Patent foramen ovale screening by ear oximetry in divers

The aim of this study was to test the hypothesis that ear oximetry immediately after the release of a sustained Valsalva maneuver accurately detects patent foramen ovale (PFO). One hundred sixty-five scuba divers underwent transesophageal echocardiography (TEE; reference method) for PFO assessment. Ear oximetry of the right earlobe was performed in a different room within a time frame of 2 hours before or after TEE. The subject and the oximetry operator were unaware of the results of TEE. Oxygen saturation (SO(2)) measurements were obtained at baseline and during the release phase of 4 Valsalva maneuvers within 10 minutes, and the average SO(2) change (SO(2) at baseline minus SO(2) at Valsalva release) was determined as the primary study end point. One hundred seventeen divers had no PFO, and 48 (29%) had PFO by TEE (mean age 39 ± 8 years). The average SO(2) change was 0.79 ± 1.13% (i.e., a slight absolute SO(2) decrease in response to the Valsalva maneuver) in the group without PFO and 1.67 ± 1.19% in the PFO group (p <0.0001). Using receiver-operating characteristic curve analysis, a PFO as defined by TEE could be detected at a threshold of a Valsalva-induced decrease in SO(2) of ≥0.825 percentage points in comparison to baseline (sensitivity 0.756, specificity 0.706, area under the receiver-operating characteristic curve 0.763, p <0.0001, negative predictive value 0.882). In conclusion, the entirely noninvasive method of ear oximetry in response to repetitive Valsalva maneuvers is accurate and useful as a screening method for the detection of a PFO, as shown in this study of divers.