Assessing the efficacy of intravenous nutrition in general surgical patients: dynamic nutritional assessment with plasma proteins

Dynamic assessment of prealbumin for nutrition support effectiveness in critically ill patients

BACKGROUND & AIMS

Serum prealbumin is considered to be a sensitive predictor of clinical outcomes and a quality marker for nutrition support. However, its susceptibility to inflammation restricts its usage in critically ill patients according to current guidelines. We assessed the performance of the initial value of prealbumin and dynamic changes for predicting the ICU mortality and the effectiveness of nutrition support in critically ill patients.

METHODS

This monocentric study included patients admitted to the ICU between 2009 and 2016, having at least one initial prealbumin value available. Prospectively recorded data were extracted from the electronic ICU charts. We used both univariable and multivariable logistic regressions to estimate the performance of prealbumin for the prediction of ICU mortality. Additionally, the association between prealbumin dynamic changes and nutrition support was assessed via a multivariable linear mixed-effects model and multivariable linear regression. Performing subgroup analysis assisted in identifying patients for whom prealbumin dynamic assessment holds specific relevance.

RESULTS

We included 3136 patients with a total of 4942 prealbumin levels available. Both prealbumin measured at ICU admission (adjusted odds-ratio (aOR) 0.04, confidence interval (CI) 95% 0.01-0.23) and its change over the first week (aOR 0.02, CI 95 0.00-0.19) were negatively associated with ICU mortality. Throughout the entire ICU stay, prealbumin dynamic changes were associated with both cumulative energy (estimate: 33.2, standard error (SE) 0.001, p < 0.01) and protein intakes (1.39, SE 0.001, p < 0.01). During the first week of stay, prealbumin change was independently associated with mean energy (6.03e-04, SE 2.32e-04, p < 0.01) and protein intakes (1.97e-02, SE 5.91e-03, p < 0.01). Notably, the association between prealbumin and energy intake was strongest among older or malnourished patients, those suffering from increased inflammation and those with high disease severity. Finally, prealbumin changes were associated with a positive mean nitrogen balance at day 7 only in patients with SOFA <4 (p = 0.047).

CONCLUSION

Prealbumin measured at ICU admission and its change during the first-week serve as an accurate predictor of ICU mortality. Prealbumin dynamic assessment may be a reliable tool to estimate the effectiveness of nutrition support in the ICU, especially among high-risk patients.

Changes in serum prealbumin as a marker for nitrogen balance in surgical oncology patients

BACKGROUND

Serum prealbumin has long been used as a marker of nutritional status. However, prealbumin is a negative acute phase reactant influenced by several non-nutritional-related factors including surgery, infection, and cancer. An increasing prealbumin has been correlated with a positive nitrogen balance in general surgery patients receiving parenteral nutrition (PN) with 88% specificity and 70% sensitivity. To date, no trial has evaluated the effect of concurrent cancer and surgery on the value of prealbumin in predicting nitrogen balance.

METHODS

This study is a concurrent retrospective design of post-operative patients (≥ 19 years of age) identified by the nutrition support service who received PN for ≥ 5 days, had a baseline and follow-up serum prealbumin and C-reactive Protein (CRP) measured, as well as a 24-h urinary urea nitrogen (UUN) performed between days 5-10 of PN. Exclusion criteria include anuric renal failure, Child-Pugh Class C liver failure, pregnancy, and corticosteroid use. Prealbumin was correlated to nitrogen balance, measuring sensitivity, specificity, and negative and positive predictive values. Information was collected regarding patient demographics and presence or absence of metastatic cancer.

RESULTS

Thirty patients were identified and evaluated for this study from December 1st, 2010 to July 15th, 2011. Patients included in the study had a mean age of 57 years old (range 20-82), 53% male, with a mean weight of 84 kg (range 42-140) and body mass index (BMI) of 29 kg/m2 (range 14.9-56.8). The mean daily caloric dose of PN per actual body weight was 21 kcal/kg (range 10-34) and the mean daily protein dose was 1.4 g/kg (range 1-2). Forty seven percent of patients were obese (BMI > 30 kg/m2) and were prescribed high-protein hypocaloric PN. The most common indication for PN was post-operative ileus (23/30 patients). 24-h urine collection for UUN was performed on average of day 8 after PN initiation (range 5-10 days). Nitrogen balance as calculated from 24-h UUN was positive in 17/30 patients. A positive prealbumin change of greater than 2.8 mg/dL was found to have a statistically significant association with positive nitrogen balance (p = 0.02). At the cut off level of positive 2.8 mg/dL, the likelihood of a positive nitrogen balance had a sensitivity of 82% (95% confidence interval (CI) 64-100%); specificity of 62% (95% CI 35-88%); positive predictive value of 74% (95% CI 54-93%); negative predictive value of 73% (95% CI 46-99%). No absolute value for prealbumin level (e.g., > 20  mg/dL) was found to be a significant predictor of positive nitrogen balance. CRP levels at initiation of PN were significantly elevated with a mean level of 147 mg/dL.

CONCLUSION

These results indicate a positive change in serum prealbumin (> 2.8 mg/dL) has sufficient sensitivity (82%) to predict positive changes in nitrogen balance in the surgical oncology population. However, the low specificity (62%) makes it less useful in predicting a negative nitrogen balance. Absolute prealbumin levels were greatly affected by inflammation, as evidenced by CRP levels, and single values were not useful in predicting positive nitrogen balance.

