Shock & Pressors Flashcards
Criteria for ARDS Diagnosis
- Acute onset
- Chest X-Ray: Bilateral diffuse infiltrates of the lungs
- No cardiovascular lesion
- No evidence of left atrial hypertension: PaO2/FiO2 ratio equal to or less than 200 mmHg.
Definition of Shock
Failure of circulatory system to maintain adequate blood flow to end organs
3 most common forms of shock
Distributive, Hypovolemic, Cardiogenic
Common causes of distributive shock
Sepsis, Anaphylaxis, Neurogenic
Equation for MAP
MAP = CO * SVR = SV * HR * SVR
Use this to figure out how to treat shock in the short-term
3 Short-term interventions for shock
1) Fluids: inc SV –> inc CO –> inc MAP
2) Vasopressors: inc SVR –> inc MAP
3) Inotropes: inc CO –> inc MAP
Hypovolemic Shock - PCWP / CO / SVR
PCWP decreases
CO decreases
SVR increases
Cardiogenic Shock - PCWP / CO / SVR
PCWP increases
CO decreases
SVR increases
Distributive Shock - PCWP / CO / SVR
PCWP decreases
CO increases or decreases
SVR decreases
How to figure out PCWP and SVR of a patient clinically
Clinically dry - decreased PCWP
Clinically wet - increased PCWP
Cold extremities - increased SVR
Warm extremities - decreased SVR
3 Types of Vasoactive agents used in shock
Vasopressors
Inodilators
Inopressors
Receptors targeted by vasoactive agents
a1 - peripheral vasoconstriction b1 - inotropy b2 - peripheral vasodilation V1 - peripheral vasoconstriction D1 - selective vasodilation of renal, mesenteric, cerebral, coronary vasculature
Volume status and Pressors
Aggressive IVF is key 1st step. Pressors can cause decreased end-organ perfusion if there’s inadequate circulating volume
Name the 6 vasoactive agents commonly used
Dobutamine - ID Epinephrine - IP Dopamine - IP Norepinephrine - IP Phenylephrine - VP Vasopressin - VP
Dobutamine
Inodilator
0-20 mcg/kg/min
b1, b2
inc CO, dec SVR
Epinephrine
Inopressor
0-10 mcg/kg/min
a1, b1, b2
inc CO, inc SVR
Dopamine
Inopressor
0-20 mcg/kg/min (renal dose 0-2.5)
Renal dose: b1, D1 - inc CO, dec SVR
Higher doses: a1, b1, D1 - inc CO, inc SVR
Norepinephrine
Inopressor
0-20 mcg/min
a1, b1
inc CO, inc SVR
Phenylephrine
Vasopressor
0-200 mcg/kg/min
a1
inc SVR
Vasopressin
Vasopressor
0.04 units/min
V1
inc SVR
First line agents in shock
Norepinephrine and Dopamine
For both Cardiogenic and Septic shock
ACC/AHA and Surviving Sepsis Campaign
SOAP II Trial (NEJM 2010)
Dopamine vs Norepinephrine 1679 pts in shock (cardiogenic & septic) No mortality diff at 28 days Dopamine had increased mortality at 28 days for pts in cardiogenic shock Dopamine pts had more arrhythmic events
Pressors in Sepsis Study (Chest 1993)
32 pts in septic shock randomized to NE vs DA. If no response, rescue w/ other agent.
DA response 31%; NE response 93%.
NE rescued 10/11 DA failures.
Survival NE 59%; DA 17%.
Renal dose DA in sepsis study (Lancet 2000)
328 septic pts w/ early renal failure
Randomize to DA vs Placebo
Results: No difference in peak Cr or clinical outcomes
Second-Line Agents for Shock
Phenylephrine and Epinephrine
Phenylephrine - data for use
Less useful in cardiogenic shock (already increased SVR).
In sepsis, potential to lower SV b/c increases SVR w/o increasing CO
Possible dec splanchnic blood flow
May be useful in pts w tachyarrhythmia, esp if worsened with NE
Epinephrine - data for use
First line for anaphylactic shock
Increases inotrophy more than NE, but more arrhythmias
Dec splanchnic Q, inc lactate
Vasopressin - data for use
Only use as adjunctive agent
Studies show lower ADH lvls in sepsis
Better HD & end-organ perfusion, lower tachyarrhythmia, higher ischemic skin lesions
Use at fixed rate of 0.04u/h - no titration
Dobutamine - data for use
Only use as adjunctive agent
Septic pts often have lower CO 2/2 endotoxins & cytokines.
Studies show no benefit and possibly harm (Systemic O2 delivery study NEJM 1994).
Never use only as lower SVR may reduce BP more than increased by higher CO.
