Evaluation of pulse oximeter at the nasal septum during general anesthesia: comparison with finger oximeter

Purpose: Though the finger is generally recommended for pulse oxygen saturation (SpO₂) monitoring site, its reliability may be compromised in conditions of poor peripheral perfusion. Therefore, we compared the performance of nasal septum SpO₂ monitoring with finger SpO₂ monitoring relative to simultaneous arterial oxygen saturation (SaO₂) monitoring in generally anesthetized patients. Methods: In 23 adult patients, comparisons of SpO₂ measured at the nasal septum and finger with simultaneous SaO₂ were made at four time points during the 90 min study period. A pulse oximetry monitoring failure was defined as a > 10 s continuous failure of in an adequate SpO₂ data acquisition. Core temperature as well as finger-tip and nasal septum temperatures were simultaneously measured at 10 min intervals. Results: A total of 92 sets of SpO₂ and SaO₂ measurements were obtained in 23 patients. The bias and precision for SpO₂ measured at the nasal septum were − 0.8 ± 1.3 (95% confidence interval: − 1.1 to − 0.6), which was similar to those for SpO₂ measured at the finger (− 0.6 ± 1.4; 95% confidence interval: − 0.9 to − 0.4) (p = 0.154). Finger-tip temperatures were consistently lower than other two temperatures at all time points (p < 0.05), reaching 33.5 ± 2.3 °C at 90 min after induction of anesthesia. While pulse oximetry monitoring failure did not occur for nasal septum probe, two cases of failure occurred for finger probe. Conclusions: Considering the higher stability to hypothermia with a similar accuracy, nasal septum pulse oximetry may be an attractive alternative to finger pulse oximetry. Trail registration This study was registered with Clinical Research Information Service (CRIS: https://cris.nih.go.kr/cris/en/; ref: KCT0008352).