(Stroke. 2001;32:448.)
© 2001 American Heart Association, Inc.
Original Contributions |
Ear Oximetry: A Noninvasive Method for Detection of Patent Foramen Ovale
A Study Comparing Dye Dilution Method and Oximetry With Contrast Transesophageal Echocardiography
From the Department of Neurology (V.K., M.H.) and the Department of Cardiology (M.I., M.N.), Oulu (Finland) University Hospital; and the Department of Cardiology (M.V.), Helsinki (Finland) University Central Hospital.
Correspondence to Vesa Karttunen, MD, University of Oulu, Department of Neurology, Box 5000, FIN-90014, University of Oulu, Finland. E-mail vesa.karttunen{at}oulu.fi
Background and Purpose—Patent foramen ovale (PFO) may play an important role as a risk factor for ischemic stroke and some other neurological conditions. There is a need for low-cost and noninvasive methods for the detection of PFO. This study evaluates the accuracy of two simple bedside tests, the dye dilution method and ear oximetry, in the detection of PFO.
Methods—Dye dilution
curves and ear oximetry recordings with a noninvasive ear
densitometer were obtained from consecutive cryptogenic stroke patients
referred for contrast transesophageal
echocardiography (TEE). All test results were
blindly assessed for the presence of PFO. Sensitivity and specificity
were calculated with TEE used as a reference method. 
statistics
were used to measure interrater agreement.
Results—Dye dilution
curves were obtained from 67 patients. Dye dilution correctly diagnosed
35 of the 46 patients who had PFO in TEE and all the 21 patients
without PFO. Thus, the sensitivity (95% CI) of the dye dilution method
was 76% (61% to 87%) and its specificity 100% (84% to 100%). Ear
oximetry was done on 83 patients. Oximetry correctly diagnosed 45 of
the 53 patients who had PFO in TEE and all of the 30 patients without
PFO. Thus, the sensitivity of ear oximetry was 85% (72% to 93%) and
its specificity 100% (88% to 100%). The interrater agreement was
excellent ( value 0.94 for dye dilution and 0.90 for
oximetry).
Conclusions—Dye dilution and oximetry are both sensitive and specific methods for the detection of PFO. Oximetry has the following primary advantages over the currently available diagnostic methods: it is noninvasive, safe, and inexpensive and causes no discomfort for the patient. We suggest that oximetry could be used as a first-line screening method for PFO in patients with cryptogenic stroke. Ear oximetry also has potential use in epidemiological studies.
Key Words: cerebrovascular disorders • echocardiography, transesophageal • foramen ovale, patent • oximetry
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