Asphyxiation

Asphyxia

broad term involving the lack of oxygen (O2) available for the cell metabolism and inability to eliminate excess carbon dioxide (CO2)

(O2 cannot get where its need, especially in the brian)

respiration

—Production of energy needed for living species usually with the intake of O2 and release of CO2 in specialized organs such as the lungs

—Ventilation: environmental O2 delivered to the lungs

—Gas exchange: Pulmonary O2 diffuses to blood; CO2 diffuses to exhaled air

—Transport: Oxygenated blood delivers O2 to tissue

—Cells uptake and use O2 for metabolism and energy, then return CO2 to blood

Ventilation

environmental O2 delivered to the lungs

gas exchange

pulmonary O2 diffuses to the blood, CO2 diffuses to exhaled air

transport

oxygenated blood delivers O2 to tissue

types of asphyxiation

• choking

• confined space

• crucifixion

• drowning

• entrapment

• hanging

• strangulation

• ligature strangulation

• manual strangulation

• mechanical asphyxia

• positional asphyxia

• suffocation

• snow immersion

• vitiated atmosphere

choking

blockage of the airway to prevent respiration below the epiglottis or any internal blockage

confined space

no exchange of O2, reduced O2 atmosphere ex: stuck in closed refrigerator or freezer

crucifixion

slow loss of muscles for breathing and respiratory arrest

drowning

liquidm usually water blockage of nose and mouth or immersion

entrapment

confinement to a reduced O2 environment or chest restriction

hanging

a force that compresses the neck from full or partial weight of the decedent’s body

strangulation

impairment of blood supply to the brain by mechanical occlusion of the neck vasculature

Ligature strangulation

a force that compresses the neck applied by the mechanism other than the decedent’s body weight

manual strangulation

a force compressing the neck comes from the hands, forearms or other limbs

mechanical asphyxia

restriction of chest movement causing ineffective respiration this includes traumatic and positional asphyxia

positional asphyxia

restriction of chest movement due to the position of the body

traumatic asphyxia

restriction of the chest movement due to heavy object pressing against the chest

suffocation

broad term reflecting the inability of O2 to reach the lungs for exchange

snow immersion

falling or crashing into the snow and being unable to extradite or breath air

vitiated atmosphere

spoiled or impaired atmosphere producing chemical interference with O2

suffocation; different types of subtypes

—Broad term reflecting the inability of O2 to reach the lungs for exchange

—Entrapment/ environmental

—Smothering

—Choking

—Mechanical asphyxia

—Suffocating gases

airway obstruction- smothering

—Blockage of the nose and mouth with inability to breathe

—It can be a component of other forms of asphyxia

—Many objects can be used to block the airway: another person’s hand, a plastic bag, duct tape, clothing etc

—Usually homicidal in nature, sometimes may be accidental (rarely be sucicdal)

airway obstruction - choking

—Internal airway occlusion of the trachea or larynx

—Often from a bolus of food

—In children, it may be due to food, toys, or pacifiers

—This may be due to allergic or anaphylactic reactions from a variety of substances

—May be reactive due to swelling from a blow to the neck

—May be inflammatory from a pseudomembrane(diphtheria) epiglottitis or, tracheobronchitis( Haemophilus influenza)

—Tracheal and laryngeal injury

—Manner of death is usually accident

—Can be homicidal if a gag is used or if there is a great physical disparity between the  victim and attacker

—Occasionally may be a suicide if an inmate or mental facility resident inserts an object in the airway

—It may be natural if it is due to a ruptured abscess, epiglottitis, or pseudomembrane formation.

choking- children

—Common cause of morbidity and mortality in children 3 years and younger

—They tend to put objects in their mouths

—They can not chew and swallow food as well as adults

—They have a smaller airway

choking- elderly

—Often have comorbidities that contribute to choking

—Poor dentition

—Dementia

—Neurologic deficits

—Psychiatric disorders

smothering

—Mechanical obstruction or occlusion of the external airway or obstruction above the epiglottis

