Peripheral perfusion index combined with end-tidal carbon dioxide in predicting sustained return of spontaneous circulation in adults with in-hospital cardiac arrest: A prospective observational study.
Higher peripheral perfusion index (PI) and end-tidal CO2 (PETCO2) during resuscitation were associated with sustained ROSC in in-hospital cardiac arrest, and combining them gave numerically better discrimination than either alone, though AUC differences were not statistically significant and external validation is needed.
Key Findings
Results
Both PI and PETCO2 trajectories during resuscitation differed significantly between patients who achieved sustained ROSC and those who did not.
The prospective observational study enrolled 125 adults with in-hospital cardiac arrest: 62 achieved sustained ROSC and 63 did not.
Linear mixed-effects models showed significant group-by-time interactions for both PI and PETCO2 (both P < 0.001).
Measurements obtained after ROSC or termination of resuscitation were excluded.
Median time to ROSC was 11 min (IQR, 5-20).
Results
Event-average PI was higher in the sustained ROSC group than in the non-ROSC group.
Event-average PI was 0.62% (IQR, 0.42-0.90) in the ROSC group vs. 0.37% (0.31-0.52) in the non-ROSC group.
The difference was significant (P < 0.001).
Results
Event-average PETCO2 was higher in the sustained ROSC group than in the non-ROSC group.
Event-average PETCO2 was 15.5 mmHg (12.2-17.8) in the ROSC group vs. 12.0 mmHg (10.4-13.7) in the non-ROSC group.
The difference was significant (P < 0.001).
Results
PI and PETCO2 each had moderate discrimination for sustained ROSC, and their combination had numerically higher AUC.
AUC was 0.756 (95% CI, 0.670-0.842) for PI and 0.753 (95% CI, 0.666-0.839) for PETCO2.
AUC for the combination was 0.808 (95% CI, 0.731-0.886).
Pairwise comparisons showed no significant differences among the AUCs.
Results
The combined PI and PETCO2 model showed little optimism on internal validation.
Internal validation used 2,000 bootstrap resamples.
The optimism-corrected AUC of the combined model was 0.800, versus an apparent AUC of 0.808.
Results
In an exploratory fully adjusted model, PETCO2 was independently associated with sustained ROSC, whereas PI was not statistically significant.
PETCO2 adjusted OR was 1.626 (95% CI, 1.148-2.302; P = 0.006).
PI adjusted OR was 1.359 per 0.1% increase (95% CI, 0.962-1.920; P = 0.082).
The model was described as exploratory.
Conclusions
The authors conclude that external validation is needed before the combined model can be used clinically.
The combination gave numerically but not significantly better discrimination than either measure alone.
Only internal (bootstrap) validation was performed.
What This Means
This study followed 125 adults who had a cardiac arrest in the hospital. Researchers tracked two measurements during CPR: the peripheral perfusion index (PI), a simple signal from a finger sensor reflecting blood flow in the extremities, and end-tidal carbon dioxide (PETCO2), the CO2 level in exhaled breath. About half the patients (62) regained a sustained heartbeat and circulation, and the rest (63) did not.
Patients who regained circulation had higher PI and higher PETCO2 during resuscitation than those who did not. Each measure alone was moderately good at telling the two groups apart (AUC about 0.75), and combining them was slightly better (AUC about 0.81, or 0.80 after internal correction). However, that improvement was not statistically significant. When other factors were taken into account, PETCO2 remained clearly linked to recovery of circulation, while PI did not reach statistical significance.
This research suggests that both measurements may offer useful real-time information about how CPR is going. The study was relatively small, was done in one setting, and was only internally validated, so the combined approach would need testing in other groups of patients before it could be used in routine care.
Zhong H, Gou X, Xu N, Li L, Du X, Gong Y, et al.. (2026). Peripheral perfusion index combined with end-tidal carbon dioxide in predicting sustained return of spontaneous circulation in adults with in-hospital cardiac arrest: A prospective observational study.. PloS one. https://doi.org/10.1371/journal.pone.0359869