RESTRAINT ASPHYXIA – SILENT KILLER

By Charly D. Miller, Paramedic, EMS Author & Educator, Consultant
Updated August, 2002

Emergency responders sometimes encounter excited, agitated and/or violent individuals.

To ensure patient* and provider* safety, to facilitate thorough evaluation and care, these individuals often require restraint. However, forcefully restraining a patient in the prone position is emphatically not appropriate! Besides seriously interfering with access for examination and care provision, the use of forceful-prone-restraint (with or without hobble or "hogtie" restraint) has been associated with causing patient death from "positional asphyxia."(1, 2, 3, 15, 17, 19, 21)

* For the purposes of this article, the term, "patient" also means "client," "student," "suspect," "criminal," "inmate," and the like. Correspondingly, the terms, "provider" or "responder" refer to law enforcement or correctional officers, fire or EMS or emergency department personnel, hospital or psychiatric facility personnel, employees of a residential facility or school for developmentally-disabled individuals, and the like.

Alternative methods of restraint are available to every emergency responder; methods easily employed and equally as immobilizing as forceful-prone-restraint ... methods that allow full access to the patient ... without the threat of death from positional asphyxia.

Physical or mechanical restraint of an individual is always a "last resort." Less-restrictive means of "restraint" (such as verbal cues or de-escalation) should always be used before resorting to hands-on or mechanical restraint. When physical restraint IS required, only the "least restrictive" means of control may be used. (Only the minimum amount of restraint required to accomplish safety, and thorough evaluation/treatment.) Additionally, provider and patient safety must be ensured during initiation, accomplishment, and maintenance of physical restraint.

DEFINITIONS

Physical Forceful-Prone-Restraint
is defined as placing an individual's body
FACE-DOWN upon a surface (such as the ground
or an ambulance wheeled stretcher), and physically
applying pressure to his posterior shoulders, torso, hips,
and/or upper legs – physically preventing him
from moving out of the prone position).

Mechanical Forceful-Prone-Restraint
is defined as placing a patient FACE-DOWN upon an
ambulance wheeled stretcher or long back board (or similar device),
and then using restraint STRAPS to forcefully affix the patient's
shoulders, torso, hips, and/or upper legs – mechanically
preventing him from moving out of a prone position.

[Obviously, "Physical" and "Mechanical" forceful-prone-restraint are relatively the same things: forceful compression of an individual while in a prone position, maintaining that compression, and preventing that individual's movement out of the prone position. For the purposes of this article, "Forceful-Prone-Restraint" refers to BOTH physical and mechanical means or forceful-prone-restraint.]

Hobble Restraint is defined as binding an
individual's wrists together behind his back,
binding his ankles together, then bending his knees and
tying his bound wrists and ankles together above his back.
This practice has also been called "hog-tying."
Hobble restraint may or may not be performed
while an individual is in a prone position.(1, 3, 9, 11, 19)

Restraint Asphyxia
is death that occurs due to Positional Asphyxia that is CAUSED BY RESTRAINT.(15, 18, 21)

Positional Asphyxia is most simply defined as when the position of a person's body interferes with respiration, resulting in death from asphyxia or suffocation. ANY body position that obstructs the airway, OR that interferes with the muscular or mechanical components of respiration, may result in positional asphyxia.(3, 4, 5, 7, 15)

In order to pronounce someone dead due to "POSITIONAL ASPHYXIA" (whether the positional asphyxia death is restraint-related, or not), requires ALL of the following three key elements:(4)

At death, the victim must be found in a position that interferes with breathing. Such a position may range from obstruction of the mouth and nose ("upper airway" obstruction), to a position that causes restriction of the chest or diaphragm.
The inability of the victim to escape this position must be explained.
Studies have shown that mechanical obstruction of dog airways causes a variable period of forceful physical reposition attempts, and muscular hyperactivity, as the animal tries to alter or alleviate the position that is interfering with breathing.(5)
In positional asphyxia deaths unrelated to restraints, unconsciousness due to severe alcohol intoxication is the most frequent explanation of the victim's inability to escape from the
asphyxiating position.(4)
ALL other CAUSES OF DEATH – natural or unnatural, medical or traumatic – must be
explored by autopsy and excluded to a reasonable degree of medical certainty.

Only if ALL of the above three elements are reported and demonstrated at autopsy, can the individual's cause of death be identified as a form of "Positional Asphyxia."

