A capnograph provides information about which of the following?

A capnograph specifically measures the concentration of carbon dioxide (CO2) in exhaled air, providing valuable information related to a patient's respiratory status during sedation. By continuously monitoring the levels of CO2, healthcare providers can assess the effectiveness of ventilation, detect any potential respiratory complications, and ensure that the patient is appropriately sedated without compromising their airway or breathing.

The other options do not pertain to the function of a capnograph. For instance, oxygen saturation levels are monitored using pulse oximetry, heart rate variability is assessed through ECG or heart rate monitoring, and blood pressure variation is typically measured with a sphygmomanometer or an automated blood pressure device. Therefore, the capnograph's primary role is to evaluate carbon dioxide levels, making it an essential tool in sedated patients.