Journal of Parenteral and Enteral Nutrition

Fatty acids are an extraordinarily diverse set of molecules that serve as sources of fuel, key components of cell structure, and parent molecules for bioactive second messengers. The metabolism of fatty acids is part of a delicate homeostasis that is fundamental to normal functioning and the response to pathophysiologic insult. The growing body of evidence on nutrition demonstrates that we truly “are what we eat,” and the fatty acid content of our diets has far-reaching physiologic implications, many of which we are only beginning to understand. As the gap between basic science and patient care becomes increasingly narrow, clinicians should have a working knowledge of fatty acid biology. This tutorial provides an overview of fatty acid biology with the goal of increasing comfort in discussing how these heterogeneous molecules are classified and metabolized, in addition to how fatty acid content influences basic cellular processes.

This lecture reviews the current understanding of how insulin resistance, as a marker of the metabolic stress, is involved in recovery after major surgery. Insulin resistance develops as a graded response related to the magnitude of the operation. It lasts for weeks after medium-size surgery and affects all parts of body metabolism. Although hyperglycemia develops, muscle and fat uptake is reduced and other non-insulin-sensitive cells have an increase in glucose uptake as a result of the elevated glucose levels. Reduced glucose uptake and storage in muscle along with loss of lean body mass help explain reduced muscle function that will impair mobilization. The increased uptake of glucose in non-insulin-sensitive cells is involved in the development of several of the most common postoperative complications, including infections and cardiovascular problems. Many of the perioperative treatments in use are outdated, and modern care involves a multimodal approach with several treatments, such as preoperative carbohydrate treatment instead of overnight fasting, continuous epidural anesthesia for postoperative pain care, early feeding, and mobilization, all of which affect insulin by reducing the stress and enhancing recovery. Most of the previous mandatory catabolic responses to surgery can be avoided, resulting in substantially faster recovery and fewer complications. Methods to implement these modern treatments have been developed and used in Europe, resulting in improved care and shorter length of stay.

The American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) developed a Web-based registry for nutrition care launched in early 2011, initially focusing on the home parenteral nutrition (HPN) patient population. The purpose of Sustain is to collect information regarding the patients and populations who require HPN in the United States, measure outcomes associated with HPN, allow institutional benchmarking against the aggregate data, and publish the findings to improve the quality of care for patients receiving HPN. The registry is open to all sites (hospital and home based) who care for new or existing HPN patients. Preliminary data should be available in early 2012.

Background: In Canada, there are an estimated 400 home parenteral nutrition (HPN) patients. In 2006, a registry was created to gather patient outcome information. The aim of this study was to validate the registry and report on HPN patient outcomes. Methods: Several demographic, clinical parameters were collected. For the validation, paired t test and intraclass correlation coefficient (ICC) were used to assess agreement between repeat entries. For the outcome report, paired t test was used to assess changes, and survival analysis was performed using the Kaplan-Meier method. Results are expressed as mean ± SEM. Results: On validation, there was high correlation/agreement (P < .05) for most parameters except vascular access/line sepsis, liver disease (ultrasound, biopsy, diagnoses), and hospitalizations. For the outcome report, 96 patients had their data entered at 2.24 ± 0.11 years after baseline. Over the period, there was a significant reduction in PN calories (P = .001) and proteins (P < .001). There were no significant changes in nutrition parameters and laboratory results except for lower platelet counts (P = .028), lower plasma potassium (P = .030), and a trend toward an increase in bilirubin from 19.29 ± 4.65 to 29.06 ± 8.73 µmol/L (P = .071). The QOL decreased significantly over time (P < .001) and the survival on HPN was 17.67 ± 1.89 years. Conclusions: The registry is a valid tool to assess several clinical parameters. On follow-up, HPN patients maintain good nutrition status while PN is reduced but do have a reduced quality of life.

