1
Q
Thermoregulation
A
The process of maintaining the core body temperature at a nearly constant value
2
Q
What does body temperature below 36 C or above 40 C cause
A
Disorientation
3
Q
Body temperature above 42 C causes?
A
Convulsions and permanent cell damage
4
Q
Normothermia
A
Normal body temperature 36.5-37.2
5
Q
Hypothermia
A
Body temperature below 36.2
6
Q
Hyperthermia
A
Body temperature above 37.6
7
Q
Hyperpyrexia
A
Extremely high body temperature above 41.5
8
Q
Fever
A
Elevation in body temperature due to a change in the hypothetical set point
Temporary resetting of the hypothalamic thermostat
9
Q
Temperature regulation varies in response to :
A
Location Activity Environment Circadian Rhythm Gender
10
Q
Heat production and conservation mechanisms
A
- Chemical reactions of metabolism
- Skeletal muscle contraction
- Chemical thermogenesis
- Vasoconstriction
- Shivering
- Voluntary mechanisms
11
Q
Processes of heat transfer
A
Radiation
Convection
Conduction
Evaporation
12
Q
Radiation
A
Objects warmer than environment lose heat as infrared radiation
Accounts for more than half of body’s heat loss
13
Q
Conduction
A
Direct transfer of energy due to physical contact with cold object
Not very effective in gaining or losing heat
14
Q
Convection
A
Heat loss to cooler air
Heat rises away from skin, cool air replaces it
Accounts for about 15% of body’s heat loss
15
Q
Evaporation
A
Water changes from liquid to vapor as it evaporates
Absorbs energy and cools surface
Insensible perspiration from lungs and skins consistent
Accounts for about 20% of body’s heat loss
Sensible perspiration from sweat glands varies in rate
16
Q
How is temperature regulation coordinated?
A
By the heat-loss centre and the heat gain centre
17
Q
What pathways does the heat-loss centre use?
A
Parasympathetic pathways
18
Q
Heat- gain centre uses which pathways
A
Sympathetic pathways
19
Q
Populations at greatest risk for problems with thermoregulation are:
A
Very young persons
Very old persons
Poor persons
Persons living in very hot or cold climates
20
Q
What damage can occur from hyperthermia
A
Nerve damage, coagulation of cell proteins and death
21
Q
How can hyperthermia occur
A
Can be accidental, therapeutic or associated with stroke or head trauma
22
Q
Thermoregulation Disorders - Hyperthermia
A
Fever
Heat stroke
Malignant Hyperthermia
23
Q
Thermoregulation Disorders- Hypothermia
A
Frostbite
24
Q
What happens when the Vasomotor centre is inhibited during hyperthermia?
A
Peripheral blood vessels dilate
Blood flows more to surface of the body
Increases heat loss by radiation and convection
25
What happens when the sweat glands are stimulated to increase secretions during hyperthermia?
Increases heat loss by evaporation
| Limited capability in higher humidity environments
26
What happens when the respiratory system is stimulated during hyperthermia?
Increased respiratory depth and breathing more through mouth
| Increased heat loss through evaporation from lungs
27
3 steps caused by hyperthermia
1. Vasomotor center inhibited
2. Sweat glands stimulated to increase secretions
3. Respiratory centres stimulated
28
At what temperature does nerve damage produce convulsions in an adult?
41 degrees C
29
What temperature causes death
43 degrees C
30
What does fever activate?
Heat production and conservation measures to a new set point
31
What kind of pyrogens are associated with fever?
Exogenous and Endogenous
32
What is a central fever caused by
Trauma
33
What are the benefits of a fever?
Kills many micro-organisms
Decreases serum levels of iron, zinc and copper
Promotes lysosomal breakdown and auto destruction of cells
Increases lymphocytic transformation and phagocyte motility
Augments antiviral interferon production and phagocytosis
34
Pharmacotherapies for fever
Antipyretics
Acetaminophen
NSAIDS
35
What is the goal of pharmacotherapies used for fevers?