CLINICAL RELEVANCY

Positive changes in serum prealbumin levels have previously been associated with a positive nitrogen balance (NB) in surgical patients receiving parenteral nutrition (PN); however, it is unclear if this is true in oncologic surgery patients. This study highlights how changing levels of serum prealbumin and C-reactive protein correlates to NB for cancer patients in the post-operative period requiring PN. Changes in prealbumin levels from baseline showed sufficient sensitivity, but not specificity to utilize routinely for predicting NB in this population.

Phase Angle Is a Stronger Predictor of Hospital Outcome than Subjective Global Assessment-Results from the Prospective Dessau Hospital Malnutrition Study

This prospective cohort study of 16,943 consecutive patients compared phase angle (PhA, foot-to-hand at 50 kHz) and subjective global assessment (SGA) to predict outcomes length of hospital stay (LOS) and in-hospital mortality in patients at risk of malnutrition (NRS-2002 ≥ 3). In 1505 patients, the independent effects on LOS were determined by competing risk analysis and on mortality by logistic regression. In model I, including influence factors age, sex, BMI, and diagnoses, malnourished (SGA B and C) patients had a lower chance for a regular discharge (HR 0.74; 95%CI 0.69−0.79) and an increased risk of mortality (OR 2.87; 95%CI 1.38−5.94). The association of SGA and outcomes regular discharge and mortality was completely abrogated when PhA was added (model II). Low PhA reduced the chance of a regular discharge by 53% in patients with a PhA ≤ 3° (HR 0.47; 95%CI 0.39−0.56) as compared to PhA > 5°. Mortality was reduced by 56% for each 1° of PhA (OR 0.44; 95%CI 0.32−0.61). Even when CRP was added in model III, PhA ≤ 3° was associated with a 41% lower chance for a regular discharge (HR 0.59; 95%CI 0.48−0.72). In patients at risk of malnutrition, the objective measure PhA was a stronger predictor of LOS and mortality than SGA.

Transthyretin for the routine assessment of malnutrition: A clinical dilemma highlighted by an international survey of experts in the field

The value of transthyretin (TTR) measurement for assessing malnutrition is under debate due to its sensitivity to inflammation and frequent confusion over its meaning (i.e. as a marker of diagnosis, prognosis, or efficacy of refeeding). Moreover, there is still no ESPEN/ASPEN guideline on its use and cut-off values. Here the aim was to evaluate the overall perception of the value of this parameter and its utilization worldwide. A panel of international experts in the field were surveyed on the use of TTR in clinical practice in their country, on the guidelines issued by their national health authorities, and on the cut-off values used to diagnose malnutrition. A total of 31 experts (nutrition [n = 9], surgery [n = 8], critical care [n = 4], geriatrics [n = 4], biology [n = 3], pediatrics [n = 1], internal medicine [n = 1] and gastroenterology [n = 1]) from 16 countries participated. TTR only appears in Italian, Polish, British and French national guidelines giving cut-off values for mild/moderate/severe malnutrition. TTR is frequently used in research yet rarely if ever in clinical practice in most countries, the reasons cited being lack of evidence for its usefulness, lack of specificity, or its high cost/effectiveness ratio. Given the difficulty of finding a consensus tool for the diagnosis of malnutrition, there is every reason to consider such a simple and inexpensive marker as TTR. However, further studies are needed to define and unify international guidelines on the use of TTR in terms of inflammation level and the associated cut-off values.

Biochemical Markers of Nutrition Support in Critically Ill Trauma Victims

BACKGROUND

In critically ill patients, plasma serum albumin and transthyretin concentrations are thought to reflect the effects of acute illness, including resuscitation and inflammation. Their use as markers for preexisting nutrition status is, therefore, not recommended. Whether they can be used to assess subsequent effectiveness of artificial nutrition support is unclear. We sought to determine if these biomarkers are associated with enteral caloric intake in critically ill trauma patients.

MATERIALS AND METHODS

We analyzed data from adult trauma victims who required ≥2 days of mechanical ventilation and ≥7 days of intensive care. We categorized patients into low, middle, or high enteral calorie delivery groups (2, 9, or 17 kcal/kg/d during the first week). We compared serial concentrations of serum albumin, transthyretin, and C-reactive protein. Multiple linear and Poisson regression were used to determine relationships between calorie intake and nutrition biomarkers.

RESULTS

In total, 1056 patients were analyzed. Their median age was 44 (interquartile range [IQR], 28-57) years, and median injury severity score was 34 (IQR, 26-41). Calorie intake during the first week was not related to biomarkers during the first or second week. However, by the beginning of the third week, the highest calorie group showed greater changes in concentrations of transthyretin (+3.0 mg/dL relative to initial concentration, P = .01) and serum albumin (+0.17 g/dL, P = .05) compared with the lowest calorie group.

CONCLUSIONS

In trauma patients requiring 1 or more weeks of intensive care, changes in transthyretin were associated with enteral caloric intake. Our data suggest that transthyretin could be used to monitor nutrition support after 2 weeks in intensive care.

