Wan XY, et al. - Researchers sought to confirm the effects of time delay and body temperature on measurements of central venous oxygen saturation (ScvO₂), venous-arterial blood carbon dioxide partial pressures difference (Pv-aCO₂), venous-arterial blood carbon dioxide partial pressures difference/arterial-venous oxygen difference ratio (Pv-aCO₂/Ca-vO₂) and lactate. They performed blood gas analyses on arterial and central venous blood samples drawn simultaneously by plastic syringes via indwelling intra-arterial and central venous catheters from a total of 30 critically ill patients and repeated the analyses after 10, 20, 30, 40, 50 and 60 min. A trend of increasing values for ScvO₂, Pv-aCO₂, Pv-aCO₂/Ca-vO₂ and lactate was noted over time. Patients with high temperature (temperature greater than 38 °C) display slightly higher differences in lactate values, relative to the patients with no high temperature after 20, 30, 40, 50 and 60 min. Hence they emphasize that analysis of arterial and central venous blood gas samples should be done quickly within 10 min, especially in patients with body temperature <38 °C.