An apparatus for augmenting ventilation of a patient and monitoring the patient's breathing patterns uses a transtracheal catheter. A substantially constant flow of oxygen/air is supplied through one of the lumens of the transtracheal catheter into the patient's trachea to augment the patient's spontaneous breathing. A respiration sensor measures a predetermined physical property (e.g., pressure or flow rate) related to the patient's respiration at the distal end of the transtracheal catheter. This data is recorded to monitor the patient's respiration patterns over time for subsequent analysis. The respiration data can be recorded on a strip chart or stored in digital form for transmission by modem or removable data storage media to a remote facility for analysis. A capnometer can be connected to one of the transtracheal catheter lumens to measure the carbon dioxide concentration of the air exhaled by the patient. The distal end of the transtracheal catheter can also be equipped with an oximetry probe that contacts the lining of the patient's trachea to measure blood oxygen saturation. The oximetry data is recorded concurrently with the respiration data and used for diagnosis and monitoring of sleep disorders, such as sleep apnea and hypopnea.