Capnogram

Question 1

What characterstics are analysed in a capnograph?

Answer 1

analyzed for 5 characteristics:–Height–Frequency–Rhythm–Baseline–Shape

Question 2

what are the phases of a normal capnogram?

Answer 2

4 phases

Phase I:
(inspiratory baseline) reflects inspired gas, which is normally devoid of carbon dioxide.

Phase II (expiratory upstroke)
Transition between VD(anatomical), which does not participate in gas exchange, and alveolar gas from the respiratory bronchioles and alveoli.

Phase III
Alveolar plateau.

Phase 0
Inspiratory downstroke, the beginning of the next inspiration

Question 3

Q. What is
- Normal EtCO2
- alpha angle
- Beta angle
- Phase IV

Answer 3

Other features:

Normal end-tidal PCO2 is approximately: 38 mmHg or 5%

Alpha angle is the transition from Phase II to phase III–>widened in severe bronchospasm

Beta angle is the transition from Phase III to Phase 0 (the start of inspiration)

Phase IV (terminal upstroke before phase 0) may be seen in pregnancy

Question 4

Causes of FLAT ETCO2 TRACE

Answer 4

• Misplaced airway- oesophageal intubation/ accidental extubation
• Apnea test in brain death
• Equipment malfunction–Ventilator disconnection/capnography malfundtion

Question 5

Causes of Increasing ETCO2

Answer 5

• Fever
• Sodium bicarbonate
• Overfeeding

=>Pulmonary perfusion

• Increased cardiac output
• Hypoventilation
• Bronchial intubation
• Partial airway obstruction
• Rebreathing

Exhausted CO2 absorber

Question 6

Causes of Low EtCO2

Answer 6

Hypothermia

=>Pulmonary perfusion
1. Reduced cardiac output
2. Hypotension
3. Hypovolaemia
4. Pulmonary embolism
5. Cardiac arrest
6. Hyperventilation
7. Apnoea
8. Total airway obstruction (note high airway pressures)
9. Extubation

Question 7

SUDDEN CHANGE IN BASELINE (NOT TO ZERO)

Answer 7

• Calibration errorWater
• drops in analyzer
• CO2 absorber saturated (check capnograph with room air)
• CO2 rebreathing

Question 8

SUDDEN INCREASE IN ETCO2

Answer 8

• ROSC during cardiac arrest
• correction of ET tube obstruction