Lecture 8: Shock I Flashcards
1
Q
Define shock
A
severe imbalance between oxygen delivery (DO2) and consumption (VO2)
2
Q
with shock there is inadequate __ production, __ death, and ___failure
A
inadequate cellular energy production, cellular death, and multi organ failure
3
Q
shock is secondary to ___ due to __ or __
A
poor tissue perfusion, due to low blood flow or inadequately distributed blood
4
Q
what is pathophysiology behind shock
A
- Inadequate cellular energy
- Na/K+ pump dysfunction
- Intracellular edema/leakage
- Systemic acidemia
- Endothelial dysfunction
- Activation of inflammatory and anti-inflammatory cascades
5
Q
what is SaO2
A
Arterial O2 saturation
6
Q
what is PaO2
A
partial pressure of arterial O2
7
Q
equation for Cardiac output
A
CO= HR X SV
8
Q
what influences SV
A
preload, afterload, contractility
9
Q
what influences preload
A
end diastolic volume
10
Q
what influences afterload
A
MAP, SVR
11
Q
define stroke volume
A
volume of blood pumped from left ventricle per beat
12
Q
Define preload
A
initial stretching of the cardiac myocytes prior to contraction
13
Q
define afterload
A
amount of pressure needed to eject the blood during ventricular contraction
14
Q
define end diastolic volume
A
amount of blood in the ventricles before the heart contracts
15
Q
define systemic vascular resistance
A
resistance in circulatory system that is used to create BP and flow of blood
16
Q
define contractility
A
ability of heart to eject stroke volume at given afterload and preload
17
Q
define inotropy
A
force or energy of muscular contractions
18
Q
define chronotropy
A
heart rate
19
Q
define lusitropy
A
rate of myocardial relaxation
20
Q
define dromotropy
A
affecting the conduction speed (magnitude of delay)
21
Q
define bathmotropy
A
degree of excitability of heart
22
Q
Decrease in oxygen delivery (DO2) will increase __ until critical DO2 is reached
A
O2ER (extraction ratio)
23
Q
Decrease in DO2 will produce __ in VO2 and __ in lactate
A
decrease, increase
24
Q
what is the endothelial glycocalyx
A
thin, carbohydrate-rich, gel-like matrix on luminal vascular endothelium
25
what is the function of endothelial surface layer of endothelial glycocalyx
regulation of hemostasis, vasomotor control and immunologic function. Vascular barrier for solute transport and osmotic balance
(Controls what is inside and outside vessel)
26
what is endothelial glycocalyx comprised of
proteoglycans, glycoaminoglycans, glycoproteins
27
what are the functions of endothelial glycocalyx
1. Fluid and solute movement
2. Modulation of inflammatory cell and platelet adhesion to endothelial cell
3. Coupling shear stress to endothelial cell responses
4. Anti-inflammatory and anti-oxidant defenses
5. Retention of anti-coagulant factors
28
fluid movement out of the capillary is __
filtration
29
what would cause filtration- fluid movement out of capillary
low capillary oncotic pressure, high capillary hydrostatic pressure
30
what term describes fluid movement from interstiitium to inside capillary
absorption
31
what would cause fluid absorption
high capillary oncotic pressure, low capillary hydrostatic pressure
32
fluid filtration depends on __ and gradient between __ and __
trans endothelial pressure differences and gradient between plasma and sub glycocalyx space
33
what are the 4 mechanisms of shock
1. Loss of intravascular volume
2. Maldistribution of vascular volume
3. Obstruction of diastolic filling
4. Failure of cardiac pump
34
what are the 6 classifications of shock
1. Hypovolemic
2. Distributive
3. Obstructive
4. Cardiogenic
5. Metabolic
6. Hypoxic
35
t or f: multiple forms of shock can occur simultaneously
true
36
what is the total body water in adults
60% of BW (kg)
37
what is intracellular % of total body water
2/3, 40% BW
38
what is extracellular TBW
1/3, 20%
39
what are the 2 subspaces that make up extracellular space
interstitial and intravascular
40
hypovolemic shock is due to loss of __ leading to inadequate __
intravascular volume leading to inadequate organ perfusion
41
hypovolemic shock leads to a shift of ___—>___ metabolism resulting in increased __, ___ and __
aerobic—> anaerobic
Increase lactate, H+ ions, O2 free radicals
42
Hypovolemic shock leads to DAMPS what is that
damage associated molecular patterns activate immune system—> systemic inflammatory response
43
What are some examples of situations that can lead to hypovolemic shock
hemorrhage, severe dehydration, trauma
44
what are the causes of hypovolemic shock
1. Internal/external blood loss
2. Excessive loss of bodily fluids (vomiting, diarrhea)
45
what is the result of hypovolemic shock
Decrease venous return to the heart—> decrease CO—> compensatory mechanisms—> increase SNS, vasoconstriction, increase contractility, tachycardia, RAAS activated—> Na+ and H20 retention
46
how Do baroreceptors compensate for hypovolemia. What triggers them, what is response and result
sense stretching/low BP
Increase SNS activation and result in increased arteriolar/venous tone, contractility and HR
47
How do peripheral chemoreceptors compensate for hypovolemia
sense changes in CO2, H+ ions, and partial pressure of O2–> vasoconstriction, increase minute ventilation
48
how doe central chemoreceptors in respirator center of medulla compensate for hypovolemia
sense CO2 rise—> decrease pH
49
define hemorrhagic shock
acute drop in RBCs—> tissue hypoxia
50
define traumatic hemorrhagic shock
acute drop in RBCs—> tissue hypoxia, SIRS
51
what can cause hypovolemic shock without hemorrhage
GI or renal loss, fluid sequestration
52
