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Nursing 272: Final Semester > Unit 2: Overview of Shock > Flashcards

Unit 2: Overview of Shock Flashcards

1
Q

How do the tissues maintain cellular functioning?

A

the tissues of the body require a continuous supply of oxygen in order to maintain cellular functioning

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2
Q

Shock

A

life-threatening syndrome

  • occurs when the circulatory system is unable to supply adequate amounts of oxygen to the tissues to meet basic metabolic requirement
  • creates a state of tissue hypoxia; an imbalance of cellular oxygen and demand
  • w/o immediate tx to reverse this imbalance, organ system failure and death may result
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3
Q

Cardiac Output

A

amount of blood ejected by the heart every minute

-function of stroke volume and heart rate

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4
Q

Stroke Volume

A

amount of blood ejected w/ each ventricular contraction

-influenced by preload, afterload, and contractility

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5
Q

Preload

A

amount of blood in the ventricles at the need of diastole

  • reflection of fluid volume status
  • “filling pressures”
  • a decrease in preload = decreased CO
  • increase in preload = increased CO
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6
Q

Afterload

A

resistance to flow that the ventricles must overcome to eject its contents
-increasing the afterload may make it harder for the heart to eject blood into systemic circulation

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7
Q

Contractility

A

refers to the force of the mechanical contraction

-poor contractility decreases stroke volume, thus decreasing CO

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8
Q

Oxygen Delivery (DO2)

A

amount of oxygen delivered to the tissues
-assessed through evaluation of CO and arterial oxygen content
>Arterial oxygen content: hemoglobin levels, percentage of hemoglobin saturated w/ oxygen, and amount of 02 dissolved in plasma (Pa02)

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9
Q

Oxygen Consumption (V02)

A

amount of oxygen extracted from the blood at tissue level

-measured through evaluation of blood sample: venous oxygen saturation (Sv02)

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10
Q

Venous Oxygen Saturation (Sv02)

A

blood sample
-reflects amount of oxygenated blood returned to the right heart by the pulmonary veins
-Normal Sv02: between 60 and 75%
-Decreased = tissues are extracting more oxygen than normal
>results from decreased oxygen delivery (DO2), which may be a decrease in oxygen content, hemoglobin, and CO
-also may reflect an inability to increase delivery in response to stressor such as pain or fever

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11
Q

Oxygen Debt

A

difference between normal V02 and V02 during the low-D02 state
(V02 = oxygen consumption)
-longer the imbalance between cellular oxygen supply and demand, the larger the debt becomes

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12
Q

Stages of Shock

A
  • Initial
  • Compensatory
  • Progressive
  • Refractory
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13
Q

Initial Stage of Shock

A

decreased oxygen delivery to the tissues

> Clinical Manifestations:
-subtle or none

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14
Q

Compensatory Stage of Shock

A

Initiation of compensatory mechanism in an effort to maintain an effort to maintain adequate volume, cardiac output, and blood flow to the tissues

  • Vasoconstriction
  • Increased sodium + water reabsorption
  • Shunting of blood away from non-essential organs
  • Increased glucose production

> Clinical manifestations:

  • restlessness, confusion
  • increased HR
  • tachypnea
  • respiratory alkalosis
  • oliguria
  • hyperglycemia
  • decreased bowel sounds
  • weak pulses
  • cool, moist skin
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15
Q

Progressive Stage of Shock

A

failure of compensatory mechanisms to maintain adequate blood pressure and circulating volumes

  • extensive shunting of blood away from nonessential organs
  • failure of sodium potassium pump

> Clinical manifestations:

  • lethargy or coma
  • hypotension
  • dysrythmias
  • anuria
  • absent bowel sounds
  • severe metabolic acidosis
  • respiratory acidosis
  • cold extremities
  • weak or absent pulses
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16
Q

Refractory Stage of Shock

A

prolonged inadequate blood supply to the cells

  • cell death and multisystem organ failure
  • inefficient anaerobic metabolism
  • extreme tissue hypoxia

> Clinical Manifestations:

  • coma
  • severe hypotension
  • severe metabolic + respiratory acidosis
  • hepatic failure
  • renal failure
  • peripheral tissue ischemia + necrosis
17
Q

Physical Assessment of Shock

A
  • Central Venous System (CNS)
  • Cardiovascular System
  • Respiratory System
  • Renal System
  • GI System
18
Q

Physical Assessment: Central Nervous System (CNS)

A
  • changes in CNS perfusion may be initial indication of inadequate D02 to tissues
  • restlessness, confusion, and irritability are beginning indicators of poor cerebral perfusion
19
Q

