Part ONE of THREE Parts

By Charly D. Miller,
Paramedic EMS Author & Educator,
Consultant Restraint Asphyxia Expert Witness
Updated (finally!) in SEPTEMBER, 2004

The original “webpage” versions of “RASK” Parts 1 & 2 remain posted on this website.
However, in December, 2005, I created and posted a PDF file containing
BOTH Parts 1 & 2 of RASK, and
the REFERENCES for all the RASK article parts!
If you’re going to PRINT these parts, I strongly suggest you print their PDF file:

Restraint Asphyxia – Silent Killer Parts 1 & 2 and References

Part ONE of THREE Parts

INFORMATION Related to TERMS Used Within This Article:
(If this is your first “trip” here, it is important that you read this section before reading the article.
On subsequent trips you can Click HERE to skip to the article.)

Although I am a woman, it is easier to use male pronouns (“he,” “him,” and so on) than writing “she/he,” “her/him,” and the like. So, that’s what I’ve done.

Because people with little-to-no medical education require this information just as much as medical professionals, I have minimized use of medical terms and explained concepts as simply as possible. Any reader who is offended by the simplicity of my explanations, can go play in my RESTRAINT ASPHYXIA LIBRARY.

Within this article, the term, “VICTIM” means:
a “patient,” “client,” “consumer,” “suspect,” “subject,” “criminal,” “inmate,” “student,” or the like!
I’ve used the term, VICTIM, because – without fail – ALL individuals who have ever died due to restraint asphyxia were “Victims” of some form of problem that caused them to involuntarily suffer some form of “ALTERED LEVEL OF CONSCIOUSNESS” that ultimately caused them to require application of restraint.

Within this article, the terms “RESPONDER”
refer to ANY PERSON who’s job description includes the responsibility of responding to, and possibly restraining, ANY individual experiencing an “emergency” that requires restraint.
And, any RESPONDER who is responsible for ensuring the care and safety of a “patient,” “client,” “consumer,” “suspect,” “subject,” “criminal,” “inmate,” or the like, becomes a RESTRAINER when they begin to apply restraint.
In other words: RESPONDERS and RESTRAINERS are Emergency Medical Services (EMS) or Fire Department personnel; Law Enforcement Officers or Correctional Facility personnel; Emergency Department (ED) personnel; General-Hospital or Psychiatric Facility personnel; OR they are Staff members of Homes, Schools, Vocational Training, or other Facilities established for the care and supervision of mentally ill or developmentally-disabled individuals AND THE LIKE!

“PHYSICAL” Restraint is defined as one or more human beings applying their HANDS (and other of their BODY PARTS) to an individual’s body, for the purpose of preventing that individual’s freedom of movement.

“MECHANICAL” Restraint is defined as affixing any form of “DEVICE” to any part of an individual’s body, for the purpose of preventing that individual’s freedom of movement.
In the past, the term “MECHANICAL Restraint” was most often used only when referring to METAL restraint devices – handcuffs, ankle “shackles, ” and the like. However, any DEVICE used for restraint (be it metal, or a roll of gauze, a sheet, a plastic or Velcro® strap, a leather or fabric cuff/strap, or the like) is, technically, a “mechanical” restraint.

Photo © 1997 BioguardianSystems,Inc
is defined as placing an individual’s body FACE-DOWN (“prone”) upon ANY surface (such as the ground, a long back board, an ambulance wheeled stretcher, a bed, or any other surface), and Restrainers physically applying pressure with their HANDS (and/or OTHER BODY PARTS) to the Victim’s shoulders, posterior torso (“back”), hips, and/or upper legs – physically preventing the Victim from moving out of the PRONE position.

is defined as placing an individual’s body FACE-DOWN upon a MOBILE surface (such as a long back board, an ambulance wheeled stretcher, a bed, or any similar device) and then using a MECHANICAL device, of any sort, to affix the Victim’s body to the mobile surface – mechanically preventing the Victim from moving out of the PRONE position.

Photo © 1997 Howard M. Paul
Clearly, “PHYSICAL” and “MECHANICAL” forms of FORCEFUL-PRONE-RESTRAINT are relatively the same thing: Application of FORCE to an individual’s body while he is in a PRONE position, and preventing his movement out of the forcefully-prone-restrained position.
Hence, within this article, “FORCEFUL-PRONE-RESTRAINT” refers to EITHER
physical or mechanical means of forcefully maintaining someone in a prone-restraint position.

Photo © 1997 Howard M. Paul
The term “HOBBLE RESTRAINT” has previously been inaccurately defined (even by ME – GASP!) as being simply another term for “HOGTIE” restraint.

Photo © 1994 Michal Heron
Technically, however, “Hobble” refers ONLY to the binding of an individual’s ANKLES together.

