POSITION OF JUGULAR OXYGEN-SATURATION CATHETER IN PATIENTS WITH HEAD TRAUMA - ASSESSMENT BY USE OF PLAIN FILMS

OBJECTIVE. The purpose of this study was to establish a plain radiogra phic technique for the assessment of the position of a jugular oxygen saturation catheter in patients with head trauma. MATERIALS AND METHOD S. In the experimental study, jugular oxygen saturation catheters were introduced into the internal jugular veins of four cadavers. Correct positioning of the catheter tips was monitored by CT. Concurrent anter oposterior radiographs of the skulls were obtained with the tubes angl ed in a transverse plane and in a sagittal plane at intervals of 5 deg rees and within a total range of 70 degrees for each plane. Three radi ologists judged the visibility of the catheter tips and measured the d istance of the catheter tips to previously determined bony landmarks o f the skull. Then, preliminary radiologic criteria for correct positio ning of the catheters were defined. In the clinical study, we prospect ively evaluated radiographs for 32 patients who received jugular oxyge n saturation catheters. Eleven patients had digital radiographs done, and 21 patients had radiographs with a conventional screen film system done. Radiographs were analyzed for consistency of findings with the experimental results and for consistency of the suspected catheter pos ition with laboratory data. RESULTS. Results of the cadaveric study sh owed that catheter position is best assessed on strict anteroposterior radiographs with the orbitomeatal-basal line perpendicular to the pla ne of the film. A correctly positioned catheter tip should lie cranial to a line extending from the atlantooccipital joint space and caudal to the lower margin of the orbit. The catheter tip also should lie cra nial to a line connecting the tips of the mastoid processes, with a ca theter tip-to-line distance averaging 20% of the overall distance betw een the tips of the mastoid processes. According to these criteria, th e catheter was properly positioned in 26 of 32 patients. In three pati ents, the catheter obviously was improperly positioned. Catheter posit ion was equivocal in three other patients; in two of these patients, t he catheter was looped within the internal jugular vein. Whereas for a ll 26 patients with properly positioned catheters values for jugular v enous oxygen saturation were congruent with other laboratory data, inc ongruent saturation values were recorded for five of the six patients with equivocally or obviously improperly positioned catheters. CONCLUS ION. Accurate assessment of the position of a jugular oxygen saturatio n catheter can be made by use of specific bony landmarks seen on anter oposterior radiographs of the skull.