Table 1_Longitudinal co-variation of radiographic chest-wall thickness and transcutaneous–arterial CO₂ discrepancy in congenital diaphragmatic hernia: a single-patient case study.pdf

The three variables showed broadly similar rise-and-fall temporal trajectories. Unadjusted within-patient correlations were strong (r = 0.766–0.813), and residual correlations persisted but were attenuated after removal of the quadratic Day/Day² trend (residual r = 0.545–0.625). These residual correlations were interpreted descriptively and not as evidence of a time-independent relationship.

PCA identified a dominant principal component explaining 85.9% of total variance, descriptively summarizing shared temporal covariance among radiographic chest-wall thickness, sensor heating power, and tcPCO₂–PaCO₂ discrepancy.</p>Conclusion<p>In this single-patient longitudinal case study, radiographic chest-wall thickness, sensor heating power, and tcPCO₂–PaCO₂ discrepancy showed parallel temporal changes. These findings generate the hypothesis that changes in local tissue conditions associated with increased radiographic chest-wall thickness may contribute to tcPCO₂–PaCO₂ disagreement, but causal inference is not possible and validation in multi-patient studies is required.</p>