Changes in End-Tidal Carbon Dioxide (ETCO2) vs. Changes in Central Venous Oxygen Saturation (ScvO2) and Lactate Clearance as a Quantitative Goal Parameter in Treatment of Suspected Septic Shock Patients

Physiologic indexes for therapeutic assessment of shock were introduced long time ago. Recent studies have evaluated central venous pressure (CVP), central venous oxygen saturation (ScvO2), lactate and end-tidal carbon dioxide (ETCO2) levels in this regard. 

To understand the potential diagnostic capability of ETCO2 in comparison with ScvO2, CVP and lactate in patients with suspected septic shock, we aimed to compare these parameters through a quantitative resuscitation treatment approach. 

In this cross-sectional study, 84 patients with suspected septic shock were selected randomly. All patients underwent quantitative resuscitation treatment approach. The following parameters were measured and recorded at baseline: ETCO2, CVP, ScvO2, mean arterial pressure (MAP), percentage of arterial oxygen saturation (SatO2), blood lactate levels, heart rate (HR), respiratory rate (RR), and the exact amount of urine output. At the time of treatment, and 3 hours and 6 hours after, all of the tests and measurements were re-implemented and registered by an emergency medicine specialist. 

There was a significant positive correlation between ETCO2 and ScvO2 at all times (baseline: r=0.566, p<0.001; after 3 hours: r=0.409, p<0.001; after 6 hours: r=0.170, p>0.05). Furthermore, there was a significant inverse correlation between ETCO2 and lactate at all times (baseline: r= -0.538, after 3 hours: r= -0.677, after 6 hours: r= -0.799). There was no significant correlation between ETCO2 and CVP at any time (p>0.05). 

All parameters significantly changed over time, and the correlation between changes in ETCo2, ScvO2 and lactate clearance was significant.