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151 Cards in this Set
- Front
- Back
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Three goals of PFTs
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1. identify pts at r/f increased mort/morb post op
2. identify pts who need short or long term ventilatory support 3. evaluate the benefit of reversing airway obstruction with bronchodilators |
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Anesthesia-specific goal of PFTs
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predict if will need vented post op
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Remember that PFTs are used
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- not used alone - used to support/exclude dx
- typically in combination with hx, exam, labs, dx studies to establish a diagnosis |
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What is FEV-1
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volume exhaled in first second of FVC maneuver
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What is FEF 25-75%
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mean expiratory flow - middle half of FVC maneuver
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What is FEF 25-75% good for measuring
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small airway diseases - reflects <2mm diameter airways
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What is FVC
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forced vital capacity - max amount of air that can be exhaled forcefully and as rapidly as possible after maximum inhalation
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Normal individual total expiratory time
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4-6 sec
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What are the expiratory times of a pt with an obstructive lung disease
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longer than 4-6 sec
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FVC for COPD patients are typically
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decreased due to air trapping
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FEVT is
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forced expired volume in a given amount of time
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FEV-1 are decreased in what type patients
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obstructive and restrictive disease patterns
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Normal FEV-1 is
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80%
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What is the actual calculation of FEV-1
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(FEV @ 1sec/FVC) x 100%
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FEV-1 decreases with
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age
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What's another name for FEF 25-75%
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MMEF (maximal mid expiratory flow)
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Peak expiratory flow (PEF) or peak flow is
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the speed of air moving out of the lungs at the beginning of exhalation
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TET
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Total expiratory time
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t
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Forced expiratory volume
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Two categories of lung pathology
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obstructive and restrictive
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Obstructive lung pathology refers to
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flow problem
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Restrictive lung pathology refers to
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volume problem
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Which lung pathology is more frequent cause of lung dysfunction
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obstructive - flow problem
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obstructive airways are characterized by
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limitation of expiratory airflow - so airways cannot empty as rapidly as normal
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Narrowed airways/bronchospasm/inflammatation are examples of
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obstructive disorders
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Examples of obstructive airway disorders include
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asthma, emphysema, cystic fibrosis
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Restrictive airways are characterized by
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reduced lung volume/decreased lung compliance
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Examples of restrictive airway disorders include
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interstitial fibrosis, scoliosis, obesity, lung resection, neuromuscular diseases, cystic fibrosis
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It is not uncommon for a disease to have
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obstructive and resistive components
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Is cystic fibrosis obstructive or resistive airway disease
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both
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PFT change is obstructive if
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FEV-1 and FVC are low AND FEV-1/FVC < 0.7
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Normal FVC is
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5L
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Normal FEV-1 is ~
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4L
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PFT change is resistive if
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FEV-1 and FVC are low AND FEV-1/FVC > 0.7
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Can you tell if pt has both restrictive and obstructive lung disease with PFT
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no
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If FEV-1 < 2L and FEV-1/FVC < 50%
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must have more sophisticated split lung functions tests before proceeding with case that will impact lung (pneumonectomy)
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FVC wnl or low
FEV-1 low FEF 25-75% low FEV-1/FVC low TLC wnl or high |
COPD
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COPD pt - why is TLC high
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air trapping
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FVC low
FEV-1 low FEF 25-75% wnl or low FEV-1/FVC wnl to high TLC low |
restrictive disorders
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FEV-1 = 3.6 L ; FVC = 4.8 L
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0.75 = restrictive
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FEV-1 = 1.8 L ; FVC = 2.2 L
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0.82 = restrictive
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FEV-1 = 2.2 L ; FVC = 4.8 L
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0.46 = obstructive
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Are PFT tests usually performed before or after bronchodilator tx
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both
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Positive response in considered in bronchodilator therapy when there is a
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15% improvement in PFT
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If there is a 15% improvement
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I think bronchodilator therapy should be started post op
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For bronchodilator therapy, look at improvement in which tests
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FVC, FEV-1 and FEF 25-75%
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Which types of lung disorders typically respond better to bronchodilator therapy
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obstructive
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TLC decreases how much after abdominal surgery
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25-50%
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TLC decreases how much after extremity surgery
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no change
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How long after general anesthesia does it take for VC to return to normal
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1-2 weeks
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VC correlates with ability to
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cough and deep breathe
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Forced VC is dependent on a patient's
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effort and cooperation
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How much of a reduction in vital capacity is there after abdominal and thoracic surgery
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60%
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How long does it take vital capacity to return to normal after abdominal and thoracic surgery
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7-10 days
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Why does it take so long for vital capacity to return to normal after abdominal and thoracic surgery
