1
Q
how does our body regulate temp?
A
Thermoregulation
- feedback mechanisms
2
Q
where are most regulating centres located?
A
Hypothalamus
3
Q
what is the variance between tympanic temp and core temp?
A
-0.5 degrees
4
Q
what are the bodies mechanisms used to preserve heat?
A
- goosebumps
- shivering and increased muscle tone
- peripheral vasoconstriction
- increased cardiac output
- increased resp rate
5
Q
What is the definition oh hypothermia?
A
condition where bodys temp drops below that required for normal metabolism and function.
Below 35 degrees
6
Q
what are the neuroprotective benefits of hypothermia
A
- reduced cerebral metabolism
- reduce the risk of brain oedema
- reduce risk of seizure activity
7
Q
what are the cardioprotective benefits of hypothermia
A
may reduce infarct size
- may help preserve ATP levels
- improve microvascular flow
8
Q
What is the ischaemic tolerance at temps less than 20 degrees?
A
10 x times the normothermic level
9
Q
What are the major ways of losing heat?
A
- Evaporation
- Respiration
- conduction
- Convection
- radiation
10
Q
What are the predisposing risk factors to hypothermia
A
- Age of patient (children and elderly art risk
- health of patient
- medications
- length of exposure
- intensity of exposure
- coexisting weather conditions
- alcohol or drug use
11
Q
why are children at greater risk of hypothermia?
A
- lose heat faster than adults
- larger head to body ratio
- ignore cold cos they having fun
- lack judgement
- infants have less efficient mechanisms for generating heat
12
Q
why are elderly at greater risk of hypothermia?
A
- reduced ability to generate heat due to decreased body mass
- sympathetic thermogensis in brown adipose tissue reduced
- reduced ability to vasoconstrict
- reduced shivering response
- impaired mobility
- inadequate diet
13
Q
what conditions can lead to impaired thermoregulation in the elderly?
A
- stroke
- cns trauma
- infection
- tumours
- haemorrhage
- renal disease
- parkinsons
- MS
- Wenicke’s
Most common = Sepsis
14
Q
What drugs precipitate hypothermia?
A
- ethanol
- barbituates
- benzodiazapines
- opiods
- alpha blockers
15
Q
What endocrine conditions can cause hypothermia?
A
- Hypothyroidism
- Hypoadrenalism
- Hypopituitarism
16
Q
why does hypothermia kill?
A
- cell membranes ionic integrity decreased
- ion leakage occurs
- cell death occurs
17
Q
What does hypothermia do to the oxyhaemoglobin dissociation curve?
A
shifts it left
- increased affinity for o2 on haemoglobin
- doesn’t release oxygen
18
Q
how does hypothermia affect haemotology?
A
- slow down clotting
- viscous blood due to increase cryofibrinogen
19
Q
how does hypothermia affect nerve transmission?
A
slows down
- reduced flux of potassium and chloride across membrane
20
Q
what happens to our joints with hypothermia>?
A
synovial fluid thickens making joints stiff
21
Q
how much heat loss does respiratory account for?>
A
10-30%
22
Q
what happens to urine level with mild hypothermia?
A
Mild:
increases initially then decreases.
Moderate:
glomerular filtration decreases
Severe:
H+ ion secretion reduced, contributing to acidosis
23
Q
what percentage does the bodies metabolism decrease with every degree in temp it decreases?
A
6% for every degree
24
Q
how does hypothermia impact the gastrointestinal tract?
A
slows under 34
stops under 28
25
What cardiovascular changes are seen in hypothermia?
- decrease depolarisation of pacemaker cells = causing brady
- MAP decreases
- osborne waves on ECG
26
What temp do osborne waves start to show?
under 33 degrees
27
what are the stages of hypothermia?
Normal - 36-37
Mild - 35-32
Moderate - 32 - 28
Severe - below 28
28
What are the clinical manifestations of mild hypothermia? 32 - 35 degrees
- shivering
- increased RR
- increased HR
- Vasoconstriction
- Lethargy
- Ataxia
- stiff uncoordinated muscles
- poor judgement
- slurred speech
- amnesia
- hyperglycaemia
29
what temp does shivering stop?
