Evaluation of an Ambu-bag valve with a self-contained, colorimetric end-tidal CO2 system in the detection of airway mishaps: An animal trial

Objective: Capno-Flo(TM) (Kirk Specialty Systems, Carrouton, TX) is a porta ble pulmonary resuscitator (self inflating ambu-bag - valve system) with a self-contained, colorimetric end-tidal CO2 detector that has the ability to pro,ide continuous CO2 monitoring for up to 2 hours. The purpose of this s tudy is to determine the accuracy and time interval for the Capno-Flo(TM) m onitor to detect acute airway obstructions and hypopharyngeal extubations i n an intubated animal model, Subjects: Five anesthetized, non-paralyzed, mechanically ventilated Yorkshi re minipigs, Methods: Complete and partial airway obstruction was simulated with complet e and partial cross-clamping of the endotracheal (ET) tube. Placement of th e ET tube into the hypopharynx was performed to simulate accidental extubat ion. In addition to the Capno-Flo(TM) colorimetric indicator, both sidestre am (SS) and mainstream (RIS) capnography were used to monitor end-tidal CO2 and comparison The time intervals for the capnograph wave to batten and fo r the monitor to display "zero" were recorded after each airway alteration. Each experiment was carried out for 180 seconds, and a total of 25 trials was performed. Results: Complete obstruction produced a color change in the Capno-Flo(TM) monitor in 9 +/- 2 seconds and battening of the SS and MS waveform in 8 +/- 2 seconds and 6 +/- 2 seconds, respectively, The SS and MS monitors displa yed zero in 49 +/- 7 seconds and 19 +/- 1 seconds, respectively. Partial ob struction did not produce color change, a flattening of the wave, or a moni tor display of zero. Hypopharyngeal extubation produced a color change in 1 0 +/- 2 seconds, flattening of the SS and MS waveform in 7 +/- 2 seconds an d 7 +/- 1 seconds, respectively. The SS and MS monitors displayed "zero" in 76 +/- 16 seconds and 18 +/- 3 seconds, respectively. Conclusion: The Capno-Flo(TM) identified all complete airway obstructions a nd hypopharyngeal extubations rapidly, The CF monitor performed comparable to the SS and MS capnographs, Neither the Capno-Flo(TM), nor the sidestream , nor the mainstream capnographs detected partial airway obstruction. The c linical application of this portable inexpensive capnometer in the continuo us monitoring of the intubated patient, especially the transport patient, s hould be investigated further.