Drowning Mechanisms and Asphyxia Quiz

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Questions and Answers

What is the mechanism of death due to fresh water drowning primarily associated with hemolysis of red blood cells?

Hypothermia

Mechanical anoxia

Hydremia & hemolysis (correct)

Electrolyte imbalance

Which of the following is an indirect cause of death in drowning that involves vagal stimulation?

Cold water exposure to nasal sinuses (correct)

Hypotonic fluid intake

Pulmonary edema

Mechanical obstruction of airways

Which statement best describes secondary drowning or post-immersion syndrome?

It refers to immediate death upon submersion in water.

It is characterized by electrolyte imbalance upon recovery.

It involves complications such as pneumonia following submersion. (correct)

It occurs due to traumatic injuries sustained during drowning.

What can cause asphyxial death in sensitive individuals due to a severe spasm?

Dry drowning Signup and view all the answers

What is a potential direct cause of drowning associated with an increase in potassium levels in the bloodstream?

Electrolyte imbalance from fresh water Signup and view all the answers

What type of hypoxia results from a decrease in the capacity of blood to carry oxygen due to the presence of abnormal hemoglobin?

Anemic hypoxia Signup and view all the answers

Which condition primarily leads to stagnant hypoxia?

Advanced heart failure Signup and view all the answers

Which of the following describes histotoxic hypoxia?

Inability of cells to utilize oxygen Signup and view all the answers

What characterizes anoxic (hypoxic) anoxia?

Oxygen deficiency in external atmosphere Signup and view all the answers

What type of asphyxia is associated with mechanical obstruction of the airway?

Traumatic asphyxia Signup and view all the answers

Which of the following conditions does NOT represent a cause of peripheral anoxia?

Obstruction of blood vessels Signup and view all the answers

In which scenario is hypoxic hypoxia most likely to occur?

High altitude environments Signup and view all the answers

Which situation is a primary cause of anemic hypoxia?

Hemolysis due to blood transfusion reaction Signup and view all the answers

What physiological response occurs during the stage of dyspnea in mechanical asphyxia?

Forced expiration followed by forced inspiration Signup and view all the answers

Which of the following symptoms is most characteristic of the stage of convulsions in mechanical asphyxia?

Protruded tongue and prominent eyeballs Signup and view all the answers

What is the primary mechanism leading to petechial hemorrhage in asphyxia?

Accumulative pressure on fragile capillaries Signup and view all the answers

What is the primary cause of death in cases of suffocation?

Reduction of oxygen concentration in the atmosphere Signup and view all the answers

In the irregular breathing stage of mechanical asphyxia, what changes typically occur?

Dilated fixed pupils and hypotension Signup and view all the answers

Which mechanism is NOT associated with fatal pressure on the neck?

Neurogenic cardiac stimulation Signup and view all the answers

What distinguishes Tardieu’s spots from other types of petechial hemorrhages?

They are restricted to visceral pleura Signup and view all the answers

Which of the following is a common autopsy finding in cases of manual strangulation?

Bruising and abrasions on the neck Signup and view all the answers

Which of the following is NOT a clinical picture associated with the stage of dyspnea in asphyxia?

Deep cyanosis of the skin Signup and view all the answers

What is one cause of choking in adults mentioned?

Denture and hemorrhage Signup and view all the answers

What physiological change occurs due to cerebral irritation during convulsions?

Higher levels of carbon dioxide accumulation Signup and view all the answers

What condition can cause postural asphyxia?

Being trapped upside down Signup and view all the answers

Which statement regarding congestion and edema in asphyxia is accurate?

Lip and tongue swelling indicates severe oxygen deficiency Signup and view all the answers

Which of the following is NOT a cause of traumatic asphyxia?

Pressure on the neck Signup and view all the answers

Which of the following is a common situation that could lead to suffocation?

Aircraft cabin failure Signup and view all the answers

What distinguishes pure asphyxia during examination?

Petechiae and congestion Signup and view all the answers

What primarily differentiates ligature strangulation from hanging?

Ligature strangulation involves constricting the neck with a ligature. Signup and view all the answers

In what scenario is strangulation most commonly identified?

Most ligature strangulations are classified as homicidal. Signup and view all the answers

What is a defining feature of hanging marks compared to ligature strangulation marks?

Hanging marks do not completely encircle the neck. Signup and view all the answers

Which of the following correctly identifies a type of hanging?

Complete hanging where the feet are not touching the ground. Signup and view all the answers

What is the most common cause of accidental drowning?

People suffering from epilepsy. Signup and view all the answers

In drowning incidents, what physiological process occurs shortly after submersion?

