Evaluation of a user-operated patient-side blood gas and chemistry monitor in children undergoing cardiac surgery

Abstract

A study was performed to evaluate a user-operated patient-side blood gas and chemistry monitor (GEM-STAT, Mallinckrodt Sensor Systems, Ann Arbor, MI) for the first time in a group of infants and children with congenital heart disease undergoing cardiac surgery. Paired blood samples from 18 patients were analyzed by the test instrument and by standard clinical laboratory instruments. One failure of the test instrument, malfunction of a cartridge, occurred during the evaluation. The integrated and external quality control functions gave readings within the manufacturer's tolerance. The differences between the measurements obtained using the GEM-STAT and the standard laboratory instruments for five of the six variables are summarized as follows (mean +/- SD, units of measure, number of samples): pH (-0.017 +/- 0.02, 132), PaCO2 (-1.90 +/- 3.3 mm Hg, 130), hematocrit (-1.3 +/- 2.3%, 129), potassium (-0.17 +/- 0.20 mmol, 112) and sodium (-2.0 +/- 3.3 mmol, 112). The mean difference in the measurements of PaO2 in the clinically important range defined by the upper quality control limit for oxygen tension of 172 mm Hg for the GEM-STAT is: (-0.20 +/- 7.26 mm Hg, 51). The mean difference between the measurements for PaO2s below the lowest quality control point (60 mm Hg) was (-2.3 +/- 5.5 mm Hg, 30). The values for all variables obtained from the GEM-STAT during the trial period, with the exception of the PaO2 less than 60 mm Hg, showed good correlation with the laboratory over the clinically useful range.(ABSTRACT TRUNCATED AT 250 WORDS)