SHOCK

Introduction


Shock is a life-threatening condition, which may result from any number of primary causes. As a medic, you must be aware of the physiologic effects of shock. Correct management of a patient in shock involves treating the underlying cause of shock and the abnormalities associated with the shock state.

Terminal Learning Objective


Given a scenario involving a patient exhibiting signs and symptoms of shock, identify the type of shock and provide treatment for shock.

1. Identify Types of Shock


a. Definition of shock - Shock is a state of inadequate tissue perfusion resulting in a decreased amount of oxygen to vital tissues and organs. Blood flow is insufficient to provide nutritional requirements of cells and remove waste products of metabolism. Management of patients in shock involves both treating the cause of shock and the abnormalities associated with the shock state.

b. Causes of shock - although shock may have a number of different origins, it is usually caused by one or more primary mechanisms

(1) Fluid loss,

(2) Significant vasodilation

(3) Cardiac pump failure

c. Classifications of shock

(1) Hypovolemic (hemorrhagic) shock - The major problem in hypovolemic shock is a loss of intravascular volume, which may occur from blood, plasma or fluid loss. Severe vomiting and/or diarrhea, internal or external blood losses are examples of causes that may result in the loss of intravascular volume. Hypovolemic shock has been addressed in the Control Bleeding and Hypovolemic Shock lesson plan.

(2) Anaphylactic shock - Anaphylactic shock is a severe response to a foreign substance (antigen) entering the body. Antigens may enter through the skin, by injections, by inhalation or by ingestion. In anaphylaxis, a reaction between the antigen and antibody triggers a series of events in the body, which leads to hypoperfusion. Responses may be mild to severe, sometimes causing swelling of the airway, severe vasodilation and bronchial constriction. If left untreated, anaphylactic shock will lead to death.

(3) Cardiogenic shock - Cardiogenic shock is caused by a failure of the heart pumping mechanism. In cardiogenic shock, there is adequate blood volume and no vessel dilatation, but the heart is not pumping properly.

(4) Septic shock - Septic shock is caused by an infection (usually bacterial) that leads to vasodilation. The blood vessels dilate due to toxins released into the bloodstream. The blood available for circulation is decreased because it is pooled in dilated veins. In addition, plasma seeps through the blood vessel walls, creating additional fluid losses.

(6) Neurogenic shock - Neurogenic shock is seen in spinal injuries. With neurogenic shock, the spinal nervous system is no longer able to control the diameter of the blood vessels. Without this control, the blood vessels dilate, increasing the volume of the cardiovascular system. Venous return to the heart decreases, and shock results.

2. Assess the Patient in Shock


a. History - Getting the history of the patient in shock is vital to the establishment of the correct diagnosis. Often the presence or the history of shock will be instantly apparent along with the underlying cause, such as a heart attack, history of a bee sting or serious infection. Some patients in shock may have few symptoms other than weakness, or altered mental status. Examples of questions typically asked are:

(1) Is there a history of trauma, which would make you suspect internal or external hemorrhage?

(2) Is there a history of cardiac problems, such as prior heart attack?

(3) Is there a history of infection? Is the patient on antibiotics, and if so, for what?

(4) Has there been trauma to spinal cord?

(5) Has there been contact with known allergic substances, such as wasps, bees, new foods or medications, latex?

(6) Is the patient taking any new medications; either prescribed, over-the-counter or recreational?

(7) Identify patients at increased risk for shock- trauma patients, pregnant women, and elderly?

b. Physical examination - No single vital sign will tell you a patient is in shock. Do not rely on any one sign or symptom to judge the degree of shock. The soldier medic must have a high index of suspicion with every patient.