A hobbled individual is not hogtied. A hogtied individual is also hobbled.

Photo © 1997 Howard M. Paul
“HOGTIE RESTRAINT” is universally (correctly!) defined as
  • binding an individual’s wrists together behind his back (usually via handcuffs),
  • then binding his ankles together (“hobbling” him),
  • then bending his knees and tying his hobbled-ankles to his bound-wrists.

Photo Source = ?

“POSITIONAL ASPHYXIA” is most simply defined as death that occurs because the POSITION of a person’s body interferes with respiration (breathing), and the person cannot get OUT of that position. Death occurs due to the person’s inability to BREATHE anymore.
ANY body position that obstructs the AIRWAY, OR that interferes with the muscular or MECHANICAL MEANS of getting air into and out of the body (the body’s “BELLOWS” function) will result in a positional asphyxia death, if the person cannot get out of it.

is a form of

The factor that distinguishes a “restraint asphyxia” death from a “positional asphyxia” death, is that some form of RESTRAINT is the reason the Victim couldn’t ESCAPE the asphyxiating position.
First proposed in 1993, the phrase “Restraint Asphyxia” has become more widely-adopted since 1998.(1,2) Yet, several other phrases continue to be used when referring to incidents of restraint asphyxia: “Mechanical Asphyxiation,” “Traumatic Asphyxiation,” “Sudden In-Custody Death,” and the like.

2004 PPt Slide, C.D.Miller
Why is this TERMINOLOGY “important?”
When unrelated to restraint, positional asphyxia deaths are caused by the “passive entrapment” of an individual – no “person” is responsible for the Victim being unable to escape the asphyxiating position. Thus, the “manner” of death historically attributed to “positional asphyxia” has always been “ACCIDENTAL.”
Since 1994, however, leading medical examiners and forensic pathologists officially recognized restraint-related forms of positional asphyxia as being quite different. Restraint asphyxia deaths are due to PEOPLE having acted to physically or mechanically entrap someone.(3-5) Thus, the “manner” of death for the majority of restraint asphyxia deaths is now recognized as “HOMICIDE.”

Now To The “BODY” of the Article!


Responders sometimes encounter excited or agitated individuals who act-out in physically-exertional, violent and dangerous manners. To ensure Victim AND Responder safety – and to facilitate thorough medical evaluation and care of the Victim – violently-exertive, excited or agitated individuals MUST be RESTRAINED.

However, just as “choking” someone into unconscious submission is NOT appropriate, restraining a violently-exertive, excited or agitated individual in any OTHER manner that prevents them from being able to BREATHE is ALSO, emphatically, NOT appropriate!

The physical or mechanical restraint of an individual is always a “last resort.” The “least-restrictive” means of restraint (or use of force) – such as verbal counsel and de-escalation techniques – should always be employed before Responders resort to using hands-on or mechanical restraint.(6-8)
Unfortunately, verbal restraint techniques are entirely ineffective when someone has become (due to any of a myriad of causes) the Victim of an ALTERED LEVEL OF CONSCIOUSNESS. Someone with an altered level of consciousness does not have the mental ability to comprehend verbal counsel or de-escalation techniques. Thus, some form of restraint application is REQUIRED to ensure the safety of the Victim and all around him.
HOWEVER. Even when restraint is REQUIRED, only the “least restrictive” means may be employed.(6-8) In other words: only the minimum amount of force or restraint necessary to ensure everyone’s “SAFETY” (and to afford thorough medical evaluation and treatment of the Victim) may be used. And, the SAFETY of both Restrainers and Victim must be ensured during the initiation, employment, and maintenance of ANY form of restraint.

Any form of restraint that interferes with someone’s AIRWAY,
or that interferes with someone’s MECHANICAL means of breathing,
can KILL the restrained Victim.

Photo © 2003 JEMS

Thankfully, “CHOKE HOLDS” (aka: “Sleeper Holds” …
“Tactical Neck Holds” … “Lateral Vascular Neck Restraints”
… and the like)

have rightly been BANNED from use by many emergency services.

CHOKE HOLDS can cause death in two different ways:
1. Death due to Airway Obstruction OR
2. Death due to “CAROTID ARTERY COMPRESSION.”(2,9)

No one argues about the fact that choking can cause death due to
Airway Obstruction.
But, anyone who promotes the idea that even a “carefully” applied form
of choke hold can “SAFELY” be employed (by avoiding obstruction of
the Victim’s AIRWAY) is obviously entirely uneducated about the OTHER,
equally-lethal, choke hold effects caused by Carotid Artery Compression.(10)
Carotid Artery Compression can cause stroke or death
due to obstruction of blood-flow to the brain – or by dislodging
a plaque embolus
(a clump of the “crud” that builds up along the lining
of some people’s arteries), and sending it to obstruct an artery in the brain).
OR Carotid Artery Compression can cause death due to
Stimulation from pressure placed on one or both carotid arteries
triggers a lethally SLOW heart-rate in fact, it can actually
STOP the heart from beating.(2)

As you can see in the diagram at right:
A Restrainer thinking to avoid compressing the
airway by using the “crook” of his arm to “cradle”
the violently-struggling Victim’s neck actually
may increase the likelihood that
or STIMULATION will occur.

