Long-term kidney function of patients discharged from hospital after an intensive care admission: observational cohort study

The long-term trajectory of kidney function recovery or decline for survivors of critical illness is incompletely understood. Characterising changes in kidney function after critical illness and associated episodes of acute kidney injury (AKI), could inform strategies to monitor and treat new or progressive chronic kidney disease. We assessed changes in estimated glomerular filtration rate (eGFR) and impact of AKI for 1301 critical care survivors with 5291 eGFR measurements (median 3 [IQR 2, 5] per patient) between hospital discharge (2004–2008) and end of 7 years of follow-up. Linear mixed effects models showed initial decline in eGFR over the first 6 months was greatest in patients without AKI (− 9.5%, 95% CI − 11.5% to − 7.4%) and with mild AKI (− 12.3%, CI − 15.1% to − 9.4%) and least in patients with moderate-severe AKI (− 4.3%, CI − 7.0% to − 1.4%). However, compared to patients without AKI, hospital discharge eGFR was lowest for the moderate-severe AKI group (median 61 [37, 96] vs 101 [78, 120] ml/min/1.73m²) and two thirds (66.5%, CI 59.8–72.6% vs 9.2%, CI 6.8–12.4%) had an eGFR of < 60 ml/min/1.73m² through to 7 years after discharge. Kidney function trajectory after critical care discharge follows a distinctive pattern of initial drop then sustained decline. Regardless of AKI severity, this evidence suggests follow-up should incorporate monitoring of eGFR in the early months after hospital discharge.

Anaemia is not a risk factor for progression of acute kidney injury: a retrospective analysis

Background

In hospitalised patients, anaemia increases the risk of developing acute kidney injury (AKI). Our aim was to determine whether anaemia also has an impact on the risk of progression from early AKI to more severe AKI in critically ill patients.

Methods

We retrospectively analysed the data of patients admitted to the adult intensive care unit between 2007 and 2009 who had AKI I as per the AKI Network classification, and who had undergone haemodynamic monitoring within 12 h of AKI I. We collected baseline characteristics, severity of illness, haemoglobin (Hb), and haemodynamic parameters in the first 12 h of AKI I and differentiated between patients who progressed to AKI III and those who did not. Univariate and multivariate logistic regression analyses were used to identify risk factors for progression. Associations between Hb, arterial oxygen saturation and cardiac index were explored by receiver operating characteristic curve analysis.

Results

Two hundred and ten patients (median age 70 years, 68 % male) underwent haemodynamic monitoring within 12 h of AKI I; 85 (41.5 %) progressed to AKI III. The proportion of patients with underlying cardiac disease was significantly higher among progressors versus non-progressors (58 % vs 34 %, respectively; p = 0.001). On the first day of AKI I, progressors had a significantly higher Sequential Organ Failure Assessment score (9 vs 8; p < 0.001), lower cardiac index (median 2.6 vs 3.3 L/min/m²; p < 0.001), higher arterial lactate (2 vs 1.6 mmol/L; p < 0.001), higher central venous pressure (16 vs 13; p = 0.02), lower mean arterial blood pressure (median 71 vs 74 mmHg; p = 0.01) and significantly higher requirement for cardiovascular and respiratory support, but there was no difference in Hb concentration (median 96 g/L in both groups). Multivariable regression analysis showed that heart disease, need for mechanical ventilation, arterial lactate, Sequential Organ Failure Assessment score, central venous pressure and cardiac index on first day of AKI I were independently associated with progression to AKI III. There was no significant difference in the risk of progression between patients with Hb ≤ or >80 g/L, and ≤ or >100 g/L on day of AKI I.

Conclusions

In critically ill patients with AKI stage 1, anaemia was not associated with an increased risk of progression to more severe AKI.

Intraoperative cell salvage versus postoperative autologous blood transfusion in hip arthroplasty: a retrospective service evaluation

INTRODUCTION

A number of ways of reducing blood loss in arthroplasty have been explored, including preoperative autologous transfusion, intraoperative cell salvage and postoperative autologous transfusions. Both intraoperative blood salvage and postoperative retransfusion drains have been shown to be effective in reducing blood loss in total hip arthroplasty. In our department there was a change in practice from using postoperative retransfusion drains to intraoperative cell salvage. To our knowledge no study has directly compared using intraoperative blood salvage and postoperative retransfusion drains alone in total hip arthroplasty.

METHODS

This was a retrospective service evaluation including all primary hip arthroplasty performed under our care between January 2006 and December 2008. Patients were divided into two groups: Group A used a postoperative autologous blood transfusion (ABT) drain and Group B used intraoperative cell salvage.

