Parenteral hyperalimentation. Metabolic problems and solutions

Hypophosphatemia and refeeding syndrome in the resumption of nutrition in critical care patients (review)

Refeeding syndrome is a life-threatening condition that occurs when nutrition is restarted in patients with initial malnutrition. For the first time refeeding syndrome was described more than 70 years ago but it still has not been studied enough. The pathophysiology of refeeding syndrome is based on severe electrolyte and metabolic disorders caused by the restoration of nutrition with an initial deficiency of phosphorus, potassium, magnesium which lead to organ failure. Hypophosphatemia is the main feature of the refeeding syndrome while in ICU patients there are many other causes of hypophosphatemia which complicates diagnostics. Most studies on refeeding syndrome have been conducted among patients with anorexia nervosa. In ICU refeeding hypophosphatemia occurs in about 34 % of cases but until recently all guidelines for the management of this condition have been extrapolated from the practice of treatment anorexia nervosa and were based on expert opinion. Several major studies have proven the effectiveness of a hypocaloric feeding during refeeding syndrome in critically ill patients recently. This review is devoted to the problem of refeeding syndrome in patients with anorexia nervosa and critical care patients, differential diagnostics and treatment approaches for this condition.

Parenteral Nutrition and Lipids

Lipids have multiple physiological roles that are biologically vital. Soybean oil lipid emulsions have been the mainstay of parenteral nutrition lipid formulations for decades in North America. Utilizing intravenous lipid emulsions in parenteral nutrition has minimized the dependence on dextrose as a major source of nonprotein calories and prevents the clinical consequences of essential fatty acid deficiency. Emerging literature has indicated that there are benefits to utilizing alternative lipids such as olive/soy-based formulations, and combination lipids such as soy/MCT/olive/fish oil, compared with soybean based lipids, as they have less inflammatory properties, are immune modulating, have higher antioxidant content, decrease risk of cholestasis, and improve clinical outcomes in certain subgroups of patients. The objective of this article is to review the history of IVLE, their composition, the different generations of widely available IVLE, the variables to consider when selecting lipids, and the complications of IVLE and how to minimize them.

Liver Enzyme Elevation associated with Total Parenteral Nutrition

A number of complications associated with total parenteral nutrition (TPN) have been identified, and methods of prevention or treatment have been developed. However, abnormal liver function continues to occur with the use of TPN, and little is known about its incidence and etiology.

Twenty-three patients, receiving TPN through the TPN program at Holy Cross Hospital from January, 1978 to May, 1978, were studied. All patients received a basic parenteral amino acid solution (Travasol®), with varying amounts of nitrogen per day, depending on nitrogen balance studies. Dextrose was supplied in quantities necessary to provide 120 percent or more of the patient's calculated basal energy expenditure (BEE). Of the 23 patients studied, elevated liver function test values were detected in two patients (8.6 percent). In both cases, the complication developed within six to eight days, and both had received calories in excess of 213 percent of their calculated BEE and had a calorie to nitrogen (kcal: N) ratio greater than 150: 1.

Mean calories as a percent of calculated BEE and kcal: N ratio were significantly higher in the patients with elevated liver function test (LFT) values than in those with normal LFT values ( p < 0.05 and p < 0.005, respectively). Following identification of the elevated LFT values, both patients were immediately placed on cyclic TPN (CyTPN). In the one patient, liver enzymes reverted toward normal after seven days of CyTPN, while the second patient required only five days. Cyclic TPN was deemed effective in the reversal of abnormal liver function in these two patients. It is speculated that the abnormal liver function was a result of fatty liver infiltration. The mechanism by which this infiltration occurs and its treatment are discussed.

Management of prolonged post-operative ileus: evidence-based recommendations

BACKGROUND

Prolonged post-operative ileus (PPOI) occurs in up to 25% of patients following major elective abdominal surgery. It is associated with a higher risk of developing post-operative complications, prolongs hospital stay and confers a significant financial load on health-care institutions. Literature outlining best-practice management strategies for PPOI is nebulous. The aim of this text was to review the literature and provide concise evidence-based recommendations for its management.

METHODS

A literature search through the Ovid MEDLINE, EMBASE, Google Scholar and Cochrane databases was performed from inception to July 2012 using a combination of keywords and MeSH terms. Review of the literature was followed by synthesis of concise recommendations for management accompanied by Strength of Recommendation Taxonomy (either A, B or C).

