room air without a corresponding increase in arterial carbon dioxide levels (PaCO2). This condition highlights a significant impairment in the lungs' capacity to oxygenate the blood.
The underlying physiological abnormalities that contribute to hypoxemic respiratory failure include:
The underlying physiological abnormalities that contribute to hypoxemic respiratory failure include:
01:19Special considerations while measuring oxygen saturation
Assessing respiratory rate concurrently with pulse measurement is fundamental to patient care, providing valuable insights into the patient's respiratory function. The normal breathing rate for an adult usually falls within a normal range of 12 to 20 breaths per minute. Abnormal respiratory rates can signal underlying health conditions or the need for immediate intervention.
Ensuring accuracy in vital sign recordings while prioritizing patient comfort and minimizing anxiety is important.
Ensuring accuracy in vital sign recordings while prioritizing patient comfort and minimizing anxiety is important.
01:23Hypoxia
Hypoxia is a medical condition characterized by an inadequate oxygen supply to body tissues. It typically manifests as a bluish discoloration of the skin and mucosae, especially in fair-skinned individuals, when hemoglobin (Hb) saturation drops below 75%.
Types of Hypoxia
There are four primary types of hypoxia, each resulting from a different cause:
1. Anemic hypoxia: This type occurs due to insufficient oxygen delivery caused by a lack of red blood cells (RBCs) or RBCs with abnormal or...
Types of Hypoxia
There are four primary types of hypoxia, each resulting from a different cause:
1. Anemic hypoxia: This type occurs due to insufficient oxygen delivery caused by a lack of red blood cells (RBCs) or RBCs with abnormal or...
01:29Oxygen Requirements and Growth Patterns
Microorganisms exhibit diverse oxygen requirements and growth patterns driven by their metabolic strategies and environmental adaptations. Oxygen, while essential for many organisms, can also be toxic under certain conditions, shaping how microorganisms grow and survive.Oxygen Requirements of MicroorganismsMicroorganisms are classified based on their ability to use or tolerate oxygen:● Obligate aerobes like Mycobacterium tuberculosis need oxygen for energy production, as it serves as the...