Relation between the serum albumin level and nutrition supply in patients with pressure ulcers: retrospective study in an acute care setting

This retrospective study examined the validity of the commonly used serum albumin level as an indicator of nutrition status of patients with pressure ulcer(s), particularly because the serum albumin level is affected by various factors and may not be specific to malnutrition. Specifically, we investigated whether nutrition supply or inflammation affects the serum albumin level in 82 patients with pressure ulcers(s) (29 in whom pressure ulcer was present upon admission and 53 in whom pressure ulcer developed after hospital admission). Serum albumin levels, blood test including C-reactive protein (CRP) levels and blood count, caloric intake, and depth and healing of pressure ulcers were compared between various subgroups of patients. Serum albumin levels correlated with red blood cell counts and hemoglobin and CRP levels but not with caloric intake. The correlation with CRP before and after several weeks of pressure ulcer treatment was negative. The serum albumin level upon admission was higher in patients in whom the ulcer healed than in those in whom it did not heal as well as in patients who were discharged than in those who died in the hospital. The serum albumin level appears to reflect inflammation, wound healing, and disease severity rather than nutrition supply in patients with pressure ulcer. J. Med. Invest. 61: 15-21, February, 2014.

Preoperative Leukocytosis in Colorectal Cancer Patients

BACKGROUND

Preoperative asymptomatic leukocytosis has been reported as a factor that affects morbidity of surgical patients. We sought to identify the relationship between asymptomatic preoperative leukocytosis and postoperative complications in elective colorectal cancer surgery.

STUDY DESIGN

The NSQIP database was used to examine the clinical data of patients who had preoperative leukocytosis (white blood cell count more than 11,000/μL) and colorectal cancer resection from 2005 to 2013. Patients with preoperative sepsis, recent steroid use, disseminated cancer, renal failure, pneumonia, and emergently admitted patients were excluded from the study. Multivariate regression analysis was performed to identify outcomes of preoperative leukocytosis.

RESULTS

We evaluated a total of 59,805 patients with a diagnosis of colorectal cancer who underwent colorectal resection. The rate of preoperative asymptomatic leukocytosis was 5.6%. Asymptomatic leukocytosis was associated with preoperative serum albumin level (adjusted odds ratio [AOR] 0.58, p < 0.01) and blood urea nitrogen/creatinine ratio (AOR 1.01, p < 0.01). Preoperative asymptomatic leukocytosis had significant associations with increased mortality (AOR 1.76, p < 0.01) and morbidity of patients (AOR 1.26, p < 0.01). Postsurgical complications that had the strongest associations with asymptomatic leukocytosis were cardiac arrest (AOR 1.78, p = 0.03) and unplanned intubation (AOR 1.61, p < 0.01). Also, infectious complications were significantly higher in patients with leukocytosis (AOR 1.18, p = 0.01).

CONCLUSIONS

Preoperative asymptomatic leukocytosis has a prevalence of 5.6% in colorectal cancer resections and carries a significant increased risk of mortality and morbidity. Asymptomatic leukocytosis is associated with preoperative dehydration and malnutrition. Further studies are indicated to validate and explain these findings.

Nutrition therapy for critically ill and injured patients

BACKGROUND

Nutrition support has undergone significant advances in recent decades, revolutionizing the care of critically ill and injured patients. However, providing adequate and optimal nutrition therapy for such patients is very challenging: it requires careful attention and an understanding of the biology of the individual patient's disease or injury process, including insight into the consequent changes in nutrients needed.

OBJECTIVE

The objective of this article is to review the current principles and practices of providing nutrition therapy for critically ill and injured patients.

METHODS

Review of the literature and evidence-based guidelines.

RESULTS

The evidence demonstrates the need to understand the biology of nutrition therapy for critically ill and injured patients, tailored to their individual disease or injury, age, and comorbidities.

CONCLUSION

Nutrition therapy for critically ill and injured patients has become an important part of their overall care. No longer should we consider nutrition for critically ill and injured patients just as "support" but, rather, as "therapy", because it is, indeed, a key therapeutic modality.

Malnutrition in the critically ill child: the importance of enteral nutrition

Malnutrition affects 50% of hospitalized children and 25-70% of the critically ill children. It increases the incidence of complications and mortality. Malnutrition is associated with an altered metabolism of certain substrates, increased metabolism and catabolism depending on the severity of the lesion, and reduced nutrient delivery. The objective should be to administer individualized nutrition to the critically ill child and to be able to adjust the nutrition continuously according to the metabolic changes and evolving nutritional status. It would appear reasonable to start enteral nutrition within the first 24 to 48 hours after admission, when oral feeding is not possible. Parenteral nutrition should only be used when enteral nutrition is contraindicated or is not tolerated. Energy delivery must be individually adjusted to energy expenditure (40-65 kcal/100 calories metabolized/day) with a protein delivery of 2.5-3 g/kg/day. Frequent monitoring of nutritional and metabolic parameters should be performed.

