Israel Medical Association Journal

Abstract

Parenteral nutrition (PN) must be initiated as soon as possible after delivery in very low birth weight (VLBW) preterm infants in order to prevent postnatal growth failure and improve neurodevelopmental outcome. When administered early, high levels of parenteral amino acids (AA) are well tolerated and prevent negative nitrogen balance. Although proteins are the driving force for growth, protein synthesis is energy demanding. Intravenous lipid emulsions (ILE) constitute a good energy source because of their high energy density and provide essential fatty acids (FA) along with their long-chain polyunsaturated fatty acid (LC-PUFA) derivatives necessary for central nervous system and retinal development. Early supply of ILE is not associated with increased morbidity. No significant differences were found between ILE based on soybean oil only and mixed ILE containing soybean oil in combination with other fat sources, except for a reduction in the incidence of sepsis with non-pure soybean ILE, and possibly less PN-associated liver disease with mixed ILE containing some fish oil. In preterm infants glucose homeostasis is still immature in the first days of life and abnormalities of glucose homeostasis are common. VLBW infants may not tolerate high levels of glucose infusion without hyperglycemia. Administering lower levels of glucose infusion as part of full early PN seems more successful than insulin at this stage. Postpartum there is a transition period when the water and electrolyte balance may be severely disturbed and should be closely monitored. Avoiding fluid overload is critical for preventing respiratory and other morbidities

Since the Surviving Sepsis Campaign Guideline (SSG) was published in 2004, critical care physicians can readily access the evidence and current recommendations regarding management of patients with severe sepsis and septic shock. However, several issues including a potential conflict of interest in developing the guidelines were disclosed. There have also been dramatic changes in the management of sepsis, supported by high levels of evidence. SSG[1] 2008 was developed to update the evidence using a new grading system. We reviewed select topics, routinely addressed by intensivists in the surgical intensive care unit, that have changed between SSG 2004 and SSG 2008: namely, glucose control, and administration of steroids, recombinant human activated protein C (rhAPC) and total parenteral nutrition.

Background: Enteral nutrition in the critically ill patient is often complicated by gastrointestinal intolerance, manifested by a large gastric residual volume. The frequency of GRV[1] assessment and the intolerant level above which feeding is stopped is controversial.

Objectives: To evaluate a novel approach to EN[2] by allowing high GRV and once-daily assessment that was correlated with the paracetamol absorption test.

Methods: We conducted a pilot prospective study in an 18 bed general intensive care unit. The study group comprised 52 consecutive critically ill mechanically ventilated patients. Enteral nutrition was started at full delivery rate. Once-daily assessment of GRV with three consecutively repeated threshold volumes of 500 ml was performed before stopping EN. The paracetamol absorption test was performed and correlated to GRV. Patients were divided into two groups: low GRV (< 500 ml), and high GRV (at least one measurement of GRV > 500 ml). Clinical outcome included maximal calories delivered, incidence of pneumonia, ICU[3] length of stay, and ICU and hospital mortality.

Results: There were 4 patients (9.5%) with ventilator-associated pneumonia in the low GRV group and 3 (30%) in the high GRV group (P = 0.12). GRV was inversely correlated to paracetamol absorption; however, neither GRV nor paracetamol absorption was associated with the development of pneumonia. Both groups had similar ICU length of stay (11.0 ± 8.2 vs. 13.8 ± 14.4 days, P = 0.41), and similar ICU (21% vs. 40%, P = 0.24) and hospital mortality (35% vs. 40%, P = 1.0).

Conclusions: In critically ill mechanically ventilated patients, allowing larger gastric residual volumes, measured once daily, enables enteral feeding with fewer interruptions which results in high calorie intake without significant complications or side effects.

Premature very low birth weight (< 1500 g) infants are one of the largest groups receiving parenteral nutrition. PN[1] should be optimized to answer their large nutritional requirements and suit their metabolic status, but should also be validated pharmaceutically. PN can be provided as a standard, usually commercial, formulation, representing the average needs of a large group of patients. Alternatively, an individualized PN compound adapted to the patient's needs can be prescribed and prepared, usually on a daily basis. The main advantage of individually prescribed PN is that it is tailored to suit a specific patient, thereby assuring the best possible nutrition and biochemical control. Batch-produced standardized PN bags can be readily available as ward stocks in neonatal intensive care units, enabling initiation of early PN immediately after the delivery of a premature infant. Moreover, standard PN solutions incorporate expert nutritional knowledge and support. A combination of standardized PN bags, prepared under strict standardization criteria, for most neonates, with a small number of specifically tailored individualized PN formulations for those in need for them, could reduce pharmacy workload and costs, and increase safety, while maintaining the desired clinical flexibility. For those in need of the individualized PN formulations, a computerized ordering system can save time, decrease prescription and compounding errors, and improve quality of nutritional care.

Background: Cholestasis is a frequent problem in patients on total parenteral nutrition. Cisapride has a prokinetic effect on the biliary system, but its effect on hepatic excretory function is unknown.

Objectives: To study the effect of cisapride on TPN-induced cholestasis in a rat model.

Methods: Bile flow and bile salt secretion rate were measured in rats given TPN. There were four groups of 8 to 13 animals each. After a one hour baseline period during which all four groups received i.v. saline infusion, two groups received a TPN solution for another 2 hours, while saline was infused in the two control groups.

At the beginning of the second hour, 2 mg/kg cisapride was injected i.v. as a bolus into one experimental and one control group. Bile was collected from the common bile duct.

Results: At the end of the third hour, TPN caused a significant reduction in bile flow (P<0.02) and bile salt secretion rate (P<0.001) (61.24 vs. 50.74 µl/min/kg, and 1.173 vs. 0.799 µmol/min/kg, respectively). Addition of cisapride abolished the cholestatic effect of TPN.

Conclusions: Cisapride has a protective effect against TPN-associated cholestasis. This may have clinical significance, and further studies are warranted.

________________________________

TPN= total parenteral nutrition