Continuous monitoring of arterial oxygen tension using a catheter-tip polarographic electrode in infants.

An oxygen electrode mounted in the tip of an umbilical artery catheter was used in 36 newborn infants with severe respiratory illnesses, 28 of whom survived. Thirty-seven electrodes were used. The median age at insertion was 4 hours (range, 30 minutes to 122 hours). Three electrodes failed to work and they were removed or replaced, and two could not be properly evaluated. Thirty-two electrodes functioned satisfactorily for 10 to 190 hours (mean, 75 hours) after a one-point calibration against blood sampled through the catheter. Twenty-two did not need recalibrating before they were removed after 10 to 190 hours (mean, 88 hours. Four of the remaining ten electrodes were recalibrated once after 33 to 97 hours and then functioned until removed 15 to 55 hours later. The other six electrodes failed after 32 to 105 hours (mean, 49 hours). Complications were few. A total of 356 arterial blood samples, obtained after the initial calibration and before any recalibration was necessary, gave a correlation coefficient of 0.93 (P less than .0001) against an independent system for measuring arterial oxygen tension (Pao2) (Radiometer Type E.5046 oxygen electrode). We conclude that the catheter-tip electrode is a safe and reliable instrument for continuously recording Pao2 in newborn infants which much simplifies the management of serious respiratory illnesses.