Nutrition in Clinical Practice

Vascular access has become a key component for a multitude of IV therapies, including parenteral nutrition. Access of the central venous system has been long recognized for its associated complications of infection, thrombosis, and occlusion. Over the past 25 years, clinical practice based on research and innovation has attempted to decrease complication rates and therefore improve the safety of vascular access. This article highlights the research and its influence on catheter care procedures, technology, and education that has led to advances in vascular access. An improved understanding of the pathophysiology associated with catheter-related complications and an ongoing evaluation of new treatment modalities has provided clinicians today with new options for improved patient care and the ability to preserve vascular access options for patients.

Background: Advances in percutaneous endoscopic gastrostomy (PEG) and laparoscopic (LAP) techniques now allow for less invasive placement of gastrostomy tubes. This study compared morbidities and feeding outcomes of these procedures with standard surgical (OPEN) insertion. Methods: Gastrostomy tubes placed in the operating room by the PEG, LAP, and OPEN methods were compared for insertion times, tube insertion and maintenance complications, enteral feeding complications, and feeding start days. Patients with concomitant intra-abdominal procedures were excluded. Patients were followed for 6 days after tube placement. Results: A total of 91 catheters (PEG = 23, LAP = 39, OPEN = 29) were inserted in the operating room for indications of ventilator-dependent respiratory failure (45), dysphagia (30), head and neck cancer (9), and decreased mental status (7). No patients were fed on the day of the procedure. Insertion times were significantly longer (p < .05) in the OPEN technique (68 minutes) vs LAP (48 minutes) and PEG (30 minutes). Insertion complications occurred in the LAP and PEG cohorts (3 failed LAP, 1 failed PEG), and maintenance complications were higher in the LAP group, including 1 episode each of cellulitis, bleeding, and serous drainage. Twenty enteral feeding complications in 17 patients occurred in all groups (9 in LAP vs 6 in PEG and 5 in OPEN), and included emesis (6), high residual (5), diarrhea (3), ileus (3), nausea (2), and pain after feeding (1). Overall complications were significantly lower in the PEG (7) and OPEN (5) groups compared with the LAP group (15). Feeding start day was significantly delayed in the OPEN technique (2.1 days vs 1.7 in PEG and 1.5 in LAP); however, no difference was found in days to goal among groups (4.4–4.8 days). Conclusions: PEG should be the procedure of choice for placement of gastrostomy tubes. If PEG is contraindicated, then OPEN technique may be best due to fewer complications, although insertion time is longer than the LAP technique.

The development of the percutaneous endoscopic gastrostomy (PEG) tube for enteral access was a revolutionary technological advance. This device has undergone some minor modification over the past 30 years but remains very similar to the original PEG tube design. Use of the PEG tube for gastric enteral feeding access continues to increase yearly both in pediatric and adult populations. One of the difficulties noted with PEG tube use in daily clinical practice is the ultimate degradation of the PEG tube wall material, leading to tube cracking, tearing, and leaking, requiring replacement of the gastrostomy tube. Historically, the predominant polymer material used for PEG tube composition was silicone. More recently, polyurethane has been examined as a potential, more durable material for PEG tube composition. Copolymers, or combinations of silicone and polyurethane and other polymer materials, are currently under investigation as the answer for the development of a bioinert, tissue-friendly, durable, PEG tube composition material.

The enteral route has become the standard of care to deliver nutrition support for hospitalized acute care and ambulatory care patients. The same access device is increasingly being used to deliver medications, which provides cost savings but also creates new challenges. Cost savings can be negated if the concomitant administration of nutrition elicits a decrease in bioavailability due to incompatibilities that alter drug or nutrition therapy. Feeding tubes can deliver nutrients and drugs to the stomach, small bowel, or both, with optimal efficacy of medications depending on delivery to the appropriate segment of the gastrointestinal tract. Liquid preparations are often the preferred formulation for enteral administration. Obstruction of the enteral access device may occur when specialized medication formulations are altered inappropriately. Occasionally, the enteral formula should be changed to modify the content of free water, fiber, electrolytes, or vitamins that may interfere with the drug therapy. Intolerance to enteral nutrition such as abdominal distention and diarrhea may be the result of the medication, and the causative agent should be identified to improve patient comfort. This article will address optimal drug delivery via enteral access devices and possible complications associated with therapy.

