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 (ScvO(2)) 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 ScvO(2) in a cohort of 200 patients presenting with severe sepsis/septic shock and its prognostic significance. The measurement of ScvO(2) 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 ScvO(2) at baseline of the study cohort was 65.95 ± 20.70%. Based on initial ScvO(2) values, 104 (52%) patients had a lower ScvO(2) level, a priori classified as the hypoxic group. Sixty-five (32.5%) patients had an initial ScvO(2) level in between 70 and 89%, categorized as normoxic group, and the remaining 31 (15.5%) patients had high ScvO(2), 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 ScvO(2) 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 ScvO(2) 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 ScvO(2) was lower in our study cohort. In the hypoxic group, patients with hospital mortality had persistently lower ScvO(2) level during the first 6 h of resuscitation. Importantly, higher mortality in the hyperoxic group with high serum lactate emphasizes the point that ScvO(2) value should be analyzed along with serum lactate levels as complimentary resuscitation endpoints.