RESULTS

Recommendations for management include regular evaluation and correction of electrolytes (B); review of analgesic prescription with weaning of narcotics and substitution with regular paracetamol, regular non-steroidal anti-inflammatory drugs if not contraindicated, and regular or as-required Tramadol (A); nasogastric decompression for those with nausea or vomiting as prominent features (C); isotonic dextrose-saline crystalloid maintenance fluids administered within a restrictive regimen (B); balanced isotonic crystalloid replacement fluids containing supplemental potassium, in equivalent volume to losses (C); regular ambulation (C); parenteral nutrition if unable to tolerate an adequate oral intake for more than 7 days post-operatively (A) and exclusion of precipitating pathology or alternate diagnoses if clinically suspected (C).

CONCLUSIONS

Recommendations have a variable and frequently inconsistent evidence base. Further research is required to validate many of the outlined recommendations and to investigate novel interventions that may be used to shorten duration of PPOI.

Appropriate protein provision in critical illness: a systematic and narrative review

BACKGROUND

Widely varying recommendations have been published with regard to the appropriate amount of protein or amino acids to provide in critical illness.

OBJECTIVE

We carried out a systematic review of clinical trials that compared the metabolic or clinical effects of different protein intakes in adult critical illness and comprehensively reviewed all of the available evidence pertinent to the safe upper limit of protein provision in this setting.

DESIGN

MEDLINE was searched for clinical trials published in English between 1948 and 2012 that provided original data comparing the effects of different levels of protein intake on clinically relevant outcomes and evidence pertinent to the safe upper limit of protein provision to critically ill adults.

RESULTS

The limited amount and poor quality of the evidence preclude conclusions or clinical recommendations but strongly suggest that 2.0-2.5 g protein substrate · kg normal body weight⁻¹ · d⁻¹ is safe and could be optimum for most critically ill patients. At the present time, most critically ill adults receive less than half of the most common current recommendation, 1.5 g protein · kg⁻¹ · d⁻¹, for the first week or longer of their stay in an intensive care unit.

CONCLUSION

There is an urgent need for well-designed clinical trials to identify the appropriate level of protein provision in critical illness.

Lipid emulsions in parenteral nutrition of intensive care patients: current thinking and future directions

Background

Energy deficit is a common and serious problem in intensive care units and is associated with increased rates of complications, length of stay, and mortality. Parenteral nutrition (PN), either alone or in combination with enteral nutrition, can improve nutrient delivery to critically ill patients. Lipids provide a key source of calories within PN formulations, preventing or correcting energy deficits and improving outcomes.

Discussion

In this article, we review the role of parenteral lipid emulsions (LEs) in the management of critically ill patients and highlight important biologic activities associated with lipids. Soybean-oil-based LEs with high contents of polyunsaturated fatty acids (PUFA) were the first widely used formulations in the intensive care setting. However, they may be associated with increased rates of infection and lipid peroxidation, which can exacerbate oxidative stress. More recently developed parenteral LEs employ partial substitution of soybean oil with oils providing medium-chain triglycerides, ω-9 monounsaturated fatty acids or ω-3 PUFA. Many of these LEs have demonstrated reduced effects on oxidative stress, immune responses, and inflammation. However, the effects of these LEs on clinical outcomes have not been extensively evaluated.

Conclusions

Ongoing research using adequately designed and well-controlled studies that characterize the biologic properties of LEs should assist clinicians in selecting LEs within the critical care setting. Prescription of PN containing LEs should be based on available clinical data, while considering the individual patient’s physiologic profile and therapeutic requirements.

Pediatric parenteral nutrition: putting the microscope on macronutrients and micronutrients

Parenteral nutrition can be a life-saving therapy, but its benefits need to be balanced with a unique set of risks and complications. Methods of practice vary because there is a dearth of research in the area of pediatric parenteral nutrition. This article reviews the available literature on parenteral nutrition in children and provides suggestions on prevention and management of parenteral nutrition-associated liver disease. Some of the issues discussed in this article include glucose infusion rates, cycling of parenteral nutrition, copper and manganese toxicity, and the provision of glutamine, selenium, and carnitine.

Current practices in the delivery of parenteral nutrition in Australia

OBJECTIVE

To determine current practice in the delivery of parenteral nutrition (PN) in Australian hospitals.

DESIGN

A cross-sectional mail survey.

SETTING

Acute-care adult hospitals with greater than 200 beds in Australia.

SUBJECTS

A total of 67 hospitals (65.7% response rate).

INTERVENTION

Surveys were posted to hospitals. A reminder letter with a second copy of the survey was posted 3 weeks later to non-respondents.