Guidelines for management of home parenteral support in adult chronic intestinal failure patients

Management of home parenteral support in adult benign but chronic intestinal failure patients requires a nutrition support team using disease-specific pathways. Education of patients to ensure they self manage home parenteral nutrition (HPN) is cornerstone to obtain minimal rate of technical complications and improvement in quality of life. Nutritive mixtures, compounded by pharmacists in single "all-in-one" bags, must be tailored according to the nutritional and intestinal status of individual patients with definition of macronutrients and water-electrolyte needs, respectively. Each PN cycle should be complete in essential nutrients to be nutritionally efficient and should have sufficient amounts of amino acids, dextrose, water, minerals, and micronutrients to avoid deficiency. When the nutritional goal is achieved, a minimum number of PN cycles per week should be implemented, guided ideally by digestive balance(s) (In-Out) of macronutrients and minerals of individual patients. Indeed, HPN is, in most cases, a complementary nonexclusive mode of nutritional support. In short gut patients--who represent 75% of chronic intestinal failure patients--encouraging enteral feeding decrease PN delivery and the risk of metabolic liver disease associated with HPN. In short gut patients with no severe renal impairment, blood citrulline dosage, in association with the remnant anatomy, is a tool to delineate transient from permanent intestinal failure. The latter group includes candidates for trophic gut factors and rehabilitative or reconstructive surgery, including intestinal transplantation. Thus, outcome improvement for intestinal failure patients needs intestinal failure teams having expertise in all medical and surgical aspects of this field.

Surrogate nutrition markers, malnutrition, and adequacy of nutrition support

Surrogate nutrition markers are used to assess adequacy of nourishment and to define malnutrition despite evidence that fails to link nourishment, surrogate markers, and outcomes. Markers such as serum levels of albumin, prealbumin, transferrin, and IGF-1 and delayed hypersensitivity and total lymphocyte count may be valid to help stratify risk. However, it is not appropriate to consider these as markers of adequacy of nourishment in the sick patient.

Nutrition in acute renal failure

Nutritional status has been considered to be one of the possible determinants of mortality rates in cases of acute renal failure (ARF). However, most studies evaluating possible mortality indicators in ARF cases have not focused on the nutritional status, possibly because of the difficulties involved in assessing the nutritional status of critically ill patients. Although the traditional methods for assessing nutritional status are used for ARF patients, they are not the best choice in this population. The use of nutritional support for these patients has produced conflicting results regarding morbidity and mortality. This review covers the mechanisms and indicators of malnutrition in ARF cases and the types of nutritional support that may be used.

Hepatic proteins and nutrition assessment

Serum hepatic protein (albumin, transferrin, and prealbumin) levels have historically been linked in clinical practice to nutritional status. This paradigm can be traced to two conventional categories of malnutrition: kwashiorkor and marasmus. Explanations for both of these conditions evolved before knowledge of the inflammatory processes of acute and chronic illness were known. Substantial literature on the inflammatory process and its effects on hepatic protein metabolism has replaced previous reports suggesting that nutritional status and protein intake are the significant correlates with serum hepatic protein levels. Compelling evidence suggests that serum hepatic protein levels correlate with morbidity and mortality. Thus, serum hepatic protein levels are useful indicators of severity of illness. They help identify those who are the most likely to develop malnutrition, even if well nourished prior to trauma or the onset of illness. Furthermore, hepatic protein levels do not accurately measure nutritional repletion. Low serum levels indicate that a patient is very ill and probably requires aggressive and closely monitored medical nutrition therapy.

Significance of transthyretin in protein metabolism

Total body nitrogen (TBN) is mainly sequestered within the metabolically active lean body mass, in close relationship with total body potassium (TBK). TBN and TBK of growing children manifest superimposed accretion rates, display a sexual difference at the onset of adolescence and during adulthood, thereafter decreasing in elderly subjects. Plasma transthyretin (TTR) follows a comparable profile from birth to death in healthy individuals. Uncomplicated protein-energy malnutrition primarily affects the activity of nitrogen metabolic pool, reducing protein syntheses to levels compatible with survival. This adaptive response is well identified by declining TTR concentrations. In various stressful conditions, in vivo responses are characterized by upregulation in injured regions and with muscle proteolysis exceeding protein synthesis, resulting in a net body negative nitrogen balance. Again, this evolutionary pattern mirrors that of plasma TTR. Attenuation of stress and/or introduction of nutritional rehabilitation allows restoration to normal of both TBN and TTR values that follow parallel slopes. Despite distinct etiopathogenic mechanisms, TTR concentrations appear to reflect the loss or gain of TBN in body pools and they predict later outcome in malnutrition and in conditions of acute and/or chronic inflammation.

Usefulness of short-lived proteins as nutritional indicators surgical patients

BACKGROUND AND AIMS

Biochemical indicators are used to assess the adequacy of nutritional support given to postoperative patients. However, the metabolic alterations present in these patients diminish the efficiency of these indicators. The objective of this work is to determine the usefulness of short-lived proteins as indicators to assess the nutritional support administered to patients during the metabolic stress phase produced by surgery.

METHODS

The nitrogen balance and plasma concentrations of transthyretin, retinol binding protein, and insulin-like growth factor-1 were determined in 24 patients who received 4 different nutritional regimens during 7 days after surgery.

RESULTS

Transthyretin and retinol binding protein, although sensitive to nutritional intake (P<0.0005 and P<0.04 respectively), were strongly affected by the stress response (P<0.008 and P<0.0003 respectively), thus limiting their usefulness for nutrition assessment. Insulin-like growth factor-1 was not influenced by the stress response and was sensitive to the nutritional supply (P<0.0001). Insulin-like growth factor-1 was the only component that showed similar efficiency than nitrogen balance as nutritional indicator.

CONCLUSIONS

Transthyretin and retinol binding protein are not adequate to assess the nutritional supply during the stress phase after surgery, while insulin-like growth factor-1 is a suitable indicator of the adequacy of recent intake in this situation, similar in performance to nitrogen balance.

