Accuracy and precision of buccal pulse oximetry

ObjectiveWe sought to describe the accuracy and precision of buccal pulse oximetry (SbpO2) compared with arterial oxygen saturation (SaO2) and pulse oximetry (SpO2) in healthy adults at normoxemia and under 3 induced hypoxemic conditions.MethodsIn this prospective, correlational study, SbpO2, SaO2, and SpO2 values were recorded at normoxemia and at three hypoxemic conditions (SpO2 = 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 SbpO2 and SaO2 measures and between SbpO2 and SpO2 measures. Data were adjusted to account for a lag time between buccal and finger sites.ResultsWhen comparing SbpO2 and SaO2 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 SbpO2 and SpO2 values, the mean differences were –1.4%, .1%, 3.3%, and 4.7% at the normoxemia, 90%, 80%, and 70% levels, respectively. The SbpO2 and SaO2 values met a priori precision criteria (1.6%; 95% confidence limit, –4.9% to 1.3%) at normoxemia. The SbpO2 and SpO2 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, SpO2 lagged 21 seconds behind SbpO2.ConclusionBuccal oximetry is an inaccurate and imprecise method of assessing SpO2 when oxygen saturation is <90%. The divergence between SbpO2 and both SaO2 or SpO2 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.