RESULTS

Twenty-seven (40.3%) of the hospitals have a PN team and 50 (74.6%) have a hospital protocol for PN delivery. An inaccessible or non-functional gastrointestinal tract is the most common indicator for commencing PN. Fat infusion is calculated by 24 (38.7%) respondents with a mean (s.d.) maximum amount of fat provided of 2.0 (0.7) g/kg/day. Over half (n=35) reported calculating carbohydrate infusion at a maximum amount of 5.4 (1.0) mg/kg/min. Two-thirds (n=41) reported commencing PN at a rate of 50% or less of goal rate. Blood glucose levels (BGL) were monitored at least once per day by the majority of respondents (n=56, 83.6%). Insulin infusion was commenced at varying BGL. Most respondents (n=40, 59.7%) reported ceasing PN when at least half of the patient's requirements are being met either orally or enterally. A number of practice guidelines were identified and the results of the survey were compared with these guidelines.

CONCLUSIONS

Where there are clear practice guidelines, current practice appears to be in line with these recommendations, however, where evidence is lacking, practice is varied.

Evaluation of the outcomes of short bowel syndrome and indications for intestinal transplantation

Long-term parenteral nutrition (PN) and intestinal transplantation (IT) are life-saving therapies for patients with short bowel syndrome (SBS). However, indications and timing of these therapies are controversial. In this study we aimed to evaluate the indications for IT. Forty-two patients, each with <100 cm of small bowel, were divided into three groups according to the length of remnant: group I patients (n = 18): colon plus 50 to 100 cm of small bowel (SB); group II patients (n = 14): colon plus <50 cm of SB; and group III patients (n = 10): <50 cm of SB without colon. One-year mortality rates for groups I, II, and III were 50%, 72%, and 100%, respectively. All group I survivors developed intestinal adaptation, returning to regular oral feedings at 1 year. Interestingly, three of four surviving patients in group II developed adaptation and were fed an oral short bowel diet (SBD) at 1 year. None of the group III patients survived >1 year, dying due to multiorgan failure in the early postoperative period or from sepsis within 1 year. We conclude that patients with a very short bowel are candidates for IT when stable. If the colon is intact, however, regardless of small bowel remnant length, the patient should be given a chance to develop intestinal adaptation before making the decision for permanent PN or IT.

Parenteral nutrition-associated liver complications in children

Parenteral nutrition is a life-saving therapy for patients with intestinal failure. It may be associated with transient elevations of liver enzyme concentrations, which return to normal after parenteral nutrition is discontinued. Prolonged parenteral nutrition is associated with complications affecting the hepatobiliary system, such as cholelithiasis, cholestasis, and steatosis. The most common of these is parenteral nutrition-associated cholestasis (PNAC), which may occur in children and may progress to liver failure. The pathophysiology of PNAC is poorly understood, and the etiology is multifactorial. Risk factors include prematurity, long duration of parenteral nutrition, sepsis, lack of bowel motility, and short bowel syndrome. Possible etiologies include excessive caloric administration, parenteral nutrition components, and nutritional deficiencies. Several measures can be undertaken to prevent PNAC, such as avoiding overfeeding, providing a balanced source of energy, weaning parenteral nutrition, starting enteral feeding, and avoiding sepsis.

The Effect of Abrupt Cessation of Total Parenteral Nutrition on Serum Glucose: A Randomized Trial

The common clinical practice of gradually tapering total parenteral nutrition (TPN) to prevent hypoglycemia may be unnecessary. This randomized prospective study assessed the blood glucose profiles of patients whose TPN was abruptly discontinued in comparison with those whose TPN was gradually tapered to determine whether abrupt cessation can be performed safely. Patients were randomized into the abrupt cessation or the tapered protocol. A symptomatic hypoglycemic questionnaire was administered at regular intervals. Fingerstick glucose sampling was performed at 30-minute intervals and compared prospectively. From October 1996 through July 1997, 21 patients receiving TPN consented to participate in this study. Inclusion criteria included 1) duration of TPN infusion >24 hours, 2) age >18 years, and 3) establishment of enteral feeding at the time of TPN discontinuation. Patients had a baseline blood glucose level followed by repeat glucose measurements at 30-minute intervals until 90 minutes after TPN was completely discontinued in the tapered group and 120 minutes after cessation in the abrupt group. The rate of TPN tapering was in 25 per cent increments over 90-minute intervals. Ten patients were randomized into the tapered group and 11 patients in the abrupt group. None of the patients developed symptomatic hypoglycemia. There was no difference between the lowest blood glucose in the abrupt group in comparison with that of the tapered group (108.6 ± 11.5 vs 108.2 ± 9.8 respectively; P = 0.98). No patient had a significant change in hypoglycemia questionnaire score. There was no significant difference in age, duration of TPN, steroid use, or enteral caloric intake between the two groups. We conclude that there was no symptomatic hypoglycemia, and glucose profiles returned to a similar baseline level in those whose TPN was abruptly stopped when compared with those in the tapered group. These data demonstrate that patients receiving TPN can have parenteral nutrition abruptly stopped without the development of significant hypoglycemia.

