Shock is the cause of death in most patients. Early interventions and proper management can safe lives. In this article the author who is a Registered Nurse and Lecturer in Health Sciences discusses the common types of shocks, how they may be diagnosed and treated. The prognosis and methods of preventing shock are also discussed.
Shock is defined as a state of circulatory dysfunction in which tissue O2 delivery is less than required. If untreated, multi-organ failure and death will result. Shock is the final common pathway of numerous disease states. Shock is a life-threatening medical emergency and is one of the leading causes of death. The primary cause may lead to many other medical emergencies like hypoxia and cardiac arrest. Hypoxia is defined as lack of oxygen to the tissues. Cardiac arrest is the cessation of cardiac contractions.
Patho physiology: There are many general classifications however the following are most widely recognised:
Most common type of shock, due to insufficient circulating volume. Main cause is loss of fluid from the circulatory system e.g. bleeding, burns.
Due to failure of the myocardium to pump effectively. Often due to damage of the heart muscle as a result of Myocardial Infarction. Other causes include arrhythmias, cardiomyopathy, Congestive Heart Failure and cardiac valve problems.
Some authors include septic shock, Anaphylactic and Neurogenic shock under this classification. Other authors classify them separately. As the name implies, in this type of shock, there is no blood loss but the shock is due to dilation of blood vessels.
Due to sepsis caused by an overwhelming infection leading vasodilatation e.g. infection by bacteria of the Proteus species. These release toxins which produce adverse biochemical, immunological and occasionally neurological effects. Patients usually have a history of fever, pyrexia and hyperthermia.
Caused by severe reaction to an allergen, antigen, drug or foreign protein. Release of histamine caused widespread vasodilatation.
C. Neurogenic Shock:
This is a very uncommon type of shock. It is most often seen in patients who have had extensive spinal cord injuries. The loss of autonomic and motor reflexes below the level of injury results in loss of sympathetic control. This leads to relaxation of vessel walls and peripheral dilation and hypotension.
Mainly due to hormone disturbances e.g. Hypothyroidism and adrenal insufficiency. Hypothyroidism is corrected with levothyroxin and adrenal insufficiency is corrected with corticosteroids.
Obstruction of blood flow results in cardiac arrest. Examples which lead to this type of shock are Cardiac tamponade, Tension pneumothorax, Pulmonary embolism and aortic stenosis.
Signs and Symptoms:
Clinical signs are for the most part non-specific. Any one or a combination of any of the following may be present. The stage and severity of the shock will influence the signs and symptoms.
- Tachycardia: Heart rate of greater than 100 b/min in an adult patient. Some authors may describe this as a “galloping heart”.
- Hypotension – Low blood pressure, particularly decreased diastolic BP
- Oliguria: Urinary output of less than 0.5ml per kg of body weight in an adult patient.
- Changed level of Consciousness, usually a decrease in LOC
- Underlying infection / blood loss, spinal cord injury
Stages of Shock
There are three stages of shock are commonly identified. Stage I, sometimes called the compensated or non progressive stage because the symptoms may be mild or non-existent. Stage II is often called the decompensated or progressive stage. Stage III may be referred to as the irreversible stage.
Stage I. Early, Reversible and Compensatory Shock
This stage is characterized by low BP. It results in decreased perfusion, particularly to the peripheral tissues. Initial signs of shock include sinus tachycardia, peripheral vasoconstriction (blood vessels throughout the body become slightly smaller in diameter) and the renal system (kidneys) works to retain fluid in the cardiovascular system. These processes are activated to maintain and restore tissue perfusion. The end result is that blood flow to key vital organs is maintained. The key vital organs are the kidneys, brain, and heart. As a result of this compensatory mechanism the body is maintained. Consequently, the patient in this stage of shock displays very few symptoms. Proper treatment at this stage can halt progression of shock.