(1) Determine level of consciousness. Report and record, using AVPU

(a) Alert - awake and oriented

(b) Responds to verbal stimuli

(c) Responds to painful stimuli

(d) Unresponsive to any stimuli

(2) Signs of early shock

(a) Minimum tachycardia - caused by epinephrine’s effect on the heart

(b) No measurable changes occur in blood pressure, pulse pressure or respiratory rate

(3) Progression of shock

(a) A decrease in systolic blood pressure and increase in diastolic blood pressure pulse pressure

(b) Increased tachycardia

(c) Increased respiratory rate (tachypnea) - caused by epinephrine’s effect on the respiratory system and hypoxia

(d) Pale, cool, clammy skin - caused by vasoconstriction and loss of circulating blood

(e) Sweating - caused by epinephrine’s effect on the sweat glands

(f) Cyanosis - nail beds, lips

(g) Oliguria (decreased urine output) - caused by hypovolemia, hypoxia, and circulating epinephrine

(h) Listlessness, stupor, and loss of consciousness as condition worsens - caused by cerebral hypoperfusion and epinephrine stimulation

3. Assessment and Treatment of Anaphylactic Shock

a. Overview

(1) Anaphylaxis is the most severe of allergic reactions. It is important to remember that even mild allergic reactions may progress to severe anaphylaxis

(2) The most common causes of serious anaphylaxis are antibiotics, such as penicillin and its derivatives; and IV contrast dyes

NOTE: Penicillin is estimated to cause 100-500 deaths annually in the United States.

(3) The next most common cause of anaphylaxis is bee, wasp and yellow jacket stings

NOTE: Bee and wasp stings cause fewer than 100 deaths annually in the United States.

(4) Other causes include

(a) Medications - aspirin, nonsteroidal anti-inflammatory drugs, sulfa drugs

(b) Foods - shellfish, nuts, milk, wheat, eggs, MSG (monosodium glutamate)

(c) Plants (i.e. poison oak, poison ivy and sumac)

(d) Latex

b. Clinical features - anaphylaxis can include any of these signs along with low blood pressure and airway compromise

(1) Signs and symptoms include

(a) Upper airway - hoarseness, stridor, edema, rhinorrhea

(b) Lower airway - bronchial constriction and spasm, wheezing, diminished breath sounds

(c) Cardiovascular system - tachycardia, hypotension, cardiac arrhythmias, chest pain and tightness

(d) Gastrointestinal system - nausea, vomiting, abdominal cramping and diarrhea

(e) Neurological system - apprehension, dizziness, weakness, progressing to coma

(f) Skin - swelling (edema) of the face, neck and extremities, itching, hives (urticaria), skin flushing, swelling and tearing of the eyes and lids

c. Diagnosis

(1) In most patients, signs and symptoms begin 15-60 minutes after exposure. Anaphylaxis may not occur after the first dose of a medication. In general, the faster the onset of symptoms, the more severe the reaction

(2) Patients treated for anaphylaxis are at risk for a recurrence of symptoms within 12 hours

(3) Many cases of anaphylaxis can easily be diagnosed by a history of exposure (ex. bee sting) combined with the symptoms listed above. However, some cases of anaphylaxis are more difficult to diagnose, for example, food allergies

d. Treatment for anaphylactic shock

(1) Securing the airway is the first priority. Give supplemental oxygen by non-rebreather mask, at a rate of 15 liters/minute. If the patient is not breathing, perform positive pressure ventilations until a Combitube or an endotracheal tube can be inserted

(2) Exposure to the causative agent, if identified and ongoing, must be terminated, i.e. remove the stinger or removal of clothing

(3) Position the conscious patient in a comfortable position (usually seated). Position the unconscious patient in a supine or Trendelenburg position

(4) Drugs

(a) Epinephrine - 0.3-0.5 mg (0.3-0.5 ml of 1:1000 solution) SC for an adult. Epinephrine may be repeated every 5-10 minutes if symptoms continue or recur.

NOTE: Repeat doses may be required. Additional dosages should be given according to initial patient response (stabilization of blood pressure, pulse, mental status, skin perfusion and respirations).

NOTE: Briskly massage site of SC injection to hasten drug response.