Lower body temperature, while treating the underlying cause of the infection
36
What is the drug of choice for treating fevers in children?
Acetaminophen
37
Action of Acetaminophen (Tylenol)
Inhibits synthesis of prostaglandins
Mild to moderate pain control
Antipyretic
38
Contraindications of Acetaminophen (Tylenol)
```
Known allergy
Severe liver disease
Genetic disease enzyme deficiency
Chronic alcoholism
Renal disease
```
39
Toxicity Symptoms of Acetaminophen (Tylenol)
```
Cyanosis
Anemia
Neutropenia
CNS Stimualtion
Delirium followed by vascular collapse
Seizures
Coma
Death
```
40
Pharmacokinetics: Absorption of Acetaminophen (Tylenol)
Well absorbed after oral administration. Rectal absorption varies.
41
Pharmacokinetics: Distribution of Acetaminophen (Tylenol)
Widely distributed, crosses placenta and enters breast milk.
42
Pharmacokinetics: Metabolism of Acetaminophen (Tylenol)
By the liver, metabolites are excepted in the liver
43
Half life of Acetaminophen (Tylenol)
1-3 hours
44
Prostaglandins
Lipids that promote inflammation and are found in all tissues
45
Cyclooxygenase
Key enzymes in the biosynthesis of prostaglandins and have 2 forms
46
2 forms of cyclooxygenase
Cyclooxygenase-1
| Cyclooxygenase-2
47
Cyclooxygenase-1 Location
Present in all tissues
48
Cyclooxygenase-1 Functions
Protects gastric mucosa, supports kidney function, promotes platelet aggregation
49
Cyclooxygenase-1 Inhibition by medications
Undesirable: increases risk for gastric bleeding and kidney failure
50
Cyclooxygenase-2 Location
Present at sites of tissue injury
51
Cyclooxygenase-2 Functions
Mediates inflammation
Sensitizes pain receptors
Mediates fever in the brain
52
Cyclooxygenase-2 Inhibition by medications
Desireable: results in suppression of inflammation
53
Misoprostol
A prostaglandin like substance that inhibits gastric acid secretions and stimulates the production of protective mucous
54
When is misoprostol usually used
used mostly when taking NSAIDS and glucocorticoids to prevent ulcers
55
What does misoprostol prevent
GI bleeds
56
What does a synthetic prostaglandin E1 analogue do?
inhibits gastric acid secretion and has a cytoprotective component
57
NSAIDS
```
A large and chemically diverse group of drugs that have:
Analgesic activities
Anti-inflammatory activities
Antipyretic activities
Aspirin-platelet inhibition
```
58
What are properties that all NSAIDS share?
Antipyretic properties
Analgesic properties
Anti-inflammatory properties
59
NSAIDS are used to relief
```
Mild to moderate headaches
Myalgia
Neuralgia
Arthralgia
Postoperative pain
treatment of gout and hyperuricemia
```
60
NSAIDS help with pain that is associated with...
Arthritic disorders like rheumatoid arthritis, juvenile arthritis, ankylosing spondylitis, and osteoarthritis
61
NSAIDS mechanisms of action
Inhibit cyclooxygenase thus blocking inflammation
| Blocking the chemical activity of the enzyme Cyclooxygenase
62
NSAIDS inhibit which pathways?
