Oxygen debt in critically ill patients monitoring and additionals

PhD ceremony: Mr. P.A. van Beest, 14.30 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Oxygen debt in critically ill patients monitoring and additionals

Promotor(s): prof. T.W.L. Scheeren

Faculty: Medical Sciences

As recognized by the international Surviving Sepsis Campaign, hemodynamic optimisation is important for the treatment of septic patients. The current data subscribe ‘Early Goal-Directed Therapy’ (EGDT) which incorporates central venous oxygen saturation (ScvO2, as a value for oxygen balance) normalization, as a valuable strategy. Despite low ScvO2 values at ICU admittance are rare in Dutch ICU’s, early recognition of critically ill patients is important. During treatment of septic patients the clinician should be aware of the described unacceptably wide limits of agreement between ScvO2 and mixed venous oxygen saturation (SvO2). Femoral venous oxygen saturation (SfvO2) disappoints as alternative for ScvO2: in outpatients, surgical patients and in critically ill patients SfvO2 does not predict ScvO2. Another suitable parameter as indicator for oxygen debt in tissue is lactate. When measured in a prehospital setting, lactate predicts hospital outcome. At a later stage, i.e., at the ICU, lactate remains valuable even after the first hours of treatment. Lactate is associated with organ failure and mortality in a heterogeneous ICU population. During treatment of critically ill patients and regular reassessments, ScvO2 and lactate are useful but not perfect tools. The arterio-venous pCO2 difference (pCO2 gap) as measure for circulation, i.e., cardiac output, may be a welcome additional application. However, the value predictive value of pCO2 gap for outcome is limited. The present results do not warrant the use of pCO2 difference in future treatment algorithms.