(b) Antihistamines - Diphenhydramine (Benadryl), 25-50 mg IM or IV

(c) Corticosteroids - will be given by a medical officer, if needed. A typical dose is 125 mg IV of Solu-Medrol

(5) Insert a large bore IV and begin infusing Normal Saline, 500cc. bolus over 30 minutes. Continue fluids according to initial patient response (stabilization of BP, pulse, mental status, skin perfusion and respirations).

(6) Cardiac monitoring, if available

(7) Pulse oximetry, if available

(8) Evacuate as soon as possible to a medical treatment facility

(9) Recurrent episodes of anaphylaxis may occur 12-24 hours after the initial episode. Patients with severe anaphylaxis should be hospitalized for observation and possible retreatment. Patients with mild symptoms (urticaria) that resolve with treatment may be discharged at the medical treatment facility

(10) Patients with minor allergic reactions that do not have hypotension or respiratory symptoms do not need epinephrine. These patients should be given Benadryl 25-50 mg PO, IM or IV and observed for a response for at least 1 hour. A medical officer must see all allergic reactions

e. Prevention of anaphylaxis

(1) Inquire carefully about any history of drug allergies before giving any medication

(2) In patients who are drunk, unconscious or have an altered mental status, search for a card, bracelet or necklace specifying drug allergies or particular problems (diabetes) which may require special attention

(3) Be cautious when administering immunizations and IV/ IM medications. Observe patients for at least 20-30 minutes after injections

(4) Patients with a history of anaphylaxis or severe allergic reactions should carry an "Ana-Kit", a self-administration Epinephrine kit. Soldiers should carry these kits when out in the field and in garrison.

4. Assessment and Treatment of Cardiogenic Shock

a. Overview

(1) Cardiogenic shock occurs when the heart's pumping mechanism no longer functions correctly. The inadequate pumping action results from a disorganized cardiac rhythm or an injury to the heart muscle. Cardiogenic shock results in inadequate perfusion to the tissue and organs. "Pump failure".

(2) Cardiogenic shock is the most frequent cause of in-hospital death from acute myocardial infarction (heart attack)

(3) Causes of cardiogenic shock include

(a) Massive Myocardial Infarction (MI)

(b) Aneurysm of the left ventricle wall

(c) Cardiac tamponade or cardiac contusions resulting from blunt trauma

(d) Cardiac dysrhythmias (abnormal heartbeat)

(e) Congestive Heart Failure (CHF)

b. Signs and symptoms of cardiogenic shock may include

(1) Chest pain

(2) Shortness of breath

(3) Weakness

(4) Cool, clammy skin

(5) Hypotension

(6) Tachycardia/tachypnea

(7) Anxiety and confusion

(8) Sweating

(9) Rales (crackles)

(10) Peripheral edema (swelling of legs)

c. Diagnosis of cardiogenic shock

(1) Can be suspected from the initial history and physical, however, additional testing inside a medical treatment facility is needed for confirmation

d. Treatment of cardiogenic shock

(1) Securing the airway is the first priority. Give supplemental oxygen by non-rebreather mask, at a rate of 15 liters/minute. If the patient is not breathing, perform positive pressure ventilations until a Combitube or an endotracheal tube can be inserted

(2) Position the patient in a supine or Trendelenburg position

(3) Start a large bore IV catheter and begin infusing Normal Saline at a TKO rate

(4) Cardiac monitor, if available

(5) Pulse oximetry, if available

(6) Evacuate as soon as possible to a medical treatment facility

(7) Aspirin may be given in route to hospital or in hospital, according to protocols

5. Assessment and Treatment of Septic Shock

a. Overview

(1) Sepsis is the body's systemic response to an infection. Septic shock is sepsis with hypotension plus decreased urine output and altered mental status

NOTE: Sepsis is the 13th leading cause of death in the United States with 2/3 of the deaths occurring in hospitalized patients.

(2) The most frequent sites of infection are the lungs, abdomen and the urinary tract

(3) Bacterial infections are the cause of the majority of septic infections in patients

(4) Factors that predispose patients to sepsis are trauma, diabetes, burns, indwelling catheters, cancer chemotherapy and cirrhosis

NOTE: Sepsis is more common in older adults. Older adults are more likely to have conditions that predispose them to bacterial infections - diabetes, surgical procedures and cancer.

