Capnography Flashcards
the device that measures CO2
capnometer
the measurement of CO2 in respiratory gases
capnometry
the graphic display of CO2 levels as they change during breathing.
Capnography
T/F PETCO2 is an accurate measurement of PaCO2!
False The most significant error is assuming that the end-expired CO2 levels can substitute for actual PaCO2 measurements
The most common problem is contamination or obstruction of the sampling system or monitor by secretions or condensate. What are good ways to prevent these problems?
Proper use of water traps and regular changing of sample tubing or chambers can help prevent this problem.
What is PET CO2
The CO2 at the end of an exhaled tidal volume
Exhaled tidal volume can be divided into thirds (which portion) all alveoli, contains the highest concentration of CO2
Last Third
Exhaled tidal volume can be divided into thirds from dead space contains only atmospheric CO2, typically 0.3%
First third
Exhaled tidal volume can be divided into thirds more CO2, transitional zone from small airways and alveoli
Second third
What are 2 pieces Measuring equipment? Which is the most common?
Mass spectrometry Infrared capnometer (Most Common)
When looking at a capnograph. What is revealed on the X-axis?
x-axis which records time
When looking at a capnograph. What is revealed on the Y-axis?
Y. axis records partial pressure of CO2
What are the two types of capnographs?
Mainstream Sidestream
Inaccurate readings with high frequencies of breathing is more of a problem for which system?
sidestream
What is an advantage of a Mainstream system?
Response time
What is an disadvantage of a Mainstream system?
weight on ET tube
What is an advantage of a Sidestream System?
Light weight on airway
What are disadvantages of a Sidestream System?
delay time in sample rate thin tube, blocked with water and mucus
Where is capnography most often used?
Anesthesia
Speed of tracing
12.5 mm per second
Trend speed
25 mm per minute
What does the trend speed provide?
Provides peak value & breathing frequency
Whats great about speed of tracing !!!
Real-time tracing Provides diagnostic shape and best detail
Under these conditions the patient cannot change their respiratory rate or tidal volume?
Anesthesia Rebreathing circuit based on patients sedated in Operating Room
What is A, B, C?
A. End Tidal CO2
B. Tidal Volume
C. ERV
What conditions represent D,E,F,G?
D. V/Q mismatch
E. Normal
F.LHF or COPD
G. Pulmonary Emboli
What is H, J, I, K, and L
H. Percent CO2
J. Time
I. Normal End of inhalation VT
K. End of exhaltion VT
L. End (maximium exhalation)
What can cause high PET CO2?
Hypoventilation –Low minute volume
Patient Can not compensate –sedation
An increase in CO2 production
Rapidly rising body temp –malignant hyperthermia
If you have low minute ventilation how will the capnograph read?
High PETCO2
What can cause Low PETCO2
Anesthesia induced Hyperventilation
High minute volume
Induction of hypothermia
Expiratory Airflow Problem will appear as what?
Shark Fin
What causes a shark fin?
Increased Expiratory Airway Resistance
bronchospasm –Asthma
Kinked ET tube
Herniated ET tube cuff
What is this ?
Curare Cleft
A whale comming out the ocean to eat a bird.
What causes a curare cleft?
Seen during reversal of anesthesia, after surgery
Lack of Coordination between Intercostal muscles and diaphragm
Recovery from neuromuscular block
spontaneous breath
fighting the vent
Camel capnogram can occur with spontaneous or controlled ventilation?
BOTH
During spontaneous or controlled ventilation
Where abouts can Camel capnogram occur?
Lateral position on the Operating Table
What can cause a sudden drop on the capnograh?
Problem with CO2 analyzer –
Occluded sample line
- sidestream
- kink
- water
- mucus
- disconnect or big leak
Causes of Exponential decrease “Wash Out”
–1 to two min
sudden decrease in pulmonary circulation
massive Pulmonary Emboli
Circulatory arrest
Cause of Gradual Increase
Increasing CO2 production (dereased VE)
rapidly rising body temperature
Developing hypoventilation
Causes of Sudden Increase
Injection of Sodium Bicarbonate
Sudden increase in blood pressure
intravenous adrenaline
Sudden release of tourniquet
Cause of Upward shift in baseline
Patient Rebreathing CO2
- Increase in dead space
CO2 absorber
- switched off
- saturated
Problem with CO2 analyzer
- calibration
Causes of Gradual Lowering
Gradual hyperventilation
Lowering body Temperature
Decreasing perfusion
During monitor failure what happens?
Plethysmogram- decrease in amplitude
Arterial line Blood pressure, decreasing
how is the Capnogram affected with BP?
Drops with BP
What are the “really bad” causes of monitor failure?
Severe blood loss
cardiac malfunction
- cardiac tamponade
- dissecting aneurysm
Anaphylactic shock
Is capnometery useful as a weaning index? Yes and No
Yes if the patient has normal lungs
- Postoperative
No if pt has parynchmal or airway disease.
What is this and the causes?
Gradual Lowering
Gradual hyperventilation
Lowering body Temperature
Decreasing perfusion
What is this?
Expiratory Airflow Problem
What is this?
Camel Capnogram
