Categories of Shock
Physiologic Components of Shock
The body does not have sufficient volume. Could be due to bleeding or dehydration.
The primary problem is preload.
Signs are a low JVP, cool extremities, and tachycardia.
The heart can't pump enough blood to perfuse the tissues.
The primary problem is contractility.
Signs are an increased JVP, cool extremities, and tachycardia.
The blood is not distributed properly to the tissues. For example, in sepsis or anaphylaxis.
The primary problem is afterload.
Signs are warm extremities, and tachycardia.
Complicated. The blood cannot get to certain areas. For example, in a pulmonary embolism or a tension pneumothorax.
The primary problem is contractility and preload.
Signs are elevated JVP, cool extremities, and tachycardia.
Shock and Organ Systems
Shock focuses primarily on five major organ systems.
Heart - hypotension, cardiac rate and rhythm
Lungs - tachypnea, hypoxemia
Kidneys - decreased urine output
CNS - decreased mentation
Skin - mottling and temperature
Adjusting Preload in Shock
Not enough preload, give fluids
Too much preload, give diuretics
Adjusting Rate in Shock
Too fast - usually need to treat the underlying cause. May need a rate-controlling agent or cardioversion.
Too slow - give atropine, epinephrine, or pacing.
Adjusting Rhythm in Shock
Anything other than sinus rhythm is usually a problem.
Consider chemical or electrical cardioversion.
Adjusting Contractility in Shock
Can be assessed with echocardiography.
If inadequate contractility, inotropes can be given. Also want to optimize oxygen delivery to the myocardium and correct any metabolic derangements.
Adjusting Afterload in Shock
Too much - give vasodilators
Too little - give vasoconstrictors
Adjusting Blood Content in Shock
The biggest bang for your buck is cardiac output. If you double cardiac output, you double oxygen delivery to the tissues.
Therefore, optimizing CO should take precedent over optimizing PaO2