"Check out the patients in the other car." What does that mean and what should you being looking for? Of course, an initial patient assessment will need to be done on each patient. But what if you don't find any obvious injuries? Then what? Every patient should be monitored for the signs and symptoms of shock.
The heart functions as the human circulatory system's pump. The heart consists of four separate chambers, two on top and two on the bottom. The lower chambers are the left and right ventricles; the upper chambers are the left and right atria (a single chamber is called the atrium). The ventricles are the larger of the two and do most of the actual pumping. The atria are somewhat less muscular and serve more as a reservoir for blood flowing into and out of the heart.
There are three main types of blood vessels in the human body: arteries, capillaries and veins. The arteries (big-flow, heavy-duty, high-pressure pipes) carry oxygenated blood away from the heart to the body. The capillaries (distribution pipes) are the smallest of the blood vessels. Capillaries form a network that distributes blood to all parts of the body. At its point of smallest diameter, a capillary is so narrow that blood cells have to flow "single file." The veins return the blood from the capillaries to the heart, where it is pumped to the lungs. There, the blood gives off carbon dioxide and takes on oxygen.
Fluid consists of blood cells and other blood components, each with a specific function. The liquid part of the blood is known as plasma. Plasma serves as the transporting medium for the "solid" parts of the blood, red blood cells, white blood cells and platelets. Red blood cells are the blood's chief oxygen and carbon dioxide carriers. White blood cells have a "search and destroy" function. They consume bacteria and viruses to combat body infections. Platelets interact with each other and with other substances in the blood to form blood clots that help stop bleeding.
The pulse is the pressure wave generated by the pumping action of the heart. The beat you feel is caused by blood surging from the left ventricle as it contracts, pushing blood out into the main arteries of the body. In counting the number of pulsations per minute, you also count heartbeats per minute. In other words, the pulse rate reflects the heart rate.
Normally, you can feel a patient's radial and carotid pulses. The radial pulse (in the wrist) is easily found in a conscious patient at the base of the thumb. If the patient is unconscious or suffering from shock or both, it may be impossible for you to feel a radial pulse. Therefore, it is vital that you know how to locate the carotid (neck) pulse. If the patient appears to be in shock or is unconscious, attempt to locate the carotid pulse first. Locate the carotid pulse by placing two fingers lightly on the larynx (voicebox) and slide the fingers off to one side until you feel a slight notch. You should be able to locate the carotid pulse within three seconds of touching a person's larynx.
Shock is defined as failure of the circulatory system. Circulatory failure has many possible causes. The three primary causes of shock are pump failure, pipe failure and fluid loss.
Pump failure (or cardiogenic shock) occurs if the heart is incapable of pumping enough blood to supply the needs of the body. Pump failure can result if the heart has been weakened by a heart attack. Inadequate pumping of the heart can cause blood to back up in the vessels of the lungs, resulting in a condition known as congestive heart failure (CHF).
Pipe failure is caused by the expansion (dilation) of the capillaries to as much as three or four times their normal size. This causes blood to pool in the capillaries instead of circulating throughout the system. When blood pools in the capillaries, there is less circulating blood for the rest of the body. The heart and other vital organs are deprived of blood. Blood pressure falls; shock results. In shock caused by sudden expansion of the capillaries, blood pressure may drop so rapidly that you are unable to feel either a radial or a carotid pulse.
Fluid loss caused by bleeding (hemorrhage) is the most common cause of shock. Blood escapes from the normally closed circulatory system through an internal or external wound, lowering the system's fluid level (blood volume) until the pump cannot operate efficiently. To compensate for fluid loss, the pump begins to work faster to maintain pressure in the pipes. But as the fluid continues to drain out, the pump eventually "loses its prime" and stops pumping.
External bleeding is not difficult to detect because you can see blood escaping from the circulatory system to the outside. With internal bleeding, blood escapes from the system but you cannot see it. Even though the escaped blood remains inside the body, it cannot re-enter the circulatory system and is not available to be pumped by the heart. Whether external or internal, unchecked bleeding causes shock, eventual pump failure and death.
The volume of blood in an average adult is about 12 pints. The loss of one pint of blood does not produce shock in a healthy adult. In fact, one pint per donor is the amount collected by blood banks. The loss of two or more pints of blood can produce shock. This amount of blood can be lost as a result of injuries such as a fractured femur.
Shock deprives the body of sufficient blood to function normally. As shock progresses, the body alters some of its functions in an attempt to maintain sufficient blood supply to its vital parts. A patient who is suffering from shock may exhibit some or all of the following signs and symptoms:
- Confusion, restlessness or anxiety. (These changes in mental status may be the first signs of shock. In severe cases, the patient loses consciousness.)
- Cold, clammy, sweaty and pale skin.
- Rapid, weak pulse.
- Increased capillary refill time.
- Rapid breathing. (Initially, the patient's breathing may be rapid and deep, but as shock progresses in severity, breathing becomes rapid and shallow.)
- Nausea and vomiting.
- Weakness or fainting.
- Thirst.
Monitoring the overall mental status of a patient can help you detect shock. Any change in mental status may be significant. If a trauma patient who has been quiet suddenly becomes agitated, restless and vocal, you should suspect shock. If a trauma patient who has been loud, vocal and belligerent becomes quiet, you should also suspect shock and begin treatment. A quiet patient is often a patient in shock. Watch carefully!
If the patient has dark skin, the skin color changes that help you to detect shock are not seen. Because you cannot see skin color changes in these patients, you must be especially alert for other signs of shock. Test for capillary refill to help determine if shock is present. Cool, clammy skin will help you recognize shock in patients who have dark skin.
As a first responder, you can take several important and simple steps to combat shock from any cause and keep it from getting worse:
- Position the patient correctly.
- Maintain the ABCs.
- Treat the cause of shock, if possible.
- Maintain the patient's body temperature.
- Make sure the patient does not eat or drink anything.
- Assist with other treatments (such as administering oxygen, if available).
- Arrange for immediate ambulance transport to an appropriate medical facility.
Rapid recognition and treatment of shock can go a long way in helping the patients that you are called upon to assist.
Garry Briese is the executive director of the International Association of Fire Chiefs (IAFC) and, along with David Schottke, co-author of the new edition of First Responder: Your First Response In Emergency Care, available in summer 1996 from Jones & Bartlett Publishers. The book is produced by the American Academy of Orthopaedic Surgeons and the National Safety Council.