Refeeding syndrome describes a constellation of metabolic disturbances that occur as a result of reinstitution of nutrition to patients who are starved or severely malnourished. Patients can develop fluid and electrolyte disorders, especially hypophosphatemia, along with neurologic, pulmonary, cardiac, neuromuscular, and hematologic complications. We reviewed literature on refeeding syndrome and the associated electrolyte abnormalities, fluid disturbances, and associated complications. In addition to assessing scientific literature, we also considered clinical experience and judgment in developing recommendations for prevention and treatment of refeeding syndrome. The most important steps are to identify patients at risk for developing refeeding syndrome, institute nutrition support cautiously, and correct and supplement electrolyte and vitamin deficiencies to avoid refeeding syndrome. We provide suggestions for the prevention of refeeding syndrome and suggestions for treatment of electrolyte disturbances and complications in patients who develop refeeding syndrome, according to evidence in the literature, the pathophysiology of refeeding syndrome, and clinical experience and judgment.

d-Lactic acidosis, also referred to as d-lactate encephalopathy, is a rare neurologic syndrome that occurs in individuals with short bowel syndrome or following jejuno-ileal bypass surgery. Symptoms typically present after the ingestion of high-carbohydrate feedings. Neurologic symptoms include altered mental status, slurred speech, and ataxia, with patients often appearing drunk. Onset of neurologic symptoms is accompanied by metabolic acidosis and elevation of plasma d-lactate concentration. In these patients, malabsorbed carbohydrate is fermented by an abnormal bacterial flora in the colon, which produces excessive amounts of d-lactate. High amounts of d-lactate are absorbed into the circulation, resulting in an elevated concentration of d-lactate in the blood. Development of neurologic symptoms has been attributed to d-lactate, but it is unclear if this is the cause or whether other factors are responsible. This review examines the pathophysiology of the production and accumulation of d-lactate while exploring the potential factors contributing to the development of neurologic manifestations. Methods of diagnosis and treatment are reviewed. Areas requiring further investigation are identified.

Dehydration is a serious risk for the long-term tube-fed patient who is not allowed oral intake, has an altered mental status, is unable to communicate, is elderly or fluid-restricted, or has thirst impairment. The intent of this review is to provide a case-based discussion regarding the evaluation, treatment, and prevention of dehydration in these types of patients. Identification of risk factors, along with evaluation of subjective, objective, and laboratory parameters, provides the basis for clinical evaluation. “Hidden” sources of fluid intake such as the water content of solid foods and water generated from nutrient oxidation and“ hidden” sources of fluid output such as evaporative losses should be considered in waterbalance calculations. The method for treatment and prevention of dehydration depends on the presence or absence of hypovolemia, type of body fluid losses, and whether the patient demonstrates hypernatremia, normonatremia, or hyponatremia.

Postoperative nutrition support for patients undergoing pancreaticoduodenectomy (Whipple's procedure) may be complicated due to gastrointestinal tract dysfunction (gastroparesis, dumping, and malabsorption) subsequent to the procedure. Clinical management of these patients may be adversely affected by procedure-specific knowledge deficits (method of gastrointestinal [GI] reconstruction), common and expected surgical complications, and the available route for alimentation. It is the aim of this report to provide the reader with an overview of the procedure, common postoperative nutrition issues, and available interventions.

