Thursday April 6, 2006
central venous O2 saturation (ScvO2) or mixed venous O2 saturation (SvO2) ?
Is ScvO2 interchangeable with SvO2 ? The answer is no but the debate is - can they be use independently in the mangement of sepsis ? SvO2 value is usually 5% lower than ScvO2 due to mixing of atrial and coronary sinus blood (and other factors 3). Some experts warn that substituting ScvO2 for Svo2 may produce large errors 1. Dr. Rivers of EGDT- Early Goal Directed Therapy (in which ScvO2 has been used as a mainstay of algorithm) discussed this debate in recent issue of "chest" (march, 2006) 2. And at this point the practice pattern is consist of as he wrote:
"irrespective of whether the ScvO2 value equals the SvO2 value, the presence of a low ScvO2 level in patients with early sepsis portends increased morbidity and mortality"
Present practice target is value of 65% for SvO2 level and 70% for Scvo2 in the resuscitation of patients with severe sepsis. ScvO2 is quick and easy to obtain in comparison to SvO2.
1. Lack of Equivalence Between Central and Mixed Venous Oxygen Saturation Chest. 2004;126:1891-1896
2. Mixed vs Central Venous Oxygen Saturation May Be Not Numerically Equal, But Both Are Still Clinically Useful Chest, March 1, 2006; 129(3): 507 - 508
3. Central or Mixed Venous Oxygen Saturation? Kopterides et al. Chest.2005; 128: 1073-1075