The risk for bloodstream infections is associated with increased parenteral caloric intake in patients receiving parenteral nutrition

Abstract

Background: Patients receiving total parenteral nutrition (TPN) are at high risk for bloodstream infections (BSI). The notion that intravenous calories and glucose lead to hyperglycemia, which in turn contributes to BSI risk, is widely held but is unproven. We therefore sought to determine the role that hyperglycemia and parenteral calories play in the development of BSI in hospitalized patients receiving TPN.

Methods: Two hundred consecutive patients initiated on TPN between June 2004 and August 2005 were prospectively studied. Information was collected on patient age, sex, admission diagnosis, baseline laboratory values, intensive care unit (ICU) status and indication for TPN. Patients in the ICU were managed with strict glycemic control, whereas control on the general ward was more liberal. The maximum blood glucose level over each 8-hour period was recorded, as were parenteral daily intake, enteral daily intake and total daily caloric intake. The primary outcome measure was the incidence of BSI. Additional endpoints were ICU length of stay, hospital length of stay and mortality.

Results: A total of 78 patients (39%) developed at least one BSI, which were more common in ICU patients than in other hospitalized patients (60/122 patients versus 18/78 patients; P < 0.001). Maximum daily blood glucose concentrations were similar in patients with BSI and in patients without BSI (197 mg/dl versus 196 mg/dl, respectively). Patients with BSI received more calories parenterally than patients without BSI (36 kcal/kg/day versus 31 kcal/kg/day, P = 0.003). Increased maximum parenteral calories, increased average parenteral calories, and treatment in the ICU were strong risk factors for developing BSI. There was no difference in mortality between patients with and without BSI.

Conclusion: Increased parenteral caloric intake is an independent risk factor for BSI in patients receiving TPN. This association appears unrelated to hyperglycemia. Based upon our observations, we suggest that parenteral caloric intake be prescribed and adjusted judiciously with care taken to account for all intravenous caloric sources and to avoid even short periods of increased intake.

Figure 1

Organisms responsible for bloodstream infections. Staphylococci were responsible for approximately 50% of the bloodstream infections. Acinetobacter was the most common Gram-negative organism isolated.

Figure 2

Maximum daily parenteral calories. Maximum parenteral calories over 24 hours for patients with and without subsequent bloodstream infections (BSI). Horizontal line, median for each group. As seen, patients who developed BSI did receive approximately 5 kcal/kg more per day than patients without BSI.

Figure 3

Occurrence of bloodstream infections according to quartile of maximum daily parenteral caloric intake. Number of patients with and without bloodstream infections plotted on the y axis against the quartile of maximum parenteral caloric intake on the x axis. There is a progressive increase in the proportion of patients with bloodstream infections with increased caloric intake.

Figure 4

Maximum daily parenteral caloric intake versus body mass index. Maximum daily parenteral calories (kcal/kg adjusted body weight) plotted on the y axis against body mass index on the x axis. It is evident that patients with higher body mass index were no more likely to receive increased parenteral calories.