First Troponin in the Truck? EMS Lab Draw for Chest Pain

October 11, 2021

Written by Andy Hogan

Spoon Feed
Blood samples drawn by EMS can be safely and accurately integrated into ED chest pain diagnostic pathways, reducing ED length of stay (LOS) for some patients.

Why does this matter?
Collecting blood samples in the prehospital setting (for analysis in the hospital lab) could expedite ED workup and disposition for patients with acute chest pain.

Blood draws in the ‘back of the Box’
This study examined whether troponin values from blood drawn in the prehospital setting could be used during ED workup of chest pain. Patients with chest pain transported by 3 third service EMS agencies to a single academic hospital were enrolled as a convenience sample. Subjects that underwent successful blood collection by EMS professionals followed by ED workup via a diagnostic pathway featuring the HEART score and serial troponin levels (0-hr/3-hr) were analyzed. Investigators substituted prehospital troponin values for 0-hr values, determined a 100% NPV (n=233) for 30-day MACE, and concluded that prehospital blood was acceptable for use in this context. The authors then calculated that the ED diagnostic pathway could be shortened (and mean LOS decreased) by 72.5 min if 3-hr troponins were timed relative to EMS samples.

While promising, reported time savings hinge upon theoretical blood draws performed 3 hours after prehospital collection. Subsequent studies should look at outcomes based upon actual samples collected at this time point. Additionally, several factors predispose these results to selection bias. Paramedics with superior phlebotomy skills or greater interest in research probably obtained blood samples from patients at higher rates. Likewise, third service EMS agencies staffed by single-role paramedics (rather than dual-role firefighters) may also succeed at blood collection more frequently. Lastly, many EMS services still struggle with prehospital recordkeeping and data linkage with hospital EMRs. These issues limit widespread implementation of EMS blood draw protocols for in-ED use. Nevertheless, this study lays promising groundwork for further research on the role of prehospital blood samples in emergency care.

Source
EMS blood collection from patients with acute chest pain reduces emergency department length of stay. Am J Emerg Med. 2021 Sep;47:248-252. doi: 10.1016/j.ajem.2021.04.073. Epub 2021 Apr 26.