When specifically referring to Restraint-Related Positional Asphyxia deaths, the phrase "Restraint Asphyxia" was first proposed in 1993.(9, 15) This phrase has been readily adopted by individuals who are well educated in this subject. However, several other phrases are still used to describe incidents of Restraint Asphyxia: "Mechanical Asphyxiation," "Traumatic Asphyxiation," "Sudden In-Custody Death," and the like.
Why is this terminology-fuss "important?" Historically, the phrase, "Positional Asphyxia" implies "passive entrapment" of an individual, and is usually considered an "accidental" cause of death.(15) Restraint Asphyxia death is clearly the result of "elective" entrapment. Thus, Restraint Asphyxia is "homicide."

Prior to the early 1990's, hobble (hogtie) restraint was frequently employed by law enforcement officers for control of significantly combative parties. In response to restraint asphyxia death research, many law enforcement and correctional services across the country – and around the world – have since BANNED the use of hobble restraint.(6, 6a-6g) Unfortunately, even these "responsible" law enforcement services continue to be confused about the greater importance of avoiding forceful-prone-restraint!

Forensic pathologists began studying sudden deaths related to law enforcement use of restraint in the 1980's.(7) As restraint asphyxia research continues, more and more is understood. Unfortunately, controversy and confusion is sometimes generated by researchers.
A November of 1997 study published in the Annals of Emergency Medicine journal, by Chan, et al (emergency and "pulmonary" physicians) has been frequently – and erroneously – cited as having shown that "Police Hogtie Restraint Doesn't Kill."(10, 11, 12) Within their report (albeit only briefly, and in vague terms), Chan et al. admitted that their research did NOT study hobble restraint as it is performed in the field.(8, 21) [This study, related letters and reviews, is available in my Web Site's "RESTRAINT ASPHYXIA LIBRARY."]
In their most recently published study – September, 1998 (13) – Chan, et al conclude that "a combination of factors" results in restraint asphyxia, not hobble restraint alone. In that, they are correct. Unfortunately, they then suggest that the other factors involved are "more important" (more responsible for the restraint asphyxia) than the restraint factor. Their suggestion is wrong. The "other factors" – by themselves – would not result in death, either.(20, 21)

To fully understand the deadly relationship between restraint asphyxia and forceful-prone-restraint
(or prone-hobble-restraint), a basic understanding of respiratory physiology
(normal breathing function) is required.

Effective Respiration depends upon a combination of three critical elements:

an open and "patent" airway (an airway that is not threatened – in any way),
adequate exchange of oxygen and carbon dioxide between the lungs and the circulation system, and
a functional muscular pump or bellows system, to achieve airflow in and out of the lungs.

If any part of the upper or lower airway becomes obstructed, respiration is impeded 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 a failure of the mechanical component of respiration occurs (the muscular pump or bellows system), effective respiration cannot be achieved.

An Effectively Functioning Muscular Pump or Bellows System
requires a combination of three critical elements:

appropriate Central Nervous System (brain-respiratory-center) control of respiratory muscle activity,
the ability of the ribcage to be expanded and relaxed by various chest muscles (such as the intercostal muscles between the ribs), AND
the ability of the diaphragm (the largest and most IMPORTANT respiratory muscle) to contract and descend into the abdomen, displacing abdominal contents downwards and outwards.

If a person's airway was open, and his chest/lungs were
in a "neutral" position – a fixed, unchanging position –
the air-pressure INSIDE the chest/lungs would be
the SAME as the air-pressure OUTSIDE the body.
An EQUAL air-pressure inside and outside
of the body results in NO AIR MOVEMENT
between these two spaces. NO "breathing."

When respiratory muscles are appropriately activated by the Central Nervous System, the ribcage is cued to expand, and the diaphragm is cued to descend into the belly, so as to create a larger intrathoracic (internal chest/lung) space. This creates a negative intrathoracic air-pressure (relative to external atmospheric air-pressure). When this occurs, and the airway is opened, this pressure-difference causes air to flow into the lungs, producing inspiration.

Since active movement
and energy-expenditure
is required to make the
intrathoracic (internal chest/lung)
space LARGER,
inspiration is also called the
"Active Phase"
of respiration.

Relaxation of the diaphragm and the ribcage's muscles results in creation of a smaller intrathoracic (internal chest/lung) space – a positive intrathoracic air-pressure (relative to external atmospheric air-pressure). When the airway is opened, this pressure-difference causes air to flow OUT of the lungs, producing expiration.

Since only relaxation
– and no "energy-expenditure" –
is required to make
the intrathoracic space smaller,
expiration is also called the
"Passive Phase"
of respiration.

If the intrathoracic air-pressure
cannot be changed,
because the size of the intrathoracic
space cannot be changed,
NO AIR MOVEMENT
occurs between the lungs
and the external atmosphere.

