9. Drowning, hypothermia and hyperthermia Flashcards
describe the mechanism of drowning
- 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)
How fast do we lose heat in water?
3x faster than in air
what to do in water to preserve heat loss?
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
survival time in cold water at temperature of 16 degrees
5 hours
survival time in cold water at temperature 7 degrees
1 hour
survival time in cold water of temperature 0-4 degrees
15-30 minutes
list findings (3) in someone who has drowned
- froth at the nose and mouth (if it re-appears when you wipe it away)
- froth in the air passages (before it emerges from the mouth and nose)
- distended lungs (from water and trapped air)
what is another situation besides drowning that can lead to appereance of froth in nose and mouth?
drug overdose (heroin)
what are immersion changes of the body (2)
- skin of the hands and feet becomes sodded and wrinkled
- 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
Post mortem examinations on bodies recovered from water aim to: (3)
- establish who the person is
- determine if they have died from drowning or from some other cause
- look for any pointer to accident, suicide, or homicide (e.g. intoxication, injuries)
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)
- identification
- cause of death
- interpretation of any injuries
- toxicology investigations
define hypothermia
clinical situation when the deep body temperature falls below 35 degrees C
at what temperature does cold body stop shivering?
at 33 degrees C
What are clinical stages of hypothermia based on temperature
35 C - shivering starts
33 C - shivering stops
30 C - unconsciousness
26 C - death (usually)
what are clinical signs of hypothermia (5 steps)
- mental confusion, shivering
- drowsiness, muscular rigidity
- low BP, slow HR
- unconsciousness
- cardiac arrhythmia and death
what are principles of treatment of hypothermia
- prevent further heat loss (take out of cold environment)
- prevent cardiac arrhythmia (lie still)
- replace heat loss (slow rewarming)
vulnerable people will develop hypothermia at what temperature?
10C
What are two broad situations at which hypothermia can occur?
- acute exposure to elements (normally fit people exposed to extreme cold e.g. sea, hills.)
- incapacitation in a cold environment - person is not capable of helping themselves (injured, intoxicated, natural disease - pneumonia, stroke, elderly people wiht confusion, mentally ill)
list physical signs of hypothermia (6)
- person is thin and unkempt
- abrasions and discolorations over the joints
- lividity may be pinker than normal
- internally small hemorrhages in the stomach and pancreatitis
- signs of period of unconsciousness
- evidence of intoxication
what are 2 most common findings in hypothermia?
abrasions over the joints and
hemorrhages in the stomach
what is paradoxical undressing?
people start taking their clothes off possibly because of disturbance of the hypothalamus and disrupted temperature perception
define hyperthermia
excessively high body temperature, above 41.5C
hyperthermia generally occurs in two types of situation, those are:
- environmental
- drug related
what are two forms of environemental hyperthermia
- heat exhaustion
- heat stroke
describe heat exhaustion
it is less serious than heat stroke, person becomes very hot, loses water and salt and feels unwell. they recover with simple measures
describe heat stroke
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
what are 3 forms of drug related hyperthemria
- malignant hyperthermia
- malignant neuroleptic syndrome
- drug abuse
define malignant hyperthermia
an inherited disorder, tirggered usually by certain anaesthetics
define malignant neuroleptic syndrome
associated with the chronic use of psychoactive drugs, develops slowly
what drug of abuse could lead to hyperthermia
MDMA (ectasy) - due to release of serotonin in the brain
