Incidence and risk factors for potentially suboptimal serum concentrations of vancomycin during cardiac surgery

Table 1 Patients’ characteristics n (%)

Characteristics
Patients	236
Age, median (range)	70 (25-86)
Male gender	149 (63)
BMI, kg/m2, median (range)	26 (18-40)
Diabetes	46 (19)
COPD	0
Hypertension	151 (64)
Smoke	28 (12)
Surgical time, min, median (range)	249 (119-593)
Surgical procedure
CABG	72 (30.5)
Valve	113 (47.9)
CABG+Valve	34 (14.4)
Other1	17 (7.2)
Off-pump CABG	21 (8.9)
Left IMA	53 (22.4)
Both IMA	17 (7.2)
EUROscore add, median (range)	5 (1-6)
EUROscore log, median (range)	4.8 (1-7.74)
Mechanical ventilation, d, median (range)	7 (2-912)
ICU stay, d, median (range)	1 (1-24)
RBC transfusions, n, median (range)	2 (0-9)

Table 2 Pharmacokinetic comparison between patients with at least 1 serum sample with a vancomycin concentration <10 mg/L (in the left column) and patients without serum samples with a vancomycin concentration <10 mg/L (in the right column)

	Vancomycin levels < 10 mg/L (n = 114)	Vancomycin levels ≥ 10 mg/L (n = 122)	P-value
Cmax (mg/L)	33.2 (6.2-122.0)	57.9 (14.6-210.0)	<0.001
AUC (mg*h/L)	119.2 (28.3-247.7)	191.7 (95.8-467.8)	<0.001
t1/2 (h)	3.9 (1.6-9.2)	4.0 (1.3-9.8)	0.437
CL (L/h)	8.4 (4.0-35.3)	5.2 (2.1-10.4)	<0.001
Vd (L)	47.2 (16.5-195.2)	29.8 (12.4-63.3)	<0.001

AUC: Area under the curve; CL: Total body clearance; C_max: Maximum concentration; t_½: Elimination half-life; V_d: Volume of distribution.

Table 3 Risk factors for vancomycin levels under 10 mg/L - univariate binary logistic model

	OR	95%CI	P-value
CPB (off-pump vs on-pump)	0.51	0.20-1.30	0.156
Vancomycin infusion (stopped vs non-stopped)	0.6	0.17-2.10	0.421
Age at surgery (> 70 yr vs ≤ 70 yr)	0.54	0.32-0.92	0.021
Gender (Female vs male)	0.44	0.26-0.76	0.003
BMI (> 25 vs ≤ 25)	2.3	1.36-3.88	0.002
Fluid balance (> 2000 mL vs ≤ 2000 mL)	1.44	0.86-2.41	0.163
CrCl (> 70 mL/min vs ≤ 70 mL/min)	2.56	1.51-4.34	<0.001
Vancomycin dosage (> 15 mg/kg vs ≤ 15 mg/kg)	0.38	0.21-0.66	0.001
Vancomycin infusion duration			0.237
50-59 min vs < 50 min	0.5	0.21-1.21	0.123
60 min vs < 50 min	0.63	0.28-1.42	0.26
61-70 min vs < 50 min	0.48	0.14-1.69	0.254
> 70 min vs < 50 min	1.2	0.44-3.31	0.719

BMI: Body mass index; CPB: Cardiopulmonary bypass; CrCl: Creatinine clearance.

Table 4 Risk factors for vancomycin levels under 10 mg/L - multivariate binary logistic model

	OR	95%CI	P-value
Age at surgery (>70 yr vs ≤ 70 yr)	0.69	0.36-1.28	0.245
Gender (Female vs male)	0.54	0.30-0.97	0.039
BMI (> 25 vs ≤ 25)	1.99	1.15-3.45	0.015
CrCl (> 70 mL/min vs ≤ 70 mL/min)	1.92	1.09-3.40	0.024
Vancomycin dosage (>15 mg/kg vs ≤ 15 mg/kg)	0.75	0.36-1.57	0.451

BMI: Body mass index; CrCl: Creatinine clearance.