The inability to CHANGE the SIZE of the internal chest space
is the ultimate cause of forceful-prone-restraint asphyxia. When standing or sitting up-right, a healthy person uses both the intercostal muscles and the diaphragm to breathe. However, when a healthy person is lying down on their back (supine) or lying down on their front (prone), breathing is normally accomplished by diaphragm movement, ONLY.(3)

When breathing becomes difficult (for any reason), accessory muscles in the trunk, neck, and arms are automatically employed to assist the intercostal muscles and diaphragm in changing the internal size of the chest, and creating the intrathoracic air-pressure changes required to achieve inspiration and expiration.

But, when forcefully-prone-restrained, a person's muscular bellows system becomes significantly compromised. By forcefully compressing the shoulders and torso to a surface, chest expansion is seriously restricted or completely prevented. By forcefully compressing the person's diaphragm (lower back and/or hips) against a surface, diaphragmatic excursion and displacement of abdominal contents is seriously restricted or completely prevented. Thus, forceful-prone-restraint significantly restricts or prevents inhalation.(1, 3, 4, 9)

If placed in a forceful-prone-position and also hobble restrained, a person's muscular bellows system becomes even more significantly compromised. The person's diaphragm (the largest/strongest muscle of respiration) is compressed against a surface, preventing downward excursion and displacement of abdominal contents. And, when in hobble restraint, the individual's shoulders are pulled up and back, locking the chest wall into a hyperexpanded position – seriously limiting chest wall relaxation OR further chest wall expansion.(1) Therefore, BOTH inhalation and exhalation are significantly prevented when someone is placed in a prone-hobble-restrained position.

Although forceful-prone-restraint and/or forceful-prone-hobble-restraint restriction of accessory muscles has not been studied, it is obvious to unbiased researchers that "any restraint that prevents a change of position could restrict breathing further by preventing (accessory) muscles from assisting in respiration."(3)

When forcefully-prone-restrained or prone-hobble-restrained, an individual must lift his entire body off of the surface he is placed upon – against physical pressure and/or restraint devices – using only his abdominal muscles, simply to take in or let out a little bit of breath. The muscular act of breathing requires a greatly increased physical effort – a greatly increased energy-expenditure. Yet, this great effort/energy-expenditure achieves (at best) only the tiniest volume of breath.

A forcefully-prone-restrained individual cannot breathe in anything even remotely resembling an "adequate" or "effective" manner.

In addition to the respiratory compromise caused by forceful-prone-restraint or prone-hobble-restraint, both these restraint positions significantly interfere with care providers being able to accomplish a complete and thorough patient examination, and significantly interfere with responders' performance of required emergency care procedures! If a patient is forcefully-prone-restrained or prone-hobble-restrained, care providers are restricted from accessing, evaluating, or controlling the most vital parts of the individual's body.

As supported by all restraint research (including that of Chan et al), interference with respiratory bellows system function is only One Factor that links use of forceful-prone-restraint or prone-hobble-restraint to restraint asphyxia death. Other, (equally important) factors include the patient's behavior and activities that precede and correspond with the use of forceful-prone-restraint or prone-hobble-restraint.

People who legitimately require total-body-restraint consistently experience Two to Three Phases of Extreme Muscle Exertion and Energy Expenditure prior to dying from restraint asphyxia.

PHASE 1 – The PRE-INTERVENTION PHASE: The individual demonstrates an altered level of consciousness, and engages in irrational behaviors with violent, aggressive, and/or paranoid features – all of which cause the individual to experience extreme physical exertion. This altered level of consciousness with exertional-behavior activity is usually referred to as a state of "excited delirium"
(or "agitated delirium").(9)

Some states of excited delirium are the result of alcohol and/or drug abuse (often cocaine).(1, 3, 9) However, states of excited delirium are also often produced by postictal states (exited altered levels of consciousness after seizures), diabetic hypoglycemia (exited altered levels of consciousness caused by low blood sugar), head trauma, exited manic-depression, or exited schizophrenic episodes.(3, 9)

Regardless of its cause, the excited delirium of Phase 1 results in profound physical exertion,
producing extreme total-body-exhaustion.

The time-length of Phase 1 varies with each incident, each incident's cause, and has variable effects upon each individual. Persons with excited post-seizure or low blood sugar episodes, or persons with acute head injuries, can experience total body exhaustion in just a few minutes. Persons with chronic diseases can become exhausted much faster than otherwise "healthy" individuals, when experiencing excited delirium.(11, 14, 16)

Regardless of its time-length, Phase 1 continues until the individual's "out of control" behavior is finally noticed by someone, and/or becomes so threatening to someone, that law enforcement, EMS, and/or fire department personnel are summoned.

