Principles Test 2- Temp

Front 1

Temperature Regulation is controlled by the ...

Back 1

Hypothalamus

Front 2

Anterior preoptic hypothalamic area has ... (3)

Back 2

-Heat sensing neurons: transmitted by unmyelinated C fibers
-Cold sensing: travel centrally via myelinated A delta fibers
-Ascending thermal: travel cephalad via the anterior spinothalmic tract

Front 3

Normothermia is a range or 'set point' that is ...
The body will activate control mechanisms in order to maintain this set point.

Back 3

36.4-37.0 Celsius or 98.0-98.6 F

Front 4

Fahrenheit (F) & Celsius (C) conversion

Back 4

F = 1.8(C) + 32
C = (F - 32)/ 1.8

Front 5

At temperatures above the set point heat loss will be greater or less than heat production?

Back 5

greater than

Front 6

At temperatures below the set point heat production will be greater or less than heat loss?

Back 6

less than

Front 7

Temperature regulation:
A .../... feedback system utilized to control temperature withing the normal range balancing heat loss and heat production mechanisms

Back 7

negative/positive

Front 8

Thermoregulatory Processing: 3 types

Back 8

Afferent Input, Central Control, Efferent Responses

Front 9

Afferent Input

Back 9

How the brain receives information that the body is exposed to a temperature change

Front 10

Centrol Control

Back 10

Hypothalamus

Front 11

Efferent Responses

Back 11

How the body responds to alterations in temperature

Front 12

Hypothermia:
definition & range...

Back 12

-Clinical state of subnormal body temperature in which the body is unable to generate enough heat for bodily functions.
-Body temperature <36C or 96.8F

Front 13

Mild Hypothermia is ___-___C and signs include?

Back 13

32-36 C
-vasoconstriction and shivering not present with GA

Front 14

Moderate hypothermia is ____-___C and signs include?

Back 14

27-32
-depression of metabolism, max vasocontriciton, cessation of shivering

Front 15

Less than ____C is associated with cardiac dysrhythmias

Back 15

30

Front 16

Less than ____C is associated with apnea

Back 16

28

Front 17

Severe hypothermia is less than ___C

Back 17

27

Front 18

Clinical Signs of Hypothermia:
Early & prolonged

Back 18

Early Signs:
shivering
decrease sweating
vasoconstriction
Prolong:
altered mental status
muscle weakness

Front 19

Defenses Against Cold (4)

Back 19

-Sympathetic stimulation & skin vasoconstriction
-Pilo-erection (goosebumps)
-Shivering: Heat production up to 300%, Increases oxygen consumption as much as 5 folds, Undesirable in patients w/ CAD & pulmonary insufficiency, Treat with meperidine 25mg IV (not given to L&D ladies)
-Sympathetic- mediated increase in basal metabolism rate, Epinephrine and norepinephrine affects, Declines by 1% per year after age 30, Increase in thyroxine

Front 20

Major Mechanisms of Heat Loss:
4 types ...

Back 20

Radiation, Evaporation, Convection, Conduction

Front 21

Radiation

Back 21

Radiation (60%): greatest source of heat loss
-loss of energy through radiant electromagnetic waves in the infrared spectrum and involves no direct contact
-due to exposed surface area, exp. warm body loses heat to any cold item in the OR

Front 22

Evaporation

Back 22

Evaporation (20%)
-loss of heat energy contained in water vapor
-loss of water to the environment
-depends on expose area and relative humidity of ambient air, exp: perspiration, open wounds

Front 23

Convection

Back 23

Convection (15%)
-heat loss through fluid (liquid or gas) currents in DIRECT CONTACT with the body's surface, exp: skin prep, IVF

Front 24

Conduction

Back 24

Conduction (5%)
-loss or gain of heat by transfer of thermal energy via DIRECT CONTACT
-transfer of heat from one surface to another, exp. warm body exposed to cold OR table/ instruments

Front 25

Patients at Risk for Hypothermia

Back 25

infants
elderly
burn patients
trauma
cardiac
ETOH (vasodilation: prevents/impairs vasoconstriction)
autonomic neuropathy (diabetic)
procedure type
procedure length
pre-op body temperature

Front 26

Risk for Hypothermia:
Infant & Children- have increase or decreased surface area (large head) per weight ratio therefore an increased or decreased O2 consumption, CO2 production, cardiac output, and alveolar ventilation.

