Asphyxia 2013

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Asphyxia

Hypoxia

and Neck compression

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Asphyxia

Asphyxia literally means

absence of pulsation,

but now is used to denote anoxia or

hypoxia.

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Respiration requires

• an intact airway,

• functioning ribcage and muscles (intercostal

and accessory), and diaphragm• intact N!,

• healthy lungs for effecti"e al"eolar#capillary

exchange,• good circulation and transport

mechanism(Hb.).

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Causes of hypoxia

Mechanical asphyxia $ struggling to breath against some

kind of interference with the mechanism of respiration.

Pathological conditions, predisposing to tissue anoxia $

lung pathology, bronchitis, emphysema, pulmonary fibrosis.

an compound the effects of other asphyxial mechanisms.

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A!%H&'A

!N!

• deep congestion of face * neck

• cyanosis

• petechiae, scleral haemorrhages

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+. bstruction of the nose and mouth- smothering,

suffocation

. bstruction of the air passages- gagging, choking,

inhalation#aspiration, cer"ical positionalasphyxia, drowning.

/. 0xternal pressure on the neck# Neck compression-

hanging, manual#ligature strangulation, arm lock,

choke hold.

1. 0xternal pressure on the chest- traumatic

asphyxia.

20HANA3 A!%H&'A

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Obstruction of the nose or mouth,

occludes the external airways and is commonly

referred to as smothering or suffocation.

xygen is not deli"ered to the al"eoli and gas

exchange cannot take place.

xygen le"els fall and carbon dioxide le"els rise.

+. !455A6N

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!mothering#suffocation is more common in the #ery

young, the #ery old, or debilitated, or

incapacitated, indi#iduals, accidentally or

homicidally.

6he nose and mouth can be co"ered by a pillow, gag,

hand etc..

!455A6N

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Plastic bag asphyxia is a relati"ely common method

of suicide, a plastic bag or sheet of plastic co"ering

the face.

8eath is usually rapid due sudden hypoxia causing

bradycardia or a cardiac arrest, without e"idence of

asphyxial signs.

!455A6N

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Accidental suffocation can occur following an

epileptic sei9ure

or if acutely intoxicated by alcohol if left face downin bedding, water or mud once unconscious.

!455A6N

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. bstruction of the air passages,

pharynx to bronchi

• hoking : ;lockage of posterior pharynx

and larynx by food or foreign ob

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ommoner in certain situations-

•elderly due to dementia or neurological in

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ommoner in certain situations associated with cerebral

cepression-

•acute alcohol intoxication- =caf$ coronary> due to a combination

of swallowing poorly chewed food and alcohol intoxication

•8rug intoxication e.g. heroin etc.

•%&'( ")*+R"&S concussion-unconscious, with slowed

neurological reflexes.

. bstruction of the air passages,

pharynx to bronchi

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. Compression of the nec/

!trangulation is a form of asphyxiacharacterised by closure of the blood

"essels and#or air passages of the neck asa result of external pressure on the neck.

/ types

3igature $ constricting band ? forceHanging $ constricting band ? body#head weight

2anual $ hands, forearms, or other limbs

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a). Hanging

b). !exual asphyxia

c). 3igature strangulation

d) 2anual strangulation

e) Arm lock: choke hold :carotid sleeper

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Associated with external markings on the neck,

depending on the mechanism, and there may be

internal bruising and damage to the larynx.

Asphyxial signs (petechiae, congestion and cyanosis)

may be present if death is not instantaneous.

n some cases death will be sudden and asphyxial

signs are absent.


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/a. Hanging

• 8efined as a form of strangulation

• %ressure on the neck is applied by a

constricting band

• 6ightened by the gra"itational effect of the

body or part of the body

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•Hanging is a common method of suicide,•occasionally accidental.

•omplete suspension not essential,•!uspension from a low le"el

•weight of the head sufficient to produce the

compressi"e force necessary.•.

/a. Hanging

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Asphyxial signs not always present

5ull suspension,• face more commonly pale

• due to complete obstruction of the neck"essels

%artial#incomplete suspension,

• petechiae more commonly seen• due to partial obstruction of "eins only

/a. Hanging

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•6he ligature mark forms an abraded groo"e around the

neck•2ark may completely encircle the neck if the noose is

secured with a slip style knot.•f the noose has a fixed circumference, mark present only

where the ligature contacts with the neck, lea"ing a gap

corresponding to the suspension point, usually in the

midline at the back of the neck or behind one of the ears.