Background: Vitamin K supplementation improves bone health, and its absence might be associated with low bone mineral density (BMD). The authors aim to assess vitamin K supplementation practices in Canadian home parenteral nutrition (HPN) programs and their relationship with BMD. Methods: This is a cross-sectional study of 189 patients from the Canadian HPN registry. Results: All 189 patients studied received M.V.I.-12, which does not contain vitamin K. Of those, 41.3% were supplemented with 10 mg of intravenous vitamin K (VK+) weekly, whereas the others did not receive vitamin K except via lipid emulsion (VK−). Short bowel syndrome accounted for 69% of VK+ and 46% of VK− patients. On univariate analysis, VK+ patients had substantially lower body mass index (BMI) and received lower bisphosphonate infusion than did VK−patients. There were no statistically significant differences in HPN calcium or lipid content, liver function test results, age, sex, or reason for HPN between the 2 groups. Patients who were VK+ had higher lumbar spine T scores and hip T scores than did VK−patients. General linear modeling analysis, adjusted for BMI, age, PN magnesium, PN phosphate, PN calcium, and bisphosphonate as possible predictors of BMD, showed a trend toward better hip T scores (P = .063) for VK+ patients compared with VK− patients. Conclusion: In HPN patients supplemented with vitamin K, the trend toward a better hip BMD compared with no supplementation suggests a role for vitamin K in preserving BMD. This requires further study.

Background: This study compared overall bacterial and bloodstream infection rates in patients receiving premixed parenteral nutrition (PN) with vs without lipid emulsion. Methods: Data from hospitalized patients who were ≥18 years of age and receiving premixed PN between 2005 and 2007 were extracted from the Premier Perspective database. Data were categorized into 2 groups: patients who received premixed PN only and those receiving premixed PN with lipids. Multiple logistic regression was used to adjust for risk factors and potential confounders, reporting the probability of risk for an infection. Results: The group without lipids was observed to have lower rates of both overall bacterial infection (43.5% vs 53.5%) and bloodstream infection (14.5% vs 18.9%). However, after adjusting for baseline characteristics, there were no significant differences in overall risk of bacterial infections (51.4% vs 53.5%; odds ratio [OR] = 1.11; 95% confidence interval [CI], 0.96–1.27) or bloodstream infections (19.6% vs 19.2%; 0.97; 0.81–1.16). In a subset of patients in the intensive care unit for ≥3 days, lower overall bacterial infection rates (58.3% vs 67.3%) and bloodstream infection rates (31.0% vs 37.0%) were observed in the group without lipids. After adjustment, there were no significant differences in risk of overall bacterial infection (OR = 0.95; 95% CI, 0.75–1.22) or bloodstream infection (0.92; 0.71–1.19) between the 2 groups. Conclusions: When administered with premixed PN, lipid emulsion was not significantly associated with an increase in the risk of infectious morbidity when compared to omitting lipids from therapy.

Objectives: Essential fatty acids are important for growth, development, and physiologic function. α-Linolenic acid and linoleic acid are the precursors of docosahexaenoic and arachidonic acid, respectively, and have traditionally been considered the essential fatty acids. However, the authors hypothesized that docosahexaenoic acid and arachidonic acid can function as the essential fatty acids. Methods: Using a murine model of essential fatty acid deficiency and consequent hepatic steatosis, the authors provided mice with varying amounts of docosahexaenoic and arachidonic acids to determine whether exclusive supplementation of docosahexaenoic and arachidonic acids could prevent essential fatty acid deficiency and inhibit or attenuate hepatic steatosis. Results: Mice supplemented with docosahexaenoic and arachidonic acids at 2.1% or 4.2% of their calories for 19 days had normal liver histology and no biochemical evidence of essential fatty acid deficiency, which persisted when observed after 9 weeks. Conclusion: Supplementation of sufficient amounts of docosahexaenoic and arachidonic acids alone without α-linolenic and linoleic acids meets essential fatty acid requirements and prevents hepatic steatosis in a murine model.

Background: Soybean oil is rich in ω-6 fatty acids, which are associated with higher incidence and more severe cases of inflammatory bowel diseases. The authors evaluated whether partial replacement of soybean oil by medium-chain triglycerides (MCTs) or olive oil influenced the incidence and severity of experimental ulcerative colitis by using different parenteral lipid emulsions (LEs). Methods: Wistar rats (n = 40) were randomized to receive parenteral infusion of the following LE: 100% soybean oil (SO), 50% MCT mixed with 50% soybean oil (MCT/SO), 80% olive oil mixed with 20% soybean oil (OO/SO), or saline (CC). After 72 hours of infusion, acetic acid experimental colitis was induced. After 24 hours, colon histology and cytokine expression were analyzed. Results: SO was not significantly associated with overall tissue damage. MCT/SO was not associated with necrosis (P < .005), whereas OO/SO had higher frequencies of ulcer and necrosis (P < .005). SO was associated with increased expression of interferon-γ (P = .005) and OO/SO with increased interleukin (IL)–6 and decreased tumor necrosis factor–α expression (P < .05). MCT/SO appeared to decrease IL-1 (P < .05) and increase IL-4 (P < .001) expression. Conclusions: Parenteral SO with high concentration of ω-6 fatty acids was not associated with greater tissue damage in experimental colitis. SO partial replacement with MCT/SO decreased the frequency of histological necrosis and favorably modulated cytokine expression in the colon; however, replacement with OO/SO had unfavorable effects.

