Introduction:
We have shown that during CPR, novel non-invasive monitoring of cerebral tissue oxygenation (StO
2
, %) and total hemoglobin concentration (THC, μmol/L) by frequency-domain diffuse optical spectroscopy (FD-DOS) is associated with ROSC in a swine model of pediatric cardiac arrest. Our objective is to find the optimal non-invasive predictor for ROSC and assess feasibility of a stable critical threshold over time in early CPR.
Hypothesis:
Stable critical thresholds with high sensitivity or specificity for ROSC may be established in early CPR (<10 min) from non-invasive cerebral StO
2
and THC measurements initiated at CPR start.
Methods:
One-month-old swine (n=31) underwent 7 minutes of asphyxia, induction of ventricular fibrillation, and up to 20 minutes of CPR till ROSC or death (no ROSC). Absolute StO
2
and THC and absolute and relative change from 1 minute into CPR (time for chest molding and FD-DOS placement) were evaluated as ROSC predictors over time. For each variable, an ROC curve and two critical thresholds, maximizing specificity (=1) or sensitivity (=1), were determined at 1-min intervals from 2-10 minutes of CPR using univariate logistic regression. Optimal predictor was selected by highest mean AUC. A stable specificity or sensitivity threshold was feasible if the mean threshold had a specificity or sensitivity >0.9 over all intervals, respectively.
Results:
Absolute change in StO
2
(ΔStO
2
) had the highest mean (SD) AUC of 0.90 (0.07). Consistently >0.8, the AUC exceeded 0.9 after 7 minutes of CPR (
see
Fig.
). The mean specificity threshold (ΔStO
2
= +5.1%) and sensitivity threshold (ΔStO
2
= +1.4%) achieved an overall specificity of 0.93 and sensitivity of 0.98, respectively.
Conclusions:
Non-invasive monitoring of absolute change in StO
2
was most predictive of ROSC and stable critical thresholds with high specificity or sensitivity were established in early CPR. Future work will independently validate this promising tool for CPR optimization.
Monitoring adaptation of skin tissue oxygenation during cycling ergometer exercise by frequency-domain diffuse optical spectroscopy
