Pulse oximetry index: a simple arterial assessment for patients with venous disease

Abstract

Pulse oximetry LOI is a simple alternative to Doppler ABPI in the screening of patients for arterial disease that could be a contraindication to, or require modification of, compression therapy. It can be measured in some legs that cannot be assessed by Doppler ultrasound.

Lanarkshire Oximetry Index as a Diagnostic Tool for Peripheral Arterial Disease in Type 2 Diabetes: A Pilot Study

“…This correlation was confirmed in both legs. Our findings concur with that of Bianchi et al, 21 but the participants recruited differ significantly between the 2 studies. Indeed, they enrolled participants with venous disease, whereas we studied type 2 diabetic patients.…”

“…This agreement did not improve after exclusion of patients with MAC, if the latter was defined as ABI > 1.3, which is the usual definition. 21 Nonetheless, using an alternative cut-off value of ABI > 1.2 for MAC resulted in improved agreement. Medial arterial calcification is a major limitation of ABI, leading to falsely elevated ABI.…”

“…This cutoff was used to determine which limbs had adequate arterial perfusion to allow compression therapy for venous ulcers. 21 Consequently, LOI < 0.8 denotes more severe PAD that would preclude compression therapy due to the risk of ischemia.…”

“…The pressure that was 20 mm Hg below the point at which the pulsatile signal was lost on the pulse oximeter was recorded as blood pressure; for example, if the signal was lost at 160 mm Hg, then pressure of 140 mm Hg was recorded. 19,21 As suggested by Bianchi et al, 19,21 the cuff was not inflated higher than 180 mm Hg; if this pressure was reached before signal loss, a pressure of 180 mm Hg was recorded. 19,21 This measurement was performed on both arms, and the higher pressure was used for the calculation of LOI index.…”

“…19,21 For each foot, LOI index was calculated by dividing hallux pressure by finger pressure. 19,21 Lanarkshire Oximetry Index measurement was performed by an operator (AM) who was blinded to Doppler examination and clinical characteristics. Two cut-off values of LOI (<0.9 and <0.8 in at least 1 leg) were examined for the diagnosis of PAD.…”