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Board Review 2020 > Shock.Lactate > Flashcards

Shock.Lactate Flashcards

1
Q

Define shock

A

any condition where metabolic oxygen demand exceeds uptake/utilization resulting in energy debt and measurable change in organ function

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2
Q

Draw tree of life

A

DO2 –> CaO2 —> Hgb, SaO2, PaO2
DO2, MAP –> CO —> SV —> preload, afterload, contractility
DO2, MAP –> CO —> HR —> SNS, PNS
MAP —> SVR–> Local (CO2, PGs, NO, histamine) & Systemic vasopressin, angiotension II, SNS

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3
Q

What are the types of shock

A

Circulatory: Hypovolemic, cardiogenic, distributive, obstructive
hypoxemic (decreased arterial O2)
Metabolic

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4
Q

List three types of distributive shock

A

sepsis, neurogenic, anaphylaxis, addisons

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5
Q

List three types of obstructive shock

A

plerual space disease, PTE, GDV

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6
Q

List three types of hypoxemic Shock

A

Low FiO2, V/q mismatch, Shunt, hypoventilation, Diffusion impairment
anemia, dyshemoglobinemias

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7
Q

List three types of metabolic shock

A

hypoglycemia, mitorcondrial dysfunction

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8
Q

What is the mechanism of distirbutive shock

A

maldistribution of blood flow due to decrease in systemic vascular resistance resulting in inadequate perfusion. CO and Vascular volume are normal
Also called vasodilatory shock

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9
Q

What is obstructive shock

A

Physical impedance of flow

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10
Q

Describe the cellular response to shock

A

Normal: excess O2 delivered to provide buffer for decrease supply. With demand tissue can increase oxygen extraction from 25% to 70-80%.
Mitochondrial - lowest level will change to anaerobic metabolism and lactate production.
Intracellular acidosis, oxygen free radicals and exchange pumps stop working

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11
Q

Describe the systemic response to shock

A

Barorecptors (decrease wall distension) and chemoreceptors (hypoxia, hypercapnia, acidosis). Catecholamine release leads to pheripheral vasoconstriction, tachycardia and increased cardiac contractility.
RAAS activation to decrease water loss and vascontriction.
Fluid shift from interstitial to intravascular.

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12
Q

What occurs to go from compensatory to decompensatory shock

A

Exahstion of compensatory mechanisms result in systemic hypotension, elevated lactate, bradycardia and vasodilation

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13
Q

In MODS name the changes that occure in the GI, Lungs, kidney, liver

A

GI: barrier loss and recovery ileus, decreased motility
Lungs: ARDS- inflammation resulting in protienacious fluid
Kidney- Tubular necrosis
Liver-

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14
Q

Name the compensatory mechanisms in Hypovolemic shock

A

Decreased CO is sensed by decreased wall stretch at the aortic arch and carotid arteries detected by baroreceptors: increased sympathetic tone and catecholamine response
Anaerobic metabolism is detected by chemorecptors (CO2 increases to buffer H+ production) to increase ventilatory drive and vasoconstrction.
RAAS stimulated with decrease stretch to the afferent arteriole and decreased chloride to macula densa
Starling Forces water moving from interstitium

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15
Q

What is the RAAS response to hypovolemic shock

A

Angiotension II peripheral vasoconstriction and maintains GFR by constriciton of efferent arteriole
Aldosterone: Na retention
ADH: vasoconstriction and water retention

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16
Q

What are the parameters to evaluate perfusion in hypovolemic shock

A

mentation, HR, pulse quality, mm color, CRT, and extremity temp

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17
Q

What is shock index and what does it mean

A

HR/ Systolic blood pressure
>0.9 -1.0 considered shock
May assist to determine when neither value is abnormal

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18
Q

What is pulse pressure variation and what is considered hypovolemic

A

[PPmax (inhalation) - PP min (exhalation) ]/ Mean of two
Expressed as percent
>10-15% consistent with hypovolemia… needs to be when mechanically ventilated

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19
Q

What ScvO2 is consistent with shock and what types of shock does it occur does it occur

A

In all types O2 sat of Hgb will be decreased due to increase in tissue O2 extraction.
ScvO2 < 70% consistent with shock

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20
Q

How can you assess the cadual vena cava for fluid balance

A

Evaluation of the CVC diameter as it goes throught the diaphragm in the DH View. Dynamic collapse during inspiration supportive of hypovolemia.

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21
Q

How much of a fluid challenge remains in the intravascular space

A

only 25% remains after 30-60 mins (source dependent) due to redistribution to the interstitial space

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22
Q

Define Cardiogenic shock

A

Decreased CO resulting in tissue hypoxia with adequate circulating volume.
Persistent hypotension (SBP <90 mmHg,MAP < 65mmHg)
reduction in cardiac index < 1.8 L/min/m2
Left ventricular end-diasolic pressure >18 mmHg

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23
Q

What are catecholamines effects in cardiogenic shock

A

increase peripheral vasoconstriction. Vasopression and ANG II increase to improve coronary and peripheral perfusion with increased afterload and increasing myocardial oxygen demand.
also are arrhythmogenic (dopamine)

24
Q

How do you treat cardiogenic shock

A

Underlying cause if able (sepsis, tamponade)
Systolic dysfunction: inotropes such as dobutamine
Pimobendain (rarely reduces systemic BP)
Glucagon: exogenous positive inotropic increase CO and BP.

