Respiratory Monitors Flashcards
What is the calculation for airway resistance?
What is the calculation for airway compliance?
What is peak inspiratory pressure?
The maximum pressure in the airway during inspiration
What is plateau pressure?
The pressure in the small airways and alveoli after the set tidal volume has been administered?
How do you assess static compliance?
Using plateau pressure
How do you assess dynamic compliance?
Using PIP
What is happening in this picture?
An increase in PIP with no increase in Plateau pressure:
Resistance has increased OR
Inspiratory flow rate has increased
What is happening in this picture?
An increase in PIP AND an increase in plateau pressure
Total compliance has decreased
OR
Tidal volume has increased
What could cause this waveform?
What could cause this waveform?
What is happening in each phase?
An increased alpha angle signifies:
Expiratory obstruction:
COPD
Bronchospasm
Kinked endotracheal tube
An increased beta angle indiciates:
rebreathing due to a faulty inspiratory valve
cardiac oscillations
incompetent inspiratory valve
airway obstruction
Pulse oximetry is based on which law?
Beer-Lambert Law
Pulse oximeters emit two types of light:
Red light (prefers deoxygenated)
Near-infrared light (prefers oxygenated)
Order pulse oximetry sites in order from most to least sensitive:
Fast: ear, nose, esophagus, forehead
Middle: Finger
Slow: Toe
What is the downside to using a central SpO2 site in trendelenberg?
The venous engorgement can lead to a falsely low pulse ox reading
An SpO2 of 90% correlates with a PaO2 of:
60
An SpO2 of 80% correlates with a PaO2 of:
50
An SpO2 of 70% correlates with a PaO2 of:
40
What is the most common method of measuring exhaled gases in the breathing circuit?
Infrared absorption
Does infrared absorption detect O2 levels?
No. Diatomic molecules don’t absorb infrared light
How does mass spectrometry work?
Bombards a gas sample with electrons, creating ion fragments.
How does Raman Scatter Spectrometry work?
High power argon laser produces photons, which in turn collide with the gas molecules
Why aren’t piezoelectric crystals used in practice?
They can only identify one gas, not several
