Clinical performance of an in-line point-of-care monitor in neonates

To evaluate the bias, precision, and blood loss characteristics of an ex vivo in-line point-of-care testing blood gas and electrolyte monitor designed for use in critically ill newborn infants.

Study participants included consecutive neonates with an umbilical artery catheter (UAC) in use for clinical laboratory testing. The in-line monitor (VIA LVM Blood Gas and Chemistry Monitoring System, VIA Medical, San Diego, CA) was directly connected to the participant's UAC and the monitor's determinations of pH, PCO(2), PO(2), sodium, potassium, and hematocrit (Hct) were compared with those simultaneously drawn and measured with a standard bench top laboratory instrument (Radiometer 625 ABL; Radiometer America, Inc, Westlake, OH). The bias (the mean difference from the reference method) and precision (1 standard deviation of the mean difference) performance criteria of the in-line monitor were derived using standard laboratory procedures.

Sixteen neonates monitored for a total of 37 days had a total of 229 paired blood samples available for comparison by the 2 methods. Bias and precision performance characteristics of the in-line monitor were similar to reports of other point-of-care devices (ie, pH: -.003 +/-.024; PCO(2):.35 +/- 2.84 mm Hg; PO(2):.39 +/- 7.30 mm Hg; sodium:.52 +/- 2.34 mmol/L; potassium:.17 +/-.18 mmol/L; and Hct:.61 +/- 2.80%). The range of values observed for each parameter included much of the range anticipated among critically ill neonates (ie, pH: 7.15-7.65; PCO(2): 25-75 mm Hg; PO(2): 25-275 mm Hg; sodium: 127-150 mmol/L; potassium: 2.6-5.5 mmol/L; and Hct: 32%-60%). Mean blood loss (+/- standard deviation) per sample with the in-line monitor was approximately one-tenth that of the reference method: 24 +/- 7 microL versus 250 microL, respectively. There was no evidence of hemolysis and no patient related safety issues were identified with use of the in-line monitor.

Repeated laboratory testing of critically ill neonates using an ex vivo in-line monitor designed for use in neonates provides reliable laboratory results. The blood loss and hemolysis data obtained suggests that this monitoring device offers potential for reducing neonatal blood loss-and possibly transfusion needs-during the first weeks of life. Before this promising technology can be routinely recommended for care of critically ill neonates, greater practical experience in a variety of clinical settings is needed.