(5) Sepsis starts as a local infection (ex. urinary tract infection, pneumonia), and then the infection releases toxins and moves through the blood system

b. Clinical features - clinical features of shock and infection are present

(1) Fever (or hypothermia)

(2) Rigors (shaking chills)

(3) Petechiae (small, purple hemorrhagic spots on the skin)

(4) Hypotension

(5) Tachycardia

(6) Tachypnea

(7) Mental status changes - may range from confusion, agitation, to lethargy and coma

(8) Localized signs may be abdominal tenderness, rectal tenderness, or extensive pneumonia

c. Diagnosis of septic shock

(1) Can be suspected from the initial history and physical, however, additional testing inside a medical treatment facility is needed for confirmation

d. Treatment of septic shock

(1) Securing the airway is the first priority. Give supplemental oxygen by non-rebreather mask, at a rate of 15 liters/minute. If the patient is not breathing, perform positive pressure ventilations until a Combitube or an endotracheal tube can be inserted

(2) Position the patient in a supine or Trendelenburg position

(3) Start a large bore IV and begin infusing Normal Saline bolus at rate of 1-2 liters given over 30-60 minutes. After initial fluids, decrease IV rate according to initial patient response (stabilization of blood pressure, pulse, mental status, skin perfusion and respirations)

(4) Cardiac monitor, if available

(5) Pulse oximetry, if available

(6) Empiric antibiotics may be given to patients who have a prolonged evacuation time. Use of empiric antibiotics must be cleared by medical direction

NOTE: Empiric antibiotics are the usage of an antibiotic prior to the establishment of the type of bacteria causing the illness.

(7) Evacuate as soon as possible to a medical treatment facility

6. Assessment and Treatment of Neurogenic Shock

a. Overview

(1) Neurogenic shock, characterized by bradycardia and hypotension, occurs after an acute spinal cord injury

(2) Acute spinal cord injury is usually due to blunt trauma; penetrating trauma causes less than 15% of cases. Motor vehicle accidents, falls and sports injuries are the most common causes of spinal cord injury from blunt trauma.

(3) The cervical spine region is the most commonly injured area; followed by lumbar and thoracic segments. The higher the spinal cord injury, the more likely or more severe the resulting neurogenic shock will be.

NOTE: Approximately 10,000 people annually in the United States sustain a significant spinal cord injury.

b. Clinical features of neurogenic shock

(1) History of spinal trauma

(2) Hypotensive

(3) Usually bradycardic- different than other types of shock

(4) Warm, dry skin- different than other types of shock

c. Diagnosis of neurogenic shock

(1) Can be suspected from the initial history and physical, however, additional testing inside a medical treatment facility is needed for confirmation

d. Treatment of neurogenic shock

(1) Securing the airway and protecting the C-spine are the first priorities. Give supplemental oxygen by non-rebreather mask, at a rate of 15 liters/minute. If the patient is not breathing, perform positive pressure ventilations until a Combitube or an endotracheal tube can be inserted

(2) Position the patient in a level position

(3) Start a large bore IV and begin infusing Normal Saline bolused at rate of 1-2 liters given over 30-60 minutes. After initial fluids, decrease IV rate according to initial patient response (stabilization of blood pressure, pulse, mental status, skin perfusion and respirations)

(4) Place patient on a spine board

(5) Cardiac monitor, if available

(6) Pulse oximetry, if available

(7) Corticosteroids-will be given by a medical officer, if needed

(8) Evacuate as soon as possible to a medical treatment facility. Any patient with neurogenic shock has suffered a severe traumatic injury and will be admitted to the hospital.

Summary

Shock is a very serious condition, which requires early detection and prompt medical intervention. As a medic, you must monitor those casualties susceptible to shock and be prepared to assist with the appropriate medical management. Early identification and treatment of shock is imperative in preventing serious injury and death.