under 32 degrees
30
What are the clinical manifestations of moderate hypothermia? 32 - 28 degrees
- shivering stops
- Pale
- Lips, ears, fingers turn white (from blue)
- pupils dilate
- stupor - sleepy
- BP unobtainable
- Cardiac arrhythmias - start around 30 degrees
- progressive decrease in HR, RR and BP
- Eventually unconscious
- bottom of range - VF likely
- no muscle reflexes or voluntary movements
31
What are the clinical manifestations of severe hypothermia? below 28 degrees
- lose ability to spontaneously return to normal
- further declinein HR, RR and BP
- bloodPH drops (become acidodic)
- electrolyte imbalances emerge
- hypovolaemia due to cold diuresis
- cerebral blood flow decreased by 66%
- hypotension
- pulmonary oedema
- pupils not reactive
- prolonged PR, QRS, QT intervals, and diminished or absent p waves
- osborne waves
- ventricular standstill
- no response to pain
32
what are some local effects of cold?
frostbite:
- anaesthesia
- skin with waxy cold and stiff
- mottling and blisters
- discoloured
- oedema
Trench foot:
- like frostbite but occurs at temperatures above freezing
Chillblains:
- damage to nerves and small blood vessels in hands and feet
Raynaud's syndrome:
- small arteries that supply your skin narrow, collapsing circulation
33
how do you treat someone with frostbite?
- do not thaw if posibility of re-freezing
- don't rewarm if pt needs to walk out
- dont massage
- dont break blisters
- administer pain relief before thawing/warming
- elevate and immobilise body part
- cover with loose, dry, sterile dressing
34
how do you treat trench foot?
- dry
- gradually warm
- aerate foot
- analgesia
- do not break blisters
- elevate foot
- cover with loose, dry, sterile dressing
35
How do you treat chillblains?
gradually warm
- avoid direct heat
- elevate
- anaglesia for pain
36
How do you treat raynauds?
- warm affected area
| - emmerse in water
37
what can happen to gag reflex in hypothermia?
may be depressed so increased risk of aspiration
38
how long should you measure pulse and resp in hypothermic patient?
30 seconds to 1 min
39
What temperature do you warm your fluids to for hypothermic patients?
37 - 42 degrees
40
What is the treatment for hypothermia in the CPG's?
mild: no fluids. warm
moderate/sever hypothermia (below 32):
10ml/kg (max 40) warmed to 37-42
Fluids only for under 32 degrees
41
What changes in hypothermic cardiac arrest?
under 30 degrees
no more than 3 shocks
adrenaline intervals double to 8 mins
42
what is rewarming shock?
as warming occurs, blood vessels dilate causing the return of cold blood and acids to the core
causes paradoxical core temp decrease
causes bp to drop
43
what effects does hyperthermia have on cell structure?
damages proteins
- collapse of cytoskeleton
- swelling mitochondria
44
what happens to Na+/K+ pump during hyperthermia?
during heat stress various processes increase such as the Na=/K= pump.
this utilises ATP and consequentially produces more heat
eventually cells become energy depleted and regular cellular functions are effected.
45
What happens in the liver with hyperthtermia?
reduced blood flow through liver, hence reduced o2 and nutrients
can lead to thermal damage and ischaemia of liver
46
what happend to haematology during hyperthermia?
heat damages vascular endothelium
- coagulation cascades and platelet aggrigation can occur
- thrombosis can occur leading to organ damage and failure
Can use up all clotting factors and bleed out
47
What is rhabdomyolysis?
where skeletal muscle is damaged and cell contents leak out into the blood
48
What is a key issue occuring with rhabdomyolysis?
myoglobin cannot be filtered properly by kidneys, ends up building up in kidney tubules leading to renal failure/damage
49
what happens with the kidneys in hyperthermia?
Plasma K+ increasing due to loss of ions in cells
- excess K+ not excreted leading to hyperkalaemia
- can lead to VF
50
WHat happens in cardiovascular systems with hyperthermia?
- increased HR and CO
- Vasoconstriction to organs and skeletal muscles, pushes blood to skin... increase in BP
- Over time HR + BP decrease due to fluid loss
- Arrhythmia can occur
51
WHat happens in lungs and resp systems with hyperthermia?
TV and RR increase to meet metabolic demand
RR usually increases faster than HR, leading to CO2 levels diminishign too quickly
- decreased co2 leads to resp alkalosis
- over time rr drops leading to resp acidosis
52
What does hyperthermia do to the oxyhaemoglobin dissociation curve?
shifts right
decreases affintiy of o2
due to temp and also low pH
53
What temp classifies hyperthermia?
over 40 degrees
54
what happens at ekevated core body temps?
enzymes cease to function
proteins denature
- cellular metabolism is hampered
55
what temp is critical thermal maximum?
over 43 degrees.
