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63 Cards in this Set
- Front
- Back
Four components that need to be intact to maintain normal tissue perfusion
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1. Intact vascular system
2. Adequate air exchange 3. Adequate volume of fluid 4. functioning pump |
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Formulas that describe the "steady state" of activity needed to maintain blood pressure (BP + cardiac output)
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Blood Pressure = Cardiac Output x Peripheral Vascular Resistance
Cardiac Output = Heart Rate x Stroke Volume |
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4 basic rules of shock management
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1. Maintain airway
2. Maintain oxygenation / ventilation 3. Control bleeding where possible 4. Maintain circulation - adequate HR and vascular volume |
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How positive pressure ventilations can have a negative effect on cardiac output
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by decreasing the blood return to the heart
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Description of shock
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condition that occurs when the perfusion of the body's tissues with oxygen, electrolytes, glucose, and fluid becomes inadequate to meet the body's needs
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the backup process of energy production the body uses when deprived of oxygen
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anaerobic metabolism
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by product of anaerobic metabolism that disrupts cellular activity
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lactic acid
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With inadequate oxygen to the body, the sympathetic nervous system increases release of what 2 circulating catecholamines? What are their effects?
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epinephrine and norepinephrine. increase in heart rate and contractility and constriction of peripheral blood vessels
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Response of the midbrain to hypoxia and acidosis
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increases respiratory rate
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Clinical manifestations of shock. When present, what do they imply?
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pale, diaphoretic, tachycardic. Cells in vital organs are vulnerable and susceptible to severe and permanent damage. Multisystem organ failure can develop days after admission to ICU
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hypotension is a late sign of the state of shock, how low can a blood pressure get and still maintain proper perfusion?
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varies with each patient; elderly or patients with chronic hypertension can't tolerate hypotension as well as a healthy young patient
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What type of shock is most often categorized into either compensated or decompensated?
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hypovolemic shock
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Shock state in which the body is able to employ regulatory mechanisms to maintain perfusion
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compensated shock
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signs and symptoms associated with compensated shock
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Weakness, thirst, pallor, tachycardia, diaphoresis, tachypnea, decreased urinary output, weakened peripheral pulses
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cause of pallor in hypovolemia
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catecholamine-induced vasoconstriction and/or loss of circulating RBC's
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cause of diaphoresis in hypovolemia
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effect of catecholamines on sweat glands
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cause of tachypnea in hypovolemia
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combined effect of stress, catecholemines, acidosis, and hypoxia
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cause of thready pulse in hypovolemia
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arteries shrink in diameter as volume is lost
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signs and symptoms of decompensated shock
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Hypotension, altered LOC, cardiac arrest
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causes of cardiac dysfunction in shock
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hypoxia and acidosis
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effects of acidosis on blood pressure
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causes a loss of response to catecholamines, worsening the drop in BP; usually the point where compensating patient crashes
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the pressure driving blood through the vascular system
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pulse pressure
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how to measure pulse pressure
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subtract diastolic from systolic
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Why is there almost always a narrowing in pulse pressure early in shock syndrome?
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vasoconstriction causes initial rise in BP, raising diastolic more than systolic
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the loss of approx. 15 - 25% of the blood volume stimulates slight to moderate compensation symptoms. pulse is fast
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early shock
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loss of approx. 30 - 45% of blood volume causes hypotension as body's ability to compensate has failed. patient is near death. pulse weak or absent
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late shock
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tip to estimating systolic BP in late shock
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radial 80
femoral 70 carotid 60 |
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What are the pros and cons of using capillary refill time as a diagnostic tool
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pros: useful in evaluating small children in whom it is difficult to get an accurate BP.
