Role of central venous oxygen saturation in prognostication of patients with severe sepsis and septic shock in emergency medical services.

INTRODUCTION: All the components of early goal-directed therapy, especially central venous oxygen saturation (ScvO2) as one of the endpoints of resuscitation, may not have mortality benefit, more so after results of the Australasian Resuscitation of Sepsis Evaluation, A Randomized Trial of Protocol-Based Care for Early Septic Shock, and The Protocolised Management in Sepsis trials. However, extrapolating results from trials undertaken in the developed world may not be entirely appropriate. MATERIALS AND METHODS: In this prospective observational study conducted in the emergency medical services, we aimed to find out the mean baseline ScvO2 in a cohort of 200 patients presenting with severe sepsis/septic shock and its prognostic significance. The measurement of ScvO2 was performed by sampling blood from the superior vena cava through the central venous catheter. RESULTS: The mean age of patients was 46.70 ± 17.64 years. The mean ScvO2 at baseline of the study cohort was 65.95 ± 20.70%. Based on initial ScvO2 values, 104 (52%) patients had a lower ScvO2 level, a priori classified as the hypoxic group. Sixty-five (32.5%) patients had an initial ScvO2 level in between 70 and 89%, categorized as normoxic group, and the remaining 31 (15.5%) patients had high ScvO2, leveled as the hyperoxic group. Sixty-six (33%) patients had hospital mortality. Of 104 hypoxemic patients, 28 (26.9%) had hospital mortality. In this group, the mean ScvO2 value in 28 nonsurvivors at baseline and after 6 h of resuscitation was 46.21 ±16.66% and 48.82 ±18.81%, respectively. Twenty-five (38.5%) patients had hospital mortality among 65 patients with baseline ScvO2 value in the normoxic range. Hospital mortality figure stood at 13 (41.9%) patients in the hyperoxic group. Among patients in the hyperoxic group, the mean serum lactate value at baseline in nonsurvivors was 4.52 ± 2.95 mmol/L, significantly higher as compared to the mean value of 2.89 ± 1.55 mmol/L in survivors. The hyperoxia group had higher hospital mortality though it was not statistically significant. CONCLUSION: The mean baseline ScvO2 was lower in our study cohort. In the hypoxic group, patients with hospital mortality had persistently lower ScvO2 level during the first 6 h of resuscitation. Importantly, higher mortality in the hyperoxic group with high serum lactate emphasizes the point that ScvO2 value should be analyzed along with serum lactate levels as complimentary resuscitation endpoints.