SpO₂ freezes in low perfusion¶
During low perfusion SpO₂ mostly holds its last value rather than blanking (55–70% of 5–20 s episodes); when the probe comes off it blanks within about a second.
| Status | established: shown on many cases, with a control. |
| Variables | SpO₂, Solar8000 pulse rate (PLETH_HR) |
What it means¶
A flat SpO₂ is not proof of a stable saturation; check the PLETH.
Evidence¶
| Study | Date | Status | Summary |
|---|---|---|---|
| SpO₂ and pulse rate latency from step events | 2026-10-12 | current | SpO₂ cannot be recomputed from one plethysmogram, so its timing comes from events that change the PLETH abruptly. SpO₂ lags the recorded PLETH by about 4 s and then smooths over roughly 10–20 s. |