Physiology Circulatory Shock

Question 1

4 compensatory mechanism

Answer 1

1. Baro R
2. Reaborption of fluid into capillary
3. falling arterial and capillary hydorstatic P –> Reduces GFR into capillary
4. Fall in renal BF and BP trigger increase in renin/angiotesnin activity / vasopressin release, and aldosterone release

Question 2

Symptoms of shock (7)

Answer 2

Pallor of skin and mucous membranes

Clammy skin

Rapid, weak, thready pulse

Arterial hypotension

Decerased core body temp

Feeble respiration

Restless, apathaic , semi-rational behavior

Question 3

What is shock

Answer 3

Failutre of cirucaltyr system to maintain cellular perfusion and fucntion

Question 4

What causes shock

Answer 4

critical impairment of BF to vital organs and tsisues and/or the ainability of tissues to utilize essential nurtrients

Question 5

Three major types of shock

Answer 5

Hypovolemic shock

Cardiogenic

Septic shock

Question 6

What is hypovolemic shock

Answer 6

Severe lsos of circualting blodo volue

Threat to ciruulation of tissues by decreasing venous return and CO

Question 7

Loss of ciruclating blood (hypovolemic shock) may reuslt from

Answer 7

Hemorrage- internal or external bleeding

Loss of vascular volume- burns, trauma, radiation

Question 8

Loss fo 5-10% blood volume

Answer 8

little or no efect on BF

Reinfusion will result in spontanous recovery of vascular funcitona nd no long-term consequnces

Question 9

Loss of 15-20% ttoal blodo volume

Answer 9

Significant all in CO

MAP is well maintaine

Blood to soe beds is signifcantly reduce,d but reinfusion will lead to spontaneous recovry

Question 10

Loss of 25-50%

Answer 10

provoeks severe drop pin venous return, CO and pulse prssure

MAP falls , thouh ti is still maintatined better than CO by baroR /symp function

early signs of circulatory shock appear

Shock state reversed by eary reinfusion of volume and aggressive treatmetn

Question 11

Loss >30%

Answer 11

pressure falls below mean levels of 50 mmHG

irrerersible shock ensues

Reinfusion of fluid ay not be able to restore normal CV fucntion

Question 12

Mechanism that help maintain CV ufcntion in the face of decrsed circulating blood

Answer 12

1. BaroR reflex (sympathetic NS, tTPR, and Heart rate inccreased)
2. Arterial and capillary hydrostatic P favor –> REABSORPTION OF FLUID INTO CAPILLARY
3. Reduction in CO –> REDUCES GLOMERULAR FILTRATION AND FAVORS RETENTION OF FLUID IN THE VASCULAR SYSTEM
4. Fall in renal BF/BP –> increase in RENIN/AGNTIOTENSIN ACTIVITY, VASOPRESSN RELEASE, AND ALODSTERONE RELEASE

Question 13

What does BaroR reflex do?

Answer 13

through SNS, total TPR and HR are increased to minimize fall in BP

Inc Symp –> increse ventricular contracility –> preload is limited

INc BaroR -> Increase Arterial Resistance in well-inenrveated vascualr beds (sphlanci, renal, skin) so aretial pressure maintainted in Heart and Brain

Increase venous tone

Question 14

Reabsorption of fluid into capillary

Answer 14

resulting shift of fluid volume from interstitium to circulation helps maintan vascualr volume

Question 15

Reduction in CO reduces blood flow and arterial pressure at the kidny\

Decreaseds GF and retention of fluid in vascular system

Answer 15

Reduction in CO reduces BF and arterial pressure at the kidny
Autoregul

Question 16

Decompensatory changes

Answer 16

With minor hemorrhage, reinfusion restores ciruclating blood volume, BP, and CO.

Reinfusion of blood after a severe or prolonged hemorrhage may fail to restore vascular function

Question 17

Expt: Hemorrhage produced hypovolemia and hypotension for more than two hours in an experimental animal

After 3 hours, animal reifused into anamimal. Result

Answer 17

Blood volume was rstored and BP and CO improved temporarilty.

