Normal jugular bulb oxygen saturation.

BACKGROUND Normal values of the jugular bulb oxygen saturation were obtained in 1942 and in 1963. Correct catheter positioning was not confirmed radiologically. OBJECTIVES To replicate the measurements during angiographic catheterisation of the jugular bulb. METHODS Oxygen saturation in the jugular bulb (SjO(2)), inferior petrosal sinus (SipsO(2)), and internal jugular vein was bilaterally measured in 12 patients with Cushing's syndrome undergoing selective bilateral catheterisation of the inferior petrosal sinus. In addition, data from the two old series were reanalysed for comparison. RESULTS SjO(2) values (44.7%) were significantly lower than in the two old series, particularly concerning the normal lower limit (54.6% and 55.0% respectively). Comparative analysis suggests that contamination with the extracerebral blood of the facial veins and inferior petrosal sinuses was responsible for falsely high SjO(2) values in the two old series. CONCLUSIONS The normal lower SjO(2) limit is lower than previously recognised. This may have practical implications for treating severe head trauma patients.