Preoxygenation Using End - tidal Oxygen Concentration / 대한마취과학회지

ABSTRACT

Preoxygenation is a standard anesthetic technique for preventing hypoxemia during the in- duction of anesthesia. This is achieved by alveolar denitrogenation while ventilating the lungs with 100% oxygen. Until recently there was no satisfactory nitrogen monitoring device except mass spectrometry which is not generally available. We used a convinient and readily available measuring technique to evaluate the effectpreoxygenation. In 31 healthy volunteers breathing 100% oxygen, end-tidal oxygen concentration have been measured at 15 seconds interval from the start of preoxygenation. A circle system was flushed with 100% oxygen and flow rate of 8 liter per minute. The gas sampling line of the Capnomac II (Datex, Finland) was placed in nasal cavity. At 1, 2, 3 minutes, mean end-tidal oxygen concentration was 78.7%, 89.2%, 91.9 % respectively. End-tidal nitrogen concentration was approximately 16.1 %, 5.8%, 3.2%. We conclude end-tidal oxygen concentration is a good indirect measure of denitrogenation.