We obtained data on laboratory turnaround time (TAT) and emergency department (ED) length of stay (LOS). We correlated potassium test TAT outlier percentage (TAT-OP) with ED LOS and found that for each outlier percentage (potassium result > 40 minutes), a projected impact on ED LOS was approximately 2.8 additional minutes (ED LOS = 2.79 TAT-OP + 78.77). To address this issue, we began implementation of a totally automated chemistry system to decrease TAT-OPs. Our TAT means did not change substantially with automation (potassium, 28 to 27 minutes); however, TAT-OPs decreased substantially (potassium, 18% to 5%). Preautomation average ED LOS correlated best with the TAT-OP (r2 = 0.98; P = .01), but this relationship weakened substantially after automation (r2 = 0.29; P > .05), suggesting the laboratory was no longer a factor in ED LOS. The postautomation ED LOS correlated best with ED patient volume (r2 = 0.88; P = .06).
Although laboratories have focused on TAT means for performance assessment, our study suggests TAT-OPs are more clinically relevant benchmarks. Furthermore, our findings suggest that total laboratory automation can effectively improve overall laboratory service reliability and help eliminate the laboratory as a factor in ED LOS.