Respiratory failure & ventilation
Testing preload responsiveness by the tidal volume challenge assessed by the photoplethysmographic perfusion index
Authors' conclusion
In patients under mechanical ventilation with no spontaneous breathing and/or atrial fibrillation, changes in PI detected during Vt-challenge reliably detected preload responsiveness.
Study context
- Population
- Critically ill patients ventilated with Vt = 6 mL/kg predicted body weight (PBW) and no spontaneous breathing63 screened
- Participants
- 42 patients
- Comparison
- Vt-challenge-induced changes in perfusion index (PI) and PVI (finger, forehead) vs changes in PPV and CI for detecting preload responsiveness
- Outcome
- Detection of preload responsiveness (PLR-induced increase in CI ≥ 10%)
Methodological details21 (33%) of screened patients excluded for unstable PI signal and/or AF
- 21 (33%) of screened patients excluded for unstable PI signal and/or AF
Performance
As reported in the abstract
AUROC for detecting preload responsiveness
| Test or model | Value | AUC |
|---|---|---|
| CI | 0.97 ± 0.02 | 0.97 ± 0.02 |
| PPV | 0.95 ± 0.04 | 0.95 ± 0.04 |
| PIforehead | 0.98 ± 0.02 | 0.98 ± 0.02 |
| PIfinger | 0.85 ± 0.05 | 0.85 ± 0.05 |
Value
CI0.97 ± 0.02
PPV0.95 ± 0.04
PIforehead0.98 ± 0.02
PIfinger0.85 ± 0.05
AUC
CI0.97 ± 0.02
PPV0.95 ± 0.04
PIforehead0.98 ± 0.02
PIfinger0.85 ± 0.05
- PIfinger vs PIforehead: P = 0.04
Further findings
Changes during Vt-challenge in preload responders
- CI decreased (percent change)
- 4.8 ± 2.8%
- PPV increased (absolute change)
- 4.4 ± 1.9%
- PIfinger decreased (percent change)
- 14.5 ± 10.7%
- PVIfinger increased (absolute change)
- 1.9 ± 2.6%
- PIforehead decreased (percent change)
- 18.7 ± 10.9
- PVIforehead increased (absolute change)
- 1.0 ± 2.5
- All changes larger than in preload non-responders
Parts of this Brief are withheld: the automatic checks could not confirm them against the abstract.
Original publication
Testing preload responsiveness by the tidal volume challenge assessed by the photoplethysmographic perfusion index. Crit Care. Published 16 September 2024. doi:10.
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