PHASE 2 – The INTERVENTION INITIATION PHASE: Interveners arrive (law enforcement, EMS, and/or fire personnel), and quickly recognize that the individual's altered level of consciousness indicates the need for restraint. A struggle and/or chase ensues – this is the start of Phase 2. In Phase 2, the individual experiences additional extreme energy expenditure while running from, and/or wrestling with, interveners. However, the individual is out-numbered, and is eventually physically restrained.

Unfortunately (due to the chase-and-tackle mechanics that almost always occur in these situations), Phase 2 physical restraint usually always begins with forceful-prone-restraint – often with one or more persons kneeling on the individual's back (torso/posterior chest) and/or hips. Such forceful-prone-restraint immediately impedes the exhausted individual's ability to breathe. (Some individuals have died from restraint asphyxia during the initial part of Phase 2 – even before the application of any kind of "mechanical" restraint!)

Next, the individual is usually placed in wrist restraints, with or without ankle restraints, and may be released from the forceful-prone-position. If release from forceful-prone-restraint occurs before the individual expires – and the individual is not impeded from moving to his side – this can be considered a "medium-restrained" individual. Once medium restraint has been accomplished, Phase 2 ends.

PHASE 3 – The CONTINUED STRUGGLE PHASE: If he survives Phase 2, the medium-restrained individual will persist in his forceful and violent attempts to defeat and escape restraint, persist in preventing complete and thorough medical assessment or treatment. After all, at this point, nothing has been done to correct the cause of his altered level of consciousness!

And, at this point, maximum restraint (total-body-restraint) IS required. (How else are we to accomplish complete and thorough medical assessment or treatment?)

Application of total-body-restraint begins Phase 3.
If forcefully restrained in a prone position (hobbled or not) during application of total-body-restraint, the individual's body is also violently struggling to breathe! This struggle is universally perceived by uneducated responders as being ONLY the individual's struggle to defeat and escape restraint in order to harm himself or others. Thus, more and more force is applied, to keep the struggling individual in the prone position.

If placed in forceful-prone-restraint during Phase 3, the energy required to fuel the individual's muscular ability to breathe is entirely ABSENT. The forcefully-prone-restrained individual becomes lethally exhausted within seconds.(1, 2, 3, 5, 8)
The individual enters respiratory arrest, closely-followed by cardiac arrest.

Pathophysiology of The Restraint-Asphyxia Exertional Phases
("WHY are these Phases so Lethal?!"):

Besides exhausting the body's muscles, the violent muscular activity that occurs during EACH of these Phases adversely effects the internal chemistry of the individuals' body.

Extreme physical energy expenditure generates excessive production of adrenalin and noradrenalin ("catecholamines"). A progressively-increasing amount of these body-chemicals in the individual's system occurs – creating a "hypercatabolic state."

A hypercatabolic state weakens ALL the body's muscles – especially the respiratory muscles.(3, 9)

Hypercatabolic states also "stress" the heart by increasing its workload (requiring faster- and stronger-than-normal contractions). Thus, the heart needs more than normal amounts of oxygen in order to keep functioning. If an individual with severe respiratory muscle fatigue, an increased heart workload, and an increased need for oxygen, is restrained in a body-position that impairs or prevents breathing ... It is easy to understand why asphyxia occurs so quickly.

Reay et al report, "Energy that is expended by the contractile machinery of the body is subtracted from the respiratory muscle needs. Muscle fatigue may induce the central nervous system to shunt energy to contracting muscles. A deficit in energy supply to respiratory muscles can influence their performance. A decrease in chemical energy supply to respiratory muscles will hasten their failure as well as the failure of other muscle groups."(3)

O'Halloran and Lewman conclude, "First, the psychiatric or drug-induced state of agitated delirium coupled with police confrontation undoubtedly places catecholamine stress on the heart. Second, the hyperactivity associated with agitated delirium coupled with struggling with police and against restraints undoubtedly increases the oxygen delivery demands of the heart and lungs. Finally, the hogtied position clearly impairs breathing in situations of high oxygen demand by inhibiting chest wall and diaphragmatic movement."(9)

Research also suggests that the violent muscular activity that occurs during each Phase causes an excessive "lactic acid" production, producing "a profound metabolic acidosis ... associated with cardiovascular collapse following exertion in a restrained position."(16) Metabolic acidosis is a state of body-chemical imbalance, that – by itself – can kill someone. "Stimulant drugs such as cocaine may promote further metabolic acidosis and impair normal behavior regulatory responses. Restrictive positioning of combative patients may impede appropriate respiratory compensation for this acidemia."
More study is needed regarding the acidosis theory. But, it is entirely likely that "Good outcomes are still possible despite the pronounced level of" metabolic acidosis, if the individual is treated with "aggressive hyperventilation" and/or rapid adminsitration of IV "bicarbonate therapy."(16)

