Continuous monitoring of arterial oxygen tension in infants: four years of experience with an intravascular oxygen electrode.

Two hundred eighty-two umbilical artery catheters with oxygen electrodes on their tips were passed into the aortas of 268 newborn infants with severe respiratory illnesses between 1974-1977; 254 (90%) of the electrodes recorded PaO2 satisfactorily for a mean of 66 hours; 212 (75%) electrodes were still functioning well when removed, because they were no longer clinically needed, after a mean of 87 hours. The 27 electrodes that failed to record PaO2 on insertion, 42 that failed later, and 25 that temporarily malfunctioned were examined after removal from the infants. A structural cause was found which accounted for the failure or malfunction of 43 electrodes. Problems with the remaining 51 electrodes were thought often to have been due to clotting over the tip of the electrode. The main complication of catheterization was temporary impairment of the circulation to the legs in 69 (26%) infants. Autopsies were done on 69 (85%) of the infants who died; 22 (32%) infants were found to have thrombi in an iliac artery, which spread in ten (15%) of the aorta. It was concluded that the intravascular electrode usually functioned satisfactorily and that the incidence of complications was no higher than that reported with ordinary umbilical artery catheters. Improvements in the performance of the catheter-tip electrode would be expected if structural causes for failure were eliminated and if means to reduce the incidence of clot formation around the catheter and electrode could be found. It is believed that intravascular electrodes cannot be replaced by skin electrodes for the initial management of severe respiratory illnesses.