Shock Classification and Management

Classification of Shock

Shock results from inadequate blood flow and oxygen delivery to meet tissue metabolic demands, with four primary categories: hypovolemic, distributive, cardiogenic, and obstructive 1
The American Heart Association recommends classifying shock into these four categories to guide management 1

The American College of Cardiology recommends using hypotension (systolic blood pressure <90 mmHg for >30 minutes, or mean arterial pressure <60 mmHg) and signs of end-organ hypoperfusion for shock diagnosis 4, 6
Signs of end-organ hypoperfusion include altered mental status, cold extremities, urine output <30 mL/h or <0.5 mL/kg/h, elevated lactate >2 mmol/L, and acute liver or kidney injury 4, 6

The American College of Cardiology recommends immediate fluid resuscitation with crystalloids for hypovolemic shock 4
For distributive (septic) shock, the Surviving Sepsis Campaign recommends early fluid resuscitation (30 mL/kg crystalloid within first 3 hours) and vasopressor therapy with norepinephrine to maintain mean arterial pressure ≥65 mmHg 5
For cardiogenic shock, the American College of Cardiology recommends immediate revascularization for AMI-related shock, hemodynamic support with vasopressors and inotropes, and mechanical circulatory support for refractory shock 4, 6

The American College of Cardiology recommends monitoring mean arterial pressure ≥65 mmHg, cardiac index >2.0-2.2 L/min/m², and pulmonary capillary wedge pressure <20 mmHg in cardiogenic shock 4, 6
Lactate trending toward normalization (<2 mmol/L) is also recommended as a monitoring parameter 4, 6

The American College of Cardiology warns against excessive fluid in cardiogenic shock, which can worsen pulmonary edema and right ventricular failure 6
Inadequate fluid in distributive shock can worsen tissue hypoperfusion, and delayed mechanical circulatory support can increase complications and mortality in refractory cardiogenic shock 2, 6