Nur 250 Exam 3 Study Guide with Questions and Correct Answers
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Course
NUR 250
Institution
NUR 250
Shock Shock is a condition in which blood flow to cells and tissues is inadequate. There is insufficient oxygen and nutrients available for cells which cause cellular hypoxia and cell death. Organ failure and death is likely if not treated
Patho of shock Decreased blood supply to cells result in t...
Nur 250 Exam 3 Study Guide with
Questions and Correct Answers
Shock ✅Shock is a condition in which blood flow to cells and tissues is inadequate.
There is insufficient oxygen and nutrients available for cells which cause cellular
hypoxia and cell death.
Organ failure and death is likely if not treated
Patho of shock ✅Decreased blood supply to cells result in the following cellular
changes:
Cells lack oxygen, nutrients and energy.
Cells start to produce energy through anaerobic metabolism.
Anaerobic metabolism produces lactic acid and increased acidity causes normal cell
function to cease.
Cells swell, cell membranes become more permeable allowing fluid and electrolytes to
seep in and out of cells.
Na/K pump becomes impaired.
Cell structures (mitochondrial and lysosomes) are damaged resulting in cell death.
In stress states, catecholamines, cortisol, glucagons and inflammatory cytokines are
released causing hyperglycemia and insulin resistance.
Patho of shock ✅Vascular Responses
Biochemical mediators (cytokines) are released from the cell communicating a need for
oxygen.
In response to the biochemical mediators, local regulatory mechanisms (autoregulation)
stimulate vasodilatation or vasoconstriction.
Patho of shock ✅Blood Pressure Regulation
Tissue perfusion and organ perfusion depend on the mean arterial pressure (MAP), the
average pressure in which blood moves through the vasculature.
MAP= Cardiac Output (stroke volume x heart rate) x Peripheral Resistance
MAP= (SBP + 2 (DBP)) ÷ 3
MAP must exceed 65 mm Hg for cells to receive oxygen and nutrients to metabolize
energy to sustain life.
Baroreceptors monitor changes in circulatory volume.
Chemoreceptors sense changes in oxygen and CO2 concentrations.
Kidneys release renin to aid in conversion of angiotensin I to angiotensin II, a potent
vasoconstrictor.
Stages of shock ✅Compensatory
Progressive
Irreversible
, Compensatory stage of shock ✅Stimulation of the sympathetic nervous system causes
vasoconstriction, increased HR, increased heart contractility.
This maintains BP, CO
Body shunts blood from skin, kidneys, & GI tract and diverts it to the heart, brain and
lungs. This results in cool, clammy skin, hypoactive bowel sounds, decreased urine
output
Perfusion of tissues is inadequate
Acidosis occurs from anaerobic metabolism
Respiratory rate increases due to acidosis, may cause compensatory respiratory
alkalosis.
Confusion may occur.
Progressive shock ✅Mechanisms that regulate BP can no longer compensate, BP and
MAP decrease
Vasoconstriction continues further compromising cellular perfusion
Patients are clinically hypotensive
All organs suffer from hypoperfusion
Progressive stage of school ✅Respiratory effects-lungs begin to fail, decreased
pulmonary blood flow causes further hypoxemia, carbon dioxide levels increase, alveoli
collapse, pulmonary edema occurs
Cardiovascular effects- inadequate perfusion of heart leads to dysrhythmias, ischemia.
Neurological effects- mental status further deteriorates from decreased cerebral
perfusion, hypoxia.
Renal effects-As MAP falls below 70, GFR cannot be maintained and acute renal failure
may occur.
Stage of shock ✅Hepatic effects- inability to metabolize medications and waste
products, unable to filter bacteria from blood, AST/ALT and bilirubin levels increase.
GI effects-ischemia may cause stress ulcers, necrotic mucosa and bacterial
translocation.
Hematologic effects-DIC (Disseminated Intravascular Coagulation) may occur as cause
or complication of shock.
Irreversible shock stage ✅At this point, organ damage so severe that patient does not
respond to treatment, cannot survive
BP remains low
Renal, liver function fail
Anaerobic metabolism worsens acidosis
Multiple organ dysfunction progresses to complete organ failure
Judgment that shock is irreversible only made in retrospect
Management of all types of shock ✅Support of the respiratory system with oxygen
and/or mechanical ventilation
Fluid replacement to restore intravascular volume
Vasoactive medications to restore vasomotor tone, improve cardiac function
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