Chapter 12: Shock Flashcards
Describes a state of collapse and failure of the cardiovascular system.
In the early stages, the body attempts to maintain homeostasis.
As shock progresses, blood circulation slows and eventually ceases.
Shock (hypoperfusion)
The circulation of an adequate amount of blood to meet the cells’ current needs.
Perfusion
First organ to be affected by lack of oxygen.
Brain
Cardiovascular system consists of three parts:
Pump (heart)
Set of pipes (blood vessels or arteries)
Contents (the blood)
These three parts can be referred to as the “perfusion triangle.”
Heart
Blood Vessels
Blood
The difference between the systolic and diastolic pressures is:
signifies the amount of force the heart generates with each contraction.
Pulse pressure
A pulse pressure less than 25 mm Hg may be seen in patients with shock.
Perfusion requires more than just having a working cardiovascular system.
Adequate oxygen exchange in the lungs
Adequate nutrients in the form of glucose in the blood
Adequate waste removal, primarily through the lungs
Damage from shock occurs because of..
insufficient perfusion of organs and tissues.
- Is caused by inadequate function of the heart, or pump failure.
- A major effect is the backup of blood into the lungs. (congestive heart failure)
- The resulting buildup of pulmonary fluid is called pulmonary edema.
Cardiogenic shock
The presence of abnormally large amounts of fluid between cells in body tissues, causing swelling.
Edema
Pulmonary edema leads to:
Impaired respiration, which may be manifested by:
An increased respiratory rate
Abnormal lung sounds (wet sounds called rales)
Cardiogenic shock develops when:
The heart cannot maintain sufficient output to meet the demands of the body.
Caused by a mechanical obstruction that prevents an adequate volume of blood from filling the heart chambers.
Three of the most common examples:
Cardiac tamponade
Tension pneumothorax
Pulmonary embolism
Obstructive Shock
Collection of fluid between the pericardial sac and the myocardium (pericardial effusion) becomes large enough to prevent ventricles from filling with blood.
Caused by blunt or penetrating trauma
Signs and symptoms are referred to as Beck triad.
Cardiac Tamponade
Caused by damage to lung tissue
The air normally held within the lung escapes into the chest cavity.
The lung collapses, and air applies pressure to the organs, including the heart and great vessels.
Tension pneumothorax
A blood clot that blocks the flow of blood through pulmonary vessels
If massive:
Can result in complete backup of blood in the right ventricle
Leads to catastrophic obstructive shock and complete pump failure
Pulmonary embolism
Results when there is widespread dilation of small arterioles, small venules, or both.
The circulating blood volume pools in the expanded vascular beds and tissue perfusion decreases.
Distributive shock
Occurs as a result of severe infections in which toxins are generated by bacteria or by infected body tissues.
Toxins damage vessel walls, causing increased cellular permeability.
Vessel walls leak and are unable to contract well.
Widespread dilation of vessels, in combination with plasma loss through the vessel walls, results in shock.
Septic shock
Usually the result of high spinal cord injury.
Muscles in the blood vessel walls are cut off from the nerve impulses that cause them to contract.
Causes include: Brain conditions Tumors Pressure on the spinal cord Spina bifida
Neurogenic shock
Occurs when a person reacts violently to a substance to which he or she has been sensitized.
Sensitization means becoming sensitive to a substance that did not initially cause a reaction.
Each subsequent exposure tends to produce a more severe reaction.
Anaphylactic shock
Anaphylactic shock
Four categories of exposure include:
Injections (tetanus antitoxin, penicillin)
Stings (wasps, bees, hornets, ants)
Ingestion (fish, shellfish, nuts, eggs, medication)
Inhalation (dust, pollen, mold)
Develops within minutes or even seconds of contact with substance
Second phase reaction can occur 1 to 8 hours after initial reaction.
Signs are very distinct.
Cyanosis (blue discoloration of skin) is a late sign.
Anaphylactic shock
Signs of shock:
Decreased BP Increased HR Flush skin Wheezing (no albuterol for allergen related) Swelling
Caused by a sudden reaction of the nervous system.
Produces temporary, generalized vascular dilation
Results in fainting (syncope)
Some causes are serious and others are not.
Life-threatening causes include irregular heartbeat and brain aneurysm.
Non–life-threatening events include receipt of bad news or experiencing fear or unpleasant sights (such as blood).
Psychogenic shock
