The required daily dietary protein intake (DPI) to preserve a positive nitrogen balance in peritoneal dialysis (PD) patients still uncertain
Nutritional status and protein intake in continuous peritoneal dialysis, general recommendations.
The required daily dietary protein
intake (DPI) to preserve a positive nitrogen balance in peritoneal dialysis
(PD) patients still uncertain. However, a minimum DPI of 1.2 g/kg per day is currently required. Despite this
recommended level, certain groups of patients may consume 0.9-1.0 g/kg/day with no apparent manifestations of malnutrition.
Despite the advent of many observational studies correlating the
risk of mortality with parameters of the nutritional status, there're no
published prospective randomized studies keeping doses of PD at constant level and
comparing the baseline care to a nutritional intervention were associated with a
better outcome. Consequently, the current recommendations relied primarily upon
indirect evidence and expert opinions.
v
Dietary instructions: at training period for PD,
patients may consume 1.2-1.3
g protein/kg/d.
v
NHANES nomograms can be applied to evaluate the
standardized body weight.
v
Utilizing these nomograms is crucial as every
patient may show different metabolic rate and body weight that may be clearly
different from normal subject in regard to age, sex, height, and body parameters.
v
Target protein consumption should not be
related to LBM, which’s recognized as the fat-free mass.
v
The measured LBM can be elevated in edematous subjects
and decreased in volume depleted ones, even with no alteration in the muscle
mass.
v
This’s in agreement with the recommendations of
the 2005 European Best Practice Guidelines for PD.
v
Diet instructions must be revised every quarter
or more frequent as clinically required.
Monitoring
Plasma levels of urea nitrogen, SCr, and
albumin should be monitored I a monthly bases. The target normal plasma albumin
level should be kept > 4.0 g/dL or 40 g/L. Dietary recommendations should be revised every
quarter or more frequently. With a generally stable patient, we can estimate
small solute clearance as per K/DOQI guidelines as
well as monitoring overnight (CAPD) or daytime (APD) drain volume, so that peritoneal
transport can be estimated.
Peritoneal membrane function parameters every
year (despite the K/DOQI guidelines only recommend these
parameters at baseline and with the presence of clinical indication). The total
cleared solutes is best attained from data of the 24-hour collection of
dialysate and urine. Dialysate as well as urine collection can provide
calculation of the PCR and Cr production. Function of the peritoneal membrane can
be recognize via the standard peritoneal equilibration testing (PET).
Patients with a lowered plasma albumin should be strictly monitored
for the presence of underlying malnutrition, especially if the albumin levels,
PCR, or LBM are deteriorating by time. It’s crucial in this setting to manage
any associated comorbid diseases that may be impeding any improvement in
nutritional status.
Furthermore, chronic inflammatory conditions should be excluded and
rapid peritoneal transporters should be also considered because of the
associated peritoneal albumin losses. If these conditions are absent, dialysis
doses can be augmented. The latter response can be mostly achieved by an increase
in the dwell volume (e.g., from 2 to 2.5 L) or by more frequent exchanges per
day. Of note under-dialysis states can
be gradually observed in patients losing their residual kidney function with
lost its contribution in clearing the uremic toxins.
An elevated BUN value may reflect a disturbed solute clearance via
the peritoneal membrane. The European
Best Practices Guidelines propose also the suggestion of monitoring the subjective
global assessment. Resistant malnutrition may also necessitates dietary
supplements despite the presence of adequate dialysis. In addition, oral protein feedings may be also
provided for patients with hypoalbuminemia (or other malnutrition
manifestations) but adequately provided dialysis. Furthermore, dialysate fluids
supplemented with amino acids instead of glucose as an osmotic agent can be
also provided. Current studies suggest that utilizing these fluids can lead to correction
of plasma albumin values and improving other biochemical parameters related to
the nutritional status.
N.B. This Blogger is created to declare the general nutritional recommendation in PD patients
REFERENCES
de
Mutsert R, Grootendorst DC, Axelsson J, et al. Excess mortality due to
interaction between protein-energy wasting, inflammation and cardiovascular
disease in chronic dialysis patients. Nephrol Dial Transplant 2008; 23:2957. -
Lindsay
RM, Nesrallah G, Suri R, et al. Is more frequent hemodialysis beneficial and
what is the evidence? Curr Opin Nephrol Hypertens 2004; 13:631.
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