Joseph A. Orr

Continuous Monitoring of Respiratory Flow and CO2

In this article, the challenges of simultaneous respiratory gas concentration and flow measurements in a breathing circuit are reviewed. The tradeoffs that were considered in the development of a clinically useful on-airway combination CO2/flow sensor are discussed as well as the applications enabled by this on-airway combination CO2/flow sensor.

Capnography: Capnography in non-invasive positive pressure ventilation

The usually more controlled circumstances of airway management in the operating room (OR) often provide better conditions, better monitoring, and more experienced personnel, particularly when a problem occurs, than is available in other critical care environments or the emergency department. While the detection of CO2 by capnography after completion of a difficult intubation procedure may suggest success, it may more precisely indicate only that the tube tip is somewhere in the respiratory path, although perhaps not exactly where the intubationist desires. A capnography pattern indicating declining CO2 in each subsequent breath over several breaths will help identify esophageal intubation. Unilateral pathophysiologic conditions that cause unilateral hypoventilation or high airway resistances would result in a biphasic waveform. Many techniques to facilitate blind nasal tracheal intubation use the detection of significant exhaled gas flow from a spontaneously breathing patient to indicate the proximity of the tube tip to the glottic opening.