Ch 13 - Shock

• Edema


  The presence of abnormally large amounts of fluid between cells in body issues, causing swelling of the affected area
• Homeostasis


  A balance of all systems of the body
• Hypothermia


  A condition in which the internal body temperature falls below 95°F (35°C)
• Hypovolemic shock


  A condition in which low blood volume, due to massive internal or external bleeding or extensive loss of body water, results in inadequate perfusion

  • hemorrhagic and nonhemorrhagic causes
  • occurs with severe thermal burns and crushing injuries
  • dehydration
• Irreversible shock


  A condition defined by the inability to successfully achieve resuscitation regardless of the methods employed
• Myocardial contractility


  The ability of the heart muscle to contract
• Neurogenic shock

  • Circulatory failure caused by paralysis of the nerves that control the size of the blood vessels, leading to widespread dilation -> increasing size and capacity of vascular system and causing blood to pool
  • usually the result of high spinal cord injury
  • S/S: absence of sweating below injury, normal and low HR in presence of hypotension, normal, warm skin -> only type of shock that presents without pale, cool, skin b/c peripheral vasoconstriction cannot be triggered thru autonomic nervous system
  • body loses control over body temperature -> hypothermia
• Obstructive shock


  • Shock that occurs when there is a block to blood flow in the heart or great vessels, causing an insufficient blood supply to the body's tissues
  • cardiac tamponade, tension pneumothorax, pulmonary embolism
• Perfusion


  • The flow of blood through body tissues and vessels in adequate amounts to meet the cells' needs
  • Includes delivery of oxygen and removal of toxic waste products
• Pericardial effusion


  A collection of fluid between the pericardial sac and the myocardium

  • if the effusion becomes large enough, it can prevent the ventricles from filling with blood -> cardiac tamponade
• Preload


  The precontraction pressure in the heart as the volume of blood builds up
• Psychogenic shock


  Shock caused by a sudden, temporary reduction in blood supply to the brain that causes fainting (syncope)

  • sudden rxn of nervous system produces temporary, generalized vasodilation
  • syncope - occurs when blood pools in dilated vessels, reducing blood supply to the brain, and temporarily stopping the brain from functioning normally
  • life-threatening causes: irregular heartbeat and brain aneurysm
  • non-life-threatening causes: receiving bad news, experiencing fear, encountering an unpleasant sight
• Pulmonary embolism 


  A blood clot that breaks off from a large vein and travels to the blood vessels of the lung, causing obstruction of blood flow

  • can prevent blood from being pumped from the right side of the heart to the left -> complete backup of blood in the right ventricle and catastrophic obstructive shock
• Pulse pressure


  The difference between the systolic and diastolic pressures

  • signifies the amount of force the heart generates with each contraction
  • shock: < 25 mm Hg
• Sensitization


  Developing a sensitivity to a substance that initially caused no allergic reaction
• Septic shock


  Shock caused by severe infection, usually a bacterial infection

  • toxins damage the vessel walls -> increased cellular permeability
  • vessel walls leak (hypovolemia) and are unable to constrict well
  • widespread dilation of vessels, in combo with plasma loss thru the vessel walls results, in shock
  • insufficient volume of fluid in container
  • fluid that has leaked out often collects in the alveoli, interfering with respiration
  • vasodilation leads to larger than normal vascular volume -> increase in space combined with smaller than normal volume of intravascular fluid leads to shock
• Shock(hypoperfusion)


  • A condition in which the circulatory system fails to provide sufficient circulation to maintain normal cellular functions AKA inadequate cellular perfusion
  • Any compromise in perfusion can lead to cellular injury or death
  • In the early stages, the body attempts to maintain homeostasis
  • Req. immediate recognition and rapid treatment
• Sphincters


  Muscles that encircle and, by contracting, constrict a duct, tube, or opening
• Syncope


  A fainting spell or transient loss of consciousness
• Afterload


  The force or resistance against which the heart pumps
• Anaphylactic shock(anaphylaxis)


  Severe shock caused by an allergic reaction

  • sensitization - becoming sensitive to a substance than did not initially cause a rxn
  • each subsequent exposure after sensitization tends to produce a more severe reaction
  • 4 categories of exposure: injections, stings, ingestion, inhalation
  • no blood loss or vascular damage, widespread vascular dilation, increased permeability, bronchoconstriction, cyanosis (late)
• Anaphylaxis


  An extreme, life-threatening, systemic allergic reaction that may include shock and respiratory failure
• Aneurysm


  A swelling or enlargement of a part of an artery, resulting from weakening of the arterial wall
• Autonomic nervous system


  The part of the nervous system that regulates involuntary activities of the body, such as heart rate, blood pressure, and digestion of food
• Cardiac tamponade


  • compression of the heart as the result of buildup of blood or large pericardial effusion -> decreased cardiac output
  • caused by blunt or penetrating trauma -> hemorrhage around heart
  • S/S = Beck triad: presence of jugular vein distention, muffled heart sounds, narrowing pulse pressure where systolic and diastolic blood pressures start to merge
• Cardiogenic shock


  • a state in which not enough oxygen is delivered to the tissues of the body
  • caused by low output of blood from the heart -> inadequate function of heart or pump failure and insufficient cardiac output
  • can be a severe complication of a large acute myocardial infarction, as well as other conditions
  • may lead to backup of blood into pulmonary vessels that forces fluid out of capillary beds that surround the alveoli -> pulmonary edema, fluid-filled alveoli, tachypnea, crackles/rales
• Compensated shock


  The early stage of shock, in which the body can still compensate for blood loss
• Cyanosis


  A blue skin discoloration that is caused by a reduced level of oxygen in the blood. Although paleness, or a decrease in blood flow, can be difficult to detect in dark-skinned people, it may be observed by examining mucous membranes inside the inner lower eyelid and capillary refill. On general observation, the patient may appear ashen or gray
• Decompensated shock


  The late stage of shock when blood pressure is falling
• Dehydration


  Loss of water from the tissues of the body

  • can cause shock
  • may be a result of severe vomiting or diarrhea
  • common in people who are very young or old
• Distributive shock


  A condition that occurs when there is widespread dilation of the small arterioles, small venules, or both

  • results in pooling of circulating blood volume in expanded vascular beds and decrease in tissue perfusion
  • septic shock, neurogenic shock, anaphylactic shock, psychogenic shock
• what function do the blood vessels perform in the perfusion triangle?

  container function
• what function does the heart perform in the perfusion triangle?

  pump function
• what function does the blood perform in the perfusion triangle?

  content function
• what are the 3 parts of the perfusion triangle?


  heart, blood vessels, blood
• heart (pump function)


  damage to the heart by disease or injury decreases the ability of the heart to properly function as a pump. therefore, it cannot move enough blood thru the body to support perfusion
• blood vessels (container function)


  if all the blood vessels dilate rapidly, the normal amount of blood volume is not enough to fill the system and provide adequate perfusion to the body
• blood (content function)


  if there is enough blood or plasma loss, the volume of fluid in the container is not enough to support the perfusion needs of the body
• 3 basic causes of shock:

  pump failure, low fluid volume, poor vessel function
• pump failure


  causes: heart attack, trauma to heart, obstructive causes (large pulmonary embolus)