Inhalation of water leading to electrolyte imbalance. Signup and view all the answers

What typically characterizes a judicial hanging?

Dislocation of the cervical spine from a sudden drop. Signup and view all the answers

What does a 'typical hanging' refer to?

The point of suspension being centrally over the occiput. Signup and view all the answers

What mechanism primarily leads to death in fresh water drowning?

Haemodilution and hyperkaleamia Signup and view all the answers

What is the typical survival rate from potentially fatal salt water submersion?

80% Signup and view all the answers

In the phases of drowning, what occurs immediately after breath-holding due to carbon dioxide accumulation?

Gulping of water Signup and view all the answers

Which postmortem finding is indicative of drowning?

Congestion of the face and conjunctivae Signup and view all the answers

What role do diatoms play in drowning investigations?

Differentiate between drowning and immersion Signup and view all the answers

What follows shortly after the inhalation of water during the drowning process?

Respiratory failure Signup and view all the answers

What physical sign is noted as 'goose skin' in drowning victims?

Cutis anserina Signup and view all the answers

What lethal timeframe is associated with fresh water drowning, according to the mechanisms of death?

Within 2-5 minutes Signup and view all the answers

Study Notes

Asphyxia

Asphyxia is the lack of oxygen. It's also characterized by the absence of pulsation, and encompasses any factor interfering with oxygen transfer
Different types of hypoxia (anoxia) include hypoxic, anemic, stagnant, and histotoxic hypoxia.

Types of Anoxic (Hypoxic) Anoxia

Ambient: Decreased oxygen content in the atmosphere, such as at high altitudes or in the presence of irrespirable gases (CO2, CO, N2, etc.)
Central: Depression of the respiratory center, caused by central depressants (like barbiturates), medulla herniation, or electric shock.

Types of Mechanical (Violent) Asphyxia

Occlusion of respiratory openings (smothering): Blocking the mouth and nose.
Occlusion of respiratory passages in the neck (strangulation, throttling, hanging): Blocking the trachea in the neck.
Prevention of respiratory movements (traumatic asphyxia): Compressing the chest and abdomen.
Internal airway obstruction by foreign body (choking): Blocking the airways from inside by objects.

Anemic Anoxia

Decreased oxygen-carrying capacity of blood due to:
- Abnormal hemoglobin (e.g., COHb in carbon monoxide poisoning, methemoglobin in nitrate toxicity)
- Massive blood loss (hemorrhage)
- Hemolysis (breakdown of red blood cells) caused by toxins, incompatible blood transfusion, etc.

Stagnant Anoxia (Stagnant Hypoxia)

Reduced oxygen delivery per unit of time due to interference in blood flow to tissues.
- Advanced heart failure
- Vagal or histaminic shock

Histotoxic Anoxia (Histotoxic Hypoxia)

Diminished ability of cells to utilize oxygen.
- Cyanide poisoning
- Exposure to extreme cold

Asphyxial Deaths

Different degrees of asphyxia result from external factors and internal factors
- Absence or reduction of oxygen tension in the external atmosphere
- Obstruction of external respiratory orifices (smothering or gagging)
- Blockage of internal respiratory passages

Further Details Regarding Asphyxia

Restriction in respiratory movements (e.g., traumatic asphyxia), or diseases preventing/reducing gas exchange in the lungs (pulmonary edema).
Reduction in cardiac function that inhibits oxygenated blood circulation
Limited oxygen transport by the blood in cases of severe anemia
Issues within the body tissues that hinder the cells' utilization of oxygen (such as cyanide poisoning).

Stages of Mechanical/Violent Asphyxia

Stage 1: Dyspnea

Physiological response to hypoxia, stimulating the respiratory center.
Symptoms include dyspnea (forced expiration then inspiration), apprehension, irritability, gasping, and blue lips.

Stage 2: Convulsions

Cerebral irritation due to anoxia and CO2 accumulation.
Symptoms like cyanosis, constricted pupils, hypertension, loss of consciousness, protruded tongue, prominent eyeballs. Capillary rupture can result in petechial hemorrhages (Tardieu spots).

Stage 3: Irregular Breathing

Loss of consciousness characterized by irregular breathing (Cheyne-Stokes respiration), deepening cyanosis, dilated and fixed pupils, hypotension, weak and rapid pulse, arrhythmias, flaccidity of muscles, and loss of reflexes.
Death often occurs within 5 minutes.

Classical Signs of Asphyxia: Petechial Hemorrhage

Small pin-point collections of blood under skin, sclera, conjunctiva, and thoracic membranes.
Vary in size (millimeters - 2 cm)
Tardieu's spots relate to petechial hemorrhages restricted to the visceral pleura.
Bleeding originates from small venules, not capillary rupture.