In other words: No matter how “carefully” any
form of “CHOKE HOLD” is employed, any Victim
subjected to a choke hold can rapidly DIE!

Because choke holds have rightly been banned from use for many years,
Restraint Asphyxia is most often caused by
“Forceful-Prone-Restraint” application.

2004 PPt Slide, C.D.Miller
Besides seriously interfering with thorough
medical examination and care provision,
forceful-prone-restraint application
(with or without the simultaneous
application of any kind of “hogtie” restraint)
has been recognized as being a cause of
restraint asphyxia deaths since 1988(11),
and its use has long been
by knowledgeable professionals.

Alternative methods of restraint are available to every Responder;

Furthermore, if access for thorough medical examination and care provision is not a “concern,”
SAFE methods of employing PRONE restraint ARE possible.

All that is required for ANY restraint method
to be SAFE and EFFECTIVE is
EFFECTIVE (in-depth) EDUCATION, practice, and team work.

In order for a Medical Examiner (or Forensic Pathologist)
to pronounce someone dead due to


(whether or not the positional asphyxia
death is restraint-related),
ALL of the following THREE key elements
during an AUTOPSY INVESTIGATION:(2,12-15)

Only if ALL of the above THREE ELEMENTS are discovered during an accurate and effective autopsy investigation, can an individual’s cause of death be identified as a form of “POSITIONAL ASPHYXIA” – whether due to restraint asphyxia, or not.

For Responders to develop an effective understanding of the deadly
relationship between forceful-prone-restraint and restraint asphyxia,
a basic understanding of

Effective Respiration is entirely dependent upon a combination of three critical elements(12):
  1. An open and “patent” airway (a passageway for air to travel from the atmosphere to the lungs, that is open and not threatened – in any way),

  2. An adequate gas exchange between the lung’s tissue (alveoli) and the body’s smallest blood vessels (the capillaries), and

  3. A functional respiratory muscular pump – or “bellows” system – the ability to change the interior size of the chest, so that airflow in and out of the lungs can be accomplished.

2004 PPt Slide, C.D.Miller
If any ONE of these elements is impaired or prevented from functioning, the act of breathing will be impaired or completely prevented.
If lung tissue or circulation is severely diseased or damaged by injury, oxygen and carbon dioxide are not exchanged adequately and breathing is ineffective.
Additionally, even with a completely open airway, perfectly healthy lungs and normal circulation, if the Victim’s mechanical component of respiration fails (if his “bellows system” fails), effective respiration cannot be achieved.

An Effectively Functioning Muscular Pump or “Bellows System”
requires – at least – the FIRST and THIRD of the following three elements(2,12):

2004 PPt Slide, C.D.Miller
  1. An appropriately functioning central nervous system control of respiratory muscle activity: an unimpaired brain “respiratory center” sending appropriate “messages” to the respiratory muscles, causing them to act in a manner that effectively produces inspiration and expiration,

  2. The ability of the ribcage to be expanded and relaxed by action of the intercostal muscles (muscles between the ribs), appropriately increasing and decreasing the size of the chest and interior lung-space.
    [If the diaphragm is properly functioning, ribcage expansion is not required for “normal” breathing to effectively be accomplished.(12)] AND
3.The ability of the diaphragm (the largest and most IMPORTANT respiratory muscle) to contract and displace abdominal contents downwards/outwards, increasing the size of the interior lung-space, so that inhalation can occur – and the ability of the diaphragm to relax and return to its normal position, decreasing the size of the interior lung-space, so that exhalation can occur.

NEXT: Normal breathing requires both effective inspiration and expiration; the movement of air in and out of the body. But, air will ONLY move from one place to another – from the atmosphere into the lungs, or from the lungs back out to the atmosphere – if the air pressure in one of those two places has been CHANGED.

If a person’s
airway was open,
but his lung-size
was in a fixed,
unchanging position,
the air-pressure
INSIDE his lungs
would be the SAME
as the air-pressure
OUTSIDE his body.

2004 PPt Slide, C.D.Miller
An EQUAL air-pressure inside and outside of the body results in
NO AIR MOVEMENT between these two spaces. NO “breathing.”

