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Table 2 Analyses of each sampling stage

From: Effect of different surgical procedures on the accuracy of prediction of the plasma concentration of fentanyl: comparison between mastectomy and laparoscopic prostatectomy

Sampling stage Stage 1 Stage 2 Stage 3 Stage 4
Sampling time <1.5 h 1.5–3 h 3–4.5 h >4.5 h
Mastectomy
 Number of samples 83 74 19 0
 Plasma fentanyl concentration (ng/mL) 2.08 ± 0.74 2.07 ± 0.70 1.88 ± 0.54  
 Simulated fentanyl concentration (ng/mL) 1.81 ± 0.54 1.68 ± 0.52 1.50 ± 0.31  
 The difference between plasma and predicted fentanyl 0.27 ± 0.48 0.38 ± 0.47 0.34 ± 0.44  
 Range of difference [−0.82, 1.52] [−1.1, 1.68] [−0.7, 1.1]  
 Number of a difference more than +0.5 ng/mL 28/83 (38%) 27/74 (36%) 6/19 (32%)  
 Number of a difference less than −0.5 ng/mL 6/83 (7%) 3/74 (4%) 1/19 (5%)  
 Median absolute performance error (%) 21 25 35  
 Fixed bias [95% confidence interval] (ng/mL) 0.27 [0.17 0.37] 0.38 [0.27 0.49] 0.38 [0.17 0.59]  
Laparoscopic prostatectomy
 Number of samples 48 59 48 27
 Plasma fentanyl concentration (ng/mL) 2.27 ± 1.26 2.08 ± 0.63 1.68 ± 0.56 1.43 ± 0.43
 Simulated fentanyl concentration (ng/mL) 1.98 ± 1.04 1.90 ± 0.47 1.83 ± 0.55 1.76 ± 0.48
 The difference between plasma and predicted fentanyl 0.29 ± 0.54 0.19 ± 0.52 −0.15 ± 0.53 −0.34 ± 0.41
 Range of difference [−0.92, 1.42] [−1.08, 1.20] [−1.52, 0.78] [−0.98, 0.30]
 Number of a difference more than +0.5 ng/mL 13/48 (27%) 14/59 (26%) 2/48 (4%) 0/27 (0%)
 Number of a difference less than −0.5 ng/mL 2/48 (4%) 5/59 (8%) 10/48 (21%) 12/48 (25%)
 Median absolute performance error (%) 18 18 20 21
 Fixed bias [95% confidence interval] (ng/mL) 0.29 [0.14 0.44] 0.18 [0.03 0.33] −0.15 [0 −0.30] −0.34 [−0.17 −0.51]