Back 26

INCREASED surface area (large head) per weight ratio therefore an INCREASED O2 consumption, CO2 production, cardiac output, and alveolar ventilation.

Front 27

Risk for Hypothermia:
Infant & Children- Low or high body fat content, thin or thick skin, allows for great or less loss of heat to the environment. Hypothermia inhibits or promotes brown fat thermogenesis

Back 27

LOW body fat content, THIN skin, allows for GREATER loss of heat to the environment. Hypothermia INHIBITS brown fat thermogenesis

Front 28

Risk for Hypothermia:
Elderly- Basal and metabolic oxygen consumption decreases or increases with age. Inefficient thermoregulation. Loss of muscle mass results in decreased or increased heat production.

Back 28

Basal and metabolic oxygen consumption DECREASES with age. Inefficient thermoregulation. Loss of muscle mass results in DECREASED heat production.

Front 29

Risk for Hypothermia:
Elderly- Heat production decreases or increases, heat loss decreases or increases, and the hypothalamus temperature regulating centers may reset to a lower or higher level

Back 29

Heat production DECREASES, heat loss INCREASES, and the hypothalamus temperature regulating centers may reset to a LOWER level

Front 30

Patient who received spinal and epidural (regional) anesthesia secondary to: Vasodilation and redistribution of heat; and Blocked dermatomes are at great risk for hypo/hyperthermia?

Back 30

Hypothermia

Front 31

Neuroaxial Anesthesia:
Neuroaxial blocks inhibit numerous aspects of ...

Back 31

thermoregulation

Front 32

Neuroaxial Anesthesia:
Vasoconstriction and shivering thresholds are enhanced or reduced?

Back 32

reduced

Front 33

Neuroaxial Anesthesia:
Sensory input from the legs is blocked during neuroaxial anesthesia and the brain interprets this as indicating that the body is cold or warm

Back 33

warm

Front 34

Neuroaxial Anesthesia:
Concurrent administration of sedatives and anesthetic drugs further alters the regulation of ...

Back 34

temperature

Front 35

Anesthesia & Decrease in Temperature:
Phase I: ...
occurs within the ... or so and is due to movement of heat from ... to ... as a result of vasodilation.

Back 35

Phase I : REDISTRIBUTION
This occurs within the FIRST HOUR or so and is due to movement of heat from CORE to PERIPHERY as a result of vasodilation.

Front 36

Anesthesia & Decrease in Temperature:
Phase II: ...
During this phase, heat loss does or does not exceed heat production; most surgery does not extend beyond this phase. Losses are due to radiation, convection, conduction, evaporation, and respiratory losses.

Back 36

Phase II: LINEAR
During this phase, heat loss EXCEEDS heat production; most surgery does not extend beyond this phase. Losses are due to radiation, convection, conduction, evaporation, and respiratory losses.

Front 37

Anesthesia & Decrease in Temperature:
Phase III:
Once temperature falls below the thermoregulatory threshold, peripheral vasoconstriction increases or decreases to limit the heat loss from the core compartment.

Back 37

Phase III: PLATAEU
Once temperature falls below the thermoregulatory threshold, peripheral vasoconstriction INCREASES to limit the heat loss from the core compartment.

Front 38

Body temperature is not uniform there is a variation between the periphery and the core of approximately ...

Back 38

2-4 ° C.

Front 39

Initial change in core temperature is related to the transfer of heat from the core/periphery to the core/periphery. Normally this is protected by tonic thermoregulatory vasoconstriction.

