Dr. John Toffaletti is a Professor of Pathology at Duke University Medical Center, where since 1979 he has worked in the Clinical Laboratories and now directs the Blood Gas Laboratory, the Clinical Pediatric Laboratory, and several outpatient clinic laboratories. He also serves as Chief of Clinical Chemistry at the Durham VA Medical Center. He earned a BS in Chemistry from the University of Florida–Gainesville, a PhD in Biochemistry from UNC Chapel Hill, and completed a Postdoctoral Fellowship in Clinical Chemistry at Hartford Hospital. He has authored and presented extensively on blood gas interpretation, cooximetry, ionized calcium, magnesium, lactate in sepsis, kidney function tests (creatinine, cystatin C, GFR), and viscoelastic testing (ROTEM and TEG). His research interests include sample collection, pre-analytical errors, analytical methods, and the clinical use of these tests.Dr. Craig R. Rackley specializes in pulmonary disease in Durham, North Carolina, and has over 18 years of experience in the field of medicine. He graduated from Georgetown University of Medicine with his medical degree in 2002 and is affiliated with numerous hospitals in North Carolina, including Duke University Medical Center, USA.