LEARNING OBJECTIVE: Recognize the signs and symptoms of shock, and determine treatment by the type of shock presented.
Shock is the collapse of the cardiovascular system, characterized by circulatory deficiency and the depression of vital functions. There are several types of shock:
Multiple types of shock may be present in varying degrees in the same patient at the same time. The most frequently encountered and most important type for the Hospital medical technician to understand is hemorrhagic shock, a type of hypovolemic shock which will be discussed later in this chapter.
Shock should be expected in all cases of major injury, including gross hemorrhage, abdominal or chest wounds, crash or blast injuries, extensive large-muscle damage (particularly of the extremities), major fractures, traumatic amputations, or head injuries, or in burns involving more than 10 percent of the body surface area.
SYMPTOMS OF SHOCK
The symptoms of shock vary from patient to patient and even within an individual during the course of illness. Evaluation of the whole situation is more important than one particular sign or symptom.
Degrees of Shock
Table 4-2 provides a generalized overview of the degrees of shock and their symptoms correlated to the approximate volume deficit.
Table 4-2.—Correlation of Magnitude of Volume Deficit and Clinical Presentation
|Decrease in Blood
Postural changes in blood pressure
Mild peripheral vasoconstriction
|1200-1800||25-35||Moderate||Thready pulse 100-120
Systolic blood pressure 90-100
Diaphoresis (profuse perspiration)
Anxiety and restlessness
Decreased urine output
|1800-2500||35-50||Severe||Thready pulse > 120
Systolic blood pressure < 60
Changes in levels of consciousness
No urine output
Shock Control and Prevention
Figure 4-19.—Symptoms of shock.
The essence of shock control and prevention is to recognize the onset of the condition and to start treatment before the symptoms fully develop. The following are general signs and symptoms of the development of shock (see figure 4-19):
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.
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.
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.
Neurogenic shock, sometimes called vasogenic shock, results from the disruption of autonomic nervous system control over vasoconstriction. Under normal conditions, the autonomic nervous system keeps the muscles of the veins and arteries partially contracted. At the onset of most forms of shock, further constriction is signaled. However, the vascular muscles cannot maintain this contraction indefinitely. A number of factors, including increased fluid loss, central nervous system trauma, or emotional shock, can override the autonomic nervous system control. The veins and arteries immediately dilate, drastically expanding the volume of the circulatory system, with a corresponding reduction of blood pressure.
Simple fainting (syncope) is a variation of neurogenic shock. It often is the result of a temporary gravitational pooling of the blood as a person stands up. As the person falls, blood again rushes to the head, and the problem is solved. Neurogenic shock may also be induced by fear or horror, which will override the autonomic nervous system control.
Shell shock and bomb shock are other variations of neurogenic shock that are important to the Hospital medical technician. These are psychological adjustment reactions to extremely stressful wartime experiences and do not relate to the collapse of the cardiovascular system. Symptoms range from intense fear to complete dementia and are manifestations of a loss of nervous control. Care is limited to emotional support of the patient and his evacuation to the care of a psychiatrist or psychologist.
Cardiogenic shock is caused by inadequate functioning of the heart, not by loss of circulating blood volume. If the heart muscle is weakened by disease or damaged by trauma or lack of oxygen (as in cases of pulmonary disease, suffocation, or myocardial infarction), the heart will no longer be able to maintain adequate circulatory pressure, even though the volume of fluid is unchanged. Shock will develop as the pressure falls. Heart attack is an extreme medical emergency all medical technicians must be ready to handle. It will be discussed in greater detail in the “Common Medical Emergencies” section of this chapter.
Septic shock usually does not develop for 2 to 5 days after an injury and the patient is not often seen by the medical technician in a first aid situation. Septic shock may appear during the course of peritonitis caused by penetrating abdominal wounds or perforation of the appendix. Gross wound contamination, rupture of an ulcer, or complications from certain types of pneumonia may also cause septic shock. Septic shock is the result of vasodilation of small blood vessels in the wound area, or general vasodilation if the infection enters the bloodstream. In addition to increasing circulatory system volume, the walls of the blood vessels become more permeable, which allows fluids to escape into the tissues. This type of shock carries a poor prognosis and should be treated under the direct supervision of a physician.
Anaphylactic shock occurs when an individual is exposed to a substance to which his body is particularly sensitive. In the most severe form of anaphylactic shock, the body goes into an almost instantaneous violent reaction. A burning sensation, itching, and hives spread across the skin. Severe edema affects body parts and the respiratory system. Blood pressure drops alarmingly, and fainting or coma may occur.
The causative agent may be introduced into the body in a number of ways. The injection of medicines (especially penicillin and horse- or egg-cultured serums) is one route. Another method is the injection of venoms by stinging insects and animals. The inhalation of dusts, pollens, or other materials to which a person is sensitive is a third route. Finally, a slightlyslower but no less severe reaction may develop from the ingestion of certain foods and medications. Specific treatment of venoms and poisons will be discussed in chapter 5, “Poisoning, Drug Abuse, and Hazardous Material Exposure.”
GENERAL TREATMENT PROCEDURES
Intravenous fluid administration is the most important factor in the treatment of all types of shock except cardiogenic shock. Ringer’s lactate is the best solution to use, although normal saline is adequate until properly cross-matched whole blood can be administered. The electrolyte solutions replace not only the lost blood volume, but also lost extracellular fluid that has been depleted. If the shock is severe enough to warrant immediate administration of intravenous fluids, or if transportation to a medical facility will be delayed and a physician is not available to write an administrative order, be conservative: Start the intravenous fluids and let them run at a slow rate of 50 to 60 drops per minute. If intravenous solutions are unavailable or transportation to a medical treatment facility will be delayed, and there are no contraindications (such as gastrointestinal bleeding or unconsciousness), you may give the patient an electrolyte solution by mouth. An electrolyte solution may be prepared by adding a teaspoon of salt and half a teaspoon of baking soda to a quart or liter of water. Allow the patient to sip the solution.
Other treatment procedures for shock are as follows:
PNEUMATIC COUNTER-PRESSURE DEVICES (MAST)
Commonly known as Medical Anti-Shock Trousers (MAST), pneumatic counter-pressure devices are designed to correct or counteract certain internal bleeding conditions and hypovolemia. The garment does this by developing an encircling pressure up to 120 mm Hg around both lower extremities, the pelvis, and the abdomen. The pressure created:
Some indications for use of the pneumatic counter-pressure devices are when:
Although the only absolute contraindication in the use of these devices is in the case of pulmonary edema, other conditional contraindications include congestive heart failure, heart attack, stroke, pregnancy, abdominal evisceration, massive bleeding into the thoracic cavity, and penetrating wounds where the object is still impaled in the victim.
Application of the anti-shock garment is a simple procedure, but it requires some important preliminary steps. When the garment is laid out flat, ensure that there are no wrinkles. If the patient is to remain clothed, remove all sharp and bulky objects from the patient’s pockets. Take vital signs before applying the MAST garment. When applying the garment, inflate sufficiently so the patient’s systolic blood pressure is brought to and maintained at 100 mm Hg. Once the garment is inflated, take the patient’s vital signs every 5 minutes. The garment should be removed only under the direct supervision of a physician.