Science, specialization, and the American Surgical Association

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The effect of changing the total parenteral nutrition order form on resident physician ordering behavior

The quality assurance process at Scott and White Hospital, Temple, Texas, identified a marked variation in total parenteral nutrition (TPN) prescriptions compared with recommendations by the Nutrition Support Service (NSS). A TPN order form with additive guidelines was designed to assist physicians in ordering TPN specific to patient needs. The effect of the change was assessed by comparing 50 TPN patients using the old form (1990) with 50 patients for whom the new form (1992) was used. The groups demonstrated no difference in demographics, mortality, length of stay, or biochemical parameters and were reflective of all TPN patients treated (1990, n = 280; 1992, n = 392). A significant decrease was noted in overfeeding of kilocalories when resident orders were compared with NSS recommendations (125% +/- 24% versus 110% +/- 29%, p = .017; and amino acids (120% +/- 32% versus 105% +/- 29%, p = .071, mean +/- SD). This resulted in a decrease of 8% in the cost of delivering a patient-day of TPN. We conclude that changing the TPN order form to a teaching vehicle results in decreased overfeeding and costs.

Factors influencing nurses' handling and control of peripheral intravenous lines--an interview study

The purpose of the study was to describe how nurses (n = 37) planned, took care of, and documented peripheral intravenous (vein) cannulae (PIV) and what controls their way of action. Knowledge, experience, and routine were said to govern the care and handling of PIV. The nurses' intention was that a PIV should be inserted for 1-3 days, but all of them were aware of PIV being inserted considerably longer, the reasons being forgetfulness, carelessness, mistake, no one to take responsibility, bad routines and stress. Patients who had received drugs or solutions daily were given less information and furthermore the same PIV-entry was used for drugs, solutions and blood. Only one nurse documented the insertion and the removal of a PIV. The nurses' personal comments were that the area was neglected and there were great variations in the care and handling of PIV. Their task is to systematically identify the patients' needs and risk factors, and to analyse, diagnose, plan, implement and evaluate the care given. Using a standardised guide could be a way to reduce the frequency of complications in the daily care of PIV.

Abrupt discontinuation of cycled parenteral nutrition is safe

PURPOSE

Abrupt discontinuation of total parenteral nutrition (TPN) has been recommended but is not widely practiced because of fear of hypoglycemia.

METHODS

To determine whether hormonal counterregulatory mechanisms prevent hypoglycemia, we studied 12 patients (10 with inflammatory bowel disease, of which 6 received dexamethasone) after both abrupt and tapered discontinuation of 3:1 TPN solution in a clinical research facility. Venous blood was drawn before reduction of TPN rate in the tapered group or 15 minutes before and at abrupt discontinuation in the abrupt group and every 15 minutes for 1.5 hours.

RESULTS

Glucose decreased from 152 +/- 56 (baseline) to 100 +/- 22 mg/dl 90 minutes after gradual discontinuation of TPN, compared with 135 +/- 45 to 96 +/- 15 mg/dl at 90 minutes after abrupt discontinuation, with no significant differences in mean glucose values. Mean epinephrine, norepinephrine, insulin, glucagon, growth hormone, cortisol, symptom score, and vital signs were not statistically different between the two groups.

DISCUSSION

Hypoglycemia does not occur after abrupt discontinuation of TPN. The same changes in counterregulatory hormones were seen whether discontinuation was tapered or abrupt. In stable patients, TPN solutions can be abruptly discontinued.

