capnography refers to the noninvasive measurement of the partial pressure of carbon dioxide (CO2) in exhaled breath expressed as the CO2 concentration over time. The relationship of CO2 concentration to time is graphically represented by the CO2 waveform, or capnogram . Changes in the shape of the capnogram are diagnostic of disease conditions, while changes in end-tidal CO2 (EtCO2), the maximum CO2 concentration at the end of each tidal breath, can be used to assess disease severity and response to treatment. Capnography is also the most reliable indicator that an endotracheal tube is placed in the trachea after intubation.

1. Capnography Monitoring

2. capnography
The term refers to the noninvasive measurement of the partial
pressure of carbon dioxide (CO2) in exhaled breath represented in graphical
form with time on x axis and expired partial pressure of co2 on y axis and
results in capnography waveform.
Whereas capnometry is the numerical value of exhaled c02.
Etco2-40 mmHg
(Numerical value)

3. Why capnography?
• Effective in the early detection of adverse respiratory events.
• Correct placement of endotracheal tube
• Effective compressions during CPR
• Recognizes ROSC

4. Sidestream vs mainstream capnography
Respiratory c02 is measured
directly using a co2 sensor and
adaptors
Respiratory co2 measured in a separate
analysis chamber within the device.
A sampling tube is used to continuously
pump a small volume of gas from the
airway into the chamber.

5. Risk factors for developing respiratory depression
Obesity
BMI >30
OSA

6. Contd…..
Advanced age
COPD

7. Contd….
Patient undergoing
surgery under general
anesthesia
Patient On
sedatives

8. Contd…
Kidney failure
Heart failure

9. Indications of Respiratory Depression
ETCO2 >50 OR <20no
waveform or
abnormal waveform
RR<10
SPO2 <80
Correlate with other
parameters and
patients
presentation

10. Normal Capnogram
A: Baseline, represents the beginning of expiration and should start at zero. B: The transitional part
of the curve represents mixing of dead space and alveolar gas. C: The alpha angle represents the
change to alveolar gas. D: The alveolar part of the curve represents the plateau average alveolar gas
concentration. E: The end-tidal carbon dioxide value. F: The beta angle represents the change to the
inspiratory part of the cycle. G: The inspiration part of the curve shows a rapid decrease in carbon
dioxide concentration.

11. Hyperventilation
Hyperventilation
Baseline at zero, but height is reduced gradually
Etco2 value will decrease
Respiratory rate will
decrease

12. hypoventilation
Hypoventilation
Base line at zero, but height is increased
gradually
Etco2 value will increase
and respiratory rate will
decrease

13. Shark-fin pattern
Bronchospasm will produce a “shark fin”-appearing capnography waveform as a result of
regional obstruction that causes a turbulent mixing of dead space air with alveolar air. The more
pronounced the shark fin and the higher the ETCO2, the greater the risk of respiratory failure
and arrest is.

14. Rebreathing
Gradual elevation of baseline and the height of the capnograms
faulty breathing circuits or inadequate fresh gas flow in some circuit types, can lead to an
increase in the inspired CO2 and consequently and increase in the expired CO2.

15. Curare notch
A notch ("curare cleft") in the plateau phase of the capnogram of the ventilated patient has been presumed to be a
typical early sign of the fading effect of muscle relaxants on the diaphragm.
Indicates a spontaneous respiratory effort during mechanical ventilation.
Curare Cleft

16. capnoapnea
Apnea
Flat line
Decrease of exhaled partial pressure of CO2 <8 mmHg for ≥15 s

17. Cardiac arrest
Loss of etc02 value and loss of square wave

18. ROSC
A sudden increase in ETCO2 value and spike in capnography waveform is often the first sign of
return of spontaneous circulation (ROSC), even before a carotid pulse can be detected.

19. PROPER
Check if the readings for quantity, rate, shape and trending are normal for that particular
patient, considering any metabolic, ventilatory or perfusion problems
QUANTITY EtCO2 value should be 35-45 mmHg or 4.0 – 5.7 kPa
RATE
Ventilation should be 12-20 breaths per minute (bpm) for adults who are breathing by
themselves; and 10-12 bpm if being ventilated. Children should be ventilated at a rate of 15-
30 bpm; 25-50 bpm for infants.
Ventilating too quickly won’t let enough CO2 build up in the alveoli, resulting in lower
EtCO2 readings. Ventilating too slowly will allow extra CO2 to build up, resulting in higher
readings
SHAPE Waveform should normally be a rectangle with rounded corners
TREND Trending of the quantity, rate and shape of EtCO2 should be stable or improving
Duckworth (2017) suggests the acronym PQRST when assessing the EtCO2 waveform.
It stands for Proper, Quantity, Rate, Shape and Trend.4

20. Thankyou