Shock and Hemodynamics Flashcards
Pt factors that impair recognition of shock
Elderly Athletes Pregnant - extra volume Medications (beta blocker, Ca channel blocker) Pacemaker Sepsis
What do you look for in clinical exam to recognize shock
- signs/sxs of hypoperfusion
- signs/sxs of catecholamine response
- baroreceptor reflex activation
consider underlying - Consider underlying scenario
- Be very suspicious
Ex: decreased consciousness/anxiety tachypnea, shallow respirations, cool/clammy skin**, prolonged capillary refill **, decreased urine output, JVD, in cardiogenic shock,
*** Or warm erythematous skin with nl cap refill in septic shock due to inflammatory mediators causing vasodilation
Is it better to use MAP or systolic/diastolic to assess BP
MAP in most cases
What is MAP
average pressure at arterial level
MAP= Systolic + (2/3)(Diastolic)
Why is MAP better than systolic/diastolic for tissue perfusion…
2/3 cardiac cycle are diastole
- remains constant as pressure wave propagates distally in veseles
- less prone to waveform dignal distortions from monitoring systems (over/underdamping)
Drawbacks to using MAP to assess tissue perfusion
less accurate as more time in dystole (tachycardia)
- variations in SVR may have acceptable MAP but CO2 too low
What does lower pulse pressure indicate
suggests significant blood loss
- result of increasing diastolic pressure from compensatory
If you can feel dorsalis pedis pulse, what is the rough BP
at least 80
If you can feel femoral pulse, what is the rough BP
70
If you can feel radial pulse, what is the rough BP
80
If you can feel carotid pulse, what is the rough BP
60
ATLS Classifications of hemorrhagic shock
Class I, II, III IV
how much blood do you lose before hypotension occurs
Class III–lose about 40% of blood
- One of last sxs of shock
- BP responds to volume loss
Consequences of hypoperfusion
tissue hypoxia -> anaerobic metabolism -> cell injury/death -> inflammatory cascade -> organ dysfunction
What causes cardiogenic shock
you get a lower cardiac output due to a lower heart rate or contractility (heart can’t squeeze as well)
- Due to changes in HR and SV
(bradycardia, tachyarrhythmias prevent filling–>decreased stroke volume, heart failure)
What is distributive/Septic shock
decreased cardiac output due to combo of impaired preload and contractility (thus making stroke volume decrease)
Preload problems: lose vasomotor tone, capillary leak
Contractility issues: inflammatory mediators cause your heart not to work as well (myocardial depression)
Sepsis: get massive swelling/edema
What is shock
inadequate tissue perfusion/cellular oxygenation
What are the 3 main types of shock
Hypovolemic
Cardiogenic
Distributive/septic
What is hypovolemic shock
Not enough preload, so the heart can’t pump as much out –> lower stroke volume
Subtypes:
- Hemorrhagic (trauma, GI bleed, maternal/fetal hemorrhage)
- Nonhemorrhagic (dehydration, gastroenteritis, infection)
Compensatory physiology ni shock
lower preload –> message to shut down vagus nerve –> Tachycardia
catecholamines released for heart to pump harder/faster. We get vasoconstriction/narrowed pulse pressure (- Pale, purple– trying to redirect bloodflow to heart and brain)
** NOTE pulse pressure is increased in septic shock since you get vasodilation and decreased diastolic pressure)
RAAS– body tells kidneys to conserve water
Tests/labs to assess for shock
Test: Serum lactic acid
Labs: ABG (pH/bicarb), lactate , CBC
- also procalcitonin–tells you if you should be concerned about microbial infection; virtual absence in health
Most common type of shock in surgery
hypovolemic