Long-term intravenous therapy with use of peripherally inserted silicone-elastomer catheters in orthopaedic patients

We studied the results of prolonged intravenous therapy with antibiotics through a central venous silicone-elastomer catheter that had been peripherally inserted in thirty-five orthopaedic patients. The catheters remained in place for an average of twenty-nine days (range, five to seventy-four days). The 20-gauge (one-millimeter-diameter) catheters used in our study were smaller in diameter than the triple-lumen catheters or the double-lumen Hickman catheters used in previous studies. The catheters in our study were left indwelling for as long as, or for longer than, those in other studies. Our patients had no serious complications related to the insertion or use of the catheter. However, three (8 per cent) of thirty-eight inserted catheters failed mechanically and had to be removed. Two additional catheters (5 per cent) were removed because the lumen became plugged. One catheter in each of these groups was not replaced, because a catheter was no longer necessary. We believe that the problems with the catheters were related to the small diameter of the tubing that was used in our series. Use of the small-diameter catheter reduces the risk of cardiac tamponade and other complications associated with catheters that have larger diameters, and small-diameter catheters can remain indwelling for a long time. The peripheral route of insertion eliminates the risk of pneumothorax associated with the subclavian route of placement and allows for greater ease of insertion. In addition, the use of catheters made of silicone elastomer reduces the risk of thrombosis and infection, which are associated with catheters made of polyethylene.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug- and nutrition-induced hypophosphatemia: mechanisms and relevance in the critically ill

OBJECTIVE

To provide an outline of the drugs and nutritional therapy that could contribute to the development of hypophosphatemia in the critically ill patient.

DATA SOURCES

Computerized abstracting services, references to primary literature articles, and review publications were screened for references to drug- or nutrition-related hypophosphatemia.

STUDY SELECTION

Studies primarily describing responses in adults were selected. Animal research is described that illustrates findings in humans.

DATA EXTRACTION

Information was abstracted from the findings of individual case reports and clinical trials.

DATA SYNTHESIS

Data are organized by mechanism of possible effect on serum phosphate concentration. No reference is made to drugs that do not have an effect on phosphate metabolism.

CONCLUSIONS

Hypophosphatemia can have significant effects that would hinder recovery of the critically ill patient. Antacids, catecholamines, beta-adrenergic agonists, sodium bicarbonate, and acetazolamide are commonly used therapeutic agents that could contribute significantly to the development of hypophosphatemia. Provision of nutrition to the chronically malnourished individual or chronic administration of phosphate-depleted parenteral nutrition could produce symptoms associated with hypophosphatemia. Other drugs could have a mild effect on lowering serum phosphate concentrations, but would be unlikely to produce symptoms unless combined with other etiologies of hypophosphatemia.

Glucose response to abrupt initiation and discontinuation of total parenteral nutrition

Plasma glucose was studied during the initiation of total parenteral nutrition (TPN) and the discontinuation of TPN without a tapering schedule. Blood was sampled every 5 minutes for 2 hours after the start of TPN and 1 week later as TPN was discontinued. A total of 14 initiations and 14 discontinuations were studied in 18 patients. Severity of illness in patients ranged from stable condition postoperatively to multiple-system failure; six patients had diabetes mellitus. The TPN solution was a 3:1 admixture that provided a caloric intake equal to 1.2 times the resting energy expenditure, with 40% fat and 60% carbohydrate calories. An average of 1963 kcal was provided per day (340 g of glucose, 79 g of fat). During the initiation phase, the mean increase in plasma glucose was 60 mg/dL. The increase for diabetic patients was 79 +/- 14 mg/dL compared with 52 +/- 23 mg/dL for the nondiabetics. During the discontinuation phase, the mean plasma glucose decreased 40 +/- 20 mg/dL; two patients with high concentrations of regular insulin (50 and 100 units) showed an increase in plasma glucose when the TPN was stopped. Plasma glucose returned to the preinfusion baseline after discontinuation. During both initiation and discontinuation, plasma glucose showed little change after the first 60 minutes. No clinical symptoms of hypoglycemia were observed. In conclusion, TPN as a 3:1 admixture can be safely started as full nutrition support and stopped abruptly without a tapering schedule. Plasma glucose response is rapid, predictable, and mostly complete within 60 minutes.

The all-in-one nutrient solution in parenteral nutrition

Dextrose, lipid emulsion, amino-acids, electrolytes, vitamins and trace elements were mixed in a well defined order to prepare 10 different total nutrient admixture solutions. The pH and osmolality of these solutions did not change significantly during 14 days of storage at 4 degrees C. Mean diameters of lipid particles on different occasions for the different solutions varied from 0.31 +/- 0.10 mum to 0.48 +/- 19 mum with 95% of particles less than 0.6 mum. Particles greater than 6 mum were not observed. Cultures were all negative. 243 patients received 5101 infusions of the admixture fluids. Patients on treatment for more than 1 week showed improved nitrogen balance. Serum transferrin and albumin were increased when treatment was ongoing for more than 2 weeks. No adverse reactions or abnormal laboratory findings were observed. One patient, with only duodenum and a part the colon left, has been maintained in good health for more than 55 months using this kind of nutritional support.

