Acute kidney injury following spinal instrumentation surgery in children

Table 1 Acute Kidney Injury Network criteria

Acute Kidney Injury Network criteria	Stage 1	Stage 2	Stage 3
Serum creatinine	1.5-1.9 times baseline or ≥ 0.3 mg/dL (≥ 26.5 μmol/L) increase	2.0-2.9 times baseline	3.0 times baseline or ≥ 4 mg/dL (353.6 μmol/L) increase or Need for RRT
Urine output	< 0.5 mL/kg per hour for ≥ 6-12 h	< 0.5 mL/kg per hour for ≥ 12 h	< 0.3 mL/kg per hour for ≥ 24 h or Anuria ≥ 12 h

Table 2 Baseline patient characteristics

Variables	AKI (n = 35)	Non-AKI (n = 36)	Total (n = 71)
Age (yr)	15.4 ± 1.75	14.4 ± 1.95	14.9 ± 1.90
Sex (male)	9 (26%)	6 (17%)	15 (21%)
Idiopathic scoliosis	24 (69%)	24 (67%)	48 (68%)
Weight (kg)	56.5 ± 16.0	45.2 ± 11.9	50.7 ± 15.1
Height (cm)	161 ± 9.8	155 ± 10.6	158 ± 10.6
BSA (kg/m2)	1.58 ± 0.27	1.38 ± 0.23	1.48 ± 0.27
Pre-op syst BP (mmHg)	116 ± 13.4	113 ± 9.8	114 ± 11.7
Pre-op diast BP (mmHg)	71 ± 11.1	71 ± 8.9	71 ± 9.9
Baseline creatinine (μmol/L)	49.9 ± 15.2	47.4 ± 13.1	48.7 ± 14.1
Baseline Hb (g/L)	138 ± 11.7	137 ± 13.1	137 ± 12.4

AKI: Acute kidney injury; Hb: Hemoglobin; BSA: Body surface area; BP: Blood pressure.

Table 3 Intra-operative/post-operative course

	AKI (n = 35)	Non-AKI (n = 36)	P value
Intra-operative course
Duration of surgery (h)	8.5 ± 2.4	8.2 ± 2.1	0.54
Cumulative intra-operative fluid administration (mL)	2555 ± 973	2732 ± 1264	0.51
Cumulative intra-operative fluid administration (mL/kg per hour )	6.2 ± 2.9	7.5 ± 3.3	0.08
Intra-operative urine output (mL/kg per hour )	1.9 ± 1.1	2.4 ± 1.5	0.17
Intra-operative fluid balance (L)	1.2 ± 1.0	1.3 ± 1.1	0.70
Max BP decline during surgery
Systolic (% from baseline)	27 ± 12	33 ± 14	0.36
Diastolic (% from baseline)	30 ± 9	34 ± 13	0.93
Patients requiring blood transfusion [n (%)]	7 (20%)	12 (33%)	0.21
Nephrotoxin exposure [n (%)]	8 (23%)	6 (17%)	0.51
Post-operative course
Duration of PICU stay (d)	1 (IQR 0, range 17)	1 (IQR 0, range 6)	0.77
Cumulative PICU fluid administration (mL)	2069 (IQR 886)	1918 (IQR 1048)	0.15
Cumulative PICU fluid administration (mL/kg per hour)	2.1 ± 0.8	2.3 ± 0.7	0.31
PICU urine output (mL/kg per hour)	0.7 ± 0.4	1.1 ± 0.4	< 0.001
PICU fluid balance (L)	1.3 ± 1.0	0.8 ± 0.8	0.02
Max Hb drop (% from baseline)	26 ± 9	26 ± 10	0.94
Nephrotoxin exposure in PICU	18 (51%)	4 (11%)	< 0.001

AKI: Acute kidney injury; PICU: Paediatric intensive care unit.