Background. Feeding difficulties and gastroesophageal reflux (GER) are common problems in neonates. The authors hypothesize that GER could be influenced by feeding mechanics by evaluating the effects of feeding volumes, feeding durations, feeding flow rates, and caloric density on the chemical composition and clearance of GER in dysphagic neonates. Methods: Symptomatic dysphagic neonates (n = 35) underwent evaluation for suspected GER using pH-impedance methods. Results: The proportions of acid and nonacid GER were different during the first, second, and third postprandial hours (P < .0001). Prolonged feeding duration was significantly associated with decreased total, nonacid GER and BCT (P < .03). Significant positive correlations (P < .05) were detected between feeding flow rate vs frequency of total, nonacid GER and BCT. Significant positive correlation (P = .002) was noted between feeding volume and BCT. BCT decreased with each hourly interval (analysis of variance [ANOVA] P < .05); however, ACT increased with each hourly interval (ANOVA P = .05). Comparison between BCT and ACT at each postprandial hour is remarkable for longer ACT during the second and third hours after the initiation of feed (P ≤ .001). No significant correlation was noted between the milk types (breast milk or formula) or caloric density with regard to the GER characteristics. Oral-fed infants had more GER events than gavage-fed infants. Conclusions: Prolonged feeding durations and slower flow rates are associated with decreased frequency of GER. Modification of feeding duration and flow rate can be a useful adjunct to ameliorate GER in dysphagic neonates.

Background: Home parenteral nutrition (PN) has improved the survival of children with intestinal failure. Important complications include catheter-related thrombosis, occlusion, and infection. This study evaluated the efficacy and safety of prophylactic anticoagulation in the prevention of these complications. Methods: Medical records were retrospectively reviewed of all children (0–18 years) with PN between January 1994 and March 2007 in 1 tertiary center. After introduction of prophylactic low molecular weight heparin or vitamin K antagonists in March 2007, all patients were prospectively followed until March 2010. Results: In sum, 14 patients did not receive prophylaxis; 13 switched from no prophylaxis to prophylaxis in March 2007; and 5 directly received prophylaxis. Median age of PN onset was 4 months (range, 0.1–202) in the nonprophylaxis group (n = 27) and 25 (range, 2–167) in the prophylaxis group (n = 18); 16 children received low molecular weight heparin and 2, vitamin K antagonists. Catheter-related thrombosis developed in 9 patients with no prophylaxis (33%) and 1 with prophylaxis (6%) (P = .034). Cumulative 5-year thrombosis-free survival was 48% and 93% in the nonprophylaxis and prophylaxis groups, respectively (P = .047). Per 1,000 PN days, the nonprophylaxis and prophylaxis groups had 2.6 and 0.1 occlusions (P = .04) and 4.6 and 2.1 infections (P = .06), respectively. Cumulative infection-free survival after 3 years was 19% and 46% in the nonprophylaxis and prophylaxis groups, respectively (P = .03). Bleeding complications did not occur. Conclusion: Thromboprophylaxis significantly decreased catheter-related thrombosis and occlusion in children with PN without complications.

The purpose of this study was to document vitamin D status in home parenteral nutrition (HPN) patients and determine if oral vitamin D supplementation has a substantial effect. Methods: A retrospective chart review of eligible adults enrolled in the Southern Alberta Home Parenteral Nutrition program (n = 15) for a minimum of 6 months was conducted. Serum measurements of 25OHD were recorded and patients were categorized by vitamin D status as follows: sufficient; insufficient; deficient with respective levels of 25OHD ≥75 nmol/L, 27.5–75 nmol/L, and ≤27.5 nmol/L; and mixed. Results: Five of 15 patients had insufficient vitamin D status throughout the study period; all had short bowel syndrome. Nine were in the mixed category; 1 was consistently sufficient, and no one was consistently deficient. Patient demographics were similar between the insufficient and mixed groups. There were no significant differences in health outcomes between the insufficient and mixed vitamin D status groups. The median (interquartile range) dose and duration of vitamin D3 supplementation for the insufficient group was 5000 IU/d (4,000–7,143) for 1,175 (1,145–1,578) total days compared to 3,000 IU/d (1,000–7,143) for 1,529 (111–1,980) days for the mixed group. Conclusions: Most patients receiving HPN had insufficient vitamin D status. When prescribed high doses of oral vitamin D, patients did not consistently achieve appropriate 25OHD levels. Alternate routes of vitamin D supplementation in patients receiving HPN should be considered. Large multicenter prospective studies are needed to best characterize the relationship between vitamin D dosing for HPN patients and vitamin D status.