25
Q

Good perfusion goals:

A

CVP: 0-5 cmH20 UOP =/> 1 ml/kg/hr
MAP 70-120 mmHg
Normal: Temp, HR, RR, heart rhythm, mm pink, CRT < 2 sec

26
Q

What is the frank starling mechanism associated with the heart

A

increased myocardial muscle fiber length initially leads to an increased stroke volume but above a certain point the fibers become over stretched and further filling results in decreased stroke volume.

27
Q

What are the types of elevated lactate

A

Type 1: increased lactate with no pH change
Type 2: increased lactate with acidemia
A- inadequate O2 dilevery to meet cellular demand
B- All causes despite adequate O2 delivery

28
Q

How does Type 1 hyperlactemia occur

A

increase in glycolysis. pH does not decrease as H+ is used in functional mitochondria and oxidative phosphorlation

29
Q

How does Type 2A hyperlactemia occur and give 3 examples

A

Indadquate O2 delivery to meet demand
Shock, regional hyperperfuslion, sever hypoxemia PaO2 < 40 mmHg
Relative: increased muscle activity: Seizures, termoring, shivering restraint

30
Q

How does Type 2B1 hyperlactemia occur and give 3 examples

A

Underlying disease proccess in which there remains adequate O2 delivery to tissues
Diabetes mellitus, liver, neoplasia, sepsis, pheochromocytoma

31
Q

How does Type 2B2 hyperlactemia occur and give 3 examples

A

Medications

Glucocortocoids, xylitol, ACE inhibitors, glucose adin, Epiniphrine, EG, propofol (people only), lactulose

32
Q

How does Type 2B3 hyperlactemia occur

A

Inborn errors of metabolism

33
Q

What can occur with delay in sample running for glucose

A

> 60 minutes continued glycolysis by RBC, PLTs, WBCs may increase up to 70%

34
Q

Name disease proccess in which elevated lactate concentration has been shown to have a poor outcome

A

IMHA, GDV, Hypotension in ICU, SIRS, Soft tissue infections, babesia, HW caval sendrome
Cats: Sepsis, HCM

35
Q

What is lactate clearance and how is it used

A

((Lactate initial - lactate delayed) / Lacate intitial ) x 100
expressed as present.
Lactate clearance < 42% at 12 hours Sen 82 Spec 100 non survival

36
Q

How much LRS is needed to elevate lactate

A

Minimal increase with 180 ml/kg in 1 hr

37
Q

What does lactate elevation mean in abdominal fluid

A

> 2.0 or 2.5 mmol/L from peripheral consitent/suggestive of bacterial septic peritonitis in dogs only

38
Q

What does lactate elevation mean in synomvial fludi

A

Dogs only > 6.5 mmol/L septic

OA, autoimmune had elevation but not as severe

39
Q

What fluids have yet to show importance of lactae

A

CSF, pericardial effusion, and dystocia (neonatal blood)

40
Q

What is lactates charge and is it a strong/weak ion

A

Negative. Strong ion

41
Q

What is lactates charge and is it a strong/weak ion

A

Negative. Strong ion

42
Q

What is the mechanism for elevated lactate with neoplasia

A

increased glycolytic enzymes, increased glucolysis intermediates, mitocondrial dysnfuction, decreased hepatic clearance, decrease thiamine

43
Q

What is the mechanism for elevated lactate with Pheochromocytoma

A

Catecholamine induced

44
Q

What is the mechanism for elevated lactate with Diabetes mellitus

A

unregulated glycolysis, reduced PDH, reduced oxidative metabolism

45
Q

What is the mechanism for elevated lactate with hepatic renal failure

A

Decreased clearance and increased production = net lactate producer with severe disease

46
Q

What is the mechanism for elevated lactate with thiamine deficincy

A

accumulation of pyruvate and lactate due to decreased PDH production (thiamine needed to produce)

47
Q

What is the mechanism for elevated lactate with hyperthyroidism

A

increase basal metabolic rate increase in glucose metabolism

48
Q

What is the mechanism for elevated lactate with Catecholamines

A

cAMP via B2 adrengic stimulation.

Increases glycolysis, glycogenolysis, lypolysis, stimulates NaKatpase pumps

49
Q

What is the mechanism for elevated lactate with Acetominophen

A

impairing mitochondrail respiration and decreased hepatic clearance.
Methemoglobinemia (decreased O2 delivery)

50
Q

What is the mechanism for elevated lactate with Propofol (people)

A

mitochondrial dysfunction

51
Q

What is the mechanism for elevated lactate with Cyanide

A

Non competively inhibits final step in electron transport chain. Favors anaerobic metabolism
Sodium ntiroprusside leads to Cyanide production

52
Q

What is the mechanism for elevated lactate with Glucocorticoids

A

Promote aminoacid conversion to pyruvate, inhibitiong PDH, altering carb metabolism, potentialting hyperlactemia effect on catecholamines

53
Q

What is the mechanism for elevated lactate with alcohols

A

Shifts NAD+/NADH ratio to favor lactate production

54
Q

What is the mechanism for elevated lactate with lactulose

A

People absorbed through colon break down products: lactate and acetate

55
Q

Why is it important to sample the site site for serial lactate measurements

A

Due to the muscle tissue and location in body a statistical difference has been shown from peripheral to central locations.

56
Q

What can interfere with lactate POC meters

A

Ethylene glycol metabolites can interfere. Generally reports a sever lactate increase.

Board Review 2020 (37 decks)

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