10 June Understanding Capnography in Anesthesia Flashcards
(33 cards)
What is the difference between capnometry and capnography?
Capnometry is the measurement of end-tidal CO2, while capnography is the visual representation (or picture) of that measurement.
Capnometry provides numerical values of CO2 levels, whereas capnography displays these values over time, usually in a waveform format.
What does hypercarbia indicate in the context of respiratory acidosis?
Hypercarbia indicates an increase in carbon dioxide levels, leading to respiratory acidosis.
This condition can cause various physiological effects, including increased blood vessel diameter and pulmonary vascular resistance.
What are the physiological effects of hypercarbia?
- Increases diameter of cerebral blood vessels, causing increased cranial pressure
- Increases pulmonary vascular resistance
- Causes potassium to shift from intracellular to intravascular spaces
- Can lead to respiratory acidosis
Hypercarbia can be particularly harmful for patients with neurological issues or heart conditions.
What is hypocapnia and how does it affect cerebral blood flow?
Hypocapnia is a condition of decreased carbon dioxide levels, which decreases cerebral blood flow.
This can be detrimental in cases of ischemic insults where increased blood flow is needed.
List some causes of decreased end-tidal CO2.
- Equipment malfunction
- Esophageal intubation
- Airway obstruction
- Hypothermia
- Pulmonary hypoperfusion
- Hyperventilation
These factors can lead to inaccurate readings and serious clinical implications.
What are some causes of increased end-tidal CO2?
- Rebreathing
- Exhausted CO2 absorbent
- Increased metabolic rate
- Fever
- Sepsis
- Seizures
Increased end-tidal CO2 often indicates a physiological response to various conditions.
What is the normal difference between pA CO2 and end-tidal CO2?
The normal difference is about 5 mmHg.
This relationship helps in estimating arterial CO2 levels based on end-tidal CO2 measurements.
What is the significance of capnograph waveforms in monitoring?
Capnograph waveforms provide insights into the respiratory pattern and can indicate problems with the patient or equipment.
The shape and changes in the waveform can signal various physiological issues or equipment malfunctions.
True or False: Hyperventilation decreases pulmonary vascular resistance.
True
However, it may not be beneficial in all cases, especially with congenital heart defects.
What are the requirements for an end-tidal CO2 monitoring machine?
- Accurate reading within ±12% of actual value
- Alarms for high and low CO2 levels
- Compatibility with common anesthetic agents
These requirements ensure the reliability and safety of monitoring during procedures.
Describe the phases of a normal capnograph.
- Phase 1: Baseline (no CO2)
- Phase 2: Rapid upstroke (beginning of exhalation)
- Alpha angle (100-110 degrees): Emptying of alveoli and transition into deadspaces if any
- Phase 3: Plateau (end-tidal CO2 level)
- Beta angle (90 degrees): begin inspiration, an angle increase would indicate inspiratory valve malfunction
- Phase 0: Rapid decline: Inspiration and CO2 should drop abruptly to 0
Each phase corresponds to different parts of the breathing cycle and provides valuable information about ventilation.
What does a change in the capnograph waveform indicate?
It indicates a potential problem with the patient or the monitoring equipment.
Variations in the waveform can signal changes in ventilation, equipment failure, or patient condition.
What is the purpose of monitoring end-tidal CO2 in sedation procedures?
To ensure the patient has normal ventilation and an open airway during sedation.
This monitoring is crucial for patient safety and effective management of sedation.
What indicates a normal end-tidal CO2 waveform?
A gradual increase on the plateau, followed by a sharp decrease during inspiration.
This indicates proper ventilation and no leaks in the system.
What happens to the end-tidal CO2 if there is an inadequate seal?
The plateau becomes shortened and more angled, indicating a leak in the system.
This may occur if the cuff of the endotracheal tube is not properly inflated or if there are loose connections.
What is the effect of hypoventilation on end-tidal CO2 levels?
End-tidal CO2 levels will increase.
This can happen due to insufficient tidal volume or respiratory rate.
What does an increase in end-tidal CO2 indicate?
Hypoventilation or inadequate ventilation.
It may also be a result of conditions like bronchospasm or CO2 absorption from the abdomen.
What is the expected change in end-tidal CO2 during hyperventilation?
End-tidal CO2 levels will decrease.
This can occur due to excessive respiratory rates or tidal volumes.
How many breaths should you bag a patient to confirm end-tidal CO2 after intubation?
Three breaths.
This is to ensure that the tube is correctly placed in the trachea and not the esophagus.
What is a sign that you may have intubated the esophagus?
A rapid decrease in end-tidal CO2 levels after initial breaths.
This indicates that the gas sampled is not from the lungs.
What indicates early loss of paralysis during surgery?
A small depression in the end-tidal CO2 waveform due to spontaneous breaths.
This suggests that the neuromuscular blockade is wearing off.
What might cause a patient to over-breathe during ventilation?
Poorly timed ventilator cycles or excessive respiratory rate.
This can lead to ineffective gas exchange.
What does an obstruction in the airway affect?
It prevents proper exhalation and affects end-tidal CO2 measurement.
This can result from various physical blockages in the airway.
Fill in the blank: If there is a leak in the endotracheal tube, the end-tidal CO2 will appear _______.
irregular or decreased.
