Trauma/ hemorrhage

Question 1

Advanced Trauma Life Support (ATLS) classes of hemorrhage:
Class II

Answer 1

(15–30% loss), tachycardia and subtle changes in mentation are observed.
Blood pressure normal

Question 1

Advanced Trauma Life Support (ATLS) classes of hemorrhage:
Class I

Answer 1

(up to 15% loss), clinical symptoms of volume loss are not readily observed.

Question 2

Advanced Trauma Life Support (ATLS) classes of hemorrhage:
Class III

Answer 2

circulatory shock and requires immediate intervention
(30–40% loss), marked tachycardia, impaired mentation, and measurable hypotension occur.

Question 3

Advanced Trauma Life Support (ATLS) classes of hemorrhage:
Class IV

Answer 3

circulatory shock and requires immediate intervention
(> 40% loss), these vital signs are further deranged and may lead to a complete loss of consciousness

Question 4

Compensatory mechanisms for declining intravascular volume: immediate

Answer 4

within minutes
baroreceptor-mediated stimulation of the sympathetic nervous system = increased HR, contractility, selective vasoconstriction
Baroreceptors - detect decreased BP –> arterial and capacitance venoconstriction –> increased HR; CO maintained despite decreased preload
Chemoreceptors - detect hypoxemia and met acidosis –> increased ventilatory drive and RR
Local tissue factors = regulate vasomotor tone

Question 5

Compensatory mechanisms for declining intravascular volume: intermediate

Answer 5

1. Transcapillary shifts (fluid from interstitium + IC –> IV)
2. RAAS activation
   a. Ang II - vasomotor tone

Question 6

Compensatory mechanisms for declining intravascular volume: late

Answer 6

net positive fluid balance occur in patients 1–48 hours after survival of the initial insult

Question 7

Compensatory mechanisms for declining intravascular volume: immediate - depressor reflex

Answer 7

slow rates and lower magnitudes of blood loss
vagal-mediated bradycardia and vasodilation predominate over the baroreceptor reflex in order to preserve blood flow while minimizing blood loss

Question 8

Location of baroreceptors
What do they detect?

Answer 8

Aortic arch, carotid sinus, left atrium
BP

Question 9

Location of chemoreceptors
What do they detect?

Answer 9

Aorta, carotid artery
Hypoxemia

Question 10

How do local tissue factors regulate vasomotor tone?

Answer 10

decreases in PaO2 and production of local metabolites (eg, CO2 , H+ ) –> vasodilation via release of prostaglandins, nitric oxide, and adenosine, allowing capillary recruitment and redistribution of blood flow

Question 11

Describe intrinsic myogenic autoregulation in normal states and during hemorrhage

Answer 11

regulates vessel tone in response to changes in local blood pressure

normal conditions - only a fraction of capillaries in organs are open to allow the passage of RBCs

hemorrhage - the number of open capillaries increases proportionally to the degree of tissue hypoxia
recruitment of capillaries promotes oxygen diffusion by decreasing the distance to tissue beds and increasing the surface area available

Question 12

Angiotensin II

Answer 12

• NE release from adrenal medulla and sympathetic nerve terminals
• vasopressin
• aldosterone
• thirst
• Na reabs in proximal tubule (activating Na-H antiporter)
• preferential efferent arteriolar vasoconstriction

Question 13

Vasopressin release stimulated by

Answer 13

increased osm, decreased ECV

Question 14

Vasopressin - actions

Answer 14

V1 - arterioles - vasoconstriction
V2 - CD - inserts aquaporins - promotes water reabsorption
Increases thirst

Question 15

Aldosterone

Answer 15

Increases Na reabsorption in the DCT

Question 16

Compensated hemorrhagic shock/ acute compensatory shock - PE findings

Answer 16

Tachycardia
Narrow pulse pressure
Vasoconstriction - prolonged CRT
Increased RR - decreased CaO2 and perceived O2 debt

Question 17

Phases of decompensated shock

Answer 17

early/acute and late
or
compensatory reversible, decompensated reversible, decompensated irreversible

Question 18

Irreversible shock

Answer 18

systemic vasodilation, decreased cardiac filling pressures, myocardial systolic depressionm widespread cellular dysfunction

Question 19

Acute traumatic coagulopathy (ATC) - factors

Answer 19

20-30 min post-injury
considered unrelated to the actual loss, consumption, inhibition, or dilution of hemostatic factors or platelets

Question 20

Proposed precipitating factors of ATC (6)

Answer 20

1. tissue injury
2. hypoperfusion (shock)
3. systemic inflammation
4. metabolic acidosis
5. hypothermia
6. hemodilution

Question 21

ATC - two main drivers

Answer 21

1. Shock due to ongoing tissue hypoperfusion
2. Severity of tissue injury