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because of the reflex diaphragmatic dysfunction due to surgical incision or presence of intraperitoneal or intrathoracic air versus post op pain
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What forced vital capacity is associated with post op pulmonary complications
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< 15 ml/kg
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Post op - the RV increases by how much after abdominal surgery
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13%
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Post op - the ERV decreases by how much after abdominal surgery
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25%
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Post op - TV decreases _____ within 24 hours, then returns to normal after _____
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20%, two weeks
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Post op - pulmonary compliance decreases by
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22%
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Post op - FRC decreases by
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22%, due to small airway closures
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Ideally, the FRC is greater than
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the closing capacity
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Post op - If FRC < closing capacity
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airways close and have increased shunting
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Post op - Upper abdominal surgeries reduce FRC by
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40-50%
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What are associated with the highest incidence of post op lung complications
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upper abdominal surgeries
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Post op - upper abdominal surgeries - how long does it take for FRC to recover
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3-7 days
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Post op - upper abdominal surgeries - how long does it take for FRC to recover if CPAP is used
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72 hours
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Post op - lower abdominal surgeries - can reduce FRC by
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30%
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Of FiO2 is 50% - what should the PaO2 be
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250 torr (mult FiO2 x 5)
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Of FiO2 is 21% - what should the PaO2 be
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105 torr (mult FiO2 x 5)
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If know FiO2 - send an ABG to find PaO2 - what can you determine
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if you have a delivery problem, underventilation problem, or lung problem
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Of FiO2 is 50% - what should the PAO2 (alveolar) be
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300 torr (mult FiO2 x 6)
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Of FiO2 is 21% - what should the PAO2 (alveolar) be
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126 torr (mult FiO2 x 6)
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If V and Q were perfectly matched - how much gradient difference would there be between PaO2 and PAO2
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zero
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In reality (normal) how much is the gradient difference between PaO2 and PAO2
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5-15torr (on 21% FiO2)
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Which has a higher gradient PaO2 or PAO2
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PAO2 (remember the formula)
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If V and Q were perfectly matched - how much gradient difference would there be between PaCO2 and PACO2
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zero
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In reality (normal) how much is the gradient difference between PaCO2 and PACO2
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2-10torr
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Is the gradient difference between PaCO2 and PACO2 affected by FiO2
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no
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ETCO2 can be substituted for PaCO2 or PACO2
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PACO2
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Which is higher PaCO2 or PACO2
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not sure - need answer here
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If a patient hypoventilates - what happens to the gradients
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no change
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if there is V:Q mismatching - what happens to the gradients
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the gradients will change
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If the gradient is normal and the patient is hypoxic
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you have a ventilation problem
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If the gradient is increased and the patient is hypoxic
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you have a V:Q problem
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Determine problem:
PaCO2 = 60torr - ETCO2 = 45torr |
gradient = 60-45 = 15
normal = 2-10 have V:Q problem |
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Determine problem:
PAO2 = 55torr - PaO2 = 45torr |
gradient - 55-45 = 10
normal - 2-10 have ventilation or O2 delivery problem |
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LOOK AT FLOW LOOPS
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LOOK AT FLOW LOOPS
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LOOK AT FLOW LOOPS
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LOOK AT FLOW LOOPS
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Origin of work capnography
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kapnos - greek meaning smoke
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where is capnography sampled
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at the Y connector, mask or NC
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Capnography gives insights into
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ventilation, cardiac output, distribution of pulmonary blood flow, metabolic activity
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Capnography refers to
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waveform
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Capnometry refers to
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monitor (digital)
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Two techniques for monitoring ETCO2
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mainstream and sidestream
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Two other terms for mainstream ETCO2 monitoring
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flow-through or in-line
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Describe mainstream ETCO2 monitoring adv and disadv
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adapter placed in breathing circuit
no gas removed from the airway adds bulk to breathing system electronics are vulnerable mechanical damage |
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Another term for sidestream analyzer
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aspiration analyzer
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Describe how sidestream analyzer works
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aspirate gas from airway sampling site transported to remote CO2 analyzer
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Adv of sidestream analyzer
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ability to analyze multiple gases
can use on non ETT pts |
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Disadv of sidestream analyzer
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potential for disconnect or leak - giving false readings
water vapor condenses |
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What device is used to protect analyzer optics
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(water trap
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Where is the water trap placed in the system
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between sample line and analyzer
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How much does sidestream analyzer withdrawal
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usually 50-500 ml/min
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Does the location of the ETCO2 analyzer matter
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yes
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ETCO2 measurements made further away from the alveolus can
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become mixed with fresh gas - causing dilution of CO2 values and rounding of capnogram
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Would you be able to see the rounding on a capnometer
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no - it's a digital readout - but the number should be lower
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ETCO2 measures the
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CO2 concentration of exhaled gas (duh!)