Leukotriene pathway, prostaglandin pathway or both
63
What is the drug of choice for mild to moderate pain, inflammation and fever
NSAIDS
64
Ibuprofen (Advil, Motrin) Action
Inhibits cyclooxygenase-1 and cyclooxygenase-2 thus decreases inflammation
65
Ibuprofen (Advil, Motrin) Dosage
Administered orally
| 200-400mg PO q6h
66
Ibuprofen (Advil, Motrin) uses
Mild to moderate pain in acute or chronic disorder
67
Ibuprofen (Advil, Motrin) Adverse effects
Headache
Dizziness
GI upset
Nephrotoxicity
68
NSAIDS Contraindications
```
Known drug allergy
Conditions that place the patient at risk for bleeding
Rhinitis
Vitamin K deficiency
Peptic ulcer disease
```
69
NSAIDS Adverse effects
```
Heartburn to severe GI bleeding
Acute kidney injury
Noncardiogenic pulmonary edema
Altered hemostasis
hepatotoxicity
Skin eruption, sensitivity hearing
Tinnitus, hearing loss
```
70
NSAIDS nursing considerations
Take with food or milk
Avoid alcohol
Assess for bleeding disorders/ GI bleed
Obtain baseline liver and renal function tests
Do not give to children
Consult with health care provider before taking herbal products
71
Use NSAIDS with care in which clients
Clients with alcoholism, CHF, Renal disease, hypertension, and fluid retention
72
How long does it take NSAIDS to reach optimal effects
1-3 weeks
73
Heatstroke
Potentially lethal result of an overstressed thermoregulatory centre
74
What temperatures can the brain not tolerate
40.5 degrees C and over
75
What happens when the body's temperature exceeds 40 degrees C?
Regulatory centre stops functioning and the body's heat loss mechanism fails
Cardiovascular and thermoregulatory centres may stop functioning
76
Causes of heatstroke
Exertion
Overexposure to heat
Impaired physiological mechanism for heat loss
77
Heatstroke Symptoms
```
High core temperature
Absence of sweating
Tachycardia
Confusion
Agitation
Coma
```
78
Heatstroke Complications
```
Cerebral edema
Degeneration of the CNS
Swollen dendrites
Renal tubular necrosis
Hepatic failure
Death
```
79
Heat Cramps
Severe spasmodic cramps in the abdomen and extremities
| Following prolonged sweating and associated sodium loss
80
Who are heat cramps more common in
Individuals not accustomed to heat or those performing strenuous work in warm climates
81
Symptoms of heat cramps
Fever
Rapid pulse
Increased BP
82
Heat exhaustion
Result of prolonged high core temperatures
| Profound vasodilation and profuse sweating
83
Manifestations of Heat Exhaustion
```
Dizziness
Weakness
Nausea
Confusion
Syncope
```
84
Malignant Hyperthermia
A potentially lethal hypermetabolic complication of a rare inherited muscle disorder that may be triggered by inhaled anaesthetics & depolarizing muscle relaxants.
85
What happens to the muscles in malignant hyperthermia
Muscle cells have an unregulated accumulation of calcium
Muscles contract and stiffen at the same time
Uncoordinated muscle contractions
86
Symptoms of Malignant hyperthermia
Absent reflexes
Fixed pupils
Apnea
Flat ECG
87
Risk factors for malignant hyperthermia
Genetic
History of heat stroke or hyperthermia after exercise
Muscle abnormalities that may be associated with malignant hyperthermia
88
Diagnosis Malignant hyperthermia
Genetic testing
| Muscle biopsy
89
Expected duration of malignant hyperthermia
With timely treatment resolution of symptoms should occur within 12-24 hours
90
Clinical manifestations of Malignant hyperthermia
```
Altered calcium function in muscle cells with hyper metabolism
Hyperthermia
Uncoordinated muscle contractions
Increased muscle work
Increased oxygen consumption
Raised level of lactic acid production
Acidosis
Rapid or painful muscles, especially in jaw
Sweating
Tachycardia
Tachypnea
Brown coloured urine
Shock
```
91
Malignant hyperthermia treatment
```
Stop giving triggering medication
Administer Dantrolene (Dantrium)
Lower body temperature
Administer oxygen
Medicate to control heartbeat, BP and correct electrolyte imbalances
```
92
Use of Dantrolene (Dantrium)
Relaxes muscles and stops the increase in muscle metabolism
| Given IV until stability is achieved, then continued PO for 3 days
93
Intervention strategies for hyperthermia
