Are ankle and toe brachial indices (ABI-TBI) obtained by a pocket Doppler interchangeable with those obtained by standard laboratory equipment?

PURPOSE: The aim of this study was to determine if the ankle and toe brachial indices obtained by an experienced registered nurse (RN) using a pocket Doppler were within acceptable levels of agreement with those obtained by a registered vascular technologist (RVT) using standard laboratory equipment.

DESIGN: A within-subjects comparative design was used.

SETTING AND SUBJECTS: Thirty subjects who were referred to a vascular laboratory for arterial studies were recruited. All tests were performed in the outpatient vascular laboratory of a large, urban medical center.

METHODOLOGY: Ankle and toe brachial indices were measured on each subject by the RN and the RVT during each visit. Data were analyzed using the Bland-Altman method to assess the level of agreement between the RN's pocket Doppler and the RVT's standard laboratory equipment.

RESULTS: Differences between each instrument's ankle brachial indices were within the a priori 15% limit of agreement. Differences between each instrument's toe brachial indices exceeded the a priori 15% limit of agreement.

CONCLUSION: The ankle brachial index obtained by using a pocket Doppler by an experienced RN is interchangeable with vascular laboratory testing for detection of lower extremity arterial disease (LEAD). The pocket Doppler-derived toe brachial index was not interchangeable with vascular laboratory testing for detection of LEAD.