Postoperative care of the pancreatic surgical patient: the role of the intensivist

Improved patient selection and intraoperative techniques have reduced the need for an intensivist in the care of the pancreaticoduodenectomy patient. Perioperative hemodynamic fine-tuning and the precise management of postoperative complications, however, are areas in which an intensivist can offer expert help. An approach to hemodynamic management and the use of mechanical ventilation is offered. Meticulous detail in each organ system is stressed.

Nutrition for the critically ill child: enteral and parenteral support

The requirements of growth and organ development create a challenge in nutrition management for the pediatric patient. The stress of critical illness further complicates the delivery of adequate nutrients. Enteral feeding has several advantages over parenteral nutrition (PN), which include preservation of the gastrointestinal mucosa and decreasing the occurrence of sepsis related to bacterial translocation. Although feeding through the gastrointestinal tract is the preferred route for nutritional management, there are specific instances when PN as adjunctive or sole therapy is necessary to meet nutritional needs. With meticulous attention to fluid, caloric, protein, and fat requirements along with monitoring the metabolic status of the patient, it is possible to provide full nutritional support for the critically ill child within 24 to 48 hours of hospital admission.

Laboratory support of the clinical nutrition service

This article critically reviews the role of the laboratory services in assessment, monitoring and management of complications in patients requiring nutritional support. It has broadly been divided into three sections. (i) Assessment of protein and energy status: whilst it is stressed that clinical judgement and anthropometric measurements are the most effective methods of evaluation of nutritional requirements, laboratory tests which can be of use in assessment of protein energy status are discussed in detail, including an appraisal of the value of each test in various clinical situations. (ii) Assessment of micronutrient and electrolyte status: the clinical justification for assessment of the various micronutrients and electrolytes is considered. A few selected examples are discussed in detail including an evaluation of the tests of status available and examples of situations where measurement may be clinically helpful. (iii) Effective use of the laboratory: this section attempts to guide the clinician in the most appropriate use of laboratory tests, firstly in the assessment of requirement for aspects of nutritional support, secondly in the continued monitoring and evaluation of the support provided, and thirdly in prevention and treatment of metabolic complications. It is emphasised that clinical nutrition is a multidisciplinary topic requiring input from the laboratory in conjunction with other specialities to provide the best available patient care.

Correlation between lung injury score and serum albumin levels in patients at risk for developing acute lung injury

This is a prospective observational study of 100 consecutive patients who were at risk for developing acute lung injury and were admitted into the surgical intensive care unit. We found a highly significant correlation between an increase in serum albumin levels and a fall in lung injury score and vice versa (r = -0.51, P = 0.000). A highly significant association was also found between mortality, fall in serum albumin levels, rise in lung injury score, and a higher simplified acute physiology score at admission (P = 0.000).

A reference standard for plasma proteins is required for nutritional assessment of adult burn patients

Plasma levels of visceral proteins (VP) are commonly used for evaluation of nutritional status. Low values observed in burn patients are caused by several factors including microvascular hyper-permeability and inflammatory processes. The aim of the study was to define a range of standard values specific to burn patients. Retrospective review: from days post-burn 12 to 43, four VP and three acute phase reactants (APR) were measured twice a week, in the plasma of 107 burn patients. From these data, standard' values were determined in respect with burn surface area (BSA) and post-burn time. The results were that the VP increase and APR decrease linearly during the study. Correlation between plasma proteins and BSA or post-burn day, change from protein to protein. Albumin and transferrin are less sensitive than prealbumin and especially retinol binding protein to variations of APR, but transferrin lacks of specificity. The conclusion of the study was that plasma levels of VP have to be compared to reference standard values. When levels lower than theoretical values are observed, simultaneous APR values (especially C reactive protein) have to be compared to their own reference standard, in order to separate nutritional from inflammatory effects.

Development and validation of an automated latex-enhanced immunoassay for prealbumin

The measurement of circulating prealbumin has been shown to be clinically useful in the assessment of nutritional status, both as an initial screen and in the monitoring of nutritional recovery. We describe a fully automated, noncompetitive, homogenous, light-scattering immunoassay that has been developed for this analyte on a Dimension® (Dade) analyzer. A sheep anti-prealbumin IgG fraction was covalently coupled to 40-nm chloromethyl styrene particles and, after the addition of sample, polyethylene glycol-assisted immunoagglutination was monitored by turbidimetry. The prealbumin working assay range was 8–550 mg/L at a sample volume of 2 μL and a reaction time of 6.5 min. When data were analyzed using ANOVA, total and within-run assay imprecision values (CVs) were 1–5%, and calibration and reagent stabilities were in excess of 40 days. Mean analytical recoveries were 102% ± 4% (SD), and there was no lack of parallelism. Hemolysis, lipemia, and bilirubin did not interfere. Both plasma anticoagulated with heparin or EDTA and serum from plain or serum-separation tubes were acceptable as sample matrices. Comparison with the Beckman Array® method gave a Passing and Bablok regression of: Dimension analyzer = 1.01Beckman + 7.1 (n = 103), using a common calibrator. We conclude that the prealbumin method is appropriate for clinical use according to the analytical criteria used in this study.

Common nutritional issues in pediatric and adult critical care medicine

This article discusses many of the nutritional topics important to the intensivist. Nutritional assessment, substrate immunonutrition, and disease specific issues are presented. Early introduction of enteral feeds and the use of nutritional modulation are emphasized.

