Immersion and Drowning

7

Drowning accounts for approximately _% of all unintentional injury-related death each year around the world.

children, males, tourists

The highest rates of drowning are among 1.) __ 2.) __and those unfamiliar with the risk associated with entering a body of water such as 3.)_ .

Drowning

is the process of experiencing respiratory impairment from submersion/immersion in liquid.

Immersion

partially or wholly within a liquid, but not necessarily fully covered

Submersion

implies being completely covered by the liquid, with the body or object entirely under the surface.

near-drowning”

The term “—” has been applied to an event in which the victim survives for a period of time after the incident

drowned

Body in water does not necessarily mean that they have __

centimeters

Fatal drowning can occur in water only a few __ deep.

myocardial infarction or stroke

Died of natural causes before falling and entering the water

myocardial infarction or stroke

Died of natural causes whilst swimming

under the influence of drugs and/or alcohol and micturating into a canal and losing balance

Died of natural causes while in the water, having entered the water either voluntarily or accidentally

particularly those with low BMIs, the young and the elderly

Died from exposure and hypothermia in the water

physical assault

Died of injuries or other unnatural cause before entering the water

diving into unrecognized shallow water, causing cranial or cervical fracture

Died of injuries following entering the water

being hit by a boat or jet ski, shark attack

Died of injuries whilst in the water

cold shock, physical incapacitation, hypovolemia

Immersion in water causes an interplay between cardiorespiratory responses to deep body temperature, including 1.) __2.) __ and 3.) __, as precursors of collapse and submersion

cardiac, pulmonary, and neurological

The outcome is determined by a mixture of 1.) __, 2.)__ and 3.)__insults

poor-decision making, aspiration of water

Cold water; hypothermia; (1)__, (2) .__

physical presence of water within the respiratory system

Drowning reflects a combination of the __ (causing mechanical asphyxia) and fluid and electrolyte changes which vary according to the medium (sea vs. fresh water) in which immersion has occurred

fluid and electrolyte changes

Drowning reflects a combination of the physical presence of water within the respiratory system (causing mechanical asphyxia) and __ which vary according to the medium (sea vs. fresh water) in which immersion has occurred

Fresh water

hypotonic; rapidly absorbed into the bloodstream; transient electrolyte dilution and hypervolemia.

Fresh water

This results in alveolar collapse and atelectasis

Saltwater

three (3) times more hyperosmolar than blood.

Saltwater

This results in the insufficiency of pulmonary surfactant, blood-air barrier disruption, inflammation; oxidative stress, autophagy and apoptosis.

Saltwater

Aspiration of salt water into the lungs promotes the diffusion of fluid from the capillaries surrounding the alveoli into the lungs due to the osmotic gradient

Saltwater

The resultant formation of pulmonary edema or fluid accumulation in the lungs disrupts pulmonary surfactant which inhibits oxygen exchange, causing hypoxia and death.

Fresh water

Aspirates of freshwater results in water diffusing from the alveoli into the surrounding capillaries, resulting in increase blood volume and subsequent hemolysis.

Fresh water

The underlying mechanism of death is attributed to cardiac arrythmias.

Dry drowning

In cases of __ and in the absence of fluid aspiration, the mechanism of death is thought to be hypoxia due to laryngospasms, pulmonary reflexes or cardiac arrest mediated by the parasympathetic nervous system.

Scene investigation difficulties

• When occurred outdoor.

• Reduces accessibility and discovery resulting in prolonged PMI.

• Environmental facts affects the integrity and preservation of the body and possible associated physical evidence.

• Animal predation can significantly alter identifiable features and signs of physical injury .

Scene investigation discovery

• Retrieval and scene investigation.

• Technologies to assist in locating bodies such as side-scan sonar technology which utilizes sound frequencies to survey the sea floor to detect submerged objects.

water temperature, nature of the water, bacterial contamination, tidal flow, nature of the sea or riverbed, presence of marine life, habits of the individual, clothing worn

Factors affecting changes to the body following water immersion (8)

not possible

It is __ to estimate the PMI from signs of immersion and decomposition as there are many factors that may influence the appearance.

Bloating

__of the body (face, abdomen, body cavities) owing to gas formation in soft tissues and body cavities; seen in temperate conditions.

Gaseous decomposition, bloating

1.)__ and 2.)__often causes the body to float.

short period

If the body is obese, it may sink for only a __, even in the absence of bloating

Post-Mortem Artefacts

Subject to movement from tidal flow, wind and waves and come into contact with sand/silt, rocks, piers, and other underwater objects.

contact with moving propellers

Specific injury patterns may be identified • Deep chop wound and/or lacerations and sometimes traumatic amputation (__).

marine life

Other injuries may be caused by __ (shark, alligators, fish, crustaceans, mollusks, and insects).

