Accuracy and precision of buccal pulse oximetry

Abstract Objective We sought to describe the accuracy and precision of buccal pulse oximetry (SbpO 2 ) compared with arterial oxygen saturation (SaO 2 ) and pulse oximetry (SpO 2 ) in healthy adults at normoxemia and under 3 induced hypoxemic conditions. Methods In this prospective, correlational study, SbpO 2 , SaO 2 , and SpO 2 values were recorded at normoxemia and at three hypoxemic conditions (SpO 2  = 90%, 80%, and 70%) for 53 healthy, nonsmoking adults who were without cardiac or pulmonary disease, baseline hypoxemia, peripheral edema, dyshemoglobinemia, and fever. Bland-Altman analyses were used to assess agreement and precision between SbpO 2 and SaO 2 measures and between SbpO 2 and SpO 2 measures. Data were adjusted to account for a lag time between buccal and finger sites. Results When comparing SbpO 2 and SaO 2 values, mean differences of –1.8%, .3%, 2.4%, and 2.6% were evident at the normoxemia, 90%, 80%, and 70% levels, respectively. When comparing SbpO 2 and SpO 2 values, the mean differences were –1.4%, .1%, 3.3%, and 4.7% at the normoxemia, 90%, 80%, and 70% levels, respectively. The SbpO 2 and SaO 2 values met a priori precision criteria (1.6%; 95% confidence limit, –4.9% to 1.3%) at normoxemia. The SbpO 2 and SpO 2 values met precision criteria at normoxemia (1.5%; 95% confidence limit, –4.4% to 1.5%) and 90% (1.9%; 95% confidence limit, –3.6% to 3.8%) conditions, but exceeded precision criteria at the other tested conditions. On average, SpO 2 lagged 21 seconds behind SbpO 2 . Conclusion Buccal oximetry is an inaccurate and imprecise method of assessing SpO 2 when oxygen saturation is 2 and both SaO 2 or SpO 2 values increased as hypoxemia worsened. The buccal method overestimated oxygen saturation in proportion to the degree of hypoxemia. Such overestimates may lead nurses to conclude falsely that a patient's arterial oxygen saturation is acceptable when further assessment or intervention is warranted.