Answer: a, b, d, e Classification schemes of shock based on cause have been developed for the seemingly dissimilar processes leading to circulatory collapse and the shock state. Hypovolemic shock, the most common, is the result of intravascular volume depletion through loss of red blood cell mass or plasma volume. Microvascular hypotension results from a combination of low intravascular blood volume, diminished cardiac output, and compensatory sympathetic peripheral vasoconstriction. Shock associated with trauma (traumatic shock) arises from the consequences of hypovolemia due to hemorrhage in conjunction with direct soft tissue injury and bone fracture. Hypovolemia caused by blood loss and fluid extravasation into injured tissues is compounded by activation of maladaptive inflammatory cascades initiated by the tissue injury. In contrast to pure hemorragic shock, subsequent organ injury and multiorgan failure syndrome (MOFS) occurs much more frequently following traumatic shock due to the over-expression of these immuno-inflammatory cascades. Cardiogenic shock is the result of failure of the heart as an effective pump, resulting in inadequate cardiac output, tissue perfusion and oxygen delivery. Intrinsic causes include myocardial infarction, cardiomyopathy, valvular heart disease, or rhythm disturbances. Compressive cardiogenic shock is a discrete entity that results when extrinsic compression of the heart limits diastolic filling and thus systolic ejection and cardiac output. Septic shock refers to hypotension and circulatory insufficiency developing as a consequence of infection and the systemic response to that infection. In its hyperdynamic form, septic shock is marked by diminished peripheral vascular resistance and generalized vasodilatation causing relative hypovolemia. In contrast, hypodynamic septic shock occurs in situations of inadequate resuscitation or preterminal cardiovascular decompensation, and is associated with vasoconstriction and a greatly increased mortality risk. Sympathetic denervation through spinal cord injury, spinal anesthesia, or severe head injury produces generalized arterial vasodilatation and venodilation. Shock occurs when the normal blood volume fails to fill the available intravascular space and severe relative hypovolemia exists. Despite hypotension, there is a noteworthy absence of sympathetic activity, as occurs in hypovolemia or cardiogenic shock. Profound shock can occur in surgical patients following stress due to the loss of the homeostatic corticosteroid response. Hemodynamic instability may develop after an operative procedure or coincident with an unrelated illness. The profound circulatory collapse is often refractory to vigorous resuscitation with fluids and pressor agents. The response to exogenous corticosteroids is usually dramatic and potentially life-saving