•At the front of the neck the mark is typically at thyro:hyoidle"el, rising obli@uely upward on either side of the neck to

the point of suspension.•2ark deepest opposite the suspension point, max weight

bearing

a. %anging

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•6he tongue is lifted by ligature and may protrude from

the mouth and be clamped between the teeth.

•f the body is left suspended after death postmortemli#idity, influenced by gra#ity, present o#er the lower

half of the body.

•3ittle or no bruising into the soft tissues of the neck

•5ractures of the thyroid cartilage or hyoid bone are less

common than in strangulation.

a. %anging

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Hanging

• apidity of onset of asphyxial signs depends on

situation of ligature on the neck

$ ;etween lower

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Hanging

• f spinal cord intact and stoppage of air is

not complete, B:Cmins is typical fatal period

• esuscitation may be successful if instituted

prior to cardiac arrest

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•4sually homicidal, rarely suicidal or accidental.

•6he "ictim of homicidal strangulation is more

commonly female or because of age, infirmity orincapacitation a person who can be easily o"ercome.

•6he ligature used depends on what is at hand e.g. tights,

flex, rope. 0xternal force is used to tighten the ligature.

•A ligature mark will be e"ident on the neck in most

cases, although a soft ligature may not lea"e a mark.

c. 0igature strangulation

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•6he mar/ tends to be hori1ontal across the

nec/ at a lower le#el than in hanging, about

midthyroid le"el i.e. lower than in hanging.

•6he mark tends to be fairly uniform in depth and can be narrower or wider than the ligature

used and has a golden, or parchmented

appearance, sometimes with a pattern

corresponding to that of the ligature.•8epending on how the ligature is applied to the

neck the mark may or may not encircle the nec/

and may e#en show a crosso#er point.

/c. 3igature strangulation

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•Abo"e the le"el of the ligature there are usually florid

asphyxial signs.

•nternally there is usually bruising under the skin, aswell as at the base of the tongue and on the posterior

pharynx.•8epending on flexibility and the amount of force

used the thyroid cartilage and-or hyoid bone maybe fractured.

/c. 3igature strangulation

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•Manual strangulation is usually homicidal as it is

impossible to manually strangle oneself.

•Howe"er it is often not premeditated and may follow a

sexual assault, the "ictims women and children or the

elderly.

d. Manual strangulation

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•ften there are "ery few external marks on the neck but the

classic in

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•6here are usually florid asphyxial signs abo"e

the neck, particularly as compression of the

neck is intermittent as the hands are released

and then reapplied.

•n cases were the asphyxial signs are

prominent there can be bleeding from the noseand ears.


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•nternally there will be fingertip bruises in the

muscles of the neck and bruising behind the

larynx where it is pressed against the spine as well

as at the base of the tongue.•2ractures of the superior horns of the thyroid

cartilage are due to pressure from the thumbs but

fractures of the hyoid bone may also occur if

"iolent force is used.•n extreme "iolence the body of the thyroid

cartilage may be fractured.


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•8ue to the forearm being pressed into the neck from

front or behind.•6he force occludes the upper airway and compresses

the carotids, causing cerebral hypoxia.•0xternally there may be a broad band of abrasion on

the front of the neck often without significant internal

in

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•8ue to the neck being compressed in the crook of the

arm, the assailant behind his "ictim.

•6his has the effect of compressing the sides and not

the front of the neck and therefore the "essels, carotid

arteries, are occluded causing cerebral ischaemia.

•4nconsciousness super"enes within +D:+Bsecs.

e. 'rm loc/ Carotid sleeper

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1. H0!6 2%0!!N

3raumatic 'sphyxia

• %ressure on chest * abdomen restricts respiratorymo"ement and inspiration

• 6his may be due to being pinned beneath rubble,masonry, sand, earth or coal, e"en if the head is free,or e"en under "ehicles.

• t can be due to crushing in crowds e.g. Hillsborough.