RESULTS

A total of 144 patients were included in this study: 84 in Group A and 60 in Group B. The mean haemoglobin difference for Group A was 3.96g/dl (standard deviation [SD]: 1.52) and for Group B it was 3.46g/dl (SD: 1.42). The mean haematocrit difference for Group A was 0.12% (SD: 0.05) and for Group B it was 0.10% (SD: 0.04). Using an independent t-test for the comparison of means, a significant difference was found between Group A and B both in regards to haemoglobin difference (p=0.009) and haematocrit difference (p=0.046).

CONCLUSIONS

We feel that intraoperative cell salvage provides a more efficient method of reducing blood loss than postoperative retransfusion in primary total hip replacement. A prospective randomised study would be useful to ascertain any clinical difference between the two methods.

High lipid parenteral feeds raise plasma branched chain amino acid concentrations--a possible therapeutic approach to portasystemic encephalopathy?

The effect of varying the calorie source of parenteral feeding from an all glucose source to a high fat source has been studied in seven patients with normal liver function by randomised crossover trial. 'Intralipid' used as the major non-nitrogen calorie source (except for 400 kcal as glucose) was associated with significantly lower plasma concentrations of insulin and glucose, significantly higher plasma concentrations of the three branched chain amino acids, and a significantly higher urinary excretion of sodium. If these effects of a high fat parenteral feed were repeatable in patients with liver failure and portasystemic encephalopathy they might be of therapeutic benefit.

Use of quantitative 16S ribosomal DNA detection for diagnosis of central vascular catheter-associated bacterial infection

Many central vascular catheters (CVCs) are removed unnecessarily because current diagnostic methods for CVC-associated infection are unreliable. A quantitative PCR assay using primers and probe targeted to bacterial 16S ribosomal DNA was used to measure the levels of bacterial DNA in blood samples drawn through the CVC in a population of patients receiving intravenous nutrition. Bacterial DNA concentrations were raised in 16 of 16 blood samples taken during episodes of probable bacterial CVC-associated infection. Bacterial DNA concentrations were raised in 4 of 29 episodes in which bacterial CVC-associated infection was unlikely. The use of this technique has the potential to substantially reduce the unnecessary removal of CVCs.

Electronic poster presentations in BAPEN--a controlled evaluation

INTRODUCTION

We sought to compare the quality of e-poster and traditional poster communications.

METHODS

At the 2001 BAPEN congress, ten presenters were invited to supplement their poster by submitting its title and contents electronically. On projection, the submissions appeared as a poster. During chaired rounds, presenters 'talked to' the projection as if it were a traditional poster. They 'clicked' onto individual tables or figures to enlarge to full screen. A further 'click' returned the screen to poster format. Delegates attending two e-poster sessions, and a control group attending two simultaneous traditional poster rounds, responded to a questionnaire, on a scale 0--4, to statements which related: to the ability to (1) hear and (2) see well, (3) the posters'clarity and attractiveness, (4) whether the format of the session captured their interest and (5) encouraged discussion. Delegates also responded on how e-posters should be used in future meetings. Comparison was made using chi2 for trend.

RESULTS

Questionnaires were returned from attendees at e-poster (27) and traditional (25) poster rounds. For all questions, the trend was in favour of e-posters with significant differences seen for 'seeing' (P= 0.009), 'interest capture' (P< 0.007) and 'encouragement of discussion' (P<0.05). Thirty-two vs one delegates thought that e-posters should be used in future, 28 vs 4 delegates thought that e-posters and traditional posters should be used together, but most(23 vs 8) thought that traditional posters should not be completely replaced.

CONCLUSIONS

E-posters enable detailed search of a computer-based database of presentations, and viewing of the full content of all posters. Post-conference collaboration is enhanced by facilitating e-mail contact. E-posters should be used in tandem with traditional posters to improve the delivery of original communications.

Should the food intake of patients admitted to acute hospital services be routinely supplemented? A randomized placebo controlled trial

BACKGROUND

Many patients admitted to acute hospital services are underweight or harbour vitamin deficiencies.

OBJECTIVES

To determine the effect on patient throughput of a policy of routine vitamin supplementation, and of early routine sipfeed supplementation in 'thin' patients (5-10% weight loss or body mass index 18-22).

DESIGN

Factorial randomized placebo controlled trial of oral multivitamins from the first day of admission, and, after nutritional screening, of a nutritionally complete sipfeed from the second day in 'thin' patients.