Other Signs of Asphyxia

Congestion and edema: Swelling and redness of the face, lips, tongue, and internal organs.
Cyanosis: Bluish discoloration due to reduced hemoglobin levels (absolute amount, not proportion).

Suffocation

Death caused by reducing oxygen in the inhaled air (e.g., cabin failure in high altitudes, fires).

Smothering

Mechanical blockage of the nose and mouth. Examples include; overlaying infants, sudden infant death syndrome (SIDS), and plastic bag suffocation.

Choking

Blockage of the internal airways (pharynx to trachea).
- Causes include foreign bodies, dentures, acute obstructive lesions (e.g., diphtheria, epiglottitis), aspiration of vomit, etc.
- Can lead to pure asphyxia (signs of congestion and petechiae) or neurogenic cardiac arrest.

Traumatic Asphyxia

Mechanical compression of the chest and abdomen. Examples are crushing in crowds.

Postural Asphyxia

Extended period of remaining in a specific position that restricts venous return to the heart; trapped individuals or those in states like drunkenness or drug use.

Fatal Pressure on the Neck

Common in forensic practices. Pressure causes airway occlusion, compression of veins, pressure on arteries, resulting in vagal cardiac arrest.

Manual Strangulation (Throttling)

Common homicide method, often seen in domestic killings (husband-wife), sex crimes, and child abuse.
Rarely performed by a woman (except on children), and men rarely strangle men of equal strength.
Autopsy findings could show signs of bruising and abrasions, bruising marks, fingernail/linear scratches, fractured hyoid bones, and superior thyroid horn fractures.

Strangulation by Ligature

Mostly homicidal.
The ligature encircles the neck horizontally, lower than in hanging.
Often has a crossover point.
Hyoid bone fracture less common than in manual strangulation.

Hanging

Ligature strangulation with the force deriving from the weight of the body or part of the body pulling on the neck (e.g., using ropes -judicial hanging).
Usually associated with complete suspension/dislocation of the cervical spine, leading to spinal cord traction, or brain stem disruption.
- complete vs. incomplete hanging, and its implications on the point of suspension as reflected in the skin marks.

Accidental Hanging

Can occur in sexual asphyxia cases (auto-erotic or masochistic), or in children.

Drowning

Prevention of air entering the lungs due to submersion in water or other fluids.
- Can be accidental (fishermen, bathers, etc.), suicidal (common amongst females), or homicidal (rare).

Drowning Pathophysiology

Water inhalation causes absorption into the bloodstream, electrolyte imbalances, and various accompanying effects. Death can occur within 2-5 minutes of complete submersion.

Drowning Mechanisms of Death

Fresh water: Large water volume leads to hemodilution (reducing sodium, increasing potassium), hemolysis (red blood cell rupture), circulatory overload, potentially hyperkalemia, ventricular fibrillation, and death 4 to 5 minutes.
Salt water: Water in the lungs causes severe edema and creates a hypertonic environment. The result is reduced blood volume (hemoconcentration), hypovolemia, shock, and subsequent asphyxia. Death may take 10 to 12 minutes to develop.

Drowning Phases

Submersion: Struggle, leading to exhaustion.
Breath holding: Continued until carbon dioxide builds up, stimulating breathing, followed by inhalation of water.
Gulping of water: Coughing and vomiting, followed by loss of consciousness.
Unconsciousness and convulsions: Further involuntary respiratory movements, and water aspiration. Respiratory failure can come before or after cardiac failure. Death commonly occurs within 2-3 minutes (though some longer periods of submersion result in some survival).

Postmortem Drowning Findings

Face and conjunctiva congestion
Fine froth (may contain blood), due to the water-air mixture, present in the nose and mouth.
Goose skin (cutis anserina). Peeling skin, and wrinkling of hands from prolonged immersion.
Stomach may contain water, mud, or algae for evidence (diatom tests— useful in differentiating true drowning from other submersions or simulated events).

Mechanisms of Death in Drowning

Direct causes: Immediate death due to mechanical anoxia or hypothermia.
Indirect causes: Reflex cardiac inhibition (e.g., from cold water), traumatic injuries
Secondary drowning (post-immersion syndrome): Survival after initial submersion episode, resulting in complications like edema, inflammation, and potential pulmonary problems like pneumonia.

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Description

Test your knowledge about the mechanisms of death associated with drowning, including the effects of hemolysis, vagal stimulation, and different kinds of hypoxia. This quiz covers a range of critical concepts including secondary drowning and conditions leading to various types of asphyxia. Dive into these complex physiological processes and solidify your understanding!