Medición bilateral de la saturación yugular de oxígeno

Objective
The objetive of this study was to obtain information about cerebral hemodynamics through retrograde cannulation of both internal jugular veins and monitoring jugular bulb oxigen saturation.

Material and methods
Fourteen (14) patients admitted to our ICU between July of 1994 and April of 1995 were prospectively studied. The intracranial pressure (ICP) was monitored and bilateral cannulation of the internal yugular vein was performed. In 9 patients, one of the two veins was channeled with an optic fiber catheter for continous monitoring at oxigen jugular saturation (SyO2)’ Simultaneus samples were obtained every 8 hours from both jugular veins for measuring SyO2 whenever therapeutic changes were needed or before an increase in the ICP was observed. A total of 140 measurements were performed (mean 10 per patient). A variance analysis, t of student and simple linear regression analysis of the pars obtained in the SyO2 were performed. Furthermore we studied the influence of the type of intracranial pathology as assessed by cranial computerized tomography (CT), as well as at different levels of raised IPC.

Results
Average monitoring time was 7.2 days (311). The brain injury in the CT was considered focal in 8 patients and mixed (focal + diffused) in 6. The correlation between the left and right SyO2 was r = 0.68 (p < 0.005). In patients with focal CT lesions correlation was r = 0.58 (p < 0.005), with true regression Y= 32 + 04X. Mean values were 61.8 ± 9% for the right jugular and 67.6 ± 12% for the left (p < 0.005). The correlation in patients with mixed CT lesions was r = 0.79 (p < 0.005) with true regression Y= 18 + O.72X. The average value was 70.9 ± 11% for the rigth jugular and 71 ± 12% for the left jugular vein (difference not significant). The correlation coefficient for ICP levels of <20, >20, >30 and >40 mm Hg was r = 0.66, r = 0.79, r = 0.85 and r = 0.89, respectively. Clinical discordance between bilateral measurements was over 30% of these in 50% of the patients.

Conclusion
The SyO2 obtained through retrograde cannulation from both jugular veins maintains a correct positive correlation that improves in intracranial hypertension situations. Correlation is better in patients with mixed CT lesion than in those with focal pathology. Our study could not determine which of the two jugular veins provided more reliable information of about intracranial hemodynamics. Consequently, we do not support the used of bilateral SyO2 monitoring in the clinical rutine.