Test 1 content-Temp management Flashcards
1
Q
What is the basic definition of hypothermia?
A
Hypothermia is defined as a body temp below 35 degrees celsius. Or a state in which the body temp of a homeothermic mammal is below normal.
2
Q
Humans are effective system that ensures body temp remains near ____ degrees regardless of environmental factors
A
37 degress
3
Q
How is cold sensed?
A
By thermoregulators in the skin
4
Q
When cold is sensed what happens?
A
- Hypothalumus triggers strong sympathetic nerve response
- Vasoconstriction of skin vessels
- decreases convective heat loss
- Skeletal muscle beds vasodialate
- Increasing (augmenting) muscle activity to produce heat
- This is done through tensing and shivering
- Then the endocrine system is activated causing increased O2 consumption, heart rate, cardiac output and blood pressure is elevated
5
Q
4 categories and temps of hypothermia
A
- Mild: (32-35 C)
- Moderate (26-31 C)
- Deep (20-25 C)
- Profound: (below 20 C)
6
Q
Things associated with hypothermia
A
- Reduction of metabolic rate
- Reduction in O2 consumption
- Lower pump flows
- Less blood trauma-(flowing less cause it doesn’t put as much trauma on cells)
- Preservation of phosphate stores and reduction of excitatory neurotransmitter release)(cns protection)
7
Q
What is the hypothermia Q10 concept?
A
Each 10 degree C drop in body temp will decrease metabolic process by 50%
8
Q
Example of hypothermia Q10 concept @ 37, 27, and 17 degrees C
A
37 degrees-Normal metabolism
27 degrees-50% reduction in metabolism
17 degrees-75% reduction in metabolism
9
Q
What are the normal values for pH and Pco2 @ 37 C?
A
pH-7.40
Pco2-40mmHg
10
Q
The solubility of gases in biologic fluids ______ with hypothermia
A
Increases
11
Q
At a constant Co2 content, PaCO2 _______ as temperature falls.
A
Decreases
12
Q
Hypothermia _____ solubility
A
Increases. Co2 is 30x more soluble than O2. Inverse relationship (temp & gas solubility)
13
Q
With hypothermia there is _____ affinity of hemoglobin with O2
A
Increased
- Left shift of oxygen-hemoglobin dissociation curve
- Less 02 released to tissues
14
Q
Hypothermia _____ CO2 production
A
Decreases.
- Decrease in metabolism decreases CO2 production
- Becomes important in blood gas management strategies at lower temps.
15
Q
As it gets colder ____ hemoglobin goes to tissue
A
Less
16
Q
Hemoglobin holds on to tissues more when ______ because metabolic demand is down
A
Colder
17
Q
O2 Hemoglobin dissociation for left shift
A
⬇️Temp ⬇️Hydrogen Ions ⬇️ Pco2 ⬇️2, 3 DPG
18
Q
O2 Hemoglobin dissociation for right shift
A
⬆️Temp ⬆️Hydrogen ion ⬆️Pco2 ⬆️2,3 DPG
19
Q
If DPG is up than oxygen affinity is ______**
A
Down
20
Q
Hypothermia causes a _____ in blood flow to all vascular beds in proportion to the reduced metabolic demands
A
Decrease
21
Q
What type of muscle sees the greatest reduction in blood flow during hypothermia?
A
Skeletal muscle
22
Q
During hypothermia the heart will see a _____ rate but contractility remains unchanged
A
Decreased
23
Q
If DPG is down than oxygen affinity is ______**
A
Up
24
Q
The myocardium is less/more sensitive at temps of 32 degrees?
A
More
25
During hypothermia the ____ see the largest proportional decrease in blood flow
Kidney's
26
During hypothermia the liver (hepatic) will see a _____ in metabolic & excretory function
Decrease
27
How will the pulmonary system react in hypothermia?
*Progressive decrease in ventilation
28
Hyperglycemia is caused by ____ insulin levels
Low
29
Hypoglycemia is caused by ______ insulin levels
High
30
In hypothermia how is the endocrine system affected?
* Hyperglycemia
* Endogenous insulin production is decreased
* Insulin administration is less effective
31
How would the sympathetic response be affected by hypothermia?
* Increase in catecholamine production
| * blood becomes more viscous and contributes to increase in vascular resistance
32
T/F- Acid base balance is significantly affected by hypothermia
True
33
Hypothermia ______ the tendency for weak acids and bases to dissociate in solution
Decreases
34
Maintenance of a constant ratio of [OH-] to [H] _____ as temp decreases
16:1
35
Alpha stat regulation preserves the ratio of OH- to H+ with temperature change and produces an _______ shift with cooling
Alkaline shift
36
pH stat regulation maintains an absolute constant of H+ regardless of temp and requires added ____, usually as CO2 with cooling
H+
* CO2 is maintained at 40mmHG and pH at 7.40
* So the total CO2 content is elevated
37
Two different strategies for cooling a patient
* pH stat
| * Alpha stat
38
During ________ cerebral blood flow is decreased, less chance of emboli to brain
Alpha stat
39
______ is not temp corrected
Alpha stat
40
Alpha stat appears advantageous in adults by _______ to the brain
Limiting micro emboli
41
Ph stat may be beneficial in infants to ________ CBF (cerebral blood flow) and allow more efficient cooling
Increase
42
Protection of the brain during deep hypothermia (temp <20 C) may be best accomplished with a mixed acid-base strategy: How?