Back 39

core to the periphery

-Redistribution Phase

Front 40

The initial phase of heat loss is approximately ... in duration

Back 40

one hour

-Redistribution Phase

Front 41

A secondary phase of heat loss occurs lasting approximately ... this is the result of heat loss exceeding heat production.

Back 41

2-4 hours

-Linear Phase

Front 42

In Linear Phase, a steady state may result in patients that are maintained in a relatively warm/cold fashion

Back 42

warm

-Linear Phase

Front 43

In Linear Phase, if continually exposed to low/high temperatures, the body will continue to loose heat to the periphery despite attempts to maintain the core temperature

Back 43

low

-Linear Phase

Front 44

Effects of Hypothermia
-Tissue solubility of volatile agents increases/decreases
-Prolonged or quick recovery from anesthesia

Back 44

-Tissue solubility of volatile agents
INCREASE in tissue solubility
-PROLONG recovery from anesthesia

Front 45

Effects of Hypothermia
-MAC (minimum alveolar concentration)
For every ... ° C in body temperature, MAC of
volatile agent decreases by ... %

Back 45

MAC- For every 1° C in body temperature, MAC of
volatile agent decrease by 5%

Front 46

Effects of Hypothermia
-Neuromuscular blocking drugs increase or decrease duration

Back 46

increase

Front 47

Effects of Hypothermia
-Coagulation,
blood loss is increased/decreased
prolongs/shortens PT/PTT
impairs ... function

Back 47

blood loss is INCREASED
PROLONGS PT/PTT
impairs PLATELET function

Front 48

Deleterious Effects of Hypothermia:
10 effects

Back 48

Cardiac arrhythmias and ischemia
Increased peripheral vascular resistance
Left shift of the oxy-hemoglobin disassociation curve
Reversible coagulopathies (platelet dysfunction)
Postoperative protein catabolism and stress
Altered mental status
Impaired renal function
Decreased drug metabolism
Poor wound healing
Increased incidence of infection

Front 49

Advantage Effects of Hypothermia
2 effects

Back 49

-Protection of the brain: after or during focal or global ischemia; For each 1 ° C decrease in temperature, cerebral oxygen consumption & cerebral blood flow decrease by 5% - 7%
-Protection spinal cord

Front 50

Therapeutic mild/mod/severe hypothermia is used in cardiac and neurosurgical procecures to protect against ... and ...

Back 50

mild hypothermia protects against ischemia and hypoxia

Front 51

Therapeutic Hypothermia decreases/increases the metabolic demand and oxygen requirement

Back 51

decreases

-also thought to decrease excitatory amino acids

Front 52

Hypothermia is thought to decrease/increase both basal and electrical metabolic requirements in the brain.

Back 52

decrease

Front 53

Ways to Prevent Hypothermia
9 ways

Back 53

-Pre-surgical warming of the patient.
-Maintenance of ambient room temperature.
-Administration of warmed fluids/blood.
-Padding of the bed/ blankets/use of a patient gown and head covering.
-Active application of forced air warming blanket.
-Reduce gas flow through anesthesia circuit.
-Warm irrigation and prep solutions .
-Use of fluid warming blanket or pad under the infant/child.
-Have surgeon cover the incision with sterile towel if case is delayed.

Front 54

Hyperthermia
Temperature > ...

Back 54

37.5 C

-uncommon in the OR

Front 55

Hyperthermia:
Hypermetabolic state with a rise in body temperature of ...° C per hour under GA

Back 55

2 ° C

Front 56

Hyperthermia:
10 Causes

Back 56

-Sepsis
-Fever
-Transfusion reaction
-Neuroleptic malignant syndrome
-**Malignant hyperthermia**
-Thyrotoxicosis (excess of thyroid hormone)
-Pheochromocytoma
-Catecholamine surges
-Production of bacteremia during surgery
-Vigorous warming techniques (Hipac surgery-heated chemo for reduction of tumor in peritoneal cavity)

Front 57

Manifestation of Hyperthermia
6 s/s

Back 57

-Increased oxygen consumption
-Increase minute ventilation
-Sweating
-Vasodilation
-Decreased intravascular volume & venous return
-Increase heart rate by 10 bpm per Centigrade

