Can pulse oximetry or a bedside swallowing assessment be used to detect aspiration after stroke?

Background and Purpose - Desaturation during swallowing may help to identify aspiration in stroke patients. This study investigated pulse oximetry, bedside swallowing assessment (BSA), and videofluoroscopy as tests for detecting aspiration after stroke. Methods - Swallowing was assessed in 189 stroke patients (mean +/- SD age, 70.9 +/- 12.3 years) within 5 days of symptom onset with a modified BSA ( water replaced by radio-opaque contrast agent, followed by chest radiography to detect aspiration). Simultaneous pulse oximetry recorded the greatest desaturation from baseline for 10 minutes from modified BSA onset. Videofluoroscopy was undertaken in 54 (28%) patients. Results - Modified BSA showed a safe swallow in 98 (51.9%), unsafe swallow in 85 (45.0%), and silent aspiration in 6 (3.2%) patients. During swallowing, desaturation by > 2% occurred in 27 (27.6%) and by > 5% in 3 (3.1%) of the 98 safe-swallow patients on modified BSA. Of the 85 unsafe-swallow patients, only 28 (32.9%) desaturated by > 2% and 6 (7.1%) by > 5%. Desaturation did not occur in any of the 6 silent aspirators. With the modified BSA to detect aspiration, sensitivity and specificity, respectively, were 0.31 and 0.72 for desaturation > 2% and 0.07 and 0.97 for desaturation > 5%. By videofluoroscopy, sensitivity and specificity for detecting aspiration were 0.47 and 0.72 for modified BSA, 0.33 and 0.62 for desaturation > 2%, and 0.13 and 0.95 for desaturation > 5%. Combining a failed modified BSA with desaturation > 2% or > 5% did not significantly improve predictive values. Conclusions - Modified BSA and pulse oximetry during swallowing, whether alone or in combination, showed inadequate sensitivity, specificity, and predictive values for detection of aspiration compared with videofluoroscopy in stroke patients.