Evaluation of Perfusion Index as a Screening Tool for Developing Critical Limb Ischemia.

Online November 9, 2021 doi: 10.3400/avd.oa.21-00100 Ann Vasc Dis Vol. 14, No. 4; 2021; pp 328–333 Original Article Evaluation of Perfusion Index as a Screening Tool for Developing Critical Limb Ischemia Nobuko Yamamoto, MD, Hideki Sakashita, MD, PhD, Noriyuki Miyama, MD, PhD, Kanako Takai, MD, and Hiroyoshi Komai, MD, PhD Objective: The perfusion index (PI) is a physiological marker for evaluating the peripheral circulation. We explored the possibility of using PI as a screening tool for development of critical limb ischemia in peripheral artery disease (PAD). Method: We measured the PI in 79 limbs of 70 PAD patients. Data were analyzed to find a correlation between the PI and PAD severity. Result: The PI tended to be lower as PAD became severer. Especially, there were significant differences between the Fontaine 1 and Fontaine 4 groups in average PI and minimum PI, and between Fontaine 1 and two other groups (Fontaine 2 and Fontaine 4 groups) in maximum PI. A mild correlation was found between PI and the ankle brachial index. These data were used to calculate an average PI of 0.27 as a cut-off value for critical limb ischemia (CLI). In 65 asymptomatic PAD patients and claudication, significantly more patients with a PI value greater than the cut-off value developed CLI than those with a PI lower than the cut-off. Conclusion: The PI can be a useful tool for evaluating the development of CLI in mild PAD patients, and patients tended not to progress to CLI when their average PI was higher than 0.27. (This is a translation of Jpn J Vasc Surg 2020; 29: 103–108.) Keywords: peripheral artery disease, critical limb ischemia, perfusion index Department of Vascular Surgery, Kansai Medical University Medical Center, Moriguchi, Osaka, Japan Received: August 16, 2021; Accepted: September 6, 2021 Corresponding author: Nobuko Yamamoto, MD. Department of Vascular Surgery, Kansai Medical University Medical Center, 10-15 Fumizono chou, Moriguchi, Osaka 570-8507, Japan Tel: +81-6-6992-1001, Fax: +81-6-6992-4846 E-mail: This is a translation of Jpn J Vasc Surg 2020; 29: 103–108. ©2021 The Editorial Committee of Annals of Vascular Diseases. This article is distributed under the terms of the Creative Commons Attribution License, which permits use, distribution, and reproduction in any medium, provided the credit of the original work, a link to the license, and indication of any change are properly given, and the original work is not used for commercial purposes. Remixed or transformed contributions must be distributed under the same license as the original. 328 Introduction Functioning limb salvage is the most important issue in the treatment of critical limb ischemia (CLI) in patients with peripheral arterial disease (PAD). Despite recent advances in revascularization techniques, there are still many cases resulted in lower-limb amputation, thus, early diagnosis of critical ischemia is essential. However, not a few patients develop CLI without an initial symptom of claudication, and we sometimes even lose the chance to perform revascularization. Although prophylactic revascularization before developing CLI is thought to be ideal, the risk of invasive procedures is often beyond the acceptable range as considering the nutritional status and comorbidities of patients with PAD. We have been investigating the difference between patients with intermittent claudication and those with CLI to identify patients with the potential of progression to CLI using biomarkers and vascular endothelial function test1–7); however, we are yet to find a useful marker. Perfusion index (PI) is a physiological marker representing the ratio of pulsatile to non-pulsatile blood volume in peripheral tissues. It is easily measured by detecting arterial oxygen saturation waveforms by pulse oximeter. PI is an index that can continuously and non-invasively evaluate peripheral perfusion without the need for maintaining constant body positions or for body movements. Recently, it has been used for evaluating the depth of the general anesthesia8) and for monitoring circulatory status in the intensive care of neonates.9) Peripheral circulation can be evaluated in a simple and non-invasive manner, thus, we hypothesized that measuring toe PI can be used to determine the severity of ischemia in patients with PAD. Patients and Methods Seventy-nine limbs of 70 patients (56 limbs in males, 23 limbs in females) with PAD (ankle-brachial index [ABI]<0.9) who presented to our department between March 2015 and August 2016 were included in the study. The patients were put in the supine position for a few minutes at room temperature (approximately 20°C to 25°C) Annals of Vascular Diseases Vol. 14, No. 4 (2021) Evaluation of Perfusion Index for Early Detection of Critical Limb Ischemia and measured the toe percutaneous oxygen saturation at the every toes on both sides by attaching the oximeter. The device specialized to calculate PI (Radical 7 pulse Cooximeter (Masimo Corporation, Irvine, CA, USA)) were used to determine PI. The accurate measurements were confirmed by continuous and stable value of the oxygen saturation. For toes in which the PI was non-measurable and for toes without pulsatile flow, the PI value was given 0. PI values were assessed with the patient information and clinical data obtained from their chart. This study was reviewed and approved by the Institutional Review Board of Kansai Medical University Medical Center (Approval No. T28-19), and written consent to participate in the study was obtained from every patient after provided with an information regarding the study. Assessment 1 The limbs were classified into 3 groups based on clinical severity according to the Fontaine classification at the time of PI measurement, with 19 limbs classified as F1 (asymptomatic or cold), 46 limbs as F2 (claudication), and 14 limbs as F4 (ulceration and necrosis), and the mean, maximum, and minimum PI of all the toes in the affected limbs were compared for each group. In addition, PI values were compared with the values obtained from conventional blood flow tests, such as ABI and skin perfusion pressure (SPP). Assessment 2 Of the aforementioned target patientsʼ limbs, the 65 limbs in the F1 and F2 groups were grouped together as the non-CLI group, whereas the 14 limbs in the F4 group were defined as the CLI group and the cutoff value for the diagnosis of CLI at the mean, maximum, and minimum PI values was calculated from receiver operating characteristic (ROC) curves. Assessment 3 In the F2 group, 6 limbs that developed CLI during the subsequent 1 year or that had SPP of ≤40 mmHg at the initial examination were considered to have the potential severe ischemia (the severe IC group), and the remaining 40 limbs were defined as the mild IC group, and differences in the PI cutoff values between the groups were Table evaluated. Statistical methods The analysis software used was JMP13.0.0 (13.0). For the analysis of assessment 1 (...truncated)