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Correspondence  |   August 1997
A Choking Hazard during Nasal End-tidal CO2Monitoring 
Author Notes
  • Associate Professor, Division of Obstetrical Anesthesia, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298–0695.
Article Information
Correspondence
Correspondence   |   August 1997
A Choking Hazard during Nasal End-tidal CO2Monitoring 
Anesthesiology 8 1997, Vol.87, 451. doi:
Anesthesiology 8 1997, Vol.87, 451. doi:
To the Editor:-Goldman [1 ] initially described the monitoring of end-tidal CO2(ETCO2) in awake and sedated patients via nasal cannula by inserting a shortened intravenous catheter into the lumen of one of the nasal prongs and connecting this to the sampling tube from the capnograph. I used this technique to monitor expired CO2in a patient undergoing dilation and curettage during intravenous sedation. Intraoperatively, the patient became apneic, so the nasal cannula was replaced immediately with face mask delivering 100% oxygen. While attempting to provide assisted ventilation, I noticed a small object at the corner of the patient's oral cavity that turned out to be the shortened intravenous catheter, which had apparently been dislodged from the nasal cannula. It was removed quickly without incident. In the process of switching from nasal cannula to face mask oxygen, the ETCO2sampling tube had to be disconnected first from the adapted intravenous catheter in the nasal cannula and then connected to the face mask. The nasal cannula was then removed and replaced by the face mask. In the process, the adapted intravenous catheter was unknowingly dislodged from the nasal cannula, falling into the oral cavity.
I urge anesthesiologists using this adapted method for ETCO sub 2 monitoring to be careful about the potential dangers that could result from dislodgement of the catheter hub.
Figure 1. Nasal cannula adapted with a shortened intravenous catheter for nasal ETCO (sub 2) monitoring. The size of the adapted intravenous catheter is shown next tothe nasal cannula.
Figure 1. Nasal cannula adapted with a shortened intravenous catheter for nasal ETCO (sub 2) monitoring. The size of the adapted intravenous catheter is shown next tothe nasal cannula.
Figure 1. Nasal cannula adapted with a shortened intravenous catheter for nasal ETCO (sub 2) monitoring. The size of the adapted intravenous catheter is shown next tothe nasal cannula.
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Peter H. Pan, MD
Associate Professor; Division of Obstetrical Anesthesia; Medical College of Virginia; Virginia Commonwealth University; Richmond, Virginia 23298–0695
(Accepted for publication April 10, 1997.)
References 
References 
Goldman JM: A simple, easy and inexpensive method for monitoring ETCO sub 2 through nasal cannulae. Anesthesiology 1987; 67:606.
Figure 1. Nasal cannula adapted with a shortened intravenous catheter for nasal ETCO (sub 2) monitoring. The size of the adapted intravenous catheter is shown next tothe nasal cannula.
Figure 1. Nasal cannula adapted with a shortened intravenous catheter for nasal ETCO (sub 2) monitoring. The size of the adapted intravenous catheter is shown next tothe nasal cannula.
Figure 1. Nasal cannula adapted with a shortened intravenous catheter for nasal ETCO (sub 2) monitoring. The size of the adapted intravenous catheter is shown next tothe nasal cannula.
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