Objectives: The objectives were to determine concentrations of calcium chloride (CaCl) and sodium phosphate (NaPhos) that can be safely added to TrophAmine-based parenteral nutrition (PN) and to measure aluminum (Al) concentrations in PN solutions containing CaCl and NaPhos vs those containing calcium gluconate (CaGlu) and potassium phosphate (KPhos). Methods: In study A, PN solutions containing varying amounts of TrophAmine, CaCl, and NaPhos were compounded and then evaluated visually for precipitation. In study B, Al concentrations were measured in PN solutions containing CaCl and NaPhos (S1), CaGlu and NaPhos (S2), or CaGlu and KPhos (S3). Results: Study A showed that a maximum phosphorus concentration of 15 mmol/L could be added to a solution containing 12.5 mmol/L of calcium without evidence of precipitation when the amino acid (AA) concentration reached ≥3 g/dL (3%). In study B, the mean (range) Al concentrations were S1 = 2.2 (1.9–2.4), S2 = 8.5 (7.8–9.3), and S3 = 11.7 (10.8–12.2) µmol/L (means of 6.0, 22.9, and 31.5 micrograms/dL, respectively). Conclusions: The data can provide a guide for compounding neonatal PN solutions containing TrophAmine, CaCl, and NaPhos. More studies are needed to determine the long-term effects of substituting CaCl for CaGlu in PN solutions for neonates. Substituting CaCl and NaPhos for CaGlu and KPhos significantly decreases Al concentrations in PN and potential Al exposure of neonatal patients.

Catheter-related bloodstream infection (CRBSI) is a common and life-threatening infectious complication of home parenteral nutrition (PN). CRBSI is associated with hospital admissions, morbidity, mortality, loss of venous access, and healthcare costs. Ethanol has bactericidal and fungicidal properties, making it an ideal locking solution for preventing CRBSI. The authors report 6 patients with a recurrence of CRBSI when ethanol lock (ETL) was withheld due to a national shortage. This is the first known report of the ramifications of a national ethanol shortage on redevelopment of CRBSI in home PN patients with a history of CRBSIs. This series further supports the existing literature showing that ETL is a viable therapy for the prevention of CRBSIs, warranting prospective research. The impact of an ethanol shortage due to a sole-source manufacturer supports the need for the Food and Drug Administration to regulate pharmaceutical products to avoid shortages.

Refeeding syndrome has been observed in patients receiving nutrition after a prolonged period of malnourishment and is characterized by multiple metabolic derangements. Besides hypophosphatemia and hypoglycemia, lipemia has been described in association with parenteral nutrition administration to the malnourished. The authors describe one anorexic patient who developed lipemia during oral refeeding, followed by a precipitous drop in hematocrit suggestive of fat overload syndrome.

Shang E, Geiger N, Sturm JW, Post S. Pump-assisted versus gravity-controlled enteral nutrition in long-term percutaneous endoscopic gastrostomy patients: a prospective controlled trial. JPEN J Parenter Enteral Nutr. 2003;27:216-219. (Original DOI: 10.1177/0148607103027003216)

Shang E, Geiger N, Sturm JW, and Post S. Pump-assisted enteral nutrition can prevent aspiration in bedridden percutaneous endoscopic gastrostomy patients. JPEN J Parenter Enteral Nutr. 2004;28:180-183. (Original DOI: 10.1177/0148607104028003180)

Shang E, Weiss C, Post S, Kaehler G. The Influence of early supplementation of parenteral nutrition on quality of life and body composition in patients with advanced cancer. JPEN J Parenter Enteral Nutr. 2006;30:222-230. (Original DOI: 10.1177/0148607106030003222)