Shock

Today we discussed an approach to hypotension and shock. A few important points:

Hypotension and shock are not synonymous; shock is tissue hypoperfusion.
e.g.
1) A patient with a baseline sBP of 180 whose sBP falls to 110 because of sepsis. If there are signs of hypoperfusion, this relatively low BP for this patient (but not necessarily someone else) means shock.
2) A patient with EF of 20 % might have a baseline sBP of 80 and be perfectly well perfused

How can you tell whether a patient is in shock?
Look for signs of hypoperfusion of different organs:
1) Brain- altered mental status
2) Kidneys- decreased urine output, prerenal failure - this is the most sensitive
3) Skin- cool, clammy, 'clamped down' (although be careful since causes of distributive shock do not do this)
4) Heart- signs of ischemia (unusual unless profound)
5) Liver- elevated liver enzymes (usually post-shock)
6) Lab sign of general tissue hypoxia: elevated lactate (type A lactic acidosis)- look for a high anion gap and a low bicarbonate

Differential diagnosis of shock and what you might find on exam:
1) Hypovolemic / hemorrhagic: usually a cause is apparent; low JVP, clear lungs, peripheral vasoconstriction (cool extremities)
2) Distributive (sepsis, anaphylaxis, neurogenic)- primary problem is uncontrolled peripheral vasodilation. Low JVP, clear lungs, peripheral vasodilation (warm extremities)
3) Cardiogenic- primary problem is low cardiac output. Peripheral vasoconstriction in response, often pulmonary edema, high JVP
4) Obstructive- Cardiac tamponade, tension pneumothorax, massive PE. Primary problem is decreased preload or R heart output. Often high JVP, clear chest, peripheral vasoconstriction

Others:
Tachy/brady arrhythmias, adrenal crisis.
Sepsis is unique in that it causes a combination of many of the above (distributive problem, hypovolemia, myocardial depression)

Special cases:
-Shock / hypotension with high JVP: cardiogenic shock, massive PE, tamponade, tension pneumothorax.
-Shock / hypotension and hypoxemia: cardiogenic shock with pulmonary edema, ARDS, PE, tension pneumothorax

Link: Click here for a previous post on acute UGIB management