BRAIN-TISSUE PO(2)-MONITORING - CATHETER STABILITY AND COMPLICATIONS

The authors report on the stability and complications of 73 LICOX brai n ti-pO(2)-microcatheters in 70 patients. Mean monitoring time was 7.5 +/- 4.0 days. Patients prone to cerebral hypoxia (after severe head i njury (GCS < 9) or a subarachnoid hemorrhage) had a ti-pO(2)-microcath eter inserted next to the ICP-probe in the typical frontal position. A fter the first 15 insertions, instead of the 3-way-screw (needing a 6 mm burrhole), a I-way-screw (needing a 2.7 mm burrhole) was used for f ixation in the bone; by doing so, the procedure can be performed in th e ICU and takes only 15 min. Whenever possible a calibration at room a ir (to determine the sensitivity-drift) and in oxygen free solution (t o determine the zero-drift) was performed after removal of the cathete rs. Ideally the expected pO(2) at room air was around 154 mmHg (temper ature dependent) and at zero calibration 0 mmHg. Mean sensitivity-drif t for 54 catheters was -8.5 +/- 15.4%. Dividing the catheters into gro ups, depending on the duration of monitoring (1-4, 5-8 and 9-16 days), revealed that the greatest part of the (negative) sensitivity-drift o ccurred during day 1-4 after insertion. After 1 week of monitoring som etimes a positive drift occurred (being far less than the negative dri ft during the first 4 days). Compared to the old catheters (-10.3 +/- 17.3%) ion the first half of the patients) the new ones showed a lower sensitivity-drift (-6.8 +/- 13.4%). The zero-drift of 56 catheters wa s low with mean drift after 7.5 +/- 4.0 days of 1.5 +/- 1.5 mmHg. Here also the highest drift occurred on day 1-4 after insertion. No infect ion was seen and 2 times (2.7%) a small hematoma, not needing evacuati on occurred. As the ti-pO(2)-catheter (having a smaller diameter) and the ICP-catheter were inserted at the same time, one cannot distinguis h which catheter caused the hematoma. A possible explanation for the o ccurrence of the two hematomas is the insertion of the catheters too c lose to the midline. The authors conclude that LICOX ti-pO(2)-monitori ng is a safe and reliable method. Further decrease of the complication rate and increase of the catheter-stability may be expected.