—Maybe homicidal, suicidal, or accidental

—Often minimal autopsy findings are present

chest compression

—Prevents effective chest respiratory movements

—Traumatic asphyxia

—Heavy weight on the chest

—Burking

—Overlaying

—Mob crush against immovable objects

—Snake constriction

chest compression- autopsy finding

—Cyanosis above the level of compression

—Facial petechial hemorrhages

—Small hemorrhages in chest muscles

—Possible rib fractures

—It may be accidental or homicidal

—Rarely suicidal

Entrapment and environmental suffocation

—Inadequate oxygen in environment

—Autopsy alone will not give cause of death

—Need to know circumstances surrounding the death including scene investigation and interviews

positional asphyxia

—Usually accidental

—Usually associated with drugs and alcohol

—Trapped in positions that impair breathing

—Congestion,cyanosis, petechiae

suffocating gases

—Gases displace oxygen from the atmosphere

—Carbon dioxide and methane are the most common

—Reduction of atmospheric oxygen in less than 25% causes  unconsiousness in seconds and death in minutes

—No specific autopsy findings

strangulation

—Hanging

—Ligature strangulation

—Manual strangulation

hanging

—Compression of the neck by noose or other object by weight of the body

—May be complete or incomplete suspension

—Compression of carotids:11lbs,  

    jugular veins:4.4lbs,vertebral arteries: 66.1lbs and trachea:33lbs

—Ligature proceeds upward with a point of suspension

—Appearance of ligature marks may vary

—Petechiae may or may not be present

—Protrusion and drying of the tongue

fractures when hanging

—Occasionally, fractures of various neck structures may be present

—Fractures increase with the age of the victim

—Accidental hanging usually involves children

—May see Tardieu spots at areas of lividity

judicial hanging

—May have fractures of c2 with injury to the spinal cord

—May have fractures of the hyoid bone, thyroid cartilage, and laceration of the vertebral artery

—Usually, consciousness is lost immediately

ligature strangulation

—Most are homicides

—Congestion of the head and face

—Petechiae

—Common ligatures: rope, electrical chords, neckties, clothing, both the victim’s and perpetrator’s

manual strangulation

—Compression of the neck by hand, forearm, or limb

—Occlusion of the carotid arteries

—Role of vasovagal reaction

—Cyanosis, petechiae, congestion

—Pulmonary edema

—Contusions, fingernail injury

—Depending on the age of the victim, fractures of the hyoid bone or thyroid cartilage may be present.

—Bones and cartilage become more brittle as one age, increasing the likelihood of fractures.

manual strangulation: One or two hands can be used

—Cannot determine which hand was used

—The attack may come from the front or the back of the victim

—Sometimes the legs can be used to strangle

ligature strangulation marks

• may be highly variable

• are usually horizontal

• are often dry and parchment- like

• may have contusion or fingernail injuries of the neck

ligature strangulation —Often has a minimal internal injury

—You may see hemorrhage in strap muscles

—Fractures of hyoid bone or thyroid cartilage are uncommon

—Pseudo ligature marks may be seen in infants and elderly

—Most are homicides

—Congestion of the head and face

—Petechiae

common ligature

• ropes

• electrical cords

uncommon ligatures

• neckties

• the victim’s and perpetrator’s clothing

martial arts (MMA)

starting to be more seen in forensic cases

people are learning MMA which teaches way to strangle and this is how people learn the techniques

with the right technique smaller people have a chance to take out a larger person

paucity of injuries

techniques such as chokeholds may leave

chokeholds

—AKA vascular neck restraint (VNR)

—They are in essence forms of strangulation

—Goal is to restrict brain blood flow to threaten or result in unconsciousness

chokeholds aka vascular neck restraint (VNR)

—A well-executed chokehold can cause LOC in less than 10 seconds

—The longer a chokehold is applied after LOC, the greater the likelihood of death or neurologic sequelae

vascular injury associated with strangulation

—Carotid artery dissection

—Occlusive thrombus of the middle cerebral artery with ischemic damage

—Vertebral artery dissection

—Various neurologic symptoms, including LOC , vertigo, hemiparesis, visual field loss, fine motor deficits, coma, death

—Symptoms may occur immediately or days after strangulation

—Death may occur after a significant hospital stay

vertebral artery dissections

—This has been documented in the forensic literature secondary to a blow or “chop” to the neck, attributed to many striking arts, such as karate.

