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IC > Shock/Hypotension > Flashcards

Shock/Hypotension Flashcards

1
Q

Arterial pressure dependent on

A

volume of blood within arterial system

rate of inflow (from LV) vs rate of runoff to veins (blood leaving)

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2
Q

Arterial pressure rises when

A

inflow is greater than outflow (rapid ejection phase of ventricular systole)

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3
Q

Arterial pressure falls when

A

inflow is less than outflow (Diastole)

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4
Q

Blood pressure in systemic arteries will be lower than normal when

A

blood volume in arteries is decreased due to decreased cardiac output or decreased TPR (inc rate of runoff from arteries to veins)

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5
Q

Diastolic pressure

A

determined by factors that alter rate or time of runoff

1) rate of runoff- how fast blood flows from arterial to vennous system (determined by TPR)
2) runoff time- runoff during diastole; determined by heart rate- dec HR longer time for runoff, diastolic pressure decreased
3) arterial systolic pressure- starting pt from which runoff causes pressure to decrease

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6
Q

Arterial systolic pressure determined by

A

1) ejection rate- from LV; how quickly blood volume in arteries increase
2) SV- arterial pulse pressure index of SV. volume increases, pulse pressure increases.
3) arterial compliance- chronic decreases in compliance increase systolic pressure
4) arterial diastolic pressure- pressure begins to increase during ejection

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7
Q

pulse pressure in aortic stenosis is

A

decreased because of rate of ejection is decreased due to high resistance of aortic valve

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8
Q

MAP calculation

A

MAP= Diastolic + 1/3 Pulse pressure

Pulse pressure= systolic - diastolic pressure

MAP=COxTPR

MAP is the driving pressure for blood flow in systemic circulation

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9
Q

HR controlled by

A

PARA and SYM on SA node

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10
Q

SYM nerves influence

A

HR, preload, afterload, inotropic state

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11
Q

SV determined by

A

preload, afterload, inotropic state

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12
Q

Preload

A

stretch on myocardial fibers before contraction
-determined by EDV
related to ventricular filling- affected by heart rate (dec hr, inc filling time, EDV greater, inc SV) and rate of venous return (inc vr, inc rate of filling, edv greater, inc sv)

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13
Q

Starling’s law

A

stroke volume inc when preload is inc due to greater stretch which results in more favorable overlap of thin and thick filaments

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14
Q

afterload

A

ventricular wall tension during ejection
-resistance that must be overcome to eject blood

pressure at start of ejection (aortic diastolic pressure) or peak pressure (aortic systolic pressure) used as indices of afterload

-changes in TPR affect afterload- inc in TPR slows rate of runoff of blood from arteries to veins- inc arterial diastolic pressure- inc afterload

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15
Q

inc in TPR will

A

slow rate of runoff from arteries to veins–> inc arterial diastolic pressure –> inc afterload

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16
Q

Inotropic state

A

represents force of contraction
dep on cytosolic calcium level
more ca- more cross bridges formed- inc contractile force

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17
Q

NE will

A

enhance calcium entry into myocytes and inc inotropic state

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18
Q

Venoconstriction

A

decrease venous compliance, increasing venous pressure- increase venous return to the heart- increasing sv on next beat

19
Q

hypovolemic shock

A

decreased blood volume resulting in inadequate CO

skin feels cold and clammy because decreased blood flow to skin

low central venous pressure

dec blood volume–> dec venous return–> dec EDV–> dec SV–> dec CO–> dec MAP

20
Q

distributive shock

A

generalized systemic vasodilation- dec TPR

warm shock

21
Q

cardiogenic shock

A

inadequate cardiac output by diseased or impaired heart

high central venous pressure

skin feels cold and clammy

22
Q

Blood flow to most systemic organs is reduced in hemorrhagic shock bc

A

map is reduced and

vascular resistance is increased due to increased sym firing to arterioles via baroreflex

23
Q

how do brain and heart maintain blood flow during shock

A

local arteriolar dilation by local vasodilators

in other organs- arterioles constrict due to inc SYN via baroreflex

24
Q

Increased myocardial O2 consumption when

A

inc inotropic state (beta1 activation)
inc hr
inc afterload, preload, hypertrophy

25
Q

ischemia of heart during shock

A

although vessels are dilated via local vasodilators, there is increased O2 demand because of the sym firing leading to inc inotropic state

26
Q

pulse during shock

A

described as weak because loss of blood impairs filling of ventricles (dec preload)
-this will result in reduced SV–> reduced pulse pressure–> weak pulse fet
red SV–> dec C–> dec MAP

27
Q

baroreceptor reflex in hemorrhagic shock

A

increased SYM and dec PARA
leads to arteriolar vasoconstriction, inc TPR, inc venous return slightly because blood volume reduced

inc inotropic state and HR but CO is still low due to low bv

also HR will increase- decrease diastolic filling time, decrease EDV–> dec SV

28
Q

change in intracellular fluid volume caused by hemorrhage or dehydration?

