Which parameter should be monitored closely to assess the effectiveness of pressure support ventilation?

• A. Blood pH level
• B. Tidal volume
• C. End-tidal CO2
• D. Respiratory rate

Answer: (C)

Monitoring end-tidal CO2 is crucial in assessing the effectiveness of pressure support ventilation because it provides direct insight into the patient’s ventilation status and how well carbon dioxide is being expelled from the body. The level of CO2 in exhaled air reflects both the patient's metabolic rate and their ability to effectively ventilate.

In the context of pressure support ventilation, where the primary goal is to assist with the patient's effort while still allowing for some degree of spontaneous breathing, monitoring end-tidal CO2 helps determine whether the ventilation is adequate. An elevated level can suggest that the patient is not ventilating effectively, while a normal or decreasing level indicates successful ventilation and proper removal of CO2.

Other parameters, while important, do not provide as immediate a gauge of ventilatory effectiveness. Tidal volume indicates how much air is being delivered with each breath but does not account for CO2 removal or metabolic demands. Blood pH levels provide information about acid-base balance but can be influenced by various factors beyond just ventilation efficiency. Respiratory rate is valuable for assessing the overall respiratory effort but does not give a complete picture of metabolic gas exchange. Therefore, end-tidal CO2 is the most direct indicator of effective gas exchange in this setting.