Graphic © 2001, C.D.Miller
When respiratory muscles are appropriately activated by messages from the brain’s respiratory center, the muscles between the ribs contract to make the ribcage expand, and the diaphragm contracts to descend into the abdomen (pushing the abdominal contents out of the way).
This INCREASES the SIZE of internal lung-space.
Ribcage expansion only slightly increases the size of the chest and internal lung-space. The greatest internal lung-space size increase occurs when the diaphragm contracts and travels down into the abdomen.(12)

When the internal lung-space size is increased, the air pressure inside the lungs becomes “stretched,” decreasing the internal air pressure, and creating a “negative intrathoracic air pressure” (relative to atmospheric air pressure). In other words, increasing the space and size of the lungs creates a “vacuum” within the lungs.
When the airway opens, air moves from the area of higher pressure (the atmosphere) to the area of lesser pressure (the lungs) = air rushes into the lungs, producing INSPIRATION. Air keeps moving into the lungs, continuing inspiration, until the air pressure inside the lungs becomes the SAME as the air pressure in the atmosphere. Once the internal and external air pressures equalize, all air movement stops, and all inspiration stops.
[Since “active” movement (energy-expenditure) is required to make the internal lung-space LARGER, inspiration is also called the “Active Phase” of respiration.]

Once full inspiration has been accomplished, the brain’s respiratory center automatically stops sending “contraction” messages to the respiratory muscles. When that happens, the respiratory muscles automatically relax and return to their normal state.
Relaxation of the ribcage’s intercostal muscles only slightly decreases the size of the chest and its internal lung-space. The greatest lung-space size decrease occurs when the diaphragm relaxes and moves back up out of the abdomen.

Graphic © 2001, C.D.Miller

Reducing the interior lung-space size causes “compaction” of the internal air pressure, increasing the internal air pressure, and creating a “positive intrathoracic air pressure” (relative to atmospheric air pressure). When the airway opens, air moves out of the lungs (now an area of higher pressure than that of the atmosphere), producing EXPIRATION.
Air keeps moving out of the lungs and into the atmosphere until the air pressure inside the lungs becomes the SAME as the air pressure outside the lungs. Once the internal and external air pressures equalize, all air movement stops, and all expiration stops.
[Since only relaxation – and no “energy-expenditure” – is required to make the intrathoracic space smaller, expiration is also called the “Passive Phase” of respiration.

When breathing becomes difficult (for whatever reason), “accessory” muscles are automatically employed to assist the intercostal muscles and diaphragm in creating the lung-space-size changes (the air pressure changes) required for inspiration and expiration to occur.(11,19)
The muscles used to assist lung-space-size changes when breathing has become difficult include: the muscles between the ribs, neck and shoulder muscles, lateral abdominal muscles, and even the muscles of the arms and legs.
In fact, it is practically impossible for Restrainers to tell the difference between a Victim struggling to “escape restraint,” and a Victim desperately struggling to BREATHE!

2004 PPt Slide, C.D.Miller
Once someone is entirely
prevented from physically
changing their internal
lung-size and space, entirely
prevented from changing the
air pressure inside their lungs,

breathing cannot occur.

When breathing cannot occur,
that condition is called,

Thus ENDS the basic explanation of
– how NORMAL BREATHING occurs!

Restraint asphyxia researchers have been warning Restrainers against the use of prone-hogtie and forceful-prone-restraint since the late 1980’s.(1,3,11,12,16,17,20) In recent years, however, restraint asphyxia researchers have come to the relatively-universal agreement that, restraint – by itself – is not solely responsible for asphyxia that occurs while a Victim is being actively restrained by others.(1,4,5,12,17,18,21-25)
Restraint asphyxia only occurs when an asphyxiating form of restraint is preceded by and associated with lethally-exhausting and body-chemical-unbalancing activities.
But, the lethally-exhausting and body-chemical-unbalancing activities preceding restraint application – by themselves – do not cause death, either. So, the asphyxiating form of restraint remains the ultimate “cause” of death.

2 to 3 “PHASES” of

have consistently been associated
with restraint asphyxia deaths.

PART TWO of this article
describes these PHASES, and
explains why they place a Victim
at risk for restraint asphyxia.

2004 PPt Slide, C.D.Miller

Patient Activities/Behaviors – Preceding Restraint
That Contribute to Restraint Asphyxia

Go to the REFERENCES for ALL parts


About the Author: Charly is an internationally-known emergency care author, EMS Instructor, Consultant, and Restraint Asphyxia Expert Witness.

A paramedic since 1985 (nine years as a “Denver General” Paramedic), Charly is a seasoned prehospital emergency care provider. With her additional experience as a psychiatric medical technician and an Army National Guard helicopter medic, Charly is one of the country’s most exciting and entertaining EMS educators.



Email Charly at:
Those are hyphens/dashes between the “c” and “d” and “miller”

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