IntroductionControversy remains regarding the relationship between central venous saturation (ScvO2) and mixed venous saturation (SvO2) and their use and interchangeability in patients with sepsis or septic shock. We tested the hypothesis that ScvO2 does not reliably predict SvO2 in sepsis. Additionally we looked at the influence of the source (splanchnic or non-splanchnic) of sepsis on this relationship.MethodsIn this prospective observational two-center study we concurrently determined ScvO2 and SvO2 in a group of 53 patients with severe sepsis during the first 24 hours after admission to the intensive care units in 2 Dutch hospitals. We assessed correlation and agreement of ScvO2 and SvO2, including the difference, i.e. the gradient, between ScvO2 and SvO2 (ScvO2 - SvO2). Additionally, we compared the mean differences between ScvO2 and SvO2 of both splanchnic and non-splanchnic group.ResultsA total of 265 paired blood samples were obtained. ScvO2 overestimated SvO2 by less than 5% with wide limits of agreement. For changes in ScvO2 and SvO2 results were similar. The distribution of the (ScvO2 - SvO2) (< 0 or ≥ 0) was similar in survivors and nonsurvivors. The mean (ScvO2 - SvO2) in the splanchnic group was similar to the mean (ScvO2 - SvO2) in the non-splanchnic group (0.8 ± 3.9% vs. 2.5 ± 6.2%; P = 0.30). O2ER (P = 0.23) and its predictive value for outcome (P = 0.20) were similar in both groups.ConclusionsScvO2 does not reliably predict SvO2 in patients with severe sepsis. The trend of ScvO2 is not superior to the absolute value in this context. A positive difference (ScvO2 - SvO2) is not associated with improved outcome.

A 45-year-old man with end-stage renal disease due to polycystic kidney disease was admitted to the hospital because of recurrent abdominal pain, progressive peripheral motor neuron neuropathy, and respiratory failure. The diagnosis of acute intermittent porphyria was confirmed by an elevated porphyrin concentration in the urine and the presence of an R167Q mutation in the porphobilinogen deaminase gene. Use of hydroxyzine, weight loss, and/or a mild upper respiratory viral infection might have been the provoking factor of the acute intermittent porphyria. Treatment with intravenous hemin (3 mg/kg) and a high-carbohydrate diet (3000 kcal/d) had no clinical effect. Tetraplegia and chronic respiratory insufficiency developed, and the patient needed a pacemaker because of a symptomatic sinus bradycardia due to autonomic dysfunction. The patient died 10 months after the first manifestation of acute intermittent porphyria.

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