Assessing Performance of i-STAT at the Point of Care in the Emergency Room

Abstract

Context: Point-of-care testing (POCT) for blood gas and chemistries is widely adopted in the emergency department (ED) for fast turnaround and critical medical decisions. Objective: To assess performance of ED physicians compared to laboratory technologists carrying out i-STAT analysis. Impact of user skill on POCT performance was also studied. Design: Over a 3-month period, ED physicians performed tests with their i-STAT unit with parallel blood specimens (n=60) sent to the central laboratory to be tested on another i-STAT unit and laboratory analysers (blood gas and chemistries). Comparisons to laboratory results (obtained with ABL 520 and Beckman-Coulter LX20PRO) were carried out. Two operators from ED and central laboratory performed side by side, repeated tests on the i-STAT units. Their overall within-run imprecision were compared. The analytical performance of i-STAT was further assessed by another laboratory technologist to verify its capability to deliver good results. Results: Platform comparisons showed that ED physicians performed poorer compared to laboratory technologists, particularly with chloride and pO2 (Spearman coefficient of correlation — 0.49 and 0.54 respectively indicate wide scatter). This is also mirrored in the higher overall within-run imprecision for chemistries (sodium, chloride, potassium, glucose, urea and creatinine) by an ED physician (5.4%) compared to a laboratory technologist (3.7%). Including blood gas results showed an even wider gap in their testing skills. Except at a low creatinine of 67 μmol/L, the i-STAT analyser delivered precise measurements for the chemistries and blood gas parameters. Conclusions: Performances by medical staff with the i-STAT analyser did not adequately approach the same skill level as laboratory technologists.