From the Guidelines
Critical limb ischemia (CLI) is diagnosed based on a combination of clinical assessment, physical examination findings, and diagnostic testing, with a focus on identifying chronic ischemic rest pain, non-healing wounds, or gangrene in the lower extremities, as defined by the 2016 AHA/ACC guideline on the management of patients with lower extremity peripheral artery disease 1. The diagnostic criteria for CLI include:
- Chronic ischemic rest pain, typically occurring at night and improving when the leg is in a dependent position
- Non-healing ulcers, especially on toes, foot, or ankle
- Tissue loss or gangrene
- Physical examination findings such as:
- Diminished or absent peripheral pulses (femoral, popliteal, dorsalis pedis, posterior tibial)
- Pallor on elevation
- Dependent rubor
- Delayed capillary refill (>3 seconds)
- Cool skin temperature
- Atrophic skin changes
- Diagnostic testing, including:
- Ankle-brachial index (ABI) measurement, with values ≤0.4 strongly suggesting CLI 1
- Toe pressures (abnormal if <30-50 mmHg) or transcutaneous oxygen pressure (abnormal if <30-40 mmHg) if ABI cannot be accurately measured due to vessel calcification
- Additional diagnostic imaging such as duplex ultrasound, CT angiography, MR angiography, or conventional angiography to confirm the diagnosis and help plan revascularization It is essential to distinguish CLI from acute limb ischemia (ALI) and to recognize that CLI represents advanced peripheral artery disease requiring urgent evaluation and treatment to prevent limb loss, as emphasized by the 2016 AHA/ACC guideline 1 and supported by other studies 1. Prompt vascular surgery consultation is necessary once the diagnosis of CLI is suspected, as it is a medical emergency that requires immediate attention to prevent limb loss and improve patient outcomes 1.
From the Research
Diagnostic Criteria for Critical Limb Ischemia (CLI)
The diagnostic criteria for CLI are based on a combination of clinical manifestations, physical examination, and non-invasive vascular tests. The key diagnostic criteria include:
- Limb pain at rest, with or without trophic skin changes or tissue loss 2
- Ankle-brachial index measurement 2
- Duplex-ultrasound 2
- Angiography 2, 3
- Transcutaneous oxygen measurement 2
- Hemodynamic criteria, including measurements of pressures and indices of microcirculation 4
Clinical Manifestations
The most common clinical manifestations of CLI are:
- Ischemic rest pain
- Tissue loss, such as non-healing ulcers or gangrene
- Trophic skin changes
Diagnostic Evaluation
The diagnostic evaluation of CLI involves a combination of physical examination, non-invasive vascular tests, and imaging modalities. The evaluation should include:
- Physical examination to assess the presence and severity of limb ischemia
- Non-invasive vascular tests, such as ankle-brachial index measurement and duplex-ultrasound
- Imaging modalities, such as angiography, to determine the feasibility and approach to arterial revascularization 3