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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