— Evolving neurology and sports medicine literature is documenting an increasing number of vertebral artery dissections associated with vascular neck restraint(VNR) seen in the grappling arts such as judo and jiu jitsu

delayed complication of vascular neck restraint (VNR)

—TIAs

—Strokes

—Carotid dissections

—Disruption of atherosclerotic plaques leading to emboli

—May result in delayed homicides

—Important for the forensic pathologist to inquire about a potential unnatural etiology of TIAs and strokes

chemical asphyxiation

—Prevents utilization of oxygen at a cellular level

—Carbon monoxide

—Hydrogen cyanide

—Hydrogen sulfide

carbon monoxide

—Colorless, odorless, tasteless

—Competes with oxygen for binding sites on oxygen-carrying proteins

—Cherry red discoloration of tissues

—Necrosis of globus pallidus, cerebral cortex and hippocampus

hydrogen cyanide

—Produces cellular hypoxia by competing with the ferric iron atom of intracellular cytochrome oxidase and inhibits oxidative phosphorylation needed for ATP formation

—It inhibits the electron transport chain in the mitochondria

Hydrocyanic acid and related compounds

—are used to manufacture organic chemicals for synthetic fibers and plastics and in electroplating and metal polishing.

—In building fires, cyanide may be liberated from the burning of nitrogen-containing synthetic materials and may be found in the blood of victims of house fires

cyanide is also present in

— in cigarette smoke

—Seen in suicides and gas chambers

—Lethal doses vary with the route of administration

—The onset of symptoms is rapid, with collapse within minutes, tachypnea, and altered mental status followed by cyanosis, coma, and death

—Some people can smell the odor of almonds

—Burns of gastric mucosa

—Pink discoloration of tissues

hydrogen sulfide

—Poisonous, colorless, flammable, lipid-soluble gas

—It accumulates as a byproduct of bacterial breakdown or organic material containing sulfur

—Produced by fermentation of organic matter

—Found in sewers and cesspools

—Low doses have a rotten egg smell

—High doses paralyze olfactory nerves, with the victim losing the awareness of danger.

—High doses cause rapid death

hydrogen sulfideDeaths can occur in industrial settings and sewers

—May occur in suicides in confined spaces, which involves mixing of a metallic sulfide containing lime sulfur or pesticide with an acid such as hydrochloric acid often found in toilet bowl cleaners or other acidic detergents

hydrogen sulfide —It exerts its toxic effects by forming

a complex with iron in mitochondrial cytochrome oxidase and then prevents oxidative phosphorylation( a mechanism similar to cyanide)

—Since it is lipophilic, it may be selectively taken up by the brainstem, especially the respiratory centers, and cause acute apnea

hydrogen sulfide gas is an:

irritant to the skin, mucous membranes, and eyes

—Fatigue, headache, dizziness, drowsiness, coughing, nausea and pain in the nose, throat and chest

hydrogen sulfide autopsy findings

—Scene investigation is critical

—Elevated concentrations of metabolic products of hydrogen sulfide, such as sulfide and thiosulfate, in the blood

—Green discoloration of the brain

—May also have dark discoloration of copper coins, buckles, snaps, and zippers in the victim’s clothing

autoerotic asphyxia

—Usually from hanging

—Anoxia increases sexual arousal during masturbation

—Typically male,nude, or partially nude

—Often surrounded by pornography

—Usually, a self-rescue device fails

—Ligature is often padded

crucifixion

—Nailed to cross with wrists and feet nailed

—Death due to shock, dehydration, and asphyxiation

—Exhalation difficult

jugular veins

4.4lbs

vertebral arteries

66.1 lbs

trachea

33 lbs