Shock Syndromes I

Patient Case

Questions 4 and 5 pertain to the following case.

J.B. is a 28-year-old man (weight 92 kg) who presented to the surgical ICU with shock after an appendectomy

was complicated by appendiceal perforation. In the operating room, the patient received 2 L of lactated Ringer’s

solution and 500 mL of 5% albumin and was initiated on norepinephrine. The patient is still receiving norepi-

nephrine 12 mcg/minute (0.13 mcg/kg/minute) with a lactate of 6.8 mmol/L and had a CO increase of 18% with

a PLR.

Which would best meet J.B.’s fluid needs?

After 12 hours in the surgical ICU, J.B. remains hypotensive with a lactate concentration of 5.2 mmol/L. He

currently requires norepinephrine 14 mcg/minute (0.15 mcg/kg/minute); his MAP is 64 mm Hg and Scvo2

is 61%. A bedside echocardiogram done by the ICU team reveals large ventricles with poor contractility.

Which action is best?

Vasodilatory shock broadly describes tissue hypoperfusion secondary to a decrease in SVR or

hypoperfusion despite a normal or elevated CO, whereas distributive shock is technically a subset

of vasodilatory shock that describes maldistribution of blood flow at the level of microcirculation

(shunting) or at the organ level. However, this differentiation is likely trivial because distributive shock

usually exists in vasodilatory shock, and the terms are often used interchangeably.

vasoactive medications having this shock type.

Septic shock is the most common cause of vasodilatory shock, but this shock type may also occur

in several other conditions, including immune-mediated (“anaphylactic”) and nonimmunologic

(“anaphylactoid”) reactions, neurogenic shock (classically secondary to spinal cord injury), intoxication,

peridural or epidural infusion, adrenal insufficiency (Addisonian crisis), and thyroid insufficiency

(myxedema coma) or as a component of ischemia-reperfusion injury (e.g., after cardiac arrest or

cardiopulmonary bypass). Vasodilatory shock also occurs because of prolonged severe hypotension

from any initial shock type (vasodilation is a final common pathway).

The three most common causes of vasodilatory shock are septic shock (which will be covered in detail

in section VII, Sepsis), immune-mediated (anaphylactic) shock, and neurogenic shock.