Capnograohy Flashcards
What is the primary focus of the guide on capnography?
Recording and analysis of the CO2 waveform and its use in differential diagnosis
What are the five characteristics used to analyze the CO2 waveform?
- Height
- Frequency
- Rhythm
- Baseline
- Shape
What is the normal end-tidal value of CO2?
Approximately 38 mmHg or 5% etPCO2
At what speeds are CO2 waveforms typically recorded?
- Real-time (high) speed at 12.5 mm/sec
- Trend (slow) speed at 25 mm/min
A sudden drop in CO2 to zero indicates what?
- Kinked ET-tube
- CO2 analyzer defective
- Total disconnection
- Ventilator defective
What does a sudden change in baseline indicate?
- Calibration error
- CO2 absorber saturated
- Water drops in analyzer or condensation in airway adapter
What does a sudden decrease in CO2 (but not to zero) indicate?
- Leakage in the respiratory system
- Obstruction
What does an exponential decrease in CO2 within one or two minutes indicate?
- Circulatory arrest
- Embolism
- Sudden decrease in blood pressure
- Sudden severe hyperventilation
What does a gradual increase in CO2 indicate?
- Developing hypoventilation
- Absorption of CO2 from peritoneal cavity
- Rapidly rising body temperature
What can cause a sudden increase in CO2 during ventilation?
- Injection of sodium bicarbonate
- Sudden release of tourniquet
- Sudden increase in blood pressure
What can a gradual upshift in the CO2 baseline and topline result from?
- Saturation of CO2 absorber
- Calibration error
- Technical error in CO2 analyzer
- Increasing dead-space
- CO2 absorber switched off
What is a ‘curare capnogram’ characterized by?
Lack of coordination between intercostal muscles and diaphragm, with a cleft in the plateau
What causes cardiogenic oscillations in a capnogram?
Beating of the heart against the lungs with small tidal volume and low respiratory rate
What defines a camel capnogram?
Seen in patients in the lateral position on the operating table
What is an iceberg capnogram caused by?
Combination of muscle relaxant and central acting analgesic drug
What does a high end-tidal CO2 with normal respiratory rate indicate?
- Low minute volume
- Rapidly rising body temperature
What does a low end-tidal CO2 with normal respiratory rate indicate?
- High minute volume
- Shock
- Low body temperature
What is Cheyne-Stokes respiration characterized by?
Cardiac oscillations after every respiratory group, seen in severe cerebral arteriosclerosis or brain damage
What can very irregular or chaotic respiration indicate?
Severe cerebral damage
What does sighing respiration indicate in adults?
Pathological condition if deep sighs are more frequent than once every 5 minutes
What happens when a patient fights the ventilator?
The capnogram pattern is interrupted, and end-tidal CO2 rises slightly
What is necessary for a correct interpretation of capnographic curves?
Comparison with other simultaneously recorded parameters
Fill in the blank: The normal capnogram has a nearly horizontal plateau between _____ and _____.
Q, R
True or False: The end-tidal CO2 value is equivalent to the alveolar CO2 only when a nearly horizontal plateau is seen.
True
