To the Editor:—
Ever since Goldman 1described 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 2and 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).
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.