Table 2.

Pearson correlation coefficient $\mathit{r}$ between different metrics of inspiratory effort, considering all observed breaths in individual patients ($\text{mean}\pm \text{SD}$), $n=43$ (and $n=42$ where ${\mathit{P}}_{\mathrm{di}}$ is involved)

	${\mathrm{ETP}}_{\mathrm{interc}}$	${\mathrm{ETP}}_{\mathrm{sel}}$	${\mathrm{PTP}}_{\mathrm{mus},\mathrm{EMG}}$	${\mathrm{PTP}}_{\mathrm{mus}}$	${\mathrm{PTP}}_{\mathrm{di}}$
${\mathrm{ETP}}_{\mathrm{di}}$	$0.74\pm 0.27$	$0.89\pm 0.16$	$0.89\pm 0.16$	$0.84\pm 0.16$	0.84 ± 0.16
${\mathrm{ETP}}_{\mathrm{interc}}$	–	$0.86\pm 0.28$	$0.86\pm 0.28$	$0.79\pm 0.25$	0.77 ± 0.26
${\mathrm{ETP}}_{\mathrm{sel}}$	$\star$	–	$1.0\pm 0.0$	$0.87\pm 0.09$	0.86 ± 0.10
${\mathrm{PTP}}_{\mathrm{mus},\mathrm{EMG}}$	$\star$	$\star$	–	$0.87\pm 0.09$	0.86 ± 0.10
${\mathrm{PTP}}_{\mathrm{mus}}$	$\star$	$\star$	$\star$	–	0.97 ± 0.05

The included effort metrics are: muscular and transdiaphragmatic pressure-time products (${\mathrm{PTP}}_{\mathrm{mus}}$ and ${\mathrm{PTP}}_{\mathrm{di}}$), EMG-time products of diaphragm, intercostal and selected channel (${\mathrm{ETP}}_{\mathrm{di}}$, ${\mathrm{ETP}}_{\mathrm{interc}}$, ${\mathrm{ETP}}_{\mathrm{sel}}$) and sEMG-derived muscular pressure-time product (${\mathrm{PTP}}_{\mathrm{mus},\mathrm{EMG}}$). Entries marked with $\star$ are given by symmetry.