At what Ankle-Brachial Index (ABI) can a pulse no longer be palpated?

At What ABI Can You No Longer Feel a Pulse

Pulses typically become non-palpable when the Ankle-Brachial Index (ABI) falls below 0.5, indicating moderate to severe peripheral arterial disease (PAD). 1

Understanding ABI and Pulse Palpation

The relationship between ABI values and pulse palpability is important for clinical assessment of peripheral arterial disease:

• ABI ≤0.90: Confirms PAD diagnosis 2, 1
• ABI 0.52 or lower: Indicates moderate to severe PAD with increased risk of cardiovascular events and amputation 1
• ABI around 0.5: Threshold below which pulses typically become non-palpable

Limitations of Pulse Palpation

Pulse palpation alone is not a reliable method for detecting PAD:

• Low sensitivity: Only 17.8-32.4% sensitivity for detecting PAD compared to ABI 3
• High specificity: 97.8-98.7% specificity for PAD detection 3
• More than two-thirds of patients with confirmed PAD still have detectable pulses 3
• Palpable and non-palpable pulses are best separated with an ABI of 0.76 as the cutoff point 4

Clinical Implications

The disconnect between pulse palpability and actual arterial disease has important clinical consequences:

• Relying solely on pulse palpation can lead to underdiagnosis of PAD in more than 30% of cases 4
• Even with an ABI indicating significant PAD (≤0.90), pulses may still be palpable 3
• The accuracy of pulse palpation varies significantly based on clinical setting and examiner experience 4

Diagnostic Approach

For accurate PAD assessment:

1. Measure ABI as the first-line objective test rather than relying on pulse palpation
2. Consider an ABI ≤0.90 diagnostic for PAD regardless of pulse status 2, 1
3. Be aware that pulses may remain palpable even with significant arterial disease
4. Use additional testing (exercise ABI, toe-brachial index) when clinical suspicion remains despite normal ABI 1

Common Pitfalls

• Assuming absence of PAD when pulses are palpable (false reassurance)
• Relying on pulse palpation in busy clinical settings where accuracy decreases 4
• Not accounting for examiner variability in pulse assessment
• Failing to use objective measurements (ABI) when ischemia is suspected, even with palpable pulses 4

The discrepancy between pulse palpability and actual arterial disease highlights the importance of objective ABI measurement rather than relying solely on pulse examination for PAD diagnosis.