Front 58

Additional Manifestations of Hyperthermia

Back 58

Increased ETCO2
tachy/hypertension
increased drug metabolism
dehydration
decreased UO and skin turgor

Front 59

Malignant Hyperthermia:
Hypermetabolic state that results from administration of ... or ... to an individual with a mutation in the ... receptor

Back 59

inhalation anesthetics or Succinylcholine
ryanodine 1 receptor

Front 60

Malignant Hyperthermia:
Uncontrolled release of ... from the sarcoplasmic reticulum results in intense muscle contracture

Back 60

Calcium

Front 61

Malignant Hyperthermia:
Increased/Decreased O2 consumption and CO2 production which results in lactic acidosis and hyperthermia

Back 61

Increased

Front 62

Tissue and cellular breakdown result in ... and ... which can result in ventricular fibrillation and death

Back 62

hyperkalemia and acidosis

Front 63

FYI: MH is a fulminant hypermetabolic crisis triggered by certain types of anesthetic agents, typically succinylcholine, sevoflurane, desflurane, isoflurane, and halothane. MH is characterized by an uncontrolled increase in skeletal muscle metabolism. Contrary to common belief, pyrexia, is not first indicator of an MH crisis. The earliest sign and symptom that will present is an increase in end-tidal carbon dioxide.

Back 63

FYI: Early signs include tachycardia, tachypnea, and rigidity of the masseter muscle called trismus. As an MH crisis progresses, other signs and symptoms are unstable BP, cyanosis, and/or mottling of the skin, diaphoresis, cardiac dysrhythmia, and a dramatic increase I the body temperature. The patient’s temperature may elevate as much as 1-2°C every 5 minutes. The surgical team may confirm that blood on the field is dark in color due to central venous saturation

Front 64

Treatment of MH:
7 steps

Back 64

-Stop the agent & Succinylcholine
-Hyperventilation w/100% O2
-Dantrolene 2.5mg/kg bolus; A total of 10mg/kg
ie 50kg, 60ml of H20, 20mg/vial; ~6-7 vials for pt
-Treat metabolic acidosis
-Treat hyperkalemia
-Institute cooling measures
-Support with inotropes
(Must reconstitute in sterile H20 not LR d/t calcium)

Front 65

Treatment of Hyperthermia in the OR
3 things

Back 65

-Cooling blankets
-Cool IV fluids
-Antipyretics

Front 66

Temperature Monitoring:
Tympanic Membrance is close to ...
Rare risk of ... and ...

Back 66

close to core via internal carotid artery
bleeding and perforation

Front 67

Temperature Monitoring:
Nasopharynx is close to ... and has risk of ...
Is contraindicated in ... trauma
Evidence of ... rhinorrhea

Back 67

-Close to Internal Carotid Artery
-Risk of bleeding nosebleed
-Contraindicated in head trauma
-Evidence of cerebrospinal fluid rhinorrhea

Front 68

Temperature Monitoring:
Esophagus is close to ...
Placed in lower ... of esophagus
Accurately reflects ...temp

Back 68

-Close to great vessels and heart
-Placed in lower 1/3 of esophagus
-Accurately reflects core temp
-Useful for auscultation

Front 69

Temperature Monitoring
Rectum

Back 69

-Rectum: Variable, not used in OR

Front 70

Temperature Monitoring
Bladder

Back 70

-Bladder: Foley catheter, Close to core, Affected by rate of urine flow

Front 71

Temperature Monitoring
Mouth

Back 71

-Mouth: Affected by food, Hyperventilation

Front 72

Temperature Monitoring
Axilla

Back 72

-Axilla: Placed over axillary artery, Approximately 1 ° C below core

Front 73

Temperature Monitoring
Skin

Back 73

-Skin: Variable accuracy, 3- 4 ° C lower

Front 74

Temperature Monitoring
Pulmonary Catheter

Back 74

-Pulmonary catheter: Most accurate, Mixed venous core temperature