Purpose: The purpose of this study was to determine whether capnography is a more sensitive monitor than auscultation of breath sounds in detecting ventilator/changes consistent with hypoventilation, obstruction, or apnea and in detecting ventilatory changes that can be associated with oxygen desaturation. Patients and Methods: Fifty-five patients received intravenous agents and supplemental oxygen to achieve a state of deep sedation or general anesthesia for removal of impacted third molars. The surgeon/anesthetist monitored respiratory status using a pretracheal stethoscope and direct observation. A blinded observer with no access to the patient or anesthetist monitored respirator/ status using capnography. A second observer monitored all respiratory parameters to allow for correlation between clinical and electronic monitors. Results: Ventilatory status was continuously represented by capnography. The Pearson correlation coefficient showed a positive correlation between increased end-tidal CO2 (P(ET)CO2) and decreased oxygen saturation that be-came stronger with greater positive changes in P(ET)CO2. An additive relationship was found between P(ET)CO2 and respiratory rate (RR), with increased P(ET)CO2 and decreased RR contributing to decreased oxygen saturation. Conclusions: Patients with nasal ventilatory exchange maintain this exchange throughout the anesthesia so that sampling of nasal P(ET)CO2 is an effective way to monitor ventilatory status. Respiratory depression or obstructive ventilatory changes detected by capnography showed a high sensitivity and low positive predictive value in detecting oxygen desaturation. The current technology does not show a clinically satisfactory correlation between P(ET)CO2 and oxygen saturation. However, a combined increase in P(ET)CO2 and decrease in RR suggested a trend of decreasing oxygen saturation.
ASJC Scopus subject areas
- Oral Surgery