• n some instances the body may be wedged in a

narrow space, the trunk or neck also acutely flexed,accelerating the asphyxiating processsuspendedupside:down, crucifiction, wedged between furniture,infants wedged in cots

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1. H0!6 2%0!!N

3raumatic 'sphyxia

• =;urking> is due to compression of the chest, in association

with occlusion of the nose and mouth, usually when the"ictim is asleep or intoxicated.

• "erlaying of infants::indistinguishable from !8!

• !tamping, kneeling, sitting astride in assaults#homicides

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•;lood is forced up into the neck "eins causing

gross asphyxial signs with intense cyanosis and

congestion of the head and neck with florid

petechiae and bleeding from the nose and ears.

•nternally, depending on the age of the "ictim

and rigidity of the ribcage, there may be no

in4uries or multiple rib fractures and

crushing of the internal organs.

1. H0!6 2%0!!N

3raumatic 'sphyxia

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%ositional asphyxia

• 8eath from postural or positional asphyxia takes place in circumstances when the "ictim>s bodyassumes an abnormal position, compromising the

process of respiration

• Associated with $ ntoxication

$ 8isability $ estraint

• 8iagnosis of exclusion

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%ositional asphyxia

• !ustained compromise of respiration due to $ nterference with the chest#diaphragm pre"enting normal

respiratory excursion

$ cclusion of the upper airway due to sustained abnormal positioning of the body

• %ositions of entrapment include $

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estraint asphyxia

• %ositional asphyxia as a result of restraint

modalities

$ %olice:public interaction

$ %atient restraints

• No other cause for death identified

• 6emporal association of death with episodeof restraint

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3rachea occluded (//lb. of pressure) causing generalised

hypoxia.

Obstruction of #enous return (1.1lb. of pressure) $ localised

hypoxia, cerebral hypoxia.

Pressure on the carotid #essels (++lb. of pressure) $ cerebral

ischaemia.

5agal inhibition - pressure on the carotid sinus - sudden

sensory stimulation due to fracture of the laryngeal

cartilages $ cardiac arrest # arrythmia.%ossibly %hrenic ner"e in

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Mechanisms of death

• mmediate death $ erebral hypoxia

• bstruction of the neck "essels $ =Eagal inhibition>

• !timulation of the carotid sinus

8eath sudden (cardiac arrest)or in 1:Bmins in uncomplicated hypoxia,

depends on indi"idual circumstances

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Mechanisms of death

• Eagal inhibition # pressure on the carotid

sinus # sudden sensory stimulation due to

fracture of the laryngeal cartilages $ cardiacarrest # arrythmia.

• ardioinhibitory reflex is an arterial

baroreflex controlling heart rate• 5undamental physiologic mechanism of

cardio"ascular homeostasis.

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Mechanisms of death

n theory : ompression of neck may cause carotid sinusreflex

• nternal carotid artery#bifurcation pressed against the spine

• arotid sinus F pressoreceptor• ;aroreceptors

• eflex stimulation of the parasympathetic area of themedulla oblongata ? inhibition of sympathetic areas

• ;radycardia, decrease blood pressure, "asodilatation

• irculatory failure to asystole

n practice $ the association between cardioinhibitory reflexand death is difficult or e"en impossible to pro"e.

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Mechanisms of death

• 3ate death

$ Non fatal cerebral hypoxia

• %ersistent "egetati"e state

$ 6hrombosis, or rupture, of neck "essels

• erebral infarction or airway obstruction

$ !urgical emphysema• 6rauma to air passage

• erebral infarction or airway obstruction

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How long does it take to suffer

irre"ersible brain damageG5ilmed se@uences (orking roup Human Asphyxia)

• apid loss of consciousness $ +D?#:/secs

• 2ild generalised con"ulsions $ +1?#:/secs

• 8ecerebrate rigidity $ +I?#:Bsecs

• 2ultiple phases of decorticate rigidity $ /C?#:+Bsecs

• 3oss of muscle tone $ +min +J?#:Bsecs

• solated muscle mo"ements end $ 1min +?#:min Isecs

• 8eep rythmic abdominal respiratory mo"ements start+I?#:Bsecs, end +min B+?#:/Dsecs

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How long does it take to dieG

0stimate : 8eath occurs within / to Bmins of

complete respiratory arrest

;ut, depends on the effecti"eness of theasphyxia and the indi"idual>s underlying

natural disease

No scientific basis for this statement

Asphyxia 2013

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