Flashcards in Critical Care Deck (44)
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1
What determine tissue perfusion?
1) CO = SV x HR
2) SV = Preload x contractility
2) SVR = (MAP - CVP)/CO
3) BP = CO x SVR
2
Hypovolemic shock
Reduced venous return, pump is working
Low preload. Low CO
Bleeding, vomiting/diarrhea, and third spacing (burns, bowel obstruction, pancreatitis)
Tachy, ortho hypo, cool skin
Will become hypotensive, low pulse pressure, confused, cold clammy skin due to clamping down of peripheral vessels via increased sympathetic tone
in trauma, assume shock is hypovolemic until proven otherwise
3
First vital organ to succumb to shock?
kidney - in hypovolemic or cardiogenic ( the cold shocks)
Blood shunted away from constricted renal arteries
CRUCIAL to monitor for renal failure. A good urine output is a great sign that treatment is working
4
What factors suppress the tachycardic response in hypovolemia?
Beta blockers
Athletes
Damage to autonomic nervous system (spinal shock)
Never use dextrose-containing solution for resuscitation
5
SIRS criteria
2+ of following:
Temp > 38C or 90
RR > 20 or PaCO2 12 or 10% bands
6
Sepsis
Identifiable source of infection + SIRS
7
Severe sepsis
Sepsis + organ dysfunction
8
Septic shock
Sepsis + cardiovascular collapse (requiring vasopressor support)
9
What kind of bacteria are notorious for causing septic shock?
gram-negative bacteria
E Coli
Kleb
Pseudomonas
Top 3 gram positives are:
Staph aureus
Enterococcus
Coag-neg staph
10
HR issues leading to shock
too slow
too fast (not enough time to fill)
11
Preload issues leading to shock
More blood into heart = more blood out
Volume down
Hemorrhage
Obstruction (tension pneumo, pericardial tamp)
12
Contractility issues leading to shock
HF
MI or myocardial contusion
13
SVR and shock
Massive vasodilation - sepsis/anaphylaxis
Spinal trauma (ANS is lost)
Anesthetics
ANS dysfunction (elderly diabetic)
14
Neurogenic shock
CNS injury causing disruption of sympathetic system, resulting in unopposed vagal outflow and vasodilation.
Hypotension and bradycardia (absence of reflex sympathetic tachy and vasoconstriction)
Usually secondary to spinal cord injury of cervical or high thoracic region
Tx = IVFs - helps to place patient in trendelenburg
Vasopressors - used early if patient unresponsive to fluids
15
End points of resuscitation for shock of any etiology
Normalization of lactate (marker of O2 debt), base deficit, pH
Normalization of mixed venous O2 sat (marker of O2 delivery and extraction) and CO
Urine output (marker of renal perfusion)***
16
Swan Ganz
Measure PCWP (preload) - normal 6-12 - reflecting pressure in LV
If pump is failing, you'll see increased wedge
Risks = infection, arrhythmia, injury of pulmonary artery
17
Mixed venous O2 sat
% of O2 bound to hemoglobin in blood returning to heart
It's the amount of O2 left over after tissues remove what they need
Normal = 60-80%
Low = CO isn't high enough to meet tissue O2 needs
BUT
Rise in setting of increased lactate means we're going to anaerobic (late septic shock or in cell poisoning)
18
Side effects of pressors
If B1 stimulation - arrhythmia
If B2 stimulation - vasodilation therefore hypotension
19
The alpha agonists
Phenylephrine, methoxamine (a1 > a2)
Clonidine, methylnorepinephrine (a2 > a1)
20
The mixed alpha and beta agonists
Norepi a1=a2; B1> B2
Epi a1=a2; B1=B2
21
Beta agonists
Dobutamine B1 > B2
Isoproterenol B1 = B2
Terbutaline, metaproterenol, albuterol, ritodrine B2 > B1
22
Dopamine agonists
Dopamine D1 = D2
Fenoldopam D1 > D2
23
Dobutamine
Strong B1 stimulator (ionotropic/chronotropic) wit mild B2 stimulation (vasodilation)
Causes increase in CO and decrease in SVR
Usually used in: Cardiogenic shock
24
Isoproterenol
Similar to dobutamine
Strong stim of B1 (ionotropic/chronotropic) and B2 (vasodilation)
Increased CO and decreased SVR
Use: Cardiogenic shock with bradycardia
25
Milrinone
Phosphodiesterase inhibitor, which results in increased cAMP. This has positive ionotropic effects on heart and also vasodilates
Increased CO and decreased SVR
Use: HF/Cardio shock
26
Dopamine
Different actions depending on dose
1) Low dose (1-3ug/kg/min) = renal dose. Stimulates dopamine recepters (dilates renal vessels) and mild B1 stim
Use: None
2) Intermed dose (5-10) = cardiac dose. Stimulation of dopamine receptors, moderate stim of B1 (heart ionotropy/chrono) and mild a2 (vasoconstriction)
Result = Increased CO
Use = cardiogenic shock
3) High dose (10-20). Stim D, B1, and strong a1 (vasoconstict)
Result = Big increase in SVR
Use = septic shock (replaced by norepi)
27
Norepinephrine
Strong stim of a1 (vasoconstrict), moderate B1 (heart ionotrope/chrono)
Result: higher SVR and higher CO
Use = septic shock
28
Epinephrine
Strong stim of B1 and B2. Also A1 and A2
Result = Increased SVR +/- Increased CO, bronchodilation
Use = Anaphylaxis, septic shock, cardiopulmonary arrest
29
Phenylephrine
Strong stim of A1 (vasoconstrict)
Result = Increased SVR
Use = septic shock, neurogenic shock, anesthesia-induced hypotension
30
