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Correspondence  |   October 1999
Carbon Dioxide Monitoring during Deep Conscious Sedation Using Nasopharyngeal Airways 
Author Notes
  • Department of Anesthesiology
  • Naval Medical Center
  • Portsmouth, Virginia 23708
Article Information
Correspondence
Correspondence   |   October 1999
Carbon Dioxide Monitoring during Deep Conscious Sedation Using Nasopharyngeal Airways 
Anesthesiology 10 1999, Vol.91, 1177. doi:
Anesthesiology 10 1999, Vol.91, 1177. doi:
To the Editor:—
Ever since Goldman 1 described a method for monitoring end-tidal carbon dioxide (ETCO2) using modified nasal cannulae in sedated patients, there have been a number of articles that report variations to the original method (e.g.  , Shah and Epstein 2 and Kempem 3). Patients under deep sedation, however, have varying degrees of upper airway obstruction.
The following method permits carbon dioxide monitoring while it relieves upper airway obstruction in deeply sedated, spontaneously breathing patients. An appropriately sized, soft, rubber nasopharyngeal airway (Rusch, Duluth, GA) is coupled to a 15-mm endotracheal tube connector (Kendall Co., Mansfield,MA). After preparation of the nasal passages and insertion, this modified nasopharyngeal airway is connected to an anesthesia breathing circuit with a gas sampling line (Sims Portex Inc., Fort Myers, FL;fig. 1).
Fig. 1. (  Top  ) Nasopharyngeal airway connected to an anesthesia breathing circuit with a gas sampling line. (  Bottom  ) Soft rubber airway and 15-mm endotracheal tube connector. 
Fig. 1. (  Top  ) Nasopharyngeal airway connected to an anesthesia breathing circuit with a gas sampling line. (  Bottom  ) Soft rubber airway and 15-mm endotracheal tube connector. 
Fig. 1. (  Top  ) Nasopharyngeal airway connected to an anesthesia breathing circuit with a gas sampling line. (  Bottom  ) Soft rubber airway and 15-mm endotracheal tube connector. 
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Similar to the carbon dioxide–sampling nasal cannulae, this system permits respiratory rate and monitoring of ETCO2trends.
I have used this modified nasopharyngeal airway system on several occasions and have found it to be an improvement over the nasal cannulae carbon dioxide sampling techniques used in sedated patients
with signs of upper airway obstruction. Moreover, the system is configured easily from equipment that is readily available in most anesthetic locations.
References 
References 
Goldman JM: A simple, easy, and inexpensive method for monitoring ETCO2through nasal cannulae (letter). A NESTHESIOLOGY 1987; 67: 606
Shah MG, Epstein L: Measurement of carbon dioxide at both nares and mouth using standard nasal cannula. A NESTHESIOLOGY 1994; 81: 779–80
Kempem P: Cost effective carbon dioxide monitoring via nasal cannula. A NESTHESIOLOGY 1999; 90: 633–4
Fig. 1. (  Top  ) Nasopharyngeal airway connected to an anesthesia breathing circuit with a gas sampling line. (  Bottom  ) Soft rubber airway and 15-mm endotracheal tube connector. 
Fig. 1. (  Top  ) Nasopharyngeal airway connected to an anesthesia breathing circuit with a gas sampling line. (  Bottom  ) Soft rubber airway and 15-mm endotracheal tube connector. 
Fig. 1. (  Top  ) Nasopharyngeal airway connected to an anesthesia breathing circuit with a gas sampling line. (  Bottom  ) Soft rubber airway and 15-mm endotracheal tube connector. 
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