Nutrition requirements in patients with toxic epidermal necrolysis

Patients with toxic epidermal necrolysis, a severe, exfoliative skin disorder, have clinical features similar to those of partial-thickness burn patients. The literature suggests that they also have similar nutritional requirements. We report two patients diagnosed with toxic epidermal necrolysis on mechanical ventilation, in whom resting energy expenditure and respiratory quotient were measured by indirect calorimetry. The patients were treated using standard burn protocols. Nitrogen balance was calculated by measuring total urinary nitrogen in urine samples obtained over 24 hours. These measurements were done while the patients were on mechanical ventilation and receiving total parenteral nutrition. As in burn patients, early in their course the two patients had resting energy expenditure values twice that predicted. After 12 days of hospitalization, nitrogen balance was negative in patient 1 and positive in patient 2. Energy and protein requirements appear to have been related to the amount of body surface affected.

Parenteral administration of different amounts of branch-chain amino acids in septic patients: clinical and metabolic aspects

OBJECTIVE

To study the effects of a total parenteral nutrition solution changing branch-chain amino acid concentrations and/or nitrogen supply on protein metabolism, length of stay, and mortality rate; and to evaluate the unique metabolic status of sepsis that leads to a search for specific total parenteral nutrition formulas.

DESIGN

Prospective, randomized, and multicenter study.

SETTING

Intensive care units (ICUs) in seven university hospitals.

PATIENTS

Sixty-nine septic patients.

MEASUREMENTS AND MAIN RESULTS

The patients were randomized into three groups according to the total parenteral nutrition administered. Group A (n = 22) and B (n = 25) patients received 1.5 g of amino acids/kg/day with a nonprotein ratio of 100:1 calories/g of nitrogen, and a varying branch-chain amino acids percentage (group A [23%); group B [45%]). Group C patients were treated with 1.1 g/kg/day of amino acids with a nonprotein ratio of 140:1 calories/g of nitrogen and 45% branch-chain amino acids. All diets were isocaloric. Prealbumin, retinol-binding protein, nitrogen balance, and plasma amino acid profiles (24 amino acids) were determined at baseline and after 3, 7, and 11 days of total parenteral nutrition. The length of stay and the mortality rate in the ICU were recorded. At baseline (preparenteral nutrition), no differences in age, gender, severity of the condition, or clinical chemistry were found between the groups. Prealbumin and retinol-binding protein increased in groups B (p < .004, p < .002, respectively) and C (p < .001, p < .002, respectively). Plasma arginine increased significantly in group C (p < .05), and plasma valine (p < .0001, p < .04, respectively), leucine (p < .005, p < .03, respectively), and isoleucine (p < .001, p < .0001, respectively) increased significantly in groups B and C. The length of stay in the ICU did not change between the groups. The mortality rate in groups B and C was less than in group A (p < .03).

CONCLUSIONS

Our results suggest that the branch-chain amino acids-rich formulas (45%) show a beneficial effect in septic patients.

Nutritional management of patients with gastrointestinal fistulas

Nutritional support plays a key and integral role in the management of patients with gastrointestinal fistulas. It needs to be instituted early to minimize erosion of body cell mass, to prevent further physiologic deterioration of the patient, and to initiate repletion in an otherwise malnourished patient. Furthermore, it allows for rest of the gastrointestinal tract and facilitates healing of the fistula.

International Federation of Clinical Chemistry. Laboratory assessment of protein-energy status

Laboratory and non-laboratory methods for assessing protein-energy nutritional status are reviewed. These are classified into methods for assessing adequacy of recent nutritional intake, methods for assessing whole body status, and tests which assist in the interpretation of these assessments. Each measurement is critically discussed in terms of the rationale for its use, the method of analysis, reference values, technical interference and limitations of methods, the effects of nutritional status and of other factors on the results, its overall usefulness in nutritional assessment, and its value relative to other methods. Non-laboratory tests such as dietary assessment, indirect calorimetry, functional tests and the many methods available for assessment of body composition, including anthropometry, bioelectrical impedance and isotope and imaging techniques, are compared with the clinical chemistry tests in common use, such as nitrogen balance, plasma protein measurements and urinary markers of muscle metabolism. This review provides comprehensive and practical advice on the use and limitations of these tests in the assessment of protein-energy nutritional status of a group, or of an individual patient.

Sequential changes in insulin-like growth factor 1, plasma proteins, and total body protein in severe sepsis and multiple injury

BACKGROUND

Our group wanted to test the hypothesis that plasma levels of insulin-like growth factor 1 (IGF-1), transferrin, and prealbumin are useful markers of nutritional progress in severe sepsis and multiple injury.

METHODS

Measurements of IGF-1 and plasma proteins were made in critically ill patients as soon as they were hemodynamically stable and 5, 10, 15, and 21 days later. The magnitude and direction of the measured changes were compared with the magnitude and direction of the change in total body protein in the same time period.

RESULTS

Fourteen patients with severe sepsis and 10 multiply injured patients were studied. As a group they had an increased metabolic expenditure that peaked at 153% of normal and lost approximately 12.0% of total body protein. An early fall in IGF-1 and plasma proteins accompanied a marked acute phase response, and recovery occurred while hypermetabolism and net proteolysis continued. No correlation existed between changes in IGF-1 or plasma proteins and the change in total body protein.

CONCLUSIONS

Plasma levels of IGF-1, transferrin, and prealbumin are not useful for following changes in protein stores early in the course of critical illness.

