Factors associated with metabolic acidosis in patients receiving parenteral nutrition.

Aims: Metabolic acidosis is a common problem after infusion with chloride-based parenteral nutrition. However, it is unknown whether the occurrence of metabolic acidosis is related to this regimen of therapy or to patient-specific risk factors.

Methods: Patients receiving parenteral nutrition from July to December 2003 at this hospital were included for a retrospective study. Patients were excluded who had illnesses that were potentially related to acid-base disorders. The remaining patients were divided on the basis of parental nutrition they had received: a chloride-base regimen group, and an acetate-based therapy group. Biochemical character and blood gas data were analysed. Continuous variables were analysed by t-test. Categorical variables were assessed by chi-squared test. Independent determinants for bicarbonate decline were analysed using forward stepwise multiple linear regression analysis.

Results: There were 29 patients (17 women, 12 men) who received chloride-based regimen and 26 patients (16 women, 10 men) took acetate-based therapy. The acetate group had significantly higher baseline serum creatinine and blood urea nitrogen than chloride group. The blood pH, CO(2), bicarbonate and base excess were significantly lower after receiving chloride-based therapy; while these changes were not observed in acetate-based therapy group. However, the serum creatinine and blood urea nitrogen levels were not statistically different. With multiple-stepwise linear regression, parenteral nutrition formula and estimated creatinine clearance are independent predictors of bicarbonate decline.

Conclusion: The acetate-base regimen can decrease the occurrence of metabolic acidosis after parenteral nutrition. In addition, the risk of acidosis is higher in patients with impaired renal function.