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Flashcards in 6 Deck (63):
1

what does oxygen delivery depend on

oxygen delivery DO2DO2 = CO x CaO2CO cardiac output = SV x HRCaO2 arterial oxygen content

2

body's compensatory response to tissue hypoxia

tachycardiatachypneaperipheral vasoconstrictionmental depression

3

common classifications of shock

1. Hypovolemic--reduced volume, reduce preload, reduce SV, reduced CO2. Cardiogenic--inability of heart to contract/propel fwd3. Distributive--impaired mx of vascular tone and relative hypovolemia4. Hypoxic--adequate perfusion but inadequate oxygenation

4

major determinant of arterial oxygen content

amount of HbCaO2= (Hb x SaO2 x 1.34) + PavO2 x 0.003

5

What does CO depend on

CO = SV x HrSV = preload, after load and contractility

6

preload

end diastolic volumeincr preload will incr stretch and incr contractility to a point (Frank Starling mx)

7

afterload

ventricular wall tension or resistance the muscle needs to counter during systoleinfluenced by vascular resistance (low BP is the major determinant of decr after load)

8

contractility

force and velocity of cardiac muscle contraction

9

what is blood flow influenced by

assumes blood flow is uniform across tissue bedsbutinfluenced by vasomotor controlcirculating blood volumeactivation of blood components

10

types of hypovolemic shock

blood lossburnssevere diarrhea, vomitingthird spacing

11

types of cardiogenic shock

systolic dysfx--CHF, DCM, arrythmias, valvular stenosis/insufficiencydiastolic dysfx--HCM, cardiac tamponade, pericardial fibrosis, tension pneumothorax (sometimes referred to as obstructive shock)

12

types of distributive shock

sepsisanaphylaxisneurogenicdrugs--anesthetics

13

types of hypoxic shock

hypoxemiaanemiamethemoglobinemiaCO poisoning cytopathic (cells aren't able to produce energy from O2 available)

14

what is Hb affinity for oxygen dependent on

pHtemperature2,3-diphosphoglycerate (DPG)CO2

15

equation for mean arterial BP

MAP = DAP + 1/3 (SAP-DAP)

16

decreases in tempincreases in pHdecreases in pCO2decreases in 2,3 DPG

shift oxygen-HB dissociation curve to the LEFTmaking oxygen less available/delivery of less oxygenincreases Hb affinity for oxygen

17

increases in tempdecreases in pHincreases in pCO2increases in 2,3 DPG

shift oxygen-Hb dissociation curve to the RIGHTmaking oxygen more available/delivers more oxygendecreases Hb affinity for oxygen

18

tissue hypoxia results from

Decreased PaO2/SaO2Impaired DO2Decreased COreduction in Hb

19

what is the main determinant of tissue perfusion

CO=SV x HR

20

three main abnormalities that will result in low CaO2 (arterial oxygen content)

--anemia--altered Hb fx--hypoxemia

21

oxygen uptake eqn

oxygen uptake VO2; rate at which oxygen leaves HbVO2 = CO x (CaO2-CvO2)FICK equation

22

if all oxygen available is delivered to tissue and is utilized, how much O2 should remain bound to Hb in venous supply?

If oxygen delivery is adequate, sufficient O2 should remain in venous blood to provide at least 70% saturation of Hb

23

oxygen extraction ratio

ratio btwn oxygen supply and utilization or oxygen delivery and uptakeO2ER= VO2/DO2 x 100

24

DO2/VO2 curve and the anaerobic threshold

over a wide range of values, VO2 is INDEPENDENT of DO2if DO2 starts to decrease, eventually it hits critical DO2 point or the anaerobic threshold where now VO2 is DEPENDENT on DO2 and below this threshold anaerobic mechanisms ensue.

25

defects in oxygen uptake

1. diffusional shunting: slow velocity blood, favors oxygen diffusion, less oxygen delivered to target tissues2. diffusional resistance: tissue edema impairs oxygen diffusion to tissues3. AV shunting: low of normal flow and bypass occurs leading to increase oxygen content in venous blood supply4. Perfusion/metabolism mismatch: delivery of oxygen is adequate but it is not taking up by diseased tissue5. cytopathic/metabolic dysfunction: intracellular interference with oxygen/aerobic metabolism

26

major sources of lactate

musclegastrointestinal tract

27

Why does the body switch to anaerobic mechanism

when DO2 can not meet tissue demandsswitch to anaerobic metabolism to save ATPglucose -->pyruvate --->lactate (via LDH)generates NAD+ but saves ATPwhen oxygen returns ATP can be used to lactate-->pyruvate-->glucose