cons: associated with late shock, associated with both false-positives and false-negatives, affected by cold, low blood volume, and vasoconstriction |
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earliest reliable sign of shock
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tachycardia - anyone sustaining HR over 100 must be suspected of having occult hemorrhage until proven otherwise; over 120 is red flag
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Factors that could prevent tachycardia in hypovolemia
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- 20% of abdomen bleeding victims don't develop tachycardia
- medications: beta-blockers, calcium channel blockers |
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capnography findings that can indicate circulatory collapse and worsening shock
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falling much under 35, especially into the 20's or below
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3 major classifications (types) of shock
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Low volume (absolute hypovolemia)
High space (relative hypovolemia) Mechanical (cardiogenic or obstructive) |
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Examples of low-volume shock
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- hemorrhage, diarrhea, vomiting
- third spacing from burns, peritonitis, etc |
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Examples of high-space shock
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- spinal injury, vasovagal syncope, sepsis, OD of vasodilators
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Examples of mechanical shock
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- damage to heart (contusion or MI), cardiac tamponade, tension pneumothorax, pulmonary embolism (obstructs pulmonary blood flow)
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number one cause of preventable death from injury
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hemorrhagic shock
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term that describes the shock that develops from loss of fluid volume only
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absolute hypovolemic shock
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another term for high-space shock
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relative
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blood volume an adult vascular system could conceivably hold if arterioles were fully dilated. What prevents this
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25 L
steady-state action of the sympathetic nervous system |
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spinal shock
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neurogenic shock
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causes/types of high-space shock
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neurogenic shock (only traumatic cause), OD, sepsis
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in neurogenic shock, the brain's sympathetic signals cannot be sent because the pathway is disrupted; what physiological factor may allow the body to maintain BP for a short time in this case?
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circulating catecholamines already present in the bloodstream
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presentation of neurogenic shock
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skin is warm, dry, and pink (no catecholamine production)
hypotensive, HR is normal or slow may have paralysis or deficit diaphragmatic breathing priapism |
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what is observed with diaphragmatic breathing
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abdomen protrudes with inspiration; often only observed when patient is asked to consciously take a deep breath
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average cardiac output for adult
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5 L / min
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type of shock caused by a traumatic or medical condition that slows or prevents normal blood flow
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mechanical shock (cardiogenic or obstructive)
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causes of mechanical shock
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tension pneumothorax, cardiac tamponade, cardiac contusion
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physiology of tension pneumothorax effect on blood flow
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developing high positive pressure in the pleural space collapses the low pressure superior and inferior vena cava, preventing blood return to the heart, thus lowering cardiac output (this is why JVD may be present)
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physiology of pericardial tamponade (cardiac tamponade)
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blood fills potential space between heart and pericardium, squeezing the heart and preventing it from filling; lowers cardiac output. (JVD may be present)
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name given to three major signs of cardiac tamponade
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Beck's triad
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3 major signs of pericardial tamponade
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JVD, muffled heart tones, pulsus paradoxus
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a drop of >10mmHg in systolic BP during inspiration (may lose radial pulse during inspiration and regain during expiration)
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pulsus paradoxus
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tx of cardiac tamponade
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surgical care for pericardial decompression
IV fluids only under medical direction (could increase filling pressure, but also increase bleeding) |
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physiology of cardiac contusion
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heart loses pumping strength due to direct injury to the heart muscle and/or disrhythmias that may result.
difficult to differentiate from cardiac tamponade in the field |
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effect of taking the time to immobilize a patient with penetrating injury to the trunk
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doubles the death rate
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signs of mechanical shock
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JVD
cyanosis - extremely late sign from lung hypoperfusion tachycardia |
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O2 administration for shock
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give high-flow to all patients at risk for shock. (don't forget to put on capnography, too)
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steps to control bleeding
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direct pressure in most cases
otherwise quickly apply tourniquet |
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body position to transport trauma patient
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horizontal
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IV gauge for trauma patient
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large bore (16 g or more)
IO if you can't get quick IV access |
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fluid administration for external controlled bleeding
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20 mL / kg IV rapidly then repeat Ongoing exam. if signs of shock persist, continue to administer fluid in boluses and reassess
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fluid administration for external uncontrolled bleeding or internal bleeding
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give only enough to maintain a BP high enough for adequate peripheral perfusion.
measured with radial pulses and LOC (brain perfusion) higher BP may be required for head injured patient or patient with hx of htn |
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recommended BP in hemorrhagic shock with head injury
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120 systolic to maintain 60 mmHg cerebral perfusion pressure
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