9. Drowning, hypothermia and hyperthermia

Question 1

describe the mechanism of drowning

Answer 1

• an initial struggle to stay afloat, holding the breath to stop swallowing water
• eventually tiredness, hypoxia and cold can cause gradually unconsciousness and the person sinks
• they can bob up and down a few times
• water goes into air passages and mixes with the mucus lining to produce a fine froth
• water also goes into the alveoli and there is an interchange of fluid and chemicals with the blood in the surrounding capillaries (osmosis)

Question 2

How fast do we lose heat in water?

Answer 2

3x faster than in air

Question 3

what to do in water to preserve heat loss?

Answer 3

in cold water, physical activity accelerates heat loss due to increased peripheral blood flow, and so it is best to keep as still as possible

Question 4

survival time in cold water at temperature of 16 degrees

Answer 4

5 hours

Question 5

survival time in cold water at temperature 7 degrees

Answer 5

1 hour

Question 6

survival time in cold water of temperature 0-4 degrees

Answer 6

15-30 minutes

Question 7

list findings (3) in someone who has drowned

Answer 7

1. froth at the nose and mouth (if it re-appears when you wipe it away)
2. froth in the air passages (before it emerges from the mouth and nose)
3. distended lungs (from water and trapped air)

Question 8

what is another situation besides drowning that can lead to appereance of froth in nose and mouth?

Answer 8

drug overdose (heroin)

Question 9

what are immersion changes of the body (2)

Answer 9

1. skin of the hands and feet becomes sodded and wrinkled
2. injuries from rocks, boats, fish

(these changes appear on the person who was immersed in the water for some time, whether or not the death was due to drowning

Question 10

Post mortem examinations on bodies recovered from water aim to: (3)

Answer 10

1. establish who the person is
2. determine if they have died from drowning or from some other cause
3. look for any pointer to accident, suicide, or homicide (e.g. intoxication, injuries)

Question 11

If a person is not recovered right away, body will sink and surface days or weeks later when it is likely to be badly decomposed and damaged which creates problems with (4)

Answer 11

1. identification
2. cause of death
3. interpretation of any injuries
4. toxicology investigations

Question 12

define hypothermia

Answer 12

clinical situation when the deep body temperature falls below 35 degrees C

Question 13

at what temperature does cold body stop shivering?

Answer 13

at 33 degrees C

Question 14

What are clinical stages of hypothermia based on temperature

Answer 14

35 C - shivering starts
33 C - shivering stops
30 C - unconsciousness
26 C - death (usually)

Question 15

what are clinical signs of hypothermia (5 steps)

Answer 15

• mental confusion, shivering
• drowsiness, muscular rigidity
• low BP, slow HR
• unconsciousness
• cardiac arrhythmia and death

Question 16

what are principles of treatment of hypothermia

Answer 16

• prevent further heat loss (take out of cold environment)
• prevent cardiac arrhythmia (lie still)
• replace heat loss (slow rewarming)

Question 17

vulnerable people will develop hypothermia at what temperature?

Answer 17

10C

Question 18

What are two broad situations at which hypothermia can occur?

Answer 18

1. acute exposure to elements (normally fit people exposed to extreme cold e.g. sea, hills.)
2. incapacitation in a cold environment - person is not capable of helping themselves (injured, intoxicated, natural disease - pneumonia, stroke, elderly people wiht confusion, mentally ill)

Question 18

list physical signs of hypothermia (6)

Answer 18

1. person is thin and unkempt
2. abrasions and discolorations over the joints
3. lividity may be pinker than normal
4. internally small hemorrhages in the stomach and pancreatitis
5. signs of period of unconsciousness
6. evidence of intoxication

Question 19

what are 2 most common findings in hypothermia?

Answer 19

abrasions over the joints and
hemorrhages in the stomach

Question 20

what is paradoxical undressing?

Answer 20

people start taking their clothes off possibly because of disturbance of the hypothalamus and disrupted temperature perception

Question 21

define hyperthermia

Answer 21

excessively high body temperature, above 41.5C

Question 22

hyperthermia generally occurs in two types of situation, those are:

Answer 22

1. environmental
2. drug related

Question 23

what are two forms of environemental hyperthermia

Answer 23

1. heat exhaustion
2. heat stroke

Question 24

describe heat exhaustion

Answer 24

it is less serious than heat stroke, person becomes very hot, loses water and salt and feels unwell. they recover with simple measures

Question 25

describe heat stroke

Answer 25

heat stroke is less common but more serious
mortality rate is around 30%
the body cannot cool itself any longer, sweating stops and the temperature rises, often over 42C
it has an often rapid onset, causing delirium, tachycardia, hyperventilation, seizures

Question 26

what are 3 forms of drug related hyperthemria

Answer 26

1. malignant hyperthermia
2. malignant neuroleptic syndrome
3. drug abuse

Question 27

define malignant hyperthermia

Answer 27

an inherited disorder, tirggered usually by certain anaesthetics

Question 28

define malignant neuroleptic syndrome

Answer 28

associated with the chronic use of psychoactive drugs, develops slowly

Question 29

what drug of abuse could lead to hyperthermia

Answer 29

MDMA (ectasy) - due to release of serotonin in the brain