Breath control

Breath control (also called breath play) is the intentional restriction of breathing for sexual gratification. When performed specifically to restrict oxygen to the brain, this is called erotic asphyxiation (or when performed alone, autoerotic asphyxiation). Breath control is a high-risk kink and the most common cause of fatalities in solo-play scenes [citation needed].

Background

Humans must breathe to survive. Breathing serves two essential purposes:

• Deliver oxygen to the body
• Remove carbon dioxide from the body

Dysfunction of either can rapidly cause serious injury or death.

Respiratory physiology

Human lungs exchange oxygen for carbon dioxide and store additional oxygen, which allows for brief periods of apnea (pauses in breathing) without harm. The amount of gas stored in the lungs at a given time is described by "lung volumes", and varies depending on what the person is doing. If breathing is paused, adequate oxygenation will be provided to the body until the remaining oxygen stored in the lungs is consumed, after which the person's oxygen saturation will rapidly decrease followed shortly by loss of consciousness.

Importantly, the body's sense of urgency to breathe is almost entirely driven by the ability to exhale carbon dioxide rather than the level of oxygen in the blood. This means that in certain circumstances (e.g. inhaling breaths of nitrous oxide continuously), the person will never feel short of breath despite low oxygen levels which can rapidly lead to unconsciousness.

The following table demonstrates how much gas remains in the lungs and how long that gas can supply enough oxygen to the body for a number of different circumstances for an average adult. Note that while the average volumes of gas vary greatly between individuals based upon their lean body weight, there is a reciprocal change in the rate of oxygen consumption meaning that the calculated times until desaturation occurs remain roughly the same.

Amount of gas stored in the lungs

	Normal breathing	Inhaling the largest breath possible	Exhaling as much gas as possible
Terminology	Functional residual capacity (FRC)	Total lung capacity (TLC)	Residual volume (RV)
Volume of gas	2 liters	5 liters	1 liter
Volume of oxygen (if breathing room air)	420 milliliters	1,050 milliliters	210 milliliters
When resting calmly
Rate of oxygen consumption	280 milliliters per minute
Time until oxygen is depleted	90 seconds	3 minutes, 45 seconds	45 seconds
During vigorous sexual activity
Rate of oxygen consumption	1,600 milliliters per minute
Time until oxygen is depleted	15 seconds	1 minute	<10 seconds

Hypoxia (Low oxygen)

Hypoxia is the term used to describe inadequate oxygen delivery to the body. When oxygen is completely depleted:

• Consciousness is lost within seconds
• Permanent brain damage occurs within minutes
• Death is all but certain after 10 minutes

When only breathing is restricted, the amount of time until oxygen is depleted is largely determined by how much oxygen remains in the lungs and the rate at which the body is using oxygen (see table above). However, in certain forms of breath play, oxygen depletion can occur much faster. For example:

• When other gases are being inhaled that significantly displace air (e.g. nitrous oxide)
• During carotid compression, which immediately completely restricts oxygen delivery to the brain

Loss of consciousness

When consciousness is lost due to hypoxia, the brain no longer communicates with the body normally and the body enters a reflexive state called posturing. Posturing results in the extreme tension of specific groups of muscles, which depend on the parts of the brain being denied oxygen. However, in all types of posturing the fingers close tightly into a fist. This has several extremely important implications:

• It is highly likely that a person will not let go of something they are holding when they lose consciousness
  • Depending on releasing an object in order to restore normal airflow is NOT a safe risk-mitigation strategy
• This grip may not release until brain death occurs
• To people unfamiliar with the appearance of posturing, it may not be apparent that loss of consciousness has occurred
  • This may delay or prevent assistance being provided, leading to further injury or death

Examples of decorticate and decerebrate posturing.

