**4. Recognition of shock**

Shock management requires securing airway, controlling breathing, and optimizing circula-

Shock is a state of circulatory insufficiency creating imbalance between oxygen delivery and demand to the tissues, resulting in end-organ dysfunction. At the cellular level, shock first affects the mitochondria. Majority of the aerobic energy comes from combustion of substrates (carbohydrates and fats) along with oxygen, forming carbon dioxide and water. But in shock there is cellular hypoxemia; the tissues enter in anaerobic state and accumulate lactic acid.

Measurement of serum lactic acid aids in detecting tissue hypoxemia. It is a reliable tool for

tion to ensure adequate tissue perfusion [2] (**Figure 1**).

Lactate starts building up in the blood and acidosis develops [3].

predicting the outcome and prognosis [4] (**Figure 2**).

**2. Pathophysiology**

**Figure 1.** Management of shock [2].

28 Essentials of Accident and Emergency Medicine

**Figure 2.** Pathophysiology of shock [2].

After the airway is secured and ventilation is optimized, the circulatory status must be evaluated. Tachycardia and cutaneous vasoconstriction may be early signs of shock. Respiratory rate and pulse pressure (difference between systolic pressure and diastolic pressure) are of significance, too [2].

Hypotension develops in late stages of shock, and its absence does not exclude shock [2].

Serum lactic acid and base deficit are good parameters for detecting the presence and severity of shock [2].

The cause of shock can be determined by taking good history, detailed physical examination, and ordering for necessary investigations (e.g., imaging, bedside ultrasound) [2].
