Correlation of maximal inspiratory pressure to transdiaphragmatic twitch pressure in intensive care unit patients

Table 1 Statistical analysis of duration of mechanical ventilation and mortality

Outcome	Index	yo	a	b	c	R²	F	p
Duration of ventilation	PdiTw	−122	−158	988	−1236	0.75	27.1	< 0.0001
Duration of ventilation	Pimax	96	−431	17193	−119569	0.42	6.4	< 0.002
Mortality	PdiTw	−12.3	290	−325	−120	0.90	129.9	< 0.0001
Mortality	Pimax	−14.9	2325	−29779	103878	0.73	40.0	< 0.0001
Duration of ventilation	PesoTw	11.6	−102	464	−435	0.72	22.9	< 0.0001
Mortality	PesoTw	−10	4.18	487	−755	0.77	50.4	< 0.0001

All relationships represent nonlinear regression curve fits to an inverse third order exponential equation, i.e. y = yo + a/x + b/x² + c/x³
The correlation coefficient of the equation is presented as R². Also provided are the F statistic for the curve fit and the p value
PdiTw transdiaphragmatic twitch pressure in response to bilateral magnetic stimulation of the phrenic nerves
PesoTw esophageal twitch pressure in response to bilateral magnetic stimulation of the phrenic nerves, Pimax maximum inspiratory pressure

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