Amino acid loss and nitrogen balance in critically ill children with acuterenal failure: A prospective comparison between classic hemofiltration andhemofiltration with dialysis
Nj. Maxvold et al., Amino acid loss and nitrogen balance in critically ill children with acuterenal failure: A prospective comparison between classic hemofiltration andhemofiltration with dialysis, CRIT CARE M, 28(4), 2000, pp. 1161-1165
Hypothesis: Amino acid (AA) loss is not equivalent on continuous venovenous
hemofiltration (CVVH) compared with continuous venovenous hemodiafiltratio
n (CVVHD). Amino acid supplementation may be necessary to adjust for a grea
ter clearance on CVVH to maintain nitrogen balance similar to that of CVVHD
.
Objective: To compare AA losses and nitrogen balance between CVVH and CVVHD
in children with acute renal failure.
Setting: Pediatric patients in the pediatric intensive care unit of a terti
ary referral center.
Design: Prospective randomized crossover study in consecutive children who
required hemofiltration.
Patients: A total of 12 plasma clearance studies for AA and urea, consistin
g of 24-hr collections of ultrafiltrate and urine for nitrogen balance, was
performed on six patients during CVVH and CVVHD. Patients received total p
arenteral nutrition (TPN) with caloric intake 20% to 30% above their restin
g energy expenditure measured by indirect calorimetry and 1.5 g/kg/day prot
ein of TPN. Study conditions were comprised of 2 L/hr/1.73 m(2) of dialysat
e or prefiltered replacement fluid and hemofilter flow rates of 4 mL/kg/min
were maintained for all patients.
Methods and Main Results: Amino acid clearances were greater on CVVH than C
VVHD, except for glutamic acid, where clearance was 6.73 +/- 2.31 (SEM) mL/
min/1.73 m(2) on CVVH and 7.59 +/- 2.79 mL/min/1.73 m(2) for CVVHD (NS). Th
e clearance difference between the two modalities was 30%. Urea clearance w
as equivalent (30.1 +/- 1.74 mL/min/1.73 m(2) and 29.0 +/- .97 mL/min/1.73
m(2)) for CVVH and CVVHD, respectively. Amino acid loss on CVVH and CVVHD w
as similar (12.50 +/- 1.29 g/day/1.73 m(2) vs. 11.61 +/- 1.86 g/day/1.73 m(
2), respectively), representing 12% and 11%, respectively, of the daily pro
tein intake. The catabolic state, as measured by urea nitrogen appearance,
was high for all patients during the 48-hr study period with a mean of 291
mg/kg/day during CVVH, and 245 mg/kg/day for CVVHD. Nitrogen balance varied
from a negative 12.95 g/day/1.73 m(2) to a positive 4.93 g/day/1.73 m(2) o
n CVVH and a negative 7.69 g/day/1.73 m(2) to a positive 5.50 g/day/1.73 m(
2) on CVVHD.
Conclusions: Clearance of AA is greater on CVVH than on CVVHD, but no signi
ficant difference in AA loss was present between the two therapies. Nitroge
n balance often is not met on either therapy when a standard 1.5 g/kg/day p
rotein and a resting energy expenditure of 120% to 130% of calories is deli
vered by TPN.