OVERWEIGHT INDIVIDUALS – those with "a large abdominal panniculus" (that's a medically-polite phrase meaning, "a big, fat, belly") – clearly appear to be at even greater risk for rapid onset of restraint asphyxia.(11, 14, 21) Dr. Reay reports, "A large, bulbous abdomen (a beer belly) presents significant risks because it forces the contents of the abdomen upward within the abdominal cavity when the body is in a prone position. This puts pressure on the diaphragm, a critical muscle responsible for respiration, and restricts its movement. If the diaphragm cannot move properly, the person cannot breathe."(14)
Think about it. If someone is overweight, forcefully restraining them on their stomach will not only prevent the contents of their belly from having room to move out of the way of their descending diaphragm, it will squish their belly contents UP INTO their diaphragm and lungs ... diminishing the size of their lung expansion ... entirely preventing their diaphragm from having room to move down into their belly ... and entirely preventing them from being able to change the internal size of their chest.

"If the diaphragm cannot move properly, [if the BELLY doesn't have room to move OUT!]
the person cannot breathe." (14)

The DANGER of using Forceful-Prone-Restraint
or Prone-Hobble-Restraint is SERIOUS!

Those who persist in ignoring this danger often cite the argument, "We only use prone/hobble restraints for a short period of transport time." Unfortunately for these providers and their patients, short transport times do not prevent restraint asphyxia death!
Published studies of deaths attributed to restraint asphyxia do not consistently (nor accurately) document the time-lapse between placement in forceful-prone-restraint and onset of unconsciousness or death. However, of the cases that HAVE reported this time period(1, 2, 3, 8), the average time between restraint application and onset of death was only 5.6 minutes!
A Wisconsin EMS case of restraint asphyxia death (one of several, but the only one to be published) occurred when the patient was "only" restrained prone and in hand cuffs (not hobbled), and was attended by a paramedic "for a five mile ambulance trip to the hospital." The patient died after being loaded into the ambulance, but prior to arrival at the hospital. The patient was not successfully resuscitated.(2)
Stratton et al reported two cases of hobble-restraint-induced asphyxia death occurring while the patient was in the care of a paramedic.(1) In each of Stratton's cases, a paramedic witnessed the patient's respiratory and/or cardiopulmonary arrest, immediately released the patient from restraints, and initiated advanced life support. In each case, all prehospital and inhospital emergency medical resuscitation efforts failed.
Thus, "We only use them for a short period of transport time" is not a legitimate excuse to continue using forceful-prone or prone-hobble restraint.

Additionally, according to ALL published case studies, deaths from restraint asphyxia do not respond to prehospital OR inhospital emergency resuscitation efforts.
[(To read the case study of an individual who entered restraint-related respiratory arrest, but who was successfully resuscitated prior to full cardiopulmonary arrest, read my "Restraint-Related Near-Death" Case Study, posted on my web site's "Restraint Asphyxia Newz" page.)]

Clearly, the use of forceful-prone-restraint or prone-hobble-restraint poses an unacceptable risk of death from restraint asphyxia. Clearly, the use of any form of PRONE restraint interferes with care providers' access to the patient for accomplishing a complete and thorough examination – interferes with performance of ALL required emergency care procedures. Clearly, the use of forceful-prone-restraint violates the emergency medicine Prime Directive, to "Do No Harm!"

Thus, such practices must immediately be banned
from ALL emergency responders' protocols of operation.

When dramatically changing any previously-accepted operational technique from use – when implementing a "change" in providers' long-time behaviors or practices – it is IMPERATIVE that providers be EDUCATED as to WHY the change must occur. Once providers are EDUCATED, no matter what technique or type of restraint they employ, they will automatically act to avoid causing restraint asphyxia.

The REFERENCE List for ALL parts of RESTRAINT ASPHYXIA – SILENT KILLER is available at http://www.charlydmiller.com/RA/restrasphyxref.html
Many of these reference articles are posted in Charly's RESTRAINT ASPHYXIA LIBRARY! If you want to read them, go to: http://www.charlydmiller.com/RA/RAlibrary.html

Charly's Web Site contains many other articles and papers regarding
Patient Restraint – and Patient COMMUNICATION – issues. http://www.charlydmiller.com

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.