To: Shirley Hilton, Chief Technologist
From: John B. Carter, M. D., Director of Clinical Laboratories
Subject: Proposed E.D. POC AMI profiling
Date: January 14, 2008
The possibility of bedside AMI profiling using the i-STAT system has been proposed, possibly by the
i-STAT sales representative.
When specifically queried, Drs. Shuler and Bryant expressed no knowledge of difficulty or clinically significant delay using our current laboratory AMI profiling, and had no concern or discontent with the current process.
I am not opposed in general to the i-STAT system, having enthusiastically proposed it nearly 15 years ago as a rapid means of obtaining basic lab test results (Hgb, glucose, BUN, electrolytes, blood gases, etc.). My proposal then was rejected due to reagent costs, but did lead to the use of i-STAT for blood gas testing at LMC's extended care services.
Thus, if there is a real clinical benefit to POC lab testing in the E.D., I suggest that the process be initiated with more basic lab testing, not with AMI profiling. The following may warrant discussion:
- In view of historical concerns as to proper specimen identification of samples procured by E.D. personnel, and with expressed concerns of the L&D nurses as to QC/QA performance by their staff, should POC testing in the E.D. be performed by E.D. or by Lab personnel?
- While the vendor-published performance of i-STAT troponin testing appears to be adequate, the
i-STAT troponin levels would need to be carefully correlated with ECI troponin levels to ensure that we did not have two separate standards of AMI profiling.
- While the i-STAT sales presentation claims a system nearly free of QC requirements, there are important cautionary notes (partially clotted samples, hemolysis, precision of operation and specimen collection, etc.) that must be precisely followed, otherwise hazarding inaccurate results.
- With any E.D. POC testing, all results will need to be incorporated into the LIS lab cumulative summary reports.
Precision, accuracy and CV studies will need to be compared with in-house troponin results.
The remaining POC AMI sample (fingerstick samples should not be used) should be properly labeled and forwarded to the Laboratory for additional or follow-up testing as appropriate.
- We are currently in discussion with LMC's cardiologists as to the process of changing our in-house (ECi) AMI profiling to a more sensitive, reputedly more precise assay. This conversion should be completed prior to serious consideration of POC AMI profiling.
(posted 19 January 2008)