28

arterial blood pressure eqn

ABP = CO x SVR

29

absence of a peripheral pulse vs absence of femoral artery pulse in relation to BP

lack of peripheral pulse SAP 80 mm Hglack of femoral pulse SAP < 60 mm Hg

30

shock organ in dog vs cat

GI doglung cat

31

T/F arterial BP is synonymous with perfusion

FALSEABP does not equal perfusionnormal ABP does not rule out hypo perfusion.low BP is not SN and late marker of uncompensated state and failure of SNS

32

minimum BP o maintain major body systems

MAP 60SAP 90

33

disadvantages to arterial catheters

technically challenging, time consuminghematoma formationthrombosis hemorrhageinflammationnecrosis distally (cats)

34

advantages of arterial catheters

GOLD std for BP monitoringcontinuous or intermittent readingsMAP, SAP, DAP

35

Doppler BP monitoring only reliably monitors what

ONLY SAPbetter than oscillometric methods (which underestimate)in anesthetized cats, doppler may more accurately represent MAP

36

normal CVP

0-5 cm H20most closely represents end diastolic volume

37

how many mm Hg in one cm H20

0.74 mm Hg in 1 cm H20

38

common causes of increased CVP

right heart failurevolume overloadpericardial effusionpleural space diseaseincreased intrathoracic pressure

39

gold standard for cardiac output measurements

thermodilutionSwan Ganz pulmonary arterial catheter(other methods lithium dilution, transpulmonary thermodilution--minimally invasive)

40

normal lactate

indicator of hypoperfusion normal < 2 mmol/Lmonitor trendsmay be prognostic indicator

41

difference between type A and type B lactic acidosis

type A: inadequate DO2 (most common)type B:adequate DO2 w hyperlactatemia from mitochondrial dysfunction

42

cyanosis of blue MM indicates

> 5 g/dl of deoxygenated Hb in circulation

43

pulse oximetry is influenced by

pigmenthypothermiavasoconstrictionperipheral hypoperfusionmovementambient light

44

rough estimate of the relationship if PaO2 and inspired oxygen

PaO2 should be ~5x FIO2ex 21% oxygen in room air x 5 = > 90 mm Hg

45

what does FAST stand for

focused assessment with sonography for trauma

46

at what rates does oxygen toxicity occur

FIO2 > 60% for more than 24 hours

47

unilateral vs bilateral nasal cannulas for oxygen supplementation at flow rate 100 ml/kg/min

unilater 40%bilateral 60%

48

methods of oxygen suppementation

flow by +/- ecollar/wrapnasal/nasopharyngealtracheal

49

common sites for IVC

jugular veinsperipheral veins (avoid hind in severe shock patients--GDV)intraosseous (trochanteric fossa, prox humerus, tibial crest)

50

inotropic support with dopamine (low, med, hi doses)

low 0.5-2.0 mcg/kg/min vasodilationmed 2-10 mcg/kg/min Beta receptors inotropic/contractilityhigh 10-20 mcg/kg/min vasoconstriction, alpha receptors

51

what is dobutamine avoided in cats

seizures in cats more beta specific inotrope

52

T/FSIRS may be infectious and/or noninfectious

TRUE

53

difference btwn SIRS and sepsis

SIRS--noninfxn and infxn causesmost common cause of SIRS is sepsissepsis --SIRS with infxn

54

septic shock definition

sepsis (SIRS with infxn) and state of acute circulatory failure

55

MODs

multiple organ dysfunction syndrome

56

ARDs

acute respiratory distress syndrome

57

diagnostic criteria for ARDS

1. acute onset < 72 hr tachypnea/labored breathing2. presence of risk factors3. pulmonary capillary leak without increased pressure4. inefficient gas exchange5. diffuse pulmonary inflamation

58

ALI vs ARDS

ALI is less severePaO2/FIO2 ratio< 300 ALI< 200 ARDS

59

5 causes of hypoxemia

1. hypoventilation2. low inspired oxygen FIO23. VQ mismatch4. AV shunting5. diffusion impairment

60

septic foci in dogs vs cats

GI (most common in dogs)repro (dog >cat)pleural space (cats>dogs)endocarditispancreatitisurinary tract nosocomial (check IVC)

61

T/F mortality can be as high as 80% with inappropriate use of Ab to treat sepsis

TRUE

62

describe de-escalation therapy

start Ab approach broad (4 quad--gm + gm - anaerobic, aerobes)then taper/narrow therapy once C&S available

63

adrenal insufficiency and septic shock

aka critical illness related corticosteroid insufficiencycortisol levels may be high or normal but adrenal response is bluntedleads to refractory hypotensiontx low dose physiology GCC (hydrocortisone)