```
Remove excess clothing and blankets
Provide external cool packs
Provide a cooling blanket
Hydrate with cool fluids
Lavage with cool fluids
Administer antipyretic drug therapy
```
94
Hypothermia
When body temperature falls below acceptable levels
95
How does the body prevent Hypothermia
heat-loss centre is inhibited and heat gain centre is activated
96
Steps of heat gain centre
1. Stimulate vasometer centre
2. Shivering thermogenesis
3. Nonshivering thermogenesis
97
Stimulation of gasometer centre does what
Constricts peripheral blood vessels, reducing heat loss by radiation, convection and conduction
98
Shivering thermogenesis does what
Activates brief contractions of skeletal muscles
99
Nonshivering thermogenesis is stimulated how
Hormonally
| Thyroid hormones and epinephrine increases metabolic activity of all tissues
100
Hypothermia produces
Ice crystals, which form inside the cells, causing them to rupture and die
101
Tissue hypothermia
Slows the rate of cellular metabolism
Increases blood viscosity and slows blood through the microcirculation
Facilitates blood coagulation and stimulates vasoconstriction
102
Hypothermia Response Mechanisms
Peripheral vasoconstriction
Intermittent repurfusion of extremities
shivering
Stupor
103
Peripheral Vasoconstriction
Shunts blood away from cooler skin to core to decrease heat loss and produces peripheral tissue ischemia
104
Intermittent reperfusion of extremities (Lewis Phenomenon)
Helps preserve peripheral oxygenation until core temps drop dramatically
105
Shivering
Induced by the hypothalamic centre
Thinking becomes sluggish
Coordination is depressed
106
Stupor
```
Heart & respiratory rate decline
Cardiac output diminishes
Metabolic rate falls
Acidosis
Eventually V fib & asystole occur at 30 degrees C
```
107
Therapeutic Hypothermia
Used to slow metabolism and preserve ischemic tissue during surgery or limb re-implantation
May lead to ventricular fibrillation and cardiac arrest
108
Accidental Hypothermia
Commonly the result of sudden immersion in cold water or prolonged exposure to cold
109
Hypothermia Risk factors
```
Hypothyroidism
Hypopitutarism
Malnutrition
Parkinson's Disease
Rheumatoid arthritis
Chronic increased vasodilation
Failure of thermoregulatory control resulting from cerebral injury, ketoacidosis, uremia, sepsis, and drug overdose
```
110
Hypothermia treatment
Reversible with rewarming
111
Hypothermic Injuries
Frost nip
Chilblains
Frostbite
Flash freeze
112
Frostnip
Mild and completely reversible injury characterized by skin pallor and numbness
113
Chilblains
More serious than frosting; violaceous skin colour with plaques or nodules, pain, and pruritus, but no ice crystal formation; chronic vasculitis can develop and is usually located on the face, anterior lower leg, hands, and feet
114
Frostbite
Tissues freeze and form ice crystals at temperature less than -2 degrees C progresses from distal to proximal and potentially reversible
115
Flash Freeze
Rapid cooling with intracellelular ice crystals associated with contact with cold metals or volatile liquids
116
What happens to frozen skin?
Becomes white or yellowish, has a waxy texture
117
What parts of the body does frostbite commonly affect
Fingers, toes, ears, nose and cheeks
118
First degree frost bite
Partial skin freezing
119
Second degree Frost bite
Full thickness skin freezing
120
Third degree Frost bite
Full thickness & subcutaneous freezing
121
Fourth degree frost bite
Deep tissue freezing
122
Intervention strategies for hypothermia
Remove person from cold
Provide external warming measures
Provide internal warming measures
123
Safety tip for core warming
Core rewarming must be done slowly to minimize the risk for dysthymias. Cardiac monitoring is required when the patient is recovering from severe hypothermia.
124
CNS trauma leads to...
Central fever
Inflammation, increased ICP, inter cranial bleeding
Does not induce sweating
Resistant to antipyretic therapy
125
Central fever
```
Sustained noninfectious fever
Appears with or without bradycardia
Caused by major body trauma
Does not induce sweating
Resistant to antipyretic therapy
```
