Fentanyl Concentrations (ng/mL)   CB PB C/P Ratio N 18 18 18 Min 0.8 0.5 0.49 Max 84 73 1.60 Mean 9.60 10.10 0.95 Median 4.6 5.9 0.94     Standard Deviation 0.26 CB = Central Blood, PB = Peripheral Blood, C/P = Central/Peripheral Blood

Table 5: Summary of 18 fentanyl cases from the San Diego Medical Examiner’s Office (C/P ratios).