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

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.

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.

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.

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).