An example of rapid loss of consciousness and onset of posturing due to bilateral carotid compression.
0:11 - Consciousness is lost
0:14 - Decorticate posturing begins
0:21 - Posturing transitions toward a decerebrate pattern. Note the right arm attempting to extend outward blocked by legs.
0:32 - Decerebrate posturing more apparent when body allowed to fully extend
0:35 - Posturing ceases, consciousness returns

Hypercarbia (high carbon dioxide)

Hypercarbia is the term used to describe the inability to eliminate carbon dioxide from the body by exhalation. When carbon dioxide cannot be eliminated, an increasingly urgent sensation to breathe develops. If airflow is not restricted, the rate and depth of breathing reflexively increase. At very high levels of carbon dioxide, a person can become unresponsive and the pH of the blood can become dangerously acidic.

During breath play, unless oxygen supplementation and/or a carbon dioxide scrubber are used, hypoxia will generally present a life-threatening problem before hypercarbia becomes dangerous.

Negative pressure pulmonary edema

If breath control is performed by occluding the mouth or nose directly, significant negative airway pressure can be generated as the person struggles to draw air into their lungs. If enough inspiratory force is applied for enough time, the negative intrathoracic pressure can cause alveolar capillaries to rupture. This can cause pulmonary edema, where the lungs rapidly fill with fluid, and is life-threatening, requiring immediate medical attention. If this happens, pink frothy fluid can be seen coming from the mouth.

Risks and risk mitigation

Breath control is an extremely high-risk form of play. The specific risks depend on the details of the scene, but can include:

• Death
• Permanent neurologic injury
• Injury to upper airway or blood vessels in the neck
• Vomiting and aspiration
• Lung injury

Many forms of breath play cannot be made completely risk-free, so full consent is complete without an understanding and acceptance of risk. Risk mitigation involves careful planning of a scene to ensure any method to restrict airflow or blood flow is fail-safe.

Some important specifics to consider include:

• What must occur in order for normal airflow and/or blood flow to be restored?
  • Ensure nothing is attached to the mouth or nose unless someone else is able to immediately remove it if necessary
  • Due to posturing, someone who has lost consciousness due to hypoxia may not release their grip on an object or move their arm away from their face, so don't rely on a released grip to restore normal flow.
• If consciousness were lost, what position(s) could the body assume?
  • Is injury from falling possible?
  • Could the body or head fall into a position that would worsen the source of airflow or blood flow restriction?
  • Could the mouth or nose become blocked?
• What is the risk that vomiting or aspiration (inhaling of vomit or saliva) could occur?
  • Concurrent intoxication tremendously increases the risk of vomiting and aspiration
  • Is the mouth covered or the head positioned in such a way that fluid in the mouth would be inhaled rather than fall away from the body?
  • In scenes with heavy bondage or sensory deprivation
    • Would an episode of vomiting be noticed by others?
    • Could the head be quickly released, turned to the side, and any obstruction in front of the mouth immediately removed?
• Are any other drugs/inhalants also being used?
  • Each drug will have its own unique risks that must be carefully considered in the context of the scene

Breath control is risky for anyone to practice. In healthy people with proper safety practices, some sources of risk can be diminished. However, for people with certain health conditions, the risks of breath control cannot be meaningfully mitigated and should be avoided entirely.

Many types of heart or lung disease can make any form of breath control unmanageably dangerous (especially severe disease). If airflow or blood flow is restricted in these individuals, a cascade of life-threatening physiologic derangements can be initiated that cannot be easily reversed, even after restoring normal flow. Additionally, breath control should not be practiced by individuals with neurovascular conditions such as carotid stenosis, Moyamoya disease, cerebral aneurysms or vascular malformations due to greatly increased risk of stroke.

Carotid compression should never be practiced when carotid plaques could be present due to the high risk of plaque dislodgement and embolic stroke. More than 50% of older adults (>60 years old) have some degree of carotid plaque formation. Middle-aged adults (40-60 years old) can develop carotid plaques, with higher prevalence among those with risk factors (hypertension, high cholesterol, smoking, diabetes, cardiovascular disease).