Module 9 Flashcards
AANA standards say that ventilation should be
Monitored by the use of continuous expired carbon dioxide and alarm should be audible
With capnography, there is a
Pressure vs time plot
These are the 2 speeds of capnography
High speed- allows for the interpretation of each breath
Slow speed- enables observation of the trend
Calculated with either diverting or non diverting systems
Chemical sensitive paper only gives a
Quantitative measurement
Carbon dioxide values can be used to estimate
Blood CO2 levels
Pulmonary blood flow
Alveolar ventilation.
The evaluation of CO2 waveform allows the identification of
Adequacy of gas sampling
Leaks
Malfunctions
What does it mean if there’s No capnography waveform
There’s a failure to ventilate the patients lungs
Due to: esophageal intubation, extubation, disconnect, failure of sampling line, apnea, bronchospasm, cardiac arrest
During inspiration or phase 0,
Fresh gas is being inhaled & therefore no CO2 flows by the CO2 sampling site; no rebreathing = concentration is 0
If CO2 is greater than 0,
CO2 is being rebreathed
What are causes of CO2 rebreathing?
Incompetent expiratory valve
Exhausted CO2 absorbent
Improperly calibrated capnography
High respiratory rate may exceed
The responsiveness of the monitor or sampling device
Inspiratory segments included phases
1-3 and occasional 4
Phase 1 appears as an extension on the horizontal baseline initiated during phase 0, but
It’s the beginning of exhalation when CO2 free gas from dead space is exiting
In phase 2, CO2 rich alveolar gas
Begins to appear as the expiratory upstroke appears; should be steep
The alpha angle is the transition between
Phase 2 & 3
Correlates with the emptying of the alveoli & thus overall VQ matching
Capnography plateaus in
Phase 3 with only a slight increase in slope
The beta angle represents
A transition from the expiratory to inspiratory segments
What increases the beta angle
Malfunctioning inspiratory valves
Rebreathibg
Low tidal volume
Presence of phase 4 is due to
VQ mismatching or air trapping, which is most frequently seen in pregnant & obese patients
What is the best measurement of ventilation
Partial pressure or arterial CO2
End tidal CO2 & arterial CO2 differ by
5mmHg due to ventilation mismatching & alveolar mixing
Increases in CO2 are caused by
PE
Bronchial intubation which causes perfusion without ventilation
Deceases in end tidal CO2 are related to
Difference between the measured CO2 level & the try CO2 level in the airway caused by CO2 sampling or problems with the capnography
Under normal conditions, the lungs excrete CO2
At the same rate as the body produces it, therefore no change in arterial CO2
What increases CO2
Respiratory acidosis
Increased CBF/ICP/PVR
K+ into serum
What decreases CO2
Respiratory alkalosis
Decreased CBF/PVR
K+ shift intercellular
End tidal CO2 is an important adjunct for predicting
Outcomes of CPR
Reflects quality of chest compressions & pulmonary circulation
CO2 greater than 15 during CPR predicts a greater chance of ROSC
What can be used in ARDS to decrease VQ mismatching and minimize Wests Zone 1
PEEP
PE can be diagnosed by
Capnography, since a PE will show an increase in alveolar dead space by decreasing perfusion
No definitive diagnosis can be made
Is etCO2 a replacement for blood gas
No