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Photodetector measures the amount of what type of light during inspiration and expiration
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infrared
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CO2 molecules absorb specific
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wavelengths of infrared light energy
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Light absorption increases directly with
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CO2 concentration
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A monitor converts the output from the infrared light absorber to the
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capnogram (waveform)
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LOOK UP PULSE OX
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LOOK UP PULSE OX
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STUDY CAPNOGRAPHY WAVEFORMS
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STUDY CAPNOGRAPHY WAVEFORMS
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How does an ETCO2 work
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uses infrared light to detect CO2 concentration of exhaled gas
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Light absorption increases as
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CO2 level increases
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Four phases of capnogram
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I, II, III, IV
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Phase I - AB represents
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exhalation of anatomic deadspace - normally devoid of CO2
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Phase II - BC represents
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(sharp upstroke of wave) - determined by evenness of ventilation and alveolar emptying
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End of phase II signifies
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usual end of expiration
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Phase III - CD represents
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exhalation of alveolar gas - considered expiratory pause
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Point D designates
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end-tidal CO2 concentration (most accurate)
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Phase IV - DE represents
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beginning of inspiration - normally gases lacing CO2 and approaching zero
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Purpose of capnogram
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provide validation of ETCO2 value
visual assmt of pt airway integrity verification of proper ETT placement assmt of ventilator/breathing circuit intregity |
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Causes of decreasing waveform to minimal
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missed intubation - in esophagus
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causes of small amplitude, then trailing waveform
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leaky or deflated ETT cuff
artificial airway is too small for pt (obstruction) connections on sample tubing loose |
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Causes for increasing ETCO2 trend
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hypoventilation - RR or TV
increased metabolic rate increased temperature release of tourniquet absorption of CO2 from peritoneal insufflation sudden increase in BP |
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Causes for gradual decreasing ETCO2 trend
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hyperventilation - RR or TV
decrease in metabolic rate decrease in temperature |
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Causes for rapid decreasing ETCO2 trend
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air or thrombus embolus
sudden hypotension circulatory arrest bone cement |
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Cause for inspired CO2 (rise in baseline)
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CO2 absorbent exhausted
faulty expiratory valve calibration error in monitor water in analyzer |
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Cause for loss of plateau/sloping of ETCO2 waveform
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obstruction of expiration (COPD, asthma, bronchospasm)
A-a gradient increased No plateau is reached prior to next inspiration kinked ETT |
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Cause for cleft in phase III of waveform
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pt is inspiring during exhalation phase
muscle relaxant levels subsiding PaCO2 increasing causing spontaneous respiration increasing pain in older texts - referred to as Curare cleft |
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Cause for cardiogenic oscillations
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by beating of heart against lungs
may be seen more as relaxant wears off and tone returns to chest, abd wall and diaphragm |
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Cardiogenic oscillations are seen more in what population
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pediatrics because chest takes up more space in chest cavity
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Ketorolac article - for our info
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24 y/o/f administered ketorolac at end of a case for post op pain - awake extubated and sent to PACU - after 15 min in the PACU, started having problems breathing - admin terbutiline for bronchodilation - condition did not improve - administered aminophylline, midazolam, methylprednisolone - meanwhile re-intubated - given H1 and H2 blockers (diphenhydramine and rantitidine) simultaneously - extubated and watched overnight
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Article - bronchial asthma is the
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most common obstructive airway disease - 3-6% of population
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Article - What is the aspirin triad
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aspirin intolerance, asthma, nasal polyps
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Article - pts with aspirin triad are also
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sensitive to derivatives of benzoic acid, so caution should be used with ester-type anesthetics
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Article - NSAIDs (ibuprofen, ketorolac, and naproxen) may induce
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asthmatic episodes due to cross-sensitivity to aspirin and/or increased leukotriene production
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Article - Three types of bronchial asthma
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exercised-induced, extrinsic, and aspirin-induced
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Article - Exercise-induced asthma is characterized by
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bronchoconstriction with increased physical activity and decreasing wall temperature
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Article - Exercise-induced asthma is typically managed with
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inhaled beta adrenergic agonists
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Article - Extrinsic asthma is AKA
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environmentally induced asthma
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Article - Extrinsic asthma is induced by
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exposure of inhaled allergenic substances to IgE antibodies
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Article - Extrinsic asthma takes how long for symptoms to manifest
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minutes to several hours - but acute attacks are not usual
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Article - Aspirin-induced asthma is often correlated with
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intrinsic type astham
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Article - Aspirin-induced asthma takes how long for symptoms to manifest
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almost immediately or delayed up to 8hrs
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Article - Treatment of aspirin-induced asthma includes
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epinephrine (potent bronchodilator) due to direct stimulation of B2 adrenergic receptors - may need multiple doses
B2 receptor agonists (terbutaline, metaproterenol, albuterol) |
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Article - Treatment of aspirin-induced asthma includes
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In both cases, they administered both H1 and H2 anagonists (diphenhydramine and ranitidine)
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Article - aspirin is second to penicillin in producing
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allergic drug reactions
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Article - aspirin intolerance is
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not a true drug allergy
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