56
what areas are responsible for thermo regulation?
Posterior hypothalamus
57
Where are the bodies thermoreceptors located?
- skin
- peripheral (body core and blood vessel walls)
- central thermoreceptors (hypothalamus)
58
What are some factors affecting thermoregulation?
- age
- health
- medications
- exposure time
59
Where is most heat produced in the body?
deep organs:
- liver
- brain
- heart
- skeletal muscles during activity
60
What are the signs and symptoms of hyperthermia?
Heat Stress:
- sweating
- increased skin temp
Thermolysis:
- altered level of consciousness
Manifestations:
- heat cramps
- heat exhaustion
- heat stroke
61
what are signs and symptoms of dehydration in heat disorders?
- nausea
- vomitting
- abdominal distress
- vision disturbance
- decreased dark urine
- poor skin turgor
- signs of hypovolaemic shock
62
how do you treat dehydration in heat disorders?
oral fluids if people are alert
| iv fluids
63
signs and symptoms of heat exhaustion and EAC?
cool (warm) skin with heavy perspiration
breathing is shallow and rapid
weak pulse
headache/anxiety/paresthesia/impaired jugement
64
what defines heat stroke?
- over 40.5 degrees
- hot dry skin
- altered mental status
65
what are the 2 categories of heat stroke?
- exertional
| - non-exertional
66
Define the categories for heat exhaustion (moderate) and heat stroke (severe)?
Heat exhaustion:
- under 40 degrees
Heat stroke:
- over 40 degrees
67
What are the signs for heat exhaustion?
- under 40 degrees
- tachycardia
- hypotension
- syncope
- diaphoresis
68
What are the symptoms for heat exhaustion?
- headache
- weakness
- nausea & vomiting
- ALtered CS
- muscle cramps
69
What are the signs for heat stroke?
- over 40 degrees
- tachycardia
- hypotension
- tachypnoea
- absence of sweating
70
What are the symptoms for heat stroke?
- nausea & vomiting
- agitated state
- altered conscious state
- unconscoious
71
how do you treat hyperthermia as per AV CPG's?
use colling techniques till temp is 38 degrees
if dehydrated - saline max 40ml/kg
if pt is over 40 degrees use cool fluids
stop cool fluids at 39 degrees
72
what is pyrexia?
fever
73
Describe BOYLES LAW?
volume of gas inversely related to pressure.
74
Describe DALTONS LAW?
in gas mixtures, partial pressure is exerted in proportion to the percentage of mixture
75
Describe HENRY's LAW?
more gas will be dissolved into a liquid at high pressure, less gas at low pressures
76
What is barotrauma?
tissue damage resulting from the expansion or contracting of enclosed gas spaces, due to changes in gas volumes
77
What are the 2 types of gas filled compartments in the body?
- compressible compartments
| - non-compressible compartments
78
what are compressible compartments in the body?
- middle ear space
- sinuses
- lungs
79
what are non- compressible compartments in the body?
Teeth
bone
liquids
80
What types of ear barotrauma are there?
External ear barotrauma
Middle ear
Inner ear
81
What are the signs and symptoms of sinus barotrauma?
pain and fullness over sinus
82
What does CAGE stand for?
cerebral arterial gas embolism
83
what are signs and symptoms of CAGE and AGE?
- sudden on set
- altered GSC
- cardiorespiratory collapse
- confusion/disorientation
- parasesthia
- paralysis
- weakness
- visual and speech disturbances
- convulsions
84
what is the treatment for CAGE and AGE?
```
lie flat
100% o2
treat for shock
IV access
monitor
recompression facility
```
85
what is decompression illness?
multisystem disorder resulting from nitrogen in compressed air
- forms bubbles in tissues and blood
- occurs when ambient pressure decreases
- diver ascends too quickly >10M/min
86
what factors affect decompression illness?
```
alcohol
smoking
dehydration
fatty tissues
drugs
fatugue
medication
```
87
What are S&S of decompression illness?
- rarely occur immediately
50% begin less than 1 hour
90% occur within 6 hours
small % over 24 hours
- skin discolouration and itching
- joints ache and pain
- nervous system numbness, weakness, balance, paraysis
- heart and lungs - low BP, shock, cyanosis, double vision
88
how do you treat DCI?
lie flat
100% o2
IV
transport to recompression
89
what considerations are there for transporting DCI patients?
can't go above 300m
consider diving buddy
transport diving comp and diving equipment with pt
PAR2022 - Trauma
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