Execution:
- The examiner compresses the patient’s nail bed
- The compression is released
- The time how long it takes until the color (blood) returns to the nail bed is taken
Positive Outcome: Blood does not return to the nail bed within 3 seconds after releasing the compression, which indicates insufficient arterial blood flow
| Study | Reliability | Sn | Sp | LR+ | LR- |
| Magee et al. (2014) | NA | NA | NA | NA | NA |
