Prehospital Point-of-Care Testing for Troponin: Are the Results Reliable?

Prehospital Emergency Care. Posted online on September 6, 2012.

Rapid assessment of patients experiencing a myocardial infact (MI) results in improved outcomes, especially if the patient is transported directly to a specialist cardiac centre. While it is common for patient’s experiencing a STEMI  to be transported to a cardiac centre which undertakes percutaneous coronary intervention (PCI), non-STEMI patients often are conveyed to the nearest emergency department, have to wait for blood results and are then transferred to a cardiac centre.  By allowing ambulance crews to use point-of-care (POC) devices to measure cardiac troponin I levels during transport of patients to the emergency department (ED) may result in earlier diagnosis of acute myocardial infarction, particularly in those patients without ST-segment elevation and, if necessary, also ensure transportation to an appropriate treatment  facility.

The authors conducted the study to determine whether POC devices (i-STAT System) operated in a moving ambulance reliably duplicate the measurement of cardiac troponin I levels obtained by POC devices in the ED.

Blood samples were obtained in the ED and the hospital from patients reporting chest pain or other cardiac complaints. Troponin I assays were then performed in a moving ambulance using two POC devices. The POC devices were placed on flat surfaces in the rear of the ambulance. The ambulance driver was instructed to keep the ambulance moving in traffic while each assay was completed. A variety of routes were taken. Each set of two assays was completed entirely during a single simulated run. The results of the two assays performed in the moving ambulance were then compared with the results of the control assay, which was performed simultaneously in the ED on the same sample.

Forty-two whole-blood samples underwent troponin I assays in a moving ambulance. Thirteen (30.9%) assays were positive. One (2.4%) was excluded because of cartridge error. Two (4.8%) were excluded because of interfering substance. No significant difference in whole-blood troponin results was found between the assays performed in the moving ambulance and those performed in the ED (intraclass correlation coefficient 0.997; 95% confidence interval 0.994 to 0.998; p < 0.005).

The authors found that when used in a moving ambulance, the POC device provided results of cardiac troponin I assays that were highly correlated to the results when the device was used in the ED. While the authors recognise that the feasibility, practicality, and clinical utility of prehospital use of POC devices must still be assessed, these POC devices may offer another tool in the rapid identification of patients with an MI.

http://informahealthcare.com/doi/abs/10.3109/10903127.2012.717166