Wk5: Shock Flashcards
Definition of shock
Hypoperfusion of vital organs including brain, heart, kidneys, lungs, gut. NOT low BP.
How to evaluate/track level of oxygen supply/demand imbalnce
Lactic acid
Autonomic response to anaerobic metabolism
Constriction of arterioles and veins, increased HR, increased contractility, release of ADH, epi, dopamine, NE, cortisol
Cellular cascade response to O2 imbalance (ATP depletion –>)
ATP depletion -> ion pump dysfunction -> Na influx/K efflux -> cellular edema -> lysosomal enzyme release -> cell death
(cytokine mediated)
Typical lab findings in shock (5)
Hyper-K, Hypo-Na, Metabolic and Lactic acidosis, Hyperglycemia
What are SIRS and MODS (define acronym)
Systemic Inflammatory Response Syndrome, Multi-Organ Dysfunction Syndrome
What findings constitute a patient on the shock continuum? (SIRS criteria)
2+ of the following:
Temp 38, HR ≥ 90, RR ≥ 20, PaCO2 <32 mmHg, WBC ≤ 4k or ≥ 12k or 10% bands
4 Clinical Stages of Shock: Stage 1
Mild resp alkalosis + oliguria + hyperglycemia
4 Clinical Stages of Shock: Stage 2
Tachypnea + hypocapnia + hypoxia. Mod liver dysfx and poss hematologic abnormalities
4 Clinical Stages of Shock: Stage 3
Azotemia + acid-base disturbance + sig coag abnormalities
4 Clinical Stages of Shock: Stage 4
Vasopressor dependent + olig/anuria + ischemic colitis + lactic acidosis
What is azotemia?
Abnormally high levels of nitrogen-containing compounds e.g. BUN and creat
Classic clinical findings in shock
Hypotension: sys 30 < usual, urine <20 cc/hr, elevated lactic acid, altered mental status
How might skin findings differ between types of shock?
Generally cool and clammy in shock BUT warm, flushed with distributive/dissociative
Calculate shock index. What’s normal?
HR/sys BP: inversely related to effective LV stroke work. Normal: 0.5 - 0.7. Note ≥1 = inc mortality
How does capillary wedge pressure work? (Not done due to associated increase in mortality)
Insert catheter through subclavian -> heart -> lung capillaries. Inflate balloon to stop pressure from behind. All pressure is assumed to be from front (estimate of LA and LV pressure)
Examples of cardiogenic shock
Acute MI, arrhythmia, hypertrophic cardiomyopathy, aortic stenosis -> decreased CO
Examples of distributive/ dissociative shock
Spinal cord injury, anaphylaxis, endo (gram neg) or exotoxin (gram pos). Dissociative = something stopping O2 from reaching cells e.g. CO, cyanide
Extracardiac shock - definition and examples
Outflow obstruction -> decreased CO due to external path e.g. PE, pericardial tamponade, pulm htn
Hypovolemic shock causes
Diarrhea, vom, diuretics, sweating, hemorrhage, burns, 3rd spacing (ascites)
Step 1 of shock treatment
Volume replacement: NS 20-30 mL/kg, blood if hgb <7
Treatments other than NS for shock
Vasopressors: NE, epi, dopamine (less so because of 3rd receptor - dopaminergic), dobutamine
How does epi work?
a1 @ post-syn a2 -> arteriolar vasoconstriction. Pre-syn a2 inhibit NE release. B1 ->pos chron and inotropic. B2 -> arteriolar vasodilation, bronch sm musc relax, inc glycogenolysis
How does dobutamine work as a vasopressor
Beta-adrenergic inotropic effects
How does dopamine work as a vasopressor?
alpha -> vasoconstriction. beta -> ino and chronotropic + vasodilation. Nonadrenergic splanchnic and renal vasodilation
How does NE work?
alpha -> vasoconstriction. beta -> ino and chronotropic
Other than NS and vasopressors, what treatments are possible depending on the situation?
antibiotics, surgery, thrombolytics, anticoagulants
