Sensitivity and specificity of radioisotope right-left shunt measurements and pulse oximetry for the early detection of pulmonary arteriovenous malformations

Study objectives: To assess the effectiveness of pulse oximetry and radiois otope measurement of right-to-left (R-L) shunt for the early detection of p ulmonary arteriovenous malformations (PAVMs) in patients with hereditary he morrhagic telangiectasia (HHT), Design: Patients with HHT had serial measurements of the following: (1) art erial, oxygen saturation (SaO(2)) by pulse oximetry in erect and supine pos itions, and on maximal exercise using cycle ergometry; (2) quantitative rad ioisotope measurements of R-L shunt using IV Tc-99m-labeled macroaggregates of albumin; and (3) routine pulmonary function. After percutaneous transca theter embolization of all PAVMs with feeding vessel diameters > 3 mm, resi dual PAVMs were assessed with selective digital subtraction pulmonary angio graphy. Using postembolization angiography as the "gold standard," SaO(2) a nd radioisotope shunt measurements after embolization were analyzed retrosp ectively using logistic regression to assess the ability of each test to pr edict for the presence of residual PAVMs. Results: Of the 66 patients included, 40 had small PAVMs remaining postembo lization. Using univariate logistic regression, radioisotope shunt and erec t saturation showed a significant relationship with the presence of residua l PAVMs (p = 0.001, 0.005, respectively), Erect SaO(2) less than or equal t o 96% had 73% sensitivity and 35% specificity for detecting PAVMs. Radioiso tope shunt >3.5% of cardiac output had 87% sensiticity and 61% specificity for detecting PAVMs, Conclusions: These results confirm that noninvasive measurements are useful in the screening of patients with HHT for the presence of PAVMs without ne ed for angiography and its associated risks, and that radionuclide scanning is better than pulse oximetry.