The Predictive Value of Prehospital Blood Lactate Measurement Following Out of Hospital Cardiac Arrest (OHCA) and Return of Spontaneous Circulation (ROSC).

This will be a prospective observational study of all primary cardiac arrest patients with prehospital (ROSC) in Alachua County, Florida. After Emergency Medical Services (EMS) activation and arrival at scene of a cardiac arrest, paramedics and Emergency Medical Technicians (EMTs) will provide standard Advanced Cardiac Life Support (ACLS) following 2010 guidelines. This may include chest compressions, early identification and shock of ventricular fibrillation and ventricular tachycardia, obtaining intravenous (IV) or intraosseous (IO) access, administration of IV or IO epinephrine, amiodarone, and pressors, oxygenation and ventilation, and other treatments as indicated for reversible causes of cardiac arrest. At time of IV or IO establishment a small blood sample will be obtained the blood will be measured for blood lactate. EMS personnel will be specifically trained to not to delay care or deviate from standard resuscitation protocols to obtain blood lactate sample. Current local paramedic protocols for cardiac arrest and general medical management include obtaining IV access and capillary blood draw and thus blood lactate measurement does not require any additional invasive procedures or medical risk. As medical director of Alachua County Fire Rescue (ACFR) as well as University of Florida faculty member, Dr. Christine Van Dillen oversees paramedic training, protocol development, and quality assurance in Alachua County, Florida. Dr Karl Huesgen is a faculty physician at the University as well, and works closely with ACFR in these regards. These investigators meet regularly with ACFR administration and provide mandatory paramedic and EMT education. Incorporation of lactate measurement into standard cardiac arrest protocols will be accomplished through the monthly administrative updates and monthly in-person training sessions. Adherence to the investigative protocol will be monitored through the standard quality assurance program in which all cardiac arrests are reviewed. Paramedics will have the option of using either capillary or venous blood for lactate measurement. This flexibility is important because cardiac arrests are often chaotic with substantial variability between site of cardiac arrests, timing of return of spontaneous circulation (e.g. if IV access obtained before cardiac rhythm restoration), patient anatomy (e.g. poor venous access), provider resources (e.g. presence of additional rescue personnel), and other factors. Ideally blood lactate measurement will occur at IV insertion, though it may be measured later with equally valid results during fingerstick glucose measurement. Of note, medical providers will be instructed to not perform any additional IV insertions or fingersticks in order to obtain lactate measurements. Patients will be transported as rapidly as possible to local hospitals.