Physical Assessment: Cardiovascular System

A
  • BP valuable indicator of fluid status and CO
  • a low BP = problem
  • In Shock, BP decreases b/c of inadequate venous return to the heart, vasodilation, or decreased contractility of heart muscle
  • Prolonged hypotension = continued presence of shock
  • Finding indicative of a compensatory stage of shock -> a narrow pulse pressure which results from compensatory vasoconstriction causing an increase in diastolic BP w/ only slight increase in systolic pressure
  • tachycardia d/t stimulation of the sympathetic nervous system as a way to increase CO
  • if shock progresses, heart rate may slow
  • b/c of shunting of blood to vital organs, the skin and periphery become cool, pale, mottled, or cyanotic w/ thready pulses and sluggish capillary refill
20
Q

Physical Assessment: Respiratory System

A
  • early stages show increased respirations in an effort to increase oxygenation and decrease carbon dioxide levels (CO2) d/t metabolic acidosis
  • oxygenation measured through pulse oximetry
  • ABGs for accurate assessment
21
Q

Physical Assessment: Renal System

A
  • poor peripheral perfusion if urine output is decreased
  • oliguria in early stages (small amount)
  • Anuria in later stages
  • increased creatinine (renal failure)
22
Q

Physical Assessments: GI System

A
  • indicates poor perfusion through sluggish, hypoactive bowel sounds
  • nausea + vomiting
  • cell damage in GI tract allows translocation of intestinal bacteria to the systemic circulation; increased risk of sepsis
23
Q

Hemodynamic Monitoring

A
  • monitoring of BP, CO, and variables that affect CO

- done through an arterial line, central venous catheter, or pulmonary artery catheter

24
Q

Arterial Line

A
  • BP continually displayed

- provides easy access for blood analysis (ABGs)

25
Q

Pulmonary Artery Catheter

A

a flexible, balloon tipped catheter that is guided through the right side of the heat and into the pulmonary artery

  • info about CO and variables that affect it: preload, afterload, contractility
  • 4 Lumens: Proximal, Distal, Thermistor, and Inflation
26
Q

PA Catheter: Proximal Lumen

A
  • monitors right atrial pressure
  • reflection of right heart preload, and right ventricular end-diastolic volume
  • port used to inject the solution to obtain a thermodilution CO
27
Q

PA Catheter: Distal Lumen

A
  • rests within pulmonary artery
  • monitors systolic, diastolic, and mean PA pressures
  • monitors pulmonary artery wedge pressure/ pulmonary artery occlusion pressure (PAOP)
  • PAOP obtained when the balloon located at the end of the inflation lumen is inflated w/ 1.5 ml of air; balloon floats into a wedge position in the PA, which occluded that branch of PA, obscuring data from the right heart
  • the values obtained reflect left heart pressures; PAOP reflects left heart preload or the amount of blood in the left ventricle at the end of diastole
  • also be used for drawing a venous oxygen saturation (SvO2)
28
Q

SvO2

A

provides a “mixed” sample of blood from both the superior and inferior vena cava
-provides info on oxygenation extraction throughout the body

29
Q

PA Catheter: Thermistor Port

A
  • built into the tip of PA catheter
  • continuously measures the ambient blood temperature around it
  • Normal CO: 4 to 6 L/min
  • Normal CI: 2.5 to 4 L/min
  • small bolus of cooler saline is inserted through the proximal lumen
30
Q

Central Venous Catheter

A

uses a long catheter threaded through the superior vena cava w/ distal port resting in the superior vena cava above the junction w/ the right atrium

  • allows central venous pressure monitoring (CVP); right heart preload
  • Decreased CVP = low volume state
  • Increased CVP = increased volume
  • can also draw a central venous oxygen saturation (SvO2), if a PA line is not in place; provides info on oxygen extraction in the brain and upper body
31
Q

Laboratory Analysis For Shock

A
  • ABGs
  • SvO2 or ScvO2
  • Base Deficit
  • Lactate Level
  • Hemoglobin + Hematocrit
  • Electrolytes
  • Renal Studies
  • Liver Studies
  • Glucose
32
Q

Arterial Blood Gases (ABGs)

A

provide info on oxygenation, ventilation, and presence of acidosis or alkalosis (metabolic or respiratory)

  • hyperventilation in early shock = respiratory alkalosis
  • later stages of shock –> metabolic acidosis
  • presence of hypoxemia, or decreased PaO2 = development of complications (acute respiratory distress syndrome; ARDS)
33
Q

SvO2 or ScvO2

A 
evaluates VO2 (oxygen consumption)
-if falls below normal = tissues are extracting more oxygen than normal; results from decreased oxygen delivery (DO2)
34
Q

Lactate

A

elevated = increased anaerobic metabolism d/t tissue hypoperfusion

35
Q

Base Deficit

A
  • obtained through ABGs
  • amount of base required to achieve a pH of 7.4
  • a higher level of base required to achieve a normal pH (a negative base deficit) is consistent w/ acidosis

Nursing 272: Final Semester (79 decks)

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