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44 Cards in this Set
- Front
- Back
- 3rd side (hint)
What is compliance?
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The ratio of change in volume to change in pressure.
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What is the calculation for Dynamic compliance?
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TV / (Peak Pressure-PEEP)
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What is the calculation for Static compliance?
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TV / (Plateau Pressure-PEEP)
What are the normal ranges for adults and children? |
Adults: 35-100 mL/cmH20
Children: >15 mL/cmH20 |
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What is Elastance?
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A measure of the tendency of a hollow organ to recoil toward its original dimensions upon removal of a distending or compressing force.
What is it reciprocal to? |
Compliance
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What is Resistance?
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Loss of pressure at the end of a tube when a fluid flows through it.
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When it comes to resistance with the airway or mechanical resistance of the trach. tube or breathing system, what is a normal resistance level?
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2-5 cm H20
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If there is a decrease in the caliber of the airway, ETT, or breathing system, what happens to resistance?
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It increases.
What are some real examples of instances when resistance would increase? |
Bronchoconstriction, secretions, tumor, swelling, foreign body, kink in tracheal tube or dislodgement of tracheal tube, constriction or sharp bends in the breathing system.
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Pressure drop can be calculated how?
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Resistance x Flow rate
How would you calculate the resistance for this equation? |
Peak - Plateau pressure
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Plateau pressure is affected only by what?
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Compliance
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If TV and inspiratory flow stay the same but resistance increases, what happens to the difference between the peak and plateau pressures?
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The difference between peak and plateau pressures INCREASES.
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What can be done to keep TV constant when resistance increases?
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Use an increased pressure or a longer flow for a longer time.
If this isn't done what will happen to the TV? |
It will drop.
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In terms of induction, what is V.1?
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The volume exhaled in the first second; this is passive.
What is a normal V.1? |
70%
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If V.1 is less than 70%, what does this indicate?
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Increased resistance or decreased compliance.
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What is FEV1?
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Active exhalation; not under anesthesia.
What is a normal FEV1? |
More than 80%
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A pressure-volume loop mainly measures what?
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Compliance
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In terms of controlled ventilation, what direction on the pressure-volume loop does inspiration and expiration follow?
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A counterclockwise loop
When is it clockwise? |
During spontaneous ventilation.
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In a pressure-volume loop, what is measured on the horizontal axis?
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Pressure
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In a pressure-volume loop, what is measured on the vertical axis?
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Volume
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In a pressure-volume loop, what two things are represented at the highest point of the loop?
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Tidal volume (read on the vertical axis) and beginning of expiration.
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How can you tell there is PEEP involved in a pressure-volume loop?
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The lowest point on the loop corresponds to a non-zero pressure on the horizontal axis.
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In a pressure-volume loop, what does the area inside the loop correspond to?
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Work of breathing
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In a pressure-volume loop, what does the slope of the loop show?
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Compliance
What does a loop that is more horizontal than the baseline loop indicate? |
A more horizontal loop indicates that a high pressure is required to deliver a relatively low volume.
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In a pressure-volume loop, what does a more vertical loop than its baseline loop indicate?
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That a low pressure is needed to give a high volume (increased compliance)
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What are some examples of factors that cause a decreased compliance in the lungs?
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Air embolism, pneumothorax, obesity, curvature of the spine, prone position, narcotics, etc.
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What are some factors that contribute to increased lung compliance?
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PEEP and resolution of factors that decrease compliance.
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How is increased resistance seen on a pressure-volume loop?
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Higher pressures with the same or decreased tidal volume.
It will be a clockwise shifted loop with large internal area. Pressure falls rapidly at end-inspiration. |
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Flow-volume loops measure what specifically?
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Resistance
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On the horizontal axis of a flow-volume loop, what is measured?
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Volume
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On the vertical axis of a flow-volume loop, what is measured?
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Flow
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Where is the zero point for volume located on the flow-volume loop?
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On the right of the horizontal axis.
What does the zero point correspond to? |
Functional Residual Capacity
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In a flow-volume loop, Inspiratory flow moves which way on the horizontal axis?
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Lefward as volume increases and drops to zero at end-inspiration. (from its negative point)
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At which point is tidal volume represented on a flow-volume loop?
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When the volume drops to zero at end-inspiration.
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On a flow-volume loop, inspiratory flow is plotted _____ the horizontal axis.
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Below
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On a flow-volume loop, expiratory flow is shown _______ the horizontal axis.
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Above
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What is the shape of the flow-volume loop determined by?
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Passive lung deflation (this includes elastic properties of the lungs/chest wall and total resistance of the tubes)
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A normal shape of a flow-volume loop is a flow rate that _______ rapidly in early _______, quickly reaches a peak, then slows and gradually returns to ______.
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increases
expiration zero |
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The shape of the expiratory portion of the flow-volume loop changes according to what?
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Changes in Resistance
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In a flow-volume loop, Increased resistance causes:
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Decreased peak expiratory flow, decreased flow throughout exhalation, and possibly decreased TV
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How does the shape of the flow-volume loop change in the instance of spontaneous ventilation instead of controlled?
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The inspiration portion is more rounded instead of a straighter, steady inhalation.
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What are some factors that could cause increased resistance?
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Tracheal tube obstruction, bronchoconstriction, airway obstruction, tracheal tube too small
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What happens to the inspiration portion of a pressure-volume loop when the patient has a spontaneous respiration?
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There will be negative pressure
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What does an open loop indicate?
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Exhaled volume is less than inhaled volume
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What are some negative factors that can cause an open loop?
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Incorrect calibration, incomplete exhalation before the next inhalation (COPD, lung retraction), a leak distal to the sensor (partial disconnect, cuff leak, tension pneumo)
What else will a tension pneumo show? |
Decreased compliance
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What are some normal causes for an open loop?
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An uncuffed ETT or use of LMA
Double lumen endobronchial tube (increased resistance) Gas exchange imbalance (O2 uptake > CO2 excretion or induction where uptake of agent/N2O is high) |
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