Intradialytic parenteral nutrition after small bowel resection

Malnutrition is frequently observed in the hemodialysis patient population. It may be associated with increased morbidity and mortality as well as affect overall quality of life, which may already be compromised from dialytic physical and psychological demands. In the past, intradialytic parenteral nutrition (IDPN) has been available to hemodialysis patients as an adjunct to their dietary intake. In this time of cost containment and the increasing need to scientifically justify the benefit of such therapies to have them paid for by third party reimbursers, IDPN is coming under much scrutiny. This report describes a case of inadequate enteral nutrient absorption in a malnourished hemodialysis patient. This is a case in which IDPN was beneficial and without which other alternatives would have proven more costly physically, emotionally, and economically to the patient.

Nutrition assessment in the 1990s: where are we now?

This review addresses some of the challenges confronting the modern nutrition support clinician in developing protocols for nutrition assessment. While it is generally agreed upon that patients who are malnourished are at greater risk for development of complications during hospitalization, there is no consensus on the best method for assessment of nutritional status. Assessment parameters currently available include clinical, biochemical, anthropometric, and functional tests designed to evaluate nutrition status as well as estimate body composition. As some of these parameters are expensive or not practical for routine clinical use, they should be evaluated carefully when a nutrition assessment protocol is designed.

[How to assess and monitor postoperative artificial nutrition?]

Quantitative and qualitative nutritional requirements depend on the level of energetic expenses. Various formulas, especially the tables by Harris and Benedict allow the estimation of the level of energetic expenses with an approximation of 14%. Corrective factors permit an adjustment of the figures, according to the level of body aggression. In complex cases, indirect calorimetry allows a more accurate appraisal of energetic expenses. This technique provides also indications on the utilisation of each substrate and allows therefore to determine the optimal carbohydrate-lipid ratio for each patient. The assessment of the direct benefit of artificial nutritional support relies on anthropometric techniques and at present on body composition appraisal by determination of its impedance. The changes in muscular strength are difficult to assess. Moreover the time course of body weight is not specific for nutritional status. Therefore other biological indicators such as the nitrogen balance, the concentration of plasma proteins and albumin are more often assessed; proteins with a short half-life depend on the body aggression level. The potassium balance, which is easy to obtain in clinical practice, is a relevant indicator for nitrogen balance and protein synthesis. Clinical monitoring includes the checking of hydratation and its impact on the circulatory, respiratory and renal functions. The tolerance of enteral nutrition is appraised by the quality of gastrointestinal function. Biological monitoring includes the electrolyte balance and various variables of carbohydrate, lipidic and proteic metabolisms. It allows to check the absence of hyperglycaemia, hyperlipidaemia and cholestasis. The daily checking of catheters is part of the monitoring of nutritional support.(ABSTRACT TRUNCATED AT 250 WORDS)

Which nutritional measurements assess protein-energy nutritional status in patients receiving home parenteral nutrition?

Weight, midarm circumference, triceps skinfold thickness, arm muscle circumference, albumin, prealbumin, transferrin and total lymphocyte count were measured at each outpatient visit in patients reveiving home parenteral nutrition from September 1987 to November 1991. Each nutritional variable was analysed for individuals and for the whole group. Group data were expressed using the actual values obtained and successive differences (the change between clinic attendances). Nutritional variables were evaluated using a correlation matrix. Identical analysis of individual and group data demonstrates that laboratory investigations are of little value in the assessment of nutritional status in patients receiving home parenteral nutrition. Anthropometry detected changes in body weight secondary to changes in muscle and/or fat in 80% of patients. Pooling anthropometric data distors the relationship between variables owing to inter-individual variability when actual values are used. The method of successive differences is the preferred method of analysis for group anthropometric data.

Role of parenteral nutrition in preventing malnutrition and decreasing bacterial translocation to liver in obstructive jaundice

Surgery in patients with obstructive jaundice is associated with significant infectious complications probably due to impaired immune function and malnutrition. Total parenteral nutrition (TPN) may alleviate malnutrition but may also promote bacterial translocation (BT) from the gut. To elucidate if TPN can prevent malnutrition without promotion of BT in obstructive jaundice, 40 dogs underwent laparotomy for tissue sampling and placement of a central venous line and were allocated into one of four groups: I (PO-control) received dog chow and water ad libitum; II (PO-CBDL) underwent ligation of common bile duct (CBDL) and was fed dog chow; III (TPN-control) received TPN; and IV (TPN-CBDL) underwent CBDL and received TPN. Body weight, blood samples for liver function tests and bacterial culture, and tissues from liver and mesenteric lymph nodes (MLN) for quantitative bacterial culture and for histology were obtained prior to and 2 weeks after the experiment. The incidence of BT to MLN was 40% in the PO-CBDL and TPN-CBDL animals, which was significantly different from the other two groups (0%; p < 0.05). The incidence of BT to liver was 70% (7/10) in the PO-CBDL animals, which was significantly higher than that in groups I, III, and IV (0%, 20%, 20%, respectively) (p < 0.05). The PO-CBDL animals showed a significant decrease in body weight and prealbumin compatible with malnutrition, whereas the TPN-CBDL animals showed a significant increase in alkaline phosphatase and a consistent cholestasis on histology. The data suggest that TPN can prevent jaundice-associated malnutrition and decrease BT to liver but should be administered cautiously because it may precipitate cholestasis.

