[Factors influencing mixed venous oxygen saturation in intensive care].
Changes in mixed venous blood oxygen saturation (SvO2) were studied in 2 groups of patients. Group I patients (n = 10) were all hypoxaemic, suffering from acute respiratory failure, requiring that FIO2 be maintained at 1 throughout the study; respiratory and haemodynamic conditions were improved using PEEP and cardiovascular support. On the other hand, Group II patients (n = 13) were non-hypoxaemic patients with circulatory shock in whom FIO2 was gradually increased, and the haemodynamic status was improved using positive inotropic drugs (dopamine, dobutamine, adrenaline, amrinone). All 23 patients had a Swan-Ganz catheter set up for monitoring; all the usual haemodynamic and respiratory parameters were measured. Haematocrit values were kept at the same level throughout the study. Haemodynamic parameters were measured each time a new therapeutic procedure was carried out. No close relationship between SvO2 changes and changes in cardiac index or O2 consumption were found. However, a close relationship existed between changes in SvO2 and changes in O2 extraction (EAO2): SvO2 = -EAO2 + 102 (Group I; r = 0.90, n = 54); SvO2 = -1.2 EAO2 + 103 (Group II; r = 0.93, n = 66). A strong relationship was also found between changes in SvO2 and in FIO2 in each patient of Group II. In the complicated physiological set-up of an intensive care patient, SvO2 reflects oxygen extraction. A fall in SvO2 is related to an altered oxygen demand: oxygen supply ratio. In the most seriously ill patients, there is no relationship between changes in SvO2 and cardiac index.
Rouby
J J
JJ
Département d'Anesthésie, Unité de Réanimation Chirurgicale, Hôpital de la Pitié, Paris.
Poète
P
P
Bodin
L
L
Bourgeois
J L
JL
Arthaud
M
M
Devilliers
C
C
Viars
P
P
D000328:Adult; D000368:Aged; D002407:Catheterization, Swan-Ganz; D003422:Critical Care; D006439:Hemodynamics; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D012131:Respiratory Insufficiency / Q000503:physiopathology; D012769:Shock / Q000503:physiopathology
D010100:Oxygen
Facteurs influençant la SvO2 en réanimation.