Auer Ch 1 Shock

Front 1

Define shock:

Back 1

Progression of a cascade of events that begins when cells/ tissues are deprived of oxygen resulting in an accumulation of waste products, failure of energy dependant functions, cellular enzyme release, calcium accumulation, and reactive oxygen species accumulation which leads to cellular death.

Front 2

3 major factors affecting blood flow:

Back 2

circulating volume, cardiac pump function, vasomotor tone (peripheral vascular resistance)

Front 3

what is the equation determining blood flow to tissues?

Back 3

Cardiac output = stroke volume x heart rate

Front 4

what affects stroke volume?

Back 4

Preload (amount of blood returning from the body entering the heart), cardiac contractility (muscular function of the heart), afterload (ABP required to push blood from into the pulmonary valves and aorta)

Front 5

Causes of decreased preload:

Back 5

loss of volume, hypovolemia, decreased vasomotor tone, vasodilation

Front 6

Cardiac out put equations:

Back 6

CO = SV x HR or CO= BP / total peripheral vascular resistance

Front 7

Classes of shock:

Back 7

Hypovolemic shock (volume deficit due to hemorrhage, 3rd space loss, severe dehydration) cardiogenic shock (stroke volume is inadequate to maintain perfusion because of cardiac muscle failure) distributive shock (loss of vasomotor tone results in loss of blood pressure and decreased venous return)

Front 8

Define transcapillary fill:

Back 8

Precapillary sphincter tone lowers capillary hydrostatic pressure which favors movement of fluid from the interstitium to the capillary beds

Front 9

Effect of transcapillary fill:

Back 9

Interstitial fluid deficit which can restore circulating fluid losses of less than 15%

Front 10

Hypodynamic shock:

Back 10

Compensatory mechanisms are insufficient to maintain ABP and perfusion of organ with blood loss greater than 15%.

Front 11

Consequences of hypodynamic shock:

Back 11

Ischemia to vital organs, cellular function failure, accumulation of waste products, acidosis

Front 12

Categories of shock based on clinical signs:

Back 12

Mild (class 1) blood loss < 15% body is capable of restoring volume with compensatory mechanisms. Hyperdynamic (early class 2) blood loss of 15-30% body can compensate but only is losses stop. Decompensatory shock (classes 3 and 4) blood loss > 30% failure of compensatory mechanisms and cycle of decreased CO, BP, and tissue perfusion results in circulatory collapse.

Front 13

Determinates of oxygen delivery:

Back 13

Concentration of oxygen in the blood (Hb & saturation of Hb) and the amount of blood perfusing tissues

Front 14

What are the negative consequences of isotonic (rapid) fluid therapy?

Back 14

80% of volume will diffuse to interstitial and intracellular spaces resulting in replacement volumes being 4-5 greater than loss. Excess fluid administration results in excess total body water, excess lytes, excerbating fluid movement out of vascular space. Cellular effects trigger inflammatory response, compartment syndrome, ARDS, CHF, dilutional coagulopathy

Front 15

goal of fluid therapy:

Back 15

restore perfusion, improve oxygen delivery

Front 16

what is the difference between replacement and maintenance fluid?

Back 16

Replacement fluids electrolyte composition closely approximates extracellular electrolyte composition

Front 17

What is the method of administering isotonic fluids for hypovolemic shock?

Back 17

Calculate fluid deficit, administer in doses of 10-20 m/kg then reassess parameters

Front 18

Mechanism of hypertonic saline:

Back 18

Pulls fluid primarily from intracellular space, expands capillaries, blunts neutrophil activation, alters balance between inflammatory & anti-inflammatory cytokines

Front 19

What is the dose of hypertonic saline?

Back 19

2-4 mL/kg

Front 20

what are the benefits of colloids?

Back 20

Large molecules retained in the intravascular space, exert an oncotic pressure opposing hydrostatic pressure to retain fluid or draw fluid to vascular space

Front 21

What is normal COP?

Back 21

20 mmHg

Front 22

Examples of natural colloids:

Back 22

Plasma, whole blood, bovine albumin

Front 23

Benefits of natural colloids:

Back 23

Provide albumin, clotting factors, antibodies, other plasma proteins

Front 24

Examples of synthetic colloids:

Back 24

Hydroxyethyl starch, dextran

Front 25

What is the COP of HES?

Back 25

30 mmHg

Front 26

how is HES eliminated?

Back 26

Renal and extravasation

Front 27

What is the dose for HES?

Back 27

10 ml/kg/day

Front 28

how long is HES active?

Back 28

At least 120 hours

Front 29

Complications of HES:

Back 29

Increased cutaneous bleeding times and decrease in vWF antigen with 20 mL/kg doses

Front 30

Advantages of whole blood:

Back 30

Clotting factors, prevents dilutional coagulopathy, improves oxygen content, proteins help retain fluid in vascular space

Front 31

Disadvantages of whole blood:

Back 31

Difficult to store/ have available, can not be rapidly infused

Front 32

benefits of dobutamine in shock resuscitation:

Back 32

b1 adrenoreceptor, weak b2 & a adrenoreceptor has positive ionotropic (increase contractility) action, improves splanchnic perfusion

Front 33

dose of dobutamine:

Back 33

1-5 ug/kg/min

Front 34

benefits of norepinephrine:

Back 34

strong b1 & a adrenorecptor increases vasoconstriction, cardiac contractility

Front 35

what are methods to monitor response to shock therapy?

Back 35

Repetitive PE, CRT, CVP, urine output, ABP, lactate, oxygen extraction, PvO2, CO, regional perfusion

Front 36

What does CVP assess?

Back 36

Cardiac function, blood volume, vascular resistance

Front 37

What is normal CVP?

Back 37

7-12 mmHg with a catheter in the right atrium, catheter in jugular vein will be higher

Front 38

what is normal urine production?

Back 38

1 mL/kg/ hr or more

Front 39

What level of urine production requires treatment?

Back 39

< 0.5 mL/kg/hr

Front 40

when does BP record below normal?

Back 40

With a 30% or more decrease in blood volume

Front 41

What BP is treatment aimed at maintaining?

Back 41

>65 mmHg

Front 42

examples of direct BP measurement:

Back 42

catheterization of transverse facial(adults & foals), metatarsal, radial, or auricular artery (foals)

Front 43

locations for indirect BP measurement:

Back 43

coccygeal or metatarsal arteries

Front 44

what is normal indirect coccygeal systolic BP?

Back 44

80-144 mmHg

Front 45

how is oxygen extraction calculated?

Back 45

Difference between central venous saturation and arterial oxygen saturation

Front 46

What is normal oxygen extraction?

Back 46

20-30%

Front 47

what is normal jugular PvO2?

Back 47

40-50 mmHg

Front 48

how is CO estimated?

Back 48

Pulmonary thermodilution, lithium dilution, transesophgeal or transthoracic Doppler

Front 49

What is the goal of hypotensive resuscitation?

Back 49

Prevent or minimize further blood loss by administering fluids to maintain a mean BP of 40-60 mmHg (or systolic BP of 80-90 mmHg)

Front 50

what occurs with prolonged catecholamine release?

Back 50

Long term increased peripheral vascular resistance and tissue ischemia

Front 51

Triggers of cortisol release:

Back 51

Catecholamines, vasopressin, angiotensin II, norepinephrine, endotoxin

Front 52

Results of cortisol release:

Back 52

Na & H2O retention (edema), insulin resistance, gluconeogenesis, lipolysis, protein catabolism