what can cause traumatic hypovolemic, non-hemorrhagic shock
burns, deep skin lesions
53
define distributive shock
hypovolemic caused by pathological redistribution of fluid, changes in vascular tone vs permeability
54
what are some causes of distributive shock
1. SIRS/MODS
2. Sepsis
3. Anaphylaxis
4. Catecholamine excess (pheochromocytoma, extreme fear)
55
define sepsis
life threatening organ dysfunction caused by a dysregulated host response to infection
56
define septic shock
persistent hypotension during vasopressin therapy
57
what is pathophysiology behind septic shock
1. Endothelial permeability and vasodilation
2. Decrease vascular filling
3. Shift in volume from intravascular to interstitial space
58
anaphylactic shock results in histamine induced __
vasodilation
59
what happens during neurogenic shock
low SNS tone, unopposed PNS stimulation of vascular smooth muscle
60
what signs occur in hyperdynamic/ vasodilatory phase of distributive shock
1. Tachycardia
2. Fever
3. Bounding pulses
4. Hyperemic MM
5. Cytokine mediated vasodilation
61
what occurs in hypodynamic phase of distributive shock
1. Tachycardia
2. Pale MM
3. Prolonged CRT
4. Hypothermia
5. Poor pulse
6. Dull mentation
7. Ileus, hematochezia, diarrhea, melena
62
what is the shock organ for dogs and what is the result
GI, results in ileus
63
What occurs in hyperdnamic phase in cats
1. Tachycardia or bradycardia
2. Pale MM
3. Weak pulses, cool extremities
4. Hypothermia
5. Weakness, collapse
6. Respiratory dysfunction
64
what is the shock organ for cats and what is result
lungs- tachypnea
65
define cardiogenic shock
failure of cardiac pump
66
what are some causes of cardiogenic shock
CHF, sepsis induced cardiomyopathy, arrhythmias, toxin
67
what happens to HR, SV, CO, BP, peripheral resistance, RA, PA, and capillary pressures during cardiogenic shock
increase HR, decrease SV, CO, and BP, increase peripheral resistance, increase RA, PA and capillary pressures
68
what is the end result for cardiogenic shock
pulmonary edema, increased respiratory effort
69
what are some causes of cardiogenic shock in dogs
DCM, valvular disease, arrhythmias, congenital
70
what are some causes of cardiogenic shock in cats
HCM, HOCM, DCM, RCM, myocarditis, congenital
71
what are clinical signs for right sided heart failure
pleural effusion, ascites, distention of jugular veins, respiratory distress
72
what are some signs of left sided heart failure
pulmonary edema, respiratory distress
73
Define obstructive shock
physical impediment of blood flow in large vessels
74
what is the result of obstructive shock
compression of heart/great vessels, compromised venous return, diastolic filling and cardiac preload—> decreased tissue perfusion—> tissue hypoxia—> end organ failure
75
what are some examples that can cause obstructive shock
GDV, obstruction of vena cava/aorta, tension pneumothorax, pericardial tamponade, high PEEP
76
define metabolic shock
deranged cellular metabolic machinery
77
what are some causes of metabolic shock
hypoglycemia, cyanide toxicity, mitochondrial dysfunction, cytopathic hypoxia of sepsis
78
define hypoxemic
decrease CaO2/ O2 in arterial blood
79
what can cause hypoxemia
anemia, severe pulmonary disease, carbon monoxide toxicity, methemoglobinema
80
How would mentation, MM, CRT, HR, RR, Pulse quality, systolic BP and lactate be with shock
mentation- depressed
MM: pale pink, white, injected
CRT: >2 sec
HR
- cats: >220 or <160
Dogs: small >160, large >100
RR: >40
Pulse quality: absent or weak pulses
Systolic BP: <90mmHg
Lactate: >2.5 mmol/L
81
what is VPOCUS good for evaluating
fluid in pericardial, pleural or peritoneal cavities, pneumothorax
82
what sign on VPOCUS would be indicative of pneumothorax
absent glide sign
83
how does O2 demand and delivery change with type A increase in lactate
increase O2 demand, decrease O2 delivery
84
what are some causes of type B increase in lactate
sepsis, DM, liver disease, drugs, toxins, metabolism/mitochondrial dysfunction
85
How does age affect assessment of hydration
skin turgor decreases with elderly and young have extra skin
86
how does weigh affect assessment of hydration
obese appear well hydrated because skin stretch
87
< or = ___% dehydration is not detectable
5%
88
what are some signs consistent with 6% dehydrated
subtle loss of skin elasticity
89
what are some signs consistent with 6-8% dehydrated
prolonged skin tent, prolonged CRT, tachy MM, mild sinking of eyes
90
what are some signs consistent with 10-12% dehydrated
hemodynamic changes, severe prolongation of skin tent, markedly sunken eyes, dry MM, tachycardia, cool extremities, weak/rapid pulses
91
what are some signs of 13-15% dehydration
hypovolemic shock- tachycardia, poor pulses, tachypnea, cool extremities, decreased mentation
92
Dehydration is a loss of fluid from __compartment
interstitial
93
what is the goal of clinical compensation of shock
increase tissue perfusion and intravascular volume
94
what is shock index formula and what value is indicative of acute blood loss and shock
shock index= HR/SBP
>0.9= acute blood loss and shock
95
what occurs during compensatory stage of shock
mild to moderate mental depression, tachycardia, normal/prolonged CRT, cool extremities, fair to moderate pulse quality, tachypnea, normal BP
96
what occurs during decompensatory stage of shock
depressed mentation, poor pulse quality, pale MM, drop in BP
97
what types of shock occur with GDV
hypovolemic, obstructive
98
what types of shock can occur from septic peritonitis
metabolic, cardiogenic, distributive, hypovolemia
