What does capnography measure in surgical patients on mechanical ventilation?

Capnography is a monitoring technique that measures the concentration of carbon dioxide (CO2) in exhaled air, specifically focusing on end-tidal CO2. This measurement is critical in surgical patients on mechanical ventilation as it provides real-time feedback on the patient's ventilation status.

Monitoring end-tidal CO2 allows healthcare providers to assess the effectiveness of ventilation and detect any potential issues, such as hypoventilation or hyperventilation. It is also a valuable tool for evaluating the patient’s metabolic status and can indicate changes in circulation or perfusion.

In contrast, oxygen saturation indicates the level of oxygen in the blood, which is measured using pulse oximetry and not capnography. Arterial blood pH is obtained through blood gas analysis, another separate measurement not provided by capnography. Lastly, while respiratory rate can be assessed in conjunction with capnography, capnography itself does not directly measure respiratory rate; it focuses on carbon dioxide levels in exhaled breath. Therefore, measuring end-tidal CO2 with capnography is essential for managing ventilated patients in surgical settings.