Continuous arterial blood gas monitoring in pediatric patients: analysis of prolonged monitoring using the Paratrend 7 system
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KeywordsOxygen Sensor Arterial Catheter Pressure Waveform Entire Apparatus Significant Drift
Continuous blood gas monitoring is a new addition to the intensive care unit. The Paratrend 7 contains sensors to measure pH and PCO2, an electrode to measure PO2, and a thermistor to measure temperature. The entire apparatus can be placed via a 20 gauge arterial catheter. Because the initial proposed life span of the sensor was 72 h, those children who had it in place greater than this period form the basis of this analysis.
Patients who had a sensor in place greater than 72 h were identified. Matched values of the arterial blood gas and the sensor were compared for pH, PCO2, and PO2 via bias and precision. Variation over time was calculated using partial and Pearson's correlation analysis. If significant drift of the values of the sensor was noted by the clinician, an in vivo calibration was performed.
Twelve patients had the sensor in place for a mean of 138.0 ± 45.4 h (range 74–238 h). The mean age of the children was 7.1 years (range 14 months to 21 years). All but one of the sensors were placed via the femoral artery. The bias/precision values were for pH 0.0034/0.0292, PCO2 -1.87/6.22, PO2 1.97/25.0. The Pearson correlation/partial correlation values were for elapsed time for pH 0.963/0.964, PCO2 0.931/0.931, and for PO2 0.806/0.8109. There were no complications from prolonged sensor use. All the arterial lines showed adequate blood pressure waveform display and ability to draw blood specimens during the entire life of the sensor. Calibration of the oxygen sensor was performed 14 times, every 54.9 ± 35.7 h.
The Paratrend 7 continuous blood gas monitor can be safely used for as long as 10 days without any complications. For pH and PCO2 no degradation in accuracy is noted over this time period. The accuracy of the oxygen sensor should be confirmed every 24–36 h via comparison to the arterial blood gas value.