Dynamics of central venous oxygen saturation and serum lactate during septic shock resuscitation

Septic shock is a serious condition leading to high mortality and morbidity. Many varieties of attempts aiming toward improving outcomes have been implemented. However the appropriate therapeutic endpoint of shock resuscitation is still under investigation. The authors report here the dynamics of commonly used parameters, namely central venous oxygen saturation (ScvO2) and lactate concentration during resuscitation.

Adult patients admitted with severe sepsis and septic shock from October 1, 2009 to January 31, 2009 were enrolled. During hemodynamic resuscitation, the central venous blood was drawn for ScvO2 and lactate measurement right after the CVC was placed (T1) and at the point where the blood pressure goal was achieved (T2). The third and the fourth measurements were obtained at 1 and 2 hours thereafter (T3 and T4). These samples were ice chilled and were sent to central laboratory for blood gas analysis and lactate determination.

Twenty patients underwent the study. There was no significant change in ScvO2 from T1 to T4. All but five ScvO2 at T1 were above 70%. Lactate level gradually declined during the course of treatment and the clearance from T1 to T3 was calculated as 15.4%. No correlation between ScvO2 and lactate level was noted at any sampling time. When partitioning venous oxygen saturation in to 4 groups, that is ScvO2 < 65, 65 - < 75, 75-<85 and > 85, respectively, those with ScvO2 > 85% had the highest lactate concentration.

Central venous oxygen saturation and its changes during treatment were heterogeneous which made this parameter less reliable than others to monitor management. The lactate clearance, although slow, is uniform and may be used alone or in combination with other parameters to monitor resuscitation.