Effects of thoraco-pelvic supports during prone position in patients with acute lung injury/acute respiratory distress syndrome: a physiological study

Table 4 Gas exchanges

Variable	Units	Supine	Prone without supports	Prone with supports
PaO₂/FiO₂	Torr [kPa]	206.2 ± 38.7 [27.5 ± 5.2]	261.8 ± 41.2^a [34.9 ± 5.5]	265.0 ± 40.0^a [35.3 ± 5.3]
PaO₂	Torr [kPa]	87.7 ± 10.2 [11.7 ± 1.4]	112.5 ± 16.0^a [15.0 ± 2.1]	113.4 ± 12.0^a [15.1 ± 1.6]
SaO₂	%	95.7 ± 1.0	96.6 ± 0.6^a	96.7 ± 0.6^a
PvO₂	Torr [kPa]	44.6 ± 4.0 [5.9 ± 0.5]	49.0 ± 6.3^a [6.5 ± 0.8]	47.7 ± 5.6^a [6.4 ± 0.7]
SvO₂	%	77.2 ± 4.4	80.3 ± 5.4^a	79.6 ± 5.7^a
pH_a		7.37 ± 0.06	7.37 ± 0.05	7.36 ± 0.06
Ve	l/minute	9.4 ± 2.5	9.6 ± 2.8	9.9 ± 3.1
PaCO₂	Torr [kPa]	43.9 ± 4.2 [5.9 ± 0.6]	43.6 ± 4.2 [5.8 ± 0.6]	44.3 ± 6.1 [5.9 ± 0.8]
PvCO₂	Torr [kPa]	51.0 ± 6.6 [6.8 ± 0.9]	52.1 ± 6.8 [6.9 ± 0.9]	52.2 ± 6.4 [7.0 ± 0.9]
pH_v		7.35 ± 0.05	7.34 ± 0.06	7.34 ± 0.05
VCO₂	ml/minute	145.5 ± 38.8	143.3 ± 40.9	140.4 ± 42.9
V_d/V_t		0.62 ± 0.10	0.63 ± 0.11	0.63 ± 0.13
V_d/V_t(alv)		0.18 ± 0.15	0.19 ± 0.15	0.18 ± 0.16

Results are means ± SD. PaO₂/FiO₂, ratio of arterial oxygen tension to fraction of inspired oxygen; SaO₂, arterial oxygen saturation; PvO₂, mixed-venous oxygen tension; SvO₂, mixed-venous oxygen saturation; pH_a, arterial blood pH; Ve, minute ventilation; PaCO₂, arterial carbon dioxide tension; PvCO₂, mixed-venous carbon dioxide tension; pH_v, venous blood pH; VCO₂, minute metabolic carbon dioxide production; V_d/V_t, dead space; V_d/V_t(alv), alveolar dead space. ^ap ≤ 0.05 compared with supine.

ISSN: 1364-8535