**1. Definition**

Circulatory shock is defined as the failure to meet the body's cellular oxygen demands. It typically occurs when the systolic blood pressure falls below 90 mmHg or the mean arterial blood pressure falls below 65 mmHg for 30 min. In circulatory shock there are signs of tissue hypoperfusion such as altered mental status, decreased urine output (<0.5 ml/kg/h), cold and clammy skin, and elevated serum lactic acid level (>1.5 mmol/l) [1].

Cardiogenic shock (CS) is the shock that results from cardiac causes and can be defined as a circulatory failure in addition to severely reduced cardiac index (<1.8 L/min/m<sup>2</sup> without support or <2.0–2.2 L/min/m with support) in the presence of adequate filling pressures (left ventricular end diastolic pressure (LVEDP) > 18 mmHg or right ventricular end diastolic pressure >10–15 mmHg) [2].

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To differentiate CS from other types of shock, the following general hemodynamic measures can be used with the help of echocardiography or pulmonary artery catheterization (**Table 1**).

PCWP, pulmonary capillary wedge pressure, LVEDP, left ventricular end diastolic pressure; SVR, systematic vascular resistance; CI, cardiac index; CO, cardiac output.

**Table 1.** General hemodynamic measures to differentiate between cardiogenic shock and other types of shock.
