Restlessness and apprehension are early symptoms, often followed by apathy.

Eyes may be glassy and dull. Pupils may be dilated. (These are also the symptoms of morphine use.)
Breathing may be rapid or labored, often of the gasping, "air hunger" type. In the advanced stages of shock, breathing becomes shallow and irregular.

The face and skin may be very pale or ashen gray; in the dark complexioned, the mucous membranes may be pale. The lips are often cyanotic.

The skin feels cool and is covered with clammy sweat. The skin's coolness is related to a decrease in the peripheral circulation.

The pulse tends to become rapid, weak, and thready. If the blood pressure is severely lowered, the peripheral pulse may be absent. The pulse rate in hemorrhagic shock may reach 140 or higher. In neurogenic shock, however, the pulse rate is slowed, often below 60.

The blood pressure is usually lowered in moderately severe shock; the systolic pressure drops below 100, while the pulse rises above 100. The body is compensating for circulatory fluid loss by peripheral vasoconstriction. This process tends to maintain the blood pressure at a nearly normal level despite a moderately severe loss of circulating blood volume. Apoint comes, however, when decompensation occurs, and a small amount of additional blood loss will produce a sudden, alarming fall in blood pressure.

There may be nausea, vomiting, and dryness of the mouth, lips, and tongue.

Surface veins may collapse. Veins normally visible at the front of the elbow, forearms,

Table 4-2.-Correlation of Magnitude of Volume Deficit and Clinical Presentation

and the back of the hands will be hard to distinguish.

There are frequent complaints of thirst. Even the severely wounded may complain of thirst rather than pain.
The kidneys may shut down. Urine formation either ceases or greatly diminishes if the systolic blood pressure falls below 80 for long periods of time.

The person may faint from inadequate venous blood return to the heart. This may be the result of a temporary gravitational pooling of the blood associated with standing up too quickly.

HYPOVOLEMIC SHOCK
Hypovolemic shock is also known as oligemic or hematogenic shock. The essential feature of all forms of hypovolemic shock is loss of fluid from the circulating blood volume, so that adequate circulation to all parts of the body cannot be maintained.

Hemorrhagic Shock
In cases where there is internal or external hemorrhage due to trauma (hemorrhagic shock), there is a loss of whole blood, including red blood cells. The diminished blood volume causes a markedly lessened cardiac output and reduced peripheral circulation. This results in reduction of oxygen transported to the tissues (hypoxia); reduction of perfusion, the circulation of blood within an organ; and reduction of waste products transported away from the tissue cells. Under these conditions, body cells are able to carry on their normal functions for only a short period of time. The body tries to restore the circulatory volume by supplying fluid from the body tissues. The result is a progressive fall in the hematocrit (ratio of red blood cells to plasma) and in the red blood cell count.

Burn Shock
In burn shock, on the other hand, there is a progressive increase in the hematocrit and red blood cell count. This increase is due to hemoconcentration from loss of the plasma fraction of the blood into and through the burned area.