Zinc in clinical surgery--a research review

Among the essential trace elements in mammals, zinc is somewhat unique in that it is a constituent of numerous metallo-enzymes having biologic significance in many respects. The discovery of zinc deficiency in man induced the remarkable progress of studies on its physiology and it is now recognized that zinc deficiency manifests itself differently in different areas of clinical medicine. It also appears reasonable to say that no trace elements have been more closely related to surgery than zinc. We discuss herein, its significance, implications and role in such areas as; (1) wound healing: where the usefulness of zinc for promoting wound healing in the presence of low plasma zinc levels has been firmly established; (2) total parenteral nutrition (TPN); zinc free TPN may cause skin eruptions associated with abdominal symptoms presenting a picture closely resembling that of acrodermatitis enteropathica; (3) specific pathological conditions: patients with Crohn's disease and other benign diseases accompanied by mal-digestion or -absorbtion are often predisposed to zinc deficiency, similar to those manifesting clinical signs in the early stage of TPN; and (4) surgical stress: which triggers the release of various mediators, possibly increasing hepatic zinc deposition and decreasing plasma and skin zinc levels.

Increased gut permeability to fluorescein isothiocyanate-dextran after total parenteral nutrition in the rat

Sepsis with subsequent multiple organ failure is the commonest complication seen in the surgical intensive care unit today. A gut mucosal barrier dysfunction is assuming an increasingly important role as one possible explanation for the initiation of the septic process. It is known that the gut bacteria and endotoxins can, in the presence of a seemingly intact epithelium, translocate to extraintestinal sites, but the exact mechanism behind this process is not understood. In the present study we have approached this problem by testing the gut permeability to two macromolecules, bovine serum albumin (BSA) and fluorescein isothiocyanate (FITC)-dextran, after 7 days of enteral or parenteral nutrition in the rat. The plasma values of FITC-dextran after 4 h of marker feeding showed a significant increase in gut permeability after parenteral but not after enteral nutrition as compared with the controls. The plasma values of BSA, however, did not show any significant change in any of the groups. Thus, parenteral nutrition, with the changes occurring in the gut mucosa, may be one of the etiologic co-factors behind a gut mucosal barrier dysfunction, eventually leading to absorption of noxious agents into the systemic circulation with subsequent multiple organ failure.

Nutritional support in the critical care setting (Part 1)

Over the past two decades nutritional support has rapidly become an integral part of the medical care of critically ill patients. As scientific evidence accumulates supporting the important role of underlying nutritional status in determining the eventual outcome of many illnesses, aggressive nutritional intervention has become commonplace in our medical and surgical ICUs. However, nutritional support, particularly parenteral alimentation, is expensive and associated with important morbidity and even mortality. Furthermore, definite evidence of its clinical efficacy under certain specific conditions is often lacking and in need of properly done prospective studies. This review summarizes the basic principles of nutrition as applied to the critically ill patient in the clinical setting. Special emphasis is on practical considerations regarding cost, efficacy (or lack thereof), and potential advantages, disadvantages, and risk of complications of each proposed approach.

Guillain-Barré syndrome due to hypophosphatemia following intravenous hyperalimentation

This case report documents the additive effects of pregnancy, hyperemesis, cholecystitis, and intravenous nutrition in causing profound hypophosphatemia. This led to severe reversible neurological sequelae for the mother and fetal demise. The etiology of hypophosphatemia and management are discussed.

Common complications in critically ill patients

Patients in intensive care units (ICUs) are subject to many complications connected with the advanced therapy required for their serious illnesses. Complications of ventilatory support include problems associated with short-term and long-term intubation, barotrauma, gastrointestinal tract bleeding, and weaning errors. Cardiac tachyarrhythmias can arise from a patient's intrinsic cardiac disease, as well as from drug therapy itself. Hemodynamic monitoring is crucial to careful patient management, but it is associated with technical complications during insertion such as pneumothorax, as well as interpretive errors such as those caused by positive end-inspiratory pressure. Acute renal failure can develop as a result both of therapy with drugs such as aminoglycosides and hypotension of many etiologies, as well as the use of contrast media. Nosocomial infection, which is a dreaded complication in ICU patients, usually arises from sources in the urinary tract, bloodstream, or lung. Complications frequently can arise if the interactions of drugs commonly used in the ICU are not recognized. Further, the ICU patient is subject to nutritional complications, acid base problems, and psychological disturbances. This monograph deals with the frequency, etiology, and prevention of these common ICU complications.