With tie, both BP and CO fell, even in teh face of continued expansion of vascular volume

Question 18

what does it mean if fialture of vasculature to recover from hypovolemia after reinfusion

Answer 18

implies that the underlying mechanisms of vascular control have been altered

in microcirculation, prolonged hyptoension reduces BF through tissue

With prolonged ischemia the endothelial cells swell and paritall occlude the capillaries

Lymphcyte aggregation, tirggered by inflammatory response, may occlude capllaries even further

Question 19

what are the tissue cahgnes in hypovolemic shock>

Answer 19

1. vascular permeability, edema, ischemia
2. Faiture of aerobmic metaoblism, membrane transprot, HBO2, transprot, lysosomal rupture –> tissue damage
3. Aerobic (glycolysis) metabolism- acidosis
4. Systemic Inflammateroy Response Syndrome

Question 20

Cardiogenic Shock– 3 kinds

Answer 20

1. Acute MI
2. Massive Valve Failture
3. Percardial effusion

Question 21

Acute MI

Answer 21

infarct invovles 30-35% or more of LV

would dramatically reduce ventricular force and SV

Small infarcts are not liekly to produce cardiogenic shock ,but may produce smaller , more progressive hane resultin gin CHF

Question 22

Massive Valve Failture

Answer 22

Rutpure (infarction) of chorda tendinae could produce massive, suden mitral regurgitation
Reuce CO suddenly

Question 23

Pericardial Effusion

Answer 23

Rutpure Coronary BV

COuld produce a heorrhage into space outside of heart and insdie inelastic PERICARDUM

cardiac filling would be mechanically reduced and severel limited

In spite of adequate atrial P, cardiac preload would be reduced and SV limited

Question 24

Massive Valve Failture

Answer 24

Rutpure (infarction) of chorda tendinae could produce massive, suden mitral regurgitation
Reuce CO suddenly

Question 25

Pericardial Effusion

Answer 25

Rutpure Coronary BV

COuld produce a heorrhage into space outside of heart and insdie inelastic PERICARDUM

cardiac filling would be mechanically reduced and severel limited

In spite of adequate atrial P, cardiac preload would be reduced and SV limited

Question 26

Pericardial Effusion

Answer 26

Rutpure Coronary BV

COuld produce a heorrhage into space outside of heart and insdie inelastic PERICARDUM

cardiac filling would be mechanically reduced and severel limited

In spite of adequate atrial P, cardiac preload would be reduced and SV limited

Question 27

What accompanies Cardiogenic Shock

Answer 27

fall in arterial systolic P below 90 or more than 60 mmgh

Cardiac INdex falls below 2.2 L/min/m2

Question 28

Is ventricular filling adequate?

Answer 28

Ventricular FillingP is adequate

Venous return is adequate

Pulmonary capillary wedge pressure is greater than 15 mmHG

Question 29

Features of Cardiogenic Shock

Answer 29

Reduced CO

Reduced arterial P

Reduced Tissue Perfusion, coronary perfusion

Reduced oxygen deliveyr, both coronary and peripheral tissue

SIRS

Vascular Collapse

Question 30

Features of Septic Shock

Answer 30

1% all hospitals admissions

Mortality between 30-80%

Insult occurs at tissue level

Bacterial or funagl

Question 31

Septic shock

Answer 31

Vascular Damage (SIRS)

Vascular permiablity, clogging, and coagulation, ischemia

Hemodynamics
REDUCED TPR!!!
incrased CO
increased central venous P

anaeroic metabolism and lactic acidosis

O2 delivery may be adeaquate; tissues can’t utilize it

Question 32

Principels of Shock Treatment

Answer 32

Improve tissue perfusion

Improve CO
-incrase left atrial P by increasing vascular volume
non-septic shock; above 2.2L/min/m2
Spetic shock; above 4.0L/min/m2

Acidosis

Primary cause: BV, Cardiac support, infection

Question 33

Treatment

Answer 33

Basic

Improve tissue perfusion!!!

Vasoldiators –> so increase O2 delviary, and tisue perfusion

Tx Acidosis with bicarb drugs