* pH-stat during initial cooling phase
| * alpha-stat during reperfusion, rewarming, and termination of CPB (less blood flow going to brain in rewarming)
43
Systemic temps less than ____ used to allow cessation of circulation for periods up to 40-60 mins
22 degrees C
44
Asanguineous means _____
bloodless
45
Pediatric cardiac surgery happens primarily in peds weighing ____
<8kg
46
______ reduces metabolic demand of nervous system. Also, _____ lengthens period of tolerated ischemia
Hypothermia
47
The ______ almost exclusively extracts energy through aerobic glycolysis
Brain
48
During DHCA what organ is at greatest risk for injury? Metabolic activity is reduced, but never ceases
The brain
49
Q(10) of 2.7 (20deg. C) predicts ____ arrest period of ___ minutes. However, ___ to ___ mins typically is tolerated
Safe, 15 mins
| 30-45 mins
50
_____ degree gradient between perfusate and body temp for cooling
10-12 degree
51
pH stat employed to dilate cerebral vessels to ensure what?
Uniform cooling of the brain
52
When cooling patient down what is the proper gradient?
10-12 deg C.
53
During DHCA you would monitor multiple sites, name the 5.
Nasopharangeal, tympanic, arterial, venous, bladder
54
Employ ______ just prior to circ arrest by getting rid of excess ______ thereby decreasing/increasing intracellular pH
Alpha stat
Co2
Increasing
55
T/F-During DHCA you would allow the patient's blood volume to grain into the reservoir? Also, you would shut off pump stopping all circulation?
True
56
What is exsanguination?
Process of draining or removing all blood
57
_______ allows for vascular decompression as well as reducing static blood
Exsanguination
58
Anesthesia gives these to preserve cell membrane
Steroids
59
What are 3 things antegrade and retrograde cerebral perfusion do?
* Replenishes with O2, substrate, and buffer
* Washes out acid metabolites
* Helps to maintain hypothermic brain temp
60
Target temp for "safe" ischemic time?
18 deg C
61
Rewarming after DHCA what would be the rewarm gradient range?
8-10 deg C between perfusate and body temp
62
Rewarming after DHCA you would employ _______ to ameliorate CO2
strict alpha-stat
Definition of ameliorate-make (something bad or unsatisfactory) better.
63
T/F- During rewarming you DO NOT want to dilate vasculature as needed
False- You will dilate vasculature as needed
64
______ ensures global reperfusion of systemic vacular beds after DHCA
CPB rewarm
65
What would you administer to counteract acidosis?
Bicarb (NaHCO3)
66
T/F during rewarming it is not important to allow for adequate time to reach a sustained systemic temp-36 deg C
False! It is important to allow adequate time to reach 36 C
67
DHCA deleterious effects
* Cognitive degeneration (decreased intelligence & intellectual development)
* Stroke
* Brain death
* Choreoathetosis (1-20% of children, basal ganglia injury)
* Seizure (as witnessed on EEG and post-op)
68
Definition of Deleterious
If something is deleterious, it does harm or makes things worse. Smoking has obvious deleterious effects on your health, not to mention your social life.
69
______ occurs commonly after cardiac surgery and should be aggressively treated b/c it may worsen ischemic damage
HYPERthermia
70
T/F-The arterial outlet underestimates cerebral temp
True
71
It is important to limit your arterial outlet to <37 deg C to avoid _______
HYPERthermia
72
When cooling, temp gradients between the arterial outlet and venous inlet should not exceed how many degrees? Why?
Should not exceed 10 deg C
Why?-To avoid generation of gaseous microemboli
73
T/F-Oxygenator outlet temperature is surrogate for cerebral temp during CPB
True
74
When arterial outlet blood temp is >/=30 deg C what gradient between arterial outlet and venous inflow should be maintained?
=4 degrees C
Maintain a rewarming rate of = 0.5 deg C/min
75
Rewarming when arterial blood outlet temp is =30 deg C what gradient between arterial outlet temp and venous inflow should be maintained?
Maintain a max gradient of 10 deg C
76
T/F-Pulmonary artery or nasopharyngeal temp recordings are reasonable for weaning
True
77
What is the gold standard in temp monitoring?
Jugular bulb (JB)
78
What 3 types of temp recordings correlate with JB monitoring?
* Arterial blood outlet temp
* Pulmonary artery
* Nasopharangeal temp
79
What temp is not as accurate in CPB cause the patient is not making urine, and not used when they are cold.
Bladder temp
80
About how many die annually of SCD sudden cardiac death? And what percent of SCD are associated with CAD?
450,000
70%
81
Hypothermic therapy increases/decreases the reperfusion injury associated with return of spontaneous circulation (ROSC)
Decreases
82
What are 5 mechanisms of thought involving therapeutic hypothermia?
* Reduction of cerebral oxygen consumption, Glutamate production, and reactive oxygen species.
* While maintaining cell membrane integrity and cellular homeostasis
83
Complications of therapeutic hypothermia (5)
Bleeding, sepsis, arrhythmias, pancreatitis, and renal insufficiency