Problems of trace elements and vitamins during long-term total parenteral nutrition: a case report of idiopathic intestinal pseudo-obstruction

An 8-year-old girl with chronic idiopathic intestinal pseudo-obstruction (CIIP), who is the first case of CIIP in Japan, has been receiving total parenteral nutrition (TPN) for more than 6 years. During this time, she experienced deficiencies of copper, zinc, vitamin A, vitamin B12, folic acid, and biotin, and an excess of vitamin A; she exhibited a series of signs and symptoms due to these deficiencies and vitamin A overdosage. Nevertheless, careful monitoring of serum levels of trace elements and vitamins and appropriate therapy have almost solved these problems. She has achieved normal physical and mental development and goes to school, while receiving home parenteral nutrition with an ambulatory infusion system.

Phosphate balance and distribution during total parenteral nutrition: effect of calcium and phosphate additives

Hypophosphatemia is occasionally observed during total parenteral nutrition (TPN). The phenomenon was recognized since the introduction of TPN and was attributed to preexisting phosphate deficits and inadequate phosphate supplements. Because of the close relationship between phosphate and calcium metabolisms, we speculated that calcium additives may also influence phosphate balance and distribution during TPN. We tested this hypothesis in previously fasted animals receiving TPN with variable amounts of calcium and maintenance or no phosphate. Fasting resulted in considerable losses of phosphate in the urine. Refeeding (with TPN) after fasting produced hypophosphatemia but only in animals receiving calcium additives and no maintenance phosphate in the solution. Addition of moderate or large amounts of calcium decreased phosphate in the muscle in groups not receiving maintenance phosphate. There were no significant changes in bone phosphate. Increasing calcium intake was accompanied by significant and progressive reductions in urine phosphate in animals receiving maintenance phosphate, thus increasing net phosphate retention in those groups. In other respects, refeeding with TPN after fasting displayed features compatible with those of the phosphate depletion syndrome, including hypophosphatemia, hypophosphaturia, hypercalcemia, and hypercalciuria. The magnitude of change in these parameters seemed to be dependent upon the amount of calcium added and the availability of phosphate in the solution.

Complications of parenteral nutrition

All hospitalized patients except infants (a total of 1,647 patients) who received central venous TPN solutions at UCDMC from 1981 through 1985 were studied to determine the incidence of complications from the use of TPN. A complication was considered to have occurred if the patient experienced obvious morbidity, mortality, or both; an event known to be deleterious, despite a lack of demonstrable morbidity; or premature loss of the central venous catheter. Complications related to catheter placement occurred in 5.7 percent of patients, sepsis in 6.5 percent, mechanical complications in 9 percent, and metabolic complications in 7.7 percent. The incidence of induction of sepsis increased during 1984 to 1985 due to the introduction of multilumen central venous catheters. The most frequent catheter placement complications were hemorrhage and pneumothorax. Major venous thrombosis and nursing mishaps were the most common mechanical complications. Metabolic complications were infrequent and were generally not severe after adjustment of the protocol in late 1981. Four patients (0.2 percent) died from TPN-associated complications: a child on home TPN who underwent a catheter change and in whom hyperosmolar hyperglycemic coma developed, a patient with end-stage chronic obstructive pulmonary disease in whom tension pneumothorax occurred, a patient who died from complications of subclavian artery laceration, and a patient who died from Candida septicemia. Complications of TPN are frequent and may be severe. Quality assurance mechanisms for identification of these complications are necessary and should form the basis for the establishment of appropriate protocols.

Parenteral nourishment of patients undergoing surgical or traumatic stress

Severe surgical or other traumatic stress initiates an integrated central nervous system and metabolic response characterized by catabolism which selectively preserves vital organs, drawing on peripheral tissue proteins for required amino acids. When oral intake is prohibited adequate intravenous nutritional support hastens convalescence and may be life-saving. Intravenous nutrients routinely consist of amino acids for replacement of lost protein, a nonprotein calorie source--usually glucose, and vitamins and minerals. Lipid, infrequently used in routine surgery as part of the calorie source, supplies essential fatty acids and prevents side effects resulting with large amounts of intravenous glucose. Lipid has other benefits. Stress-induced hormones stimulate lipid catabolism. When lipid is used for part of the calorie requirement in intravenous feedings, the plasma insulin level is reduced and peripheral amino acids become available for synthesis of critically needed visceral proteins. Recent work has shown that the branched chain amino acids carnitine and some species of lipid added to intravenous nutrient formulations postoperatively affect the nitrogen retention and may hasten convalescence. Further work should be directed at understanding the unique biochemical changes occurring after injury, devising objective assay procedures to measure the severity of the response and improving intravenous formulations for the acutely ill surgical patient.

