. 2013 Mar 11;7:139–148. doi: 10.2147/DDDT.S40622

Table 3.

Relation between arterial end-tidal PCO₂ difference and dead-space components

Surfactant group	Variable	Correlation coefficients
Surfactant group	Variable	r	r2	P
Synsurf	V_Dalv	0.88	0.78	0.0004
	V_Dalv/V_T	0.87	0.75	0.0005
	V_Dphys	0.63	0.40	0.0382
	V_Dphys/V_T	0.70	0.49	0.0172
Exosurf	V_Dalv	0.74	0.54	0.0096
	V_Dalv/V_T	0.19	0.04	0.5788
	V_Dphys	0.51	0.26	0.1071
	V_Dphys/V_T	0.35	0.13	0.2861
Exosurf + Ca²⁺	V_Dalv	0.90	0.81	0.0002
	V_Dalv/V_T	0.93	0.87	0.00003
	V_Dphys	0.74	0.55	0.0091
	V_Dphys/V_T	0.81	0.66	0.0024

Abbreviations: V_Dalv, alveolar dead space; V_Dalv/V_T, alveolar dead space/tidal volume ratio; V_Dphys, physiologic dead space; V_Dphys/V_T, physiologic dead space/tidal volume ratio.