Respiratory Monitors And Equipment Flashcards
What is the Peak Inspiratory Pressure?
It’s the maximum pressure in the patient’s airway during inspiration.
What is the equation for dynamic compliance?
Dynamic compliance = tidal volume / peak inspiratory pressure - PEEP
What is plateau pressure?
It is the pressure in the small airways and alveoli after the target tidal volume is delivered
At what plateau pressure does the risk of barotrauma occur?
> 35 cm/H2O
What is the equation for static compliance?
Static compliance = tidal volume / plateau pressure - PEEP
What is phase 1 (A-B) of the capnograph?
Exhalation of anatomical dead space
What is phase II (B-C) of the capnograph?
Exhalation of dead space AND alveolar gas (mixture)
What is phase III (C-D) of the capnograph?
Exhalation of alveolar gas
What is phase IV (D-E) of the capnograph?
Inspiration of fresh gas that does not contain CO2
Where is the alpha angle measured?
At point C
What does an increased alpha angle signify?
Expiratory airflow obstruction, bronchospasm, or a kinked ETT
Where is the beta angle measured?
Point D.
What are the two methods of CO2 analysis?
Mainstream (in line)
Sidestream (diverting)
What are some traits of a mainstream CO2 analyzer?
Attached to ETT
No need for water trap or pulping mechanism
Increased dead space
What are some traits about sidestream (diverting CO2) analysis?
Outside of the airway
Response time is slower
Requires water trap
What law is pulse oximetry based on?
Beer-lambert law
What wavelength preferentially absorbs deoxyhemoglobin?
660
Remember lower wavelength, lower amount of o2
What wavelength preferentially absorbs oxygenated hemoglobin?
940
Higher wavelength, higher O2
What pulse oximetry sites are the most responsive? Most to least
As a rule, the closer to central circulation, the fast the response
(Ear, nose, tongue, esophagus, forehead > finger > toe
What PaO2 corresponds to a SpO2 of 90%?
60 mmHg
What PaO2 corresponds to a SpO2 of 80%?
50 mmHg
What PaO2 corresponds to a SpO2 of 70%?
40 mmHg
What are some methods to improve the SpO2 signal?
Place a digital block
Warm the extremity
Protect from ambient light
Vasodilating cream
Arterial vasodilator
What is pulse oximetry a monitor of?
Hemoglobin Saturation
Heart rate
Fluid responsiveness
(Also tissue perfusion/compression)
What are some optical things that may cause for an inaccuracy in pulse ox readings
Dyes (methylene blue, Indocyanine green, and indigo carmine)
Nail polish -blue, black, and green (NOT PURPLE or RED)
External light
What is considered an increased risk in corneal abrasion?
Placing the pulse oximetry in the index finger
What is the most common way of measuring exhaled gas?
Infrared Absorption
What is infrared absorption Spectrophotometry?
Each has has a signature “fingerprint.” Deals with the partial pressure of gases
What is Mass Spectrometry analysis?
Bombards a gas sample with electrons creating ion fragments ~ these are then separated and identified based on their MASS!!
What is Raman Scatter Spectrometry?
Uses a high power argon laser to produce photons which turn and collide with the gas molecules. These are then measured
What is Piezoelectric crystals?
A tool that can detect inspired, expired, and breath to breath changes of a particular gas by incorporating a lipid layer on the crystal.
