High protein intake during continuous hemodiafiltration: impact on amino acids and nitrogen balance.
OBJECTIVE
To study the effect of combined continuous veno-venous hemodiafiltration (CVVHDF) and high (2.5 g/kg/day) parenteral amino acid supplementation on nitrogen balance, amino acid losses and azotemic control in a cohort of patients with severe acute renal failure (ARF).


METHODS
We administered 2.5 grams/kg/day of amino acids intravenously to seven critically ill patients with ARF. We obtained paired blood and ultrafiltrate (UF) samples (n=20) and calculated amino acid clearances and losses, nitrogen balance, protein catabolic rate and total nitrogen losses.


RESULTS
The median total serum amino acid concentration was high at 5.2 mmol/L with particularly high concentrations of ornithine, lysine, and phenylalanine, but a low level of histidine. The median overall amino acid clearance was 18.6 ml/min (range: 12 to 29 ml/min). UF losses as percentage of administered dose were high for tyrosine (53.6%) but low for methionine (3.0%) and arginine (2.3%). A positive nitrogen balance was achieved in 7 (35%) of the 20 study days with an overall median nitrogen balance of -1.8 g/day. Urea levels were maintained at a median of 26.6 mmol/L.


CONCLUSIONS
High protein intake increases the serum concentrations of most amino acids. Such protein supplementation, when coupled with CVVHDF achieves a slightly negative overall nitrogen balance in extremely catabolic patients while still allowing adequate azotemic control.
Bellomo
R
R
Intensive Care Unit, Austin and Repatriation Medical Centre, Heidelberg, Victoria, Australia. rb@austin.unimelb.edu.au
Tan
H K
HK
Bhonagiri
S
S
Gopal
I
I
Seacombe
J
J
Daskalakis
M
M
Boyce
N
N
D058186:Acute Kidney Injury / Q000378:metabolism* / Q000628:therapy; D000328:Adult; D000368:Aged; D000596:Amino Acids / Q000008:administration & dosage* / Q000097:blood*; D004044:Dietary Proteins / Q000008:administration & dosage*; D004573:Electrolytes; D005260:Female; D005526:Food, Formulated; D005947:Glucose; D017583:Hemodiafiltration; D006801:Humans; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000378:metabolism*; D010288:Parenteral Nutrition; D057947:Parenteral Nutrition Solutions; D012996:Solutions
D000596:Amino Acids; D004044:Dietary Proteins; D004573:Electrolytes; D057947:Parenteral Nutrition Solutions; D012996:Solutions; C545824:amino-acid, glucose, and electrolyte solution; D005947:Glucose; D009584:Nitrogen