Table 1.
Categorization of Shock States based on the Weil and Shubin8 Nosology
| Shock state | Pathophysiology | Disease States | Hemodynamic Monitoring Pattern |
|---|---|---|---|
| Hypovolemic | Decrease in effective circulating blood volume and venous return | Primary intravascular volume loss (hemorrhage, capillary leak) Secondary intravascular volume loss (third-space loss, burns, diarrhea, vomiting) |
↓ filling pressures (↓Pra and Ppao) ↓ CO ↑ SVR |
| Cardiogenic | Primary cardiac failure | Impaired contractility (myocardial ischemia/infarction, electrolyte imbalance, hypoxemia, hypothermia, endocrinologic diseases, metabolic poisoning, beta-blockers) Pump function (valvulopathy, ventriculoseptal defect, dysrhythmias) Diastolic compliance (left ventricular hypertrophy, fibrosis, infiltrative cardiomyopathies, asymmetric septal hypertrophy, cor pulmonale) |
↑ back pressure to cardiac filling (↑Pra and Ppao) ↓ CO ↑ SVR |
| Obstructive | Blockage of blood flow in heart’s outflow tracts | RV outflow obstruction (pulmonary embolism, lung hyperinflation and pulmonary artery compression) LV outflow obstruction (aortic stenosis, dissecting aortic aneurysm) Cardiac Tamponade (pericardial effusion, lung hyperinflation and atrial compression) |
↑CVP ↓ Ppao relative to CVP ↓ CO ↑ SVR |
| Distributive | Loss of blood flow regulation | Sepsis (increased capillary leak with secondary loss of intravascular volume, and inappropriate clotting in the microcirculation) Neurogenic shock (acute spinal injury above the upper thoracic level, spinal anesthesia, general anesthesia, neurotoxic poisoning and central nervous system catastrophe) Acute adrenal insufficiency (hyperpyrexia and circulatory collapse) |
↓CVP ↓ filling pressures (↓Pra and Ppao) ↑ SvO2 ↓ MAP |
Abbreviations: right atrial pressure, Pra; pulmonary artery occlusion pressure, Ppao; cardiac output, CO; systemic vascular resistance, SVR; mean arterial pressure, MAP, central venous pressure, CVP, venous oxygen saturation, SvO2.