nvic academy

Shock is the clinical expression of circulatory failure that results in inadequate cellular oxygen utilization. Shock is a common condition in critical care, affecting about one third of patients in the intensive care unit (ICU).1 A diagnosis of shock is based on clinical, hemodynamic, and biochemical signs, which can broadly be summarized into three components. First, systemic arterial hypotension is usually present, but the magnitude of the hypotension may be only moderate, especially in patients with chronic hypertension. Typically, in adults, the systolic arterial pressure is less than 90 mm Hg or the mean arterial pressure is less than 70 mm Hg, with associated tachycardia. Second, there are clinical signs of tissue hypoperfusion, which are apparent through the three “windows” of the body2: cutaneous (skin that is cold and clammy, with vasoconstriction and cyanosis, findings that are most evident in low-flow states), renal (urine output of 1.5 mmol per liter) in acute circulatory failure.