Post-operative substrate utilisation and gas exchange using two different TPN-systems: Glucose versus fat

Twenty patients were studied over the first 4 post-operative days following abdominal aortic surgery. Ten patients had 93% of their non-protein energy as glucose and insulin was given to keep blood glucose below 10 mmol/l. The other 10 patients had 80% of non-protein energy as fat (Intralipid). Amino acids corresponding to 12 g of nitrogen were given in both groups. Gas exchange, nitrogen balance, phosphate balance, vanillylmandelic acid (VMA) excretion, 1- and 3-methylhistidine in urine, acute phase proteins, immunoglobulins and albumin were followed. Substrate utilisation was calculated from indirect calorimetry data and nitrogen excretion. Metabolism in the early post-operative phase was found to adapt to the nutrition regimen given even though the composition was extreme either in fat or carbohydrate content. The glucose-insulin regimen had a better nitrogen sparing effect and based on the difference in 3-methylhistidine excretion it is suggested that mainly protein muscle benefitted from this. Regardless of the TPN-regimen given, those patients whose RQ deviated the most from the average in their group had the highest nitrogen excretion. The two groups showed no differences in plasma proteins and catecholamine excretion.

[Effect of exclusive enteral feeding with Enteronutril on serum lipids]

Ten patients aged between 18 and 73 years admitted to our intensive care unit were placed on exclusive artificial nutrition with Enteronutril receiving on average 2.855 +/- 496 kcal/day (715 +/- 125 g). This solution is poor in lipids (1.5%) and contains no linoleic acid (C18:2). Its effects on serum lipids were analysed after 5, 10 and 15 days of treatment. Total cholesterol (TC) and phospholipids (PL) showed no significant change. However, triglycerides (TG) rose on d15 and pre-beta-lipoproteins were significantly higher on d5. The latter rose further from d10 to d15. The C18:2 fraction of total lipids (TL) fell precipitously on d5 (-50%). Although C18:2 remained stable from d5 to d10, a new, slower decrease occurred from d10 to d15. This decrease was accompanied by a specific rise in oleic (C18:1) and palmitoleic (C16:1) acids. Palmitic (C16:0) and stearic (C18:0) acids were unaffected. Arachidonic acid (C20:4) remained within normal limits up to d15. Eicosatrienoic acid which was measurable on d0 presented no significant rise during the course of the study. The changes in C18:2 were inversely proportional to those of C18:1 or C16:1. This translated a lack of C18:2 relative to delta 9 desaturase (freed of the inhibition usually exerted by C18:2). These results showed that the body could maintain a sufficient level of linoleic acid to synthesize arachidonic acid by drawing on its C18:2 reserves from fatty tissue. Nevertheless, these reserves were progressively exhausted beyond d10, thereby causing a shortage of arachidonic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Energy replacement during parenteral nutrition in surgery, sepsis and cancer

For many years, the increased nutritional requirements of surgical, septic and cancer patients were identified, but no effective therapy existed for averting their negative calorie and nitrogen balance. Parenteral nutrition offered an answer in many of these situations. However, abnormalities in liver function, ventilatory load, hyperglycemia and a disturbed metabolic homeostasis showed that in excessive amounts, glucose can behave as a relatively toxic substance. For cases with increased energy expenditure, new alternatives had to be devised in order to avoid excessive glucose intakes. One obvious possibility in these cases was to refrain from offering more than the basal caloric needs, until the patient had passed the period of acute injury, or other measures had effectively controlled the sepsis or cancer. Other options included the partial substitution of glucose by lipids or amino acids. Preliminary information suggests that this approach could lead to better nutritional outcome and survival rates, but additional studies are required.

Parenteral nutrition complications in a voluntary hospital

A prospective study analyzing the complications in 307 patients who had specialized nutrition support administered by their private practitioners was performed and compared to other series in which a nutrition support service exclusively provided such care of patients. The mechanical complication rate of 4.6%, septic complication rate of 2.9%, and metabolic complication rate of 4.2% compared favorably with the reported literature. A new category of complications, the judgmental complication, is described and was 12.7% in the reported series. The Saint Barnabas Medical Center experience suggests that individual practitioners can satisfactorily administer intravenous specialized nutrition support if in fact an involved nutrition support service functions administratively and supportively in the background.