A

dehydration

  • ecf is hypertonic, so blood will leak out of cells and icf volume is decreased
  • hypertonic contraction
29
Q

Distributive- septick shock mechanism

A

release of inflammatory mediators–> vasodilation via NO in endothelial cells and impaired vascular reactivity–> dec TPR–> dec MAP

30
Q

What happens to afterload in distributive shock

A

it is decreased because of decrease in TPR

Increase in SYM firing due to the decrease in MAP will result in inc inotropic state

31
Q

systemic arteriolar dilation

A

decreases TPR- lower resistance to flow, higher rate of runoff, lower arterial diastolic pressure

32
Q

systemic arteriolar constriction

A

increases TPR- higher resistance to flow–> lower rate of runoff–> inc arterial diastolic pressure (afterload)

33
Q

venoconstriction

A

SYM response

decrease venous capacity to hold blood, so more blood will return to the heart

34
Q

Edema in shock

A

Leukocyte adherence to post capillary venules results in increased vascular permeability- development of edema
O2 diffusion into cells impaired

Even though there is the presence of NO, which normally inhibits leukocyte adherence, pro inflammatory mediators outweigh NO and adherence occurs

35
Q

Anaphylactic shock

A

allergen–> mast cell degranulation–> release of histamine–> arteriolar vasodilation–> dec TPR–> dec MAP
Inc vascular permeability due to histamine causes plasma loss to interstitium (must give antihistamines)

36
Q

Neurogenic shock

A

Loss of vascular tone due to inhibition of normal tonic activity of SYM vasoconstrictor nerves
-deep general anesthesia, pain reflexes associated with traumatic injury, transient vasovagal syncope
dec TPR and dec MAP due to generalized arteriolar vasodilation

37
Q

Cardiac tamponade- cardiogenic shock

A

pericardial sac surrounding heart gets filled with fluid, impairing filling of heart- dec magnitude on ecg

dec ventricular filling and EDV–> SV dec–> CO dec–> dec MAP

38
Q

paradoxical pulse

A

in cardiac tamponade

  • greater than normal decline in systolic arterial pressure during inspiration (>10 mmHg)
  • inc in venous return to rv during inspiration causes exaggerated reduction in lv volume becauuse it causes the septum to bulge into left ventrical
39
Q

Physiological splitting of second heart sound

A

inspiration causes increase in intrathoracic volume, decreasing intrathoracic pressure–> dec right atrial pressure–> increases gradient between peripheral veins and RA–> inc blood flow into right atrium and inc EDV of RVentricle–> inc SV–> inc ejection time–> delayed closure of pulmonic valve

40
Q

Affect of inspiration on left ventricle

A

Increase in intrathoracic volume will decrease intrathoracic pressure–> distending pulmonary veins–> dec pressure in pulmonary veins and pooling of blood–> dec return to LA–> dec EDV of LV–> dec SV

41
Q

Beta 1 receptors activated by

A

NE from SYM

  • SA node: inc HR
  • AV node: inc conduction velocity (dec PR interval)
  • atrial and ventricular muscle- increase inotropic state
42
Q

Alpha 1 receptors in

A

vascular smooth muscle

  • arteriolar constriction- inc TPR
  • venoconstriction- inc venous return
43
Q

Beta2 receptors in

A

skeletal muscle arterioles

  • circulating Epi causes vasodilation
  • fight or flight response
44
Q

Irreversible shock

A

due to prolonged shock and impaired organ blood flow causing local accumulation of vasodilator metabolites (overcome effects of SYM) and lactic acid

  • arteriolar vasodilation- low TPR
  • cellular injury bc of impaired blood flow- release of toxic factors (myocardial depressant factor)- impaired contractility- dec CO

IC (31 decks)

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