External foam/froth and frothy fluid in the airways

reflects an admixture of bronchial secretion/mucus, proteinaceous material and pulmonary surfactant with aspirated fluid. This froth/foam has been likened to whisked egg white in texture and consistency, with a different quality to that seen in, for example, cardiac failure

Emphysema aquosum/heavy lungs

describes hyperexpanded and 'water-logged' lungs, whose medial margins meet in the midline and which do not collapse on removal from the body. There may be rib imprints on the surface of the lungs, and copious frothy fluid may exude from their cut surfaces. Combined lung weights of over 1 kg has been said to indicate freshwater drowning

Pleural fluid accumulation

has been associated with drowning, the volume of which controversially being said to reflect the post mortem interval.

Subpleural haemorrhages Paltauf's spots

named after Arnold Paltauf (1860-1893) an Austrian medical examiner who described petechial haemorrhages located beneath the pulmonary pleura, probably reflect haemolysis within intra-alveolar haemorrhages, and have been described in 5%-60% of drownings).

Miscellaneous signs

including middle ear congestion/haemorrhage, bloody/watery fluid in the intracranial sinuses, engorgement of solid organs, reduced weight of the spleen and muscular haemorrhages in the neck and back have all been proposed as additional physical signs of drowning.

Microscopy of the lungs

revealing alveolar distension, haemorrhage and rupture, and narrowed capillaries, has been proposed as a sign of drowning but remains open to debate.

External findings

• Foam around the nose

• Wrinkling of the hands and feet

• Mud/debris in the mouth

• Abrasions on the dorsal surface of the feet, hands, and knees

Auditory

Middle ear/mastoid air cell hemorrhage

Respiratory

• Airway foam (diagnostic feature of drowning, but not consistent)

• Fluid sinuses (Svechnikov’s sign) Merely a sign of immersion but does not indicate whether the fluid was aspirated before death or entered body spaces after death

• Pleural effusions

• Pulmonary edema and/or hemorrhage

• Increased lung volume

• Hyperinflated lungs (emphysema aquosum) Increased production of mucus and edema foam, blocking the airways preventing effective respiration.

• Rib indentations on the lungs

• Focal hemorrhage (Paltauf’s spots) Found in the lower lobes of the lungs

Airway foam

diagnostic feature of drowning, but not consistent

Svechnikov’s sign

Fluid sinuses, Merely a sign of immersion but does not indicate whether the fluid was aspirated before death or entered body spaces after death

emphysema aquosum

Hyperinflated lungs, Increased production of mucus and edema foam, blocking the airways preventing effective respiration.

Paltauf’s spots

Focal hemorrhage, Found in the lower lobes of the lungs

Circulatory

• Differential staining of aortic root/pulmonary trunk

• Dilation of the right side of the heart

Digestive

• Fluid in the stomach (Wydler’s sign) Presentation of three (3) layers: (1) an upper layer of frothy material; (2) a middle layer of fluid; (3) a lower layer of dense semi-digested material.

• Superficial tears in the stomach mucosa (Sehrt’s sign)

Wydler’s sign

Fluid in the stomach. Presentation of three (3) layers: (1) an upper layer of frothy material; (2) a middle layer of fluid; (3) a lower layer of dense semi-digested material.

Sehrt’s sign

Superficial tears in the stomach mucosa

Neck hemorrhage

Result of violent agonal movements and muscle contractions.

Reduced spleen volume

Probably due to sympathetic stimulation induced by hypoxia.

Adipocere

a waxy, soap-like substance formed during the decomposition of body fat in anaerobic, moist environments

Fatal arrythmia

• Stimulation of trigeminal nerve receptors (elicit reflex apnea, bradycardia, and peripheral vasoconstriction)

• “diving response” that is augmented by anxiety/fear, water temperature of less than 20-degree Celsius, and possibly alcohol increases the likelihood of the development of fatal arrythmia.

diving response

“__’ that is augmented by anxiety/fear, water temperature of less than 20-degree Celsius, and possibly alcohol increases the likelihood of the development of fatal arrythmia

Cold shock response

Initiated by peripheral subcutaneous receptors (causes respiratory and cardiovascular effects)

Role of Alcohol and Drugs

• Concussive head injuries.

• Vasodilation (may initiate and worsen hypothermia).

• May encourage risk-taking behavior.

• Reduced ability to respond appropriately and may be hampered by confusion, ataxia, and incoordination as a direct result of the substance use.

Strontium (Sr) concentration

• Tooth samples

• Used in diagnosis of seawater drowning (research).

Lung-body weight (LB) ratio with post-mortem vitreous humor sodium and chloride (PMVSC)

To diagnose saltwater drowning when immersion time is less than 1 hour

Real time PCR assay

To differentiate freshwater from marine bacterioplankton

Diatoms

Microscopic organisms present in sea and fresh water and have a siliceous capsule that survives acid digestion in the laboratory.

Diatoms

Its presence in the lung tissues, internal organs and bone marrow is considered as supportive evidence in the diagnosis of death by drowning.

Diatoms

Remains controversial as diatoms can be found to be ubiquitous in food and environment.