End-tidal carbon dioxide variation after a 100- and a 500-ml fluid challenge to assess fluid responsiveness

Annals of Intensive Care

Table 3 Main characteristics of ROC curves built for hemodynamic variables of interest

	AUC	Best thresholds (%)	Compared with AUC = 0.5	Specificity	Sensitivity	PPV	NPV	LR+	LR−	Youden index
varEtCO₂500	0.82 [0.67; 0.97]	5.89	0.006	1 [1.0; 1.0]	0.6 [0.33 0.87]	1.0	0.81	Infinite	0.4	0.6
varEtCO₂100	0.74 [0.60; 0.89]	3.0	0.034	1 [1.0; 1.0]	0.33 [0.13; 0.6]	1.0	0.68	Infinite	0.67	0.33
varMAP₅₀₀	0.62 [0.44; 0.83]		0.31
varPP₅₀₀	0.62 [0.43; 0.82]		0.31
varHR₅₀₀	0.65 [0.44; 0.82]		0.29
FtC	0.49 [0.37; 0.67]		0.09

Mean arterial pressure (MAP), pulse pressure (PP), heart rate (HR), corrected systolic flow time (Ftc), and end-tidal carbon dioxide (EtCO₂). Data are expressed as variation from baseline (i.e., ΔEtCO₂ for EtCO₂ variation) after different volumes of infused fluid: 100 and 500 ml. Area under the curve (AUC), positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), negative likelihood ratio (LR−)