The effect of body heating and cooling on the ankle and toe systolic pressures in arterial disease

Ankle brachial pressure index (ABPI): An update for practitioners

Peripheral vascular disease affects some 12%-14% of the general population, and the majority of people with the disease are asymptomatic. The ankle brachial pressure index (ABPI) test is widely used by a diverse range of practitioners (in the community and hospital setting) in order to screen asymptomatic patients, diagnose patients with clinical symptoms, and to monitor patients who have had radiological or surgical intervention. This paper explains the theoretical basis of the ABPI test, as well as the relevance of the common modifications of the test. It explores the background to the quoted normal ranges for the ABPI test. It reviews the large body of literature that has developed on the association between ABPI and cardiovascular risk, as well as ABPI as a predictor for cardiovascular morbidity and mortality, highlighting the evidence that can inform practice. The review looks critically at the limitations of the ABPI test, providing practitioners with an evidence-based update on the importance and challenges of standardizing ABPI methodology. This paper highlights the influence of the key technical aspects of the ABPI test that all practitioners need to consider in order to be able to make more reliable and informed management decisions based on ABPI findings.

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.

Get the LEAD Out

Lower extremity arterial disease affects approximately one third of individuals 66 years of age and older and has a high risk for nonhealing wounds, infection, and limb loss. Much wound care is given by or under the direction of nurses. Therefore, the assessment and management of these patients presents many opportunities and challenges. Assessment is the cornerstone of effective care, but traditional methods of lower extremity arterial assessment, such as pulse palpation and pain history, are insufficient to determine the presence and extent of ischemia. Recently published national guidelines for assessment and management of patients with lower extremity wounds have recommended using noninvasive tests such as the ankle brachial index and toe brachial index to rule out lower extremity arterial disease, which complicates wound healing. However, the ankle brachial index can be falsely elevated in patients with diabetes and renal failure because of calcification of the arteries, which causes them to be incompressible. In these situations, it has been advised to obtain a toe pressure or toe brachial index because digital arteries are usually less affected by calcification. There is a paucity of data about the knowledge of principles and performance of the ankle brachial index/toe brachial index by nurses, particularly in the United States, using pocket-sized portable Doppler equipment. Therefore, the purpose of this article is to provide an overview and synthesis of relevant studies and published expert opinion regarding noninvasive arterial assessment using ankle brachial and toe brachial indexes as a basis for developing protocols for performing the tests and identifying gaps in research where further investigation is needed.

Ankle to arm index response to exercise and heat stress in healthy subjects

Ankle to arm index (AAI) defined as the ratio of ankle systolic blood pressure (ASBP), to brachial systolic blood pressure is largely used in the study of lower extremity arterial disease (LEAD). To study the hypothesis of the shunt of blood away from the skin as the explanation of AAI decrease in exercise, we studied the AAI and ASBP responses to an increase in cardiac output originating from an increase either in muscle blood flow (exercise) or in cutaneous blood flow (thermal stress). Brachial systolic pressure, ankle systolic pressure and heart rate (HR) were measured in 9 healthy subjects at rest, during heart thermal stress and following maximal exercise on a cycle ergometer. Compared to resting values, AAI decreased in all subjects from 1.05 +/- 0.07 to 0.75 +/- 0.07 (P < 0.05) 1 min following exercise and from 1.08 +/- 0.07 to 0.94 +/- 0.05 (P < 0.05) during heat stress. On the other hand, HR increased from 72.8 +/- 12.2 to 112.4 +/- 19.6 (P < 0.05) min following exercise and from 75.5 +/- 13.6 to 96.8 +/- 15.3 (P < 0.05) during heat stress. Since a comparable relation exists between AAI and HR in thermal stress and exercise, we suggest that the decrease in AAI in normal subjects following exercise is due to turbulences at high flow levels, rather than the shunting of blood to active muscles in exercise.