Evaluation of i-STAT portable clinical analyzer in a neonatal and pediatric intensive care unit

Objective: To evaluate the Point-of-Care (POC) i-STAT system for measuring blood gases (pH, pCO(2), pO(2)) and whole blood electrolytes (sodium, Na+; potassium, K+ and ionized calcium, iCa(2+)) in the neonatal and pediatric intensive care units. Design and Methods: The i-STAT system was evaluated for imprecision, necessity of running quality control and accuracy. Comparison of patients' samples analyzed by the i-STAT system and the Ciba Coming 288 blood gas analyzer were performed. The reliability of the i-STAT system when performed by non-laboratory personnel was assessed. Results: The system was evaluated for imprecision and linearity using three concentrations of aqueous standards. Except for pO(2), the %CVs were <3.0 for all the analytes (pH, pCO(2), Na+, K+ and iCa(2+)) at all the three concentrations. Using whole blood studies the precision data gave %CVs that were <3.5 for all the analytes. Linearity studies showed good linearity over the five different concentrations tested. Comparison of the i-STAT and the Ciba Coming 288 blood gas analyzer was assessed by split sample measurement. Patients' results from the i-STAT correlated well with the Ciba Coming 288 blood gas analyzer (r = 0.99 for pH, pCO(2) and pO(2) and 0.95 to 0.99 for Na+ and K+) with the exception of iCa(2+) (r = 0.73). There was no significant difference in the results when operated by PICU/NICU nurses or laboratory personnel. A further study was made to assess whether routine quality control (CC) samples are necessary when using the i-STAT system. The regression analysis (slope and correlation coefficient) of the results from instruments run with and without QC samples gave results close to 1, indicating that there is no need to run additional quality control (QC). Conclusion: The POC testing analyzer i-STAT is a reliable alternative to the traditional blood gas analyzers and provides marginal improvement in turnaround time when compared with the service received from the PICU/NICU laboratory. Costs need to be carefully controlled.