Cap Obstructs CO2 Sampling

Davide Cattano, MD, PhD; Samir J. Gandhi, MD; Katherine C. Normand, MD

To the Editor

Figure 1. The CO2 connector (elbow) and the misadventurous cap on the wrong side.

We recently discovered an interesting finding with our circuit after failing to document end-tidal CO2 during bag-mask ventilation after induction. Upon further inspection of the circuit, we noted a blue cap inside the elbow connector (DynJaa, Medline Circuit, see Figure 1). It was soon realized that the blue cap that normally comes attached to the outside of the elbow connector, where the sampling line attaches, was actually inverted and pushed inside the connector. After a vigorous tapping of the elbow connector, the blue cap fell out, and we reattached our sampling line and confirmed end-tidal CO2. Thankfully, no adverse outcomes were encountered, but we could easily imagine a scenario during bag mask-ventilation, where the cap could fall straight down into the patient’s oropharyngeal cavity, possibly leading to aspiration. We can only speculate as to how the cap ended up inside the elbow connector (new anesthesia tech, accidental loss of the cap), but wanted to share this finding with the readers of the APSF Newsletter. A preoperative machine check was done; however, this event was not detected since the cap obstructed CO2 sampling but did not obstruct airflow within the circuit.


Davide Cattano, MD, PhD, Samir J. Gandhi, MD, Katherine C. Normand, MD Department of Anesthesiology, the University of Texas HSC at Houston.