The importance of capnometry and end-tidal carbon dioxide (ETCO2) has been underscored in recent years by guidelines as a method to continuously monitor adequacy of ventilation during sedation and anesthesia. Guidelines for cardiopulmonary resuscitation (CPR) recommend attempts to improve CPR quality if ETCO2 is lower than 10 mmHg. ETCO2 is thus a time-critical parameter that may benefit from being delivered in real time to health care providers. We performed a pilot study to investigate whether the addition of audible capnometric cues after each breath enhanced providers' ability to maintain appropriate ventilation over conventional capnography. The addition of audible cues was confirmed to enhance control of ETCO2 during manual ventilation. We subsequently developed five distinct audible capnometric cues corresponding to different levels of ETCO2. We performed a study using ten random simulated test cases to confirm whether changes between levels as well as the direction of change could be distinguished using these audible cues. Audible cues were found to be easily distinguishable. 16 evaluators correctly identified presence and direction of change in ETCO2 with an average pass rate of 89%. It is anticipated that this "ETCO2 Audible Cue" feature will be able to improve the quality of patient monitoring, as well help improve the quality of CPR.