Background: Past studies document decreased levels of antioxidants and selenium and increased levels of oxidative stress in people living with HIV/acquired immunodeficiency syndrome (AIDS). Cigarette smoking is another source of oxidative stress. Excessive oxidative stress can induce HIV replication, resulting in disease progression. The purpose of this study was to determine whether subjects with HIV/AIDS who smoke cigarettes have increased oxidative stress and decreased antioxidant status compared with nonsmokers with HIV/AIDS. Methods: Thirty-one men with HIV/AIDS (adhering to highly active antiretroviral therapy for the previous 3 months) were recruited during regular visits to a Veterans Affairs Medical Center Infectious Disease Clinic in a southeastern US city. Plasma was obtained from a 1-time blood draw for this comparison study. Plasma lipid peroxide (LPO) was used as a marker of oxidative stress. Indicators of antioxidant capacity included plasma glutathione peroxidase (GPx, the functional indicator of selenium status), vitamin C, and antioxidant potential (AOP). Results: Fifteen smokers and 10 nonsmokers with HIV/AIDS were enrolled. Median plasma LPO level was above the normal range of 0–1.3μ mol/L in both nonsmokers (2.5 [0–23.4] μmol/L, median [range]) and smokers (4.0 [0–47.5] μmol/L), but there was no difference between groups. Plasma GPx concentration was significantly lower in smokers (169 [118–295] μmol/min/L) compared with nonsmokers (197 [149–414] μmol/min/L). Vitamin C and AOP levels were not different between groups. Conclusions: This pilot study suggests that effects of smoking on oxidative stress are not additive, as no striking differences were observed in oxidative stress or antioxidant capacity between clinically stable smoking and nonsmoking men with HIV/AIDS.

Background: The use of protease inhibitor (PI) –based highly active antiretroviral therapy (HAART) in patients infected with human immunodeficiency virus (HIV) has been linked to alterations in lipid profiles. Methods: Longitudinal cohort study. Lipid profiles were evaluated pre- and post-PI therapy in 49 HIV-infected patients. Diet was also evaluated to determine any contribution to alterations in lipid levels. Results: Pre- and post-PI-based HAART samples were examined from 42 men and 7 women, mean age 40.6 years. Mean CD4 count pre-PI was 242 ± 205 cells/mm³; HIV RNA was 4.2 log₁₀ copies/mL; body mass index (BMI) was 24.7 ± 3.6 kg/m²; body fat was 17.1± 9.1 kg by bioelectrical impedance analysis (BIA), dietary intake was 2654 ± 732 kcal/day. Post-PI samples were collected 5.7 ± 1.66 months after starting therapy. CD4 counts increased to 384 ± 323 cells/mm³ and RNA decreased 1 log post-PI. Post-PI BMI (25.2 kg/m2), percent body fat (17.4%) and caloric intake (2656 kcal/day) were unchanged. Pre-PI total cholesterol (TC) in men was 167.6 ± 42.4 mg/dL; TC increased (190.4 ± 47.9 mg/dL) post-PI (p < .0001). Pre-PI triglycerides (TG) were 154.5 ± 109.4 mg/dL; TG increased post-PI (266.1 ± 363.6 mg/dL, p < .03). Low-density lipoprotein (LDL) -C was 97.8 ± 31 mg/dL pre-PI and rose to 107.1± 34.7 mg/dL post-PI (p < .05). High density lipoproteins (HDLs) were below desired levels before initiation of PI therapy and remained low. Conclusions: PI therapy significantly alters lipid profiles in HIV-infected patients. Dietary intake did not contribute to changes in lipid profile. More longitudinal studies are needed to demonstrate whether these alterations contribute to additional cardiovascular risk.

Feeding intolerance is a common problem in infants who have had multiple or extensive resections of their small bowel. Chronic malabsorption and diarrhea are common side effects that inhibit the advancement of enteral feedings and prolong dependence on parenteral nutrition (PN). Poor growth, recurrent central line infections, cholestasis, and osteopenia are well-known complications associated with long-term PN dependency. It has been shown that, in adults with short bowel syndrome, providing dietary fiber can improve tolerance to enteral feeding. There are no published studies that have addressed the influence of dietary fiber on feeding intolerance in infants after bowel resections. The ensuing case studies illustrate the positive outcomes of fiber use in infants with diarrhea secondary to small bowel resections.