Capnography Exam

A PetCO2 reading of 3mmHg in a normotensive patient who has just been intubated indicates an esophageal intubation. This means that the endotracheal tube has been mistakenly placed in the esophagus instead of the trachea. This can lead to inadequate ventilation and oxygenation of the patient, as the lungs are not being properly ventilated. Prompt recognition and correction of the esophageal intubation is necessary to ensure the patient's safety and well-being.

The given correct answer is A, B, and C. This means that all three options A (bronchospasm), B (pulmonary emboli), and C (V/Q mismatch) are possible causes for the variation in the reading. Each of these conditions can affect the exchange of gases in the lungs, leading to a difference between the End Tidal CO2 reading and the PaCO2. Bronchospasm can cause airway constriction and decrease ventilation, leading to a difference in CO2 levels. Pulmonary emboli can block blood flow to the lungs, impairing gas exchange. V/Q mismatch refers to an imbalance between ventilation and perfusion in the lungs, which can also affect CO2 levels.

Capnography systems measure end tidal CO2 using infrared absorption. Infrared light is passed through the exhaled breath and the amount of light absorbed by CO2 molecules is measured. This measurement is then used to determine the concentration of CO2 in the breath. Infrared absorption is a commonly used method for measuring CO2 as it is accurate, reliable, and non-invasive. It allows for real-time monitoring of CO2 levels, which is important in various medical settings such as anesthesia management and respiratory monitoring.

The correct answer is that the alveoli empty at varied rates and degrees. This means that not all alveoli empty at the same time or at the same rate. The emptying of alveoli is influenced by factors such as their compliance (ability to expand and contract), location (apices vs dependent regions), and other individual variations. Therefore, the emptying of alveoli is not uniform and can vary between different areas of the lungs and between different individuals.

In a normal patient, the end-tidal carbon dioxide (ETCO2) reading is expected to be within 3-10 mmHg of the arterial partial pressure of carbon dioxide (PaCO2). This is because ETCO2 is a non-invasive measurement of the level of carbon dioxide in exhaled breath, which is expected to closely reflect the level of carbon dioxide in the arterial blood. Therefore, a difference of 3-10 mmHg between ETCO2 and PaCO2 is considered within the normal range.