Table 3

Between-group comparisons of responses to supplemental oxygen

	MD (Δ at 20 min)*	95% CI	Main effect: group		Interaction: time by group
	MD (Δ at 20 min)*	95% CI	Raw p value	Adj. p value	Raw p value	Adj. p value
PavCO₂ (kPa)	0.31	0.13 to 0.49	<0.001	0.010	<0.001	0.014
pH	−0.014	−0.023 to −0.005	<0.001	0.011	0.001	0.019
V_E (L/min)	−0.8	−1.3 to −0.38	0.045	0.585	0.051	0.612
V_D/V_T (ratio)	0.01	−0.03 to 0.01	0.085	0.850	0.128	>0.999

Adj. p value: significance level from general linear model analysis, OHS versus controls, after Holm's Bonferroni correction.
*MD: mean difference (OHS–control) for Δ values at 20 min.
OHS, obesity hypoventilation syndrome; PavCO₂, arterialised-venous carbon dioxide; V_D/V_T, physiological dead space to tidal volume ratio; V_Dphys, physiological dead space; V_E, minute ventilation.