The effects of recombinant human growth hormone and intradialytic parenteral nutrition in malnourished hemodialysis patients

Malnutrition in hemodialysis patients is associated with increased morbidity and mortality. The use of intradialytic parenteral nutrition (IDPN) to improve nutritional parameters has been shown to be of limited benefit in most studies. We studied the use of recombinant human growth hormone (rHuGH) in potentiating the effects of IDPN in seven hemodialysis patients dialyzed with a Kt/V of 1.03 +/- 0.11 (mean +/- SEM), but with evidence of malnutrition: albumin, 3.2 +/- 0.18 g/dL; transferrin, 215 +/- 30 mg/dL; insulin-like growth factor-1 (IGF-1), 115 +/- 19 ng/mL, protein catabolic rate (PCR), 0.70 +/- 0.05 g/kg/d; and weight, 12.3% +/- 4.0% below ideal body weight. During 6 weeks of IDPN, resulting in an additional 18 +/- 4 kcal and 0.69 +/- 0.03 g of protein/kg body weight per dialysis session, albumin concentration increased to 3.5 +/- 0.14 g/dL (compared with baseline, P = NS), transferrin increased to 279 +/- 36 mg/dL (P < 0.002), IGF-1 increased to 152 +/- 32 ng/mL (P = NS), and PCR increased to 0.81 +/- 0.04 g/kg/d (P = NS). During the next 6 weeks, IDPN administration was continued and rHuGH, at a dose of 5 mg subcutaneously during each dialysis, was added to the regimen. This resulted in an increase in albumin concentration to 3.8 +/- 0.08 g/dL (P < or = 0.04 compared with end of IDPN phase), an increase in transferrin to 298 +/- 41 mg/dL (P = NS compared with end of IDPN phase), and an increase in IGF-1 to 212 +/- 45 ng/mL (P = 0.05 compared with end of IDPN phase).(ABSTRACT TRUNCATED AT 250 WORDS)

Serum visceral protein levels reflect protein-calorie repletion in neonates recovering from major surgery

Protein catabolism resulting from acute metabolic stress causes significant postoperative decreases in visceral proteins, including albumin (Alb) and prealbumin (PA). Although clinical trials have suggested an advantage of PA over Alb in monitoring the visceral protein response to nutritional supplementation following surgery, the capability of the neonate to generate such a response has yet to be evaluated. Therefore, this study was undertaken to determine if PA is superior to Alb in assessing postoperative repletion of the visceral protein pool in neonates. Serum Alb and PA levels were measured and energy balance (EB) and protein intake (PI) were recorded in 10 neonates less than 48 hours after major surgery and again following 4 consecutive days of positive EB. Resting energy expenditure (REE) was measured using indirect calorimetric methodology. Mean PI (g/kg/d) was lower (0.78 +/- 0.78) and mean EB (kcal/kg/d) was negative (-2.92 +/- 10.05) less than 48 hours postoperatively compared with mean PI (2.52 +/- 0.57; P = .0006) after 4 consecutive days of positive EB (34.84 +/- 16.5; P = .0004). Mean percent change (mean% delta) from negative EB to positive EB was significantly greater for PA (100%; P = .0002) as compared with Alb (18.5%). These data appear to support the conclusion that serial serum PA levels are superior to Alb to monitor the visceral protein response to nutritional supplementation in neonates following surgery.

Evaluation of serum visceral protein levels as indicators of nitrogen balance in thermally injured patients

The use of serum visceral protein concentrations as predictors of nitrogen balance was assessed during the first 4 weeks following thermal injury. The correlation between nitrogen balance and serum albumin was not significant. Statistically significant correlations were found between nitrogen balance and serum prealbumin, retinol-binding protein, and transferrin. However, even the best correlation (retinol-binding protein, r = 0.388) was too weak to permit prediction of nitrogen balance on the basis of the visceral protein concentration. The correlation between change in direction of nitrogen balance and change in direction of protein concentration over time showed all four visceral proteins to be poor predictors of change in nitrogen balance. The efficiency was less than 50% for each visceral protein. Stepwise multiple regression analysis performed to determine which indices were most closely correlated with nitrogen balance showed that a calculation using readily available information (nitrogen intake, postburn day, percent total body surface burned, and age) provided better prediction of nitrogen balance (r = 0.765) than any of the visceral protein concentrations. In view of these findings, measurement of serum visceral protein concentrations to monitor adequacy of nutritional support seems an unwarranted expense in patients with thermal injury.

Enteral nutrition: background, indications and management

Enteral nutrition is only part of the wider field of clinical nutrition in which great advances in both theory and practice have been made over the last decade. We have attempted to summarize what we consider to be the advances that have most relevance to the clinical practice of enteral nutrition. This chapter reviews our present understanding of the processes of digestion and absorption of protein, carbohydrate and fats, and examines how this theoretical understanding can be applied to patients in the clinical situation. A broad classification of the different enteral diets is undertaken, and the reasons for the development of particular diets are discussed. The clinical value of these diets is assessed. The wide variety of indications for enteral (as opposed to parenteral) nutrition are discussed and the specific benefits of enteral nutrition for the patient are highlighted. Techniques of administration of enteral nutrition are reviewed in detail, and the methods by which enteral nutrition should be monitored are outlined. Finally, complications of enteral nutrition are summarized and advice given on how to prevent or treat them.