Influence of Central Venous Oxygen Saturation on In-hospital Mortality of Surgical Patients

Abstract

Low central venous oxygen saturation (ScvO₂) indicates an imbalance between cellular oxygen supply and consumption and, consequently, worse prognosis for critical patients. However, it is not clear what the value of this marker in surgical patients. The objective of the present study was to evaluate whether low perioperative ScvO₂ determines a worse prognosis. This is a 6-month observational study carried on in a tertiary hospital. Patients who needed to be in the intensive care unit (ICU) postoperatively, with age ≥ 18 years, who underwent large surgeries, were included. Patients who underwent palliative surgeries and those with severe heart failure were excluded. Levels of ScvO₂ were measured before the surgery, during the procedure, and after the surgery in the ICU. Sixty-six patients were included in this study, but 25.8% of them did not survive. Mean ScvO₂ levels were higher intraoperatively, 84.7 ± 8.3%, than preoperatively and in the ICU, 74.1 ± 7.6% and 76.0 ± 10.5% (p = 0.0001), respectively. However, only preoperative SvcO₂ levels of non-surviving patients were significantly lower than those who survived. By logistic regression, preoperative ScvO₂, OR = 0.85 (95% CI 0.74-0.98) (p = 0.02), was an independent factor of in-hospital mortality. Patients with preoperative ScvO₂ < 70% had greater need of intraoperative blood transfusion (80.0% versus 37.0%, p = 0.001) and volume replacement, 8,000.0 (6,500.0-9,225.0) mL versus 6,000.0 (4,500.0-8,500.0) mL (p = 0.04), with greater chances of postoperative complications (75% versus 45.7%, p = 0.02) and longer time in the ICU, 4.0 (20.0-5.0) days versus 3.0 (1.7-4.0) days (p = 0.02). Intraoperative ScvO₂ levels are higher than those both in the pre- and postoperative period. However, low preoperative ScvO₂ determines worse prognosis.