SETTING

Acute medical, surgical and orthopaedic hospital services of a London teaching hospital.

PARTICIPANTS

1561 patients admitted as emergencies were included in the vitamin study of which 549 were included in the sipfeed study.

MAIN OUTCOME MEASURE

Length of hospital stay (LOS).

RESULTS

Offering multivitamins to acute admissions resulted in a mean change (reduction) in LOS of -0.4 days 95% CI (-2-1.2days). The results suggest greater reductions for those discharged after 10 days: mean change=-2.3 days 95% CI (-5.7 to 1.2). Sipfeed supplementation was associated with an increased mean length of stay 2.8 days 95% CI (-0.8-6.3). 18% of acute admissions were classified undernourished on the basis of BMI, MUAC or percent weight loss combined.

CONCLUSIONS

No benefit was observed for sipfeed intervention although a small benefit of less than one day is not excluded. Vitamin supplementation may have slight but economically important benefit.

The postprandial rates of glycogen and lipid synthesis of lean and obese female Zucker rats

OBJECTIVE

To determine the relative rates of glycogenesis and lipogenesis following administration of a test meal in lean and obese Zucker rats.

PROTOCOL

Nine-week-old lean and obese Zucker rats were fasted overnight, then tube-fed a test meal of balanced composition amounting to 16kJ (lean rats and one group of obese rats) or 24kJ (one group of obese rats) and containing 200 mg 1-(13)C glucose. Immediately after the meal the rats were injected intraperitoneally with 5 mCi of 3H2O and killed 1 h later.

METHODS

Glycogenesis was calculated from the incorporation of 3H into liver glycogen divided by the specific activity of plasma water. Lipogenesis was calculated similarly from the incorporation of 3H into saponifiable lipids in liver and perirenal adipose tissue. The proportion of glycogen synthesized by the indirect pathway via pyruvate was determined from the ratio of 3H labelling at positions C6 and C2 in the glycogen glucose residues. Glycogen synthesis from glucose was determined from the ratio of 13C enrichment in liver glycogen to that in plasma glucose.

RESULTS

The rate of synthesis of glycogen was considerably lower in the livers of obese rats than those of lean controls, with the larger meal causing a small but significant increase in glycogenesis. The proportion of glycogen synthesized via pyruvate showed a non-significant increase in the obese rats, while the amount of glycogen synthesized from glucose was significantly decreased. Hepatic lipogenic rates were about five times higher in both groups of obese rats than the lean controls. In adipose tissue, lipogenesis per g tissue was slightly reduced in the obese rats, although there was clearly an increase in adipose tissue lipogenic activity per whole animal. The larger meal caused a greater rise in plasma glucose and insulin concentrations but did not affect lipogenic rates, although it did cause a greater suppression of lipolysis, as indicated by a lower plasma glycerol concentration.

CONCLUSION

Ingested carbohydrate is partitioned predominantly into hepatic fatty acid synthesis in obese Zucker rats. Hepatic glycogen synthesis is suppressed and comes mainly from precursors other than glucose. The suppression of hepatic glycogen synthesis may contribute to the increased energetic efficiency of obese Zucker rats.

Insulin reduces leucine oxidation and improves net leucine retention in parenterally fed humans

Protein metabolism during parenteral feeding was measured with and without euglycemic hyperinsulinemic clamping in five healthy human subjects using the primed continuous infusion of [(13)C]leucine (LEU) tracer methodology. All subjects underwent two periods of protein measurement. Subjects were randomized to have the clamp first or second. Two subjects had the clamp first, and they participated in another study in which the measurement period after the clamp was increased by another 2 h. Insulin reduced LEU oxidation (from 26 to 22 microM. kg(-1). h(-1); P < 0.05) and improved net LEU balance (from 3 to 7 microM. kg(-1). h(-1); P < 0. 05). The order of the clamp influenced the effects of insulin. With clamping performed second, insulin reduced LEU flux (from 152 to 134 microM. kg(-1). h(-1); P < 0.01), endogenous LEU rate of appearance (Ra; from 125 to 107 microM. kg(-1). h(-1); P < 0.01), and non-oxidative LEU disappearance (NOLD; from 128 to 113 microM. kg(-1). h(-1); P < 0.01). With clamping performed first, NOLD decreased after insulin was stopped (from 129 to 121 microM. kg(-1). h(-1); P < 0.05), but no change was seen in the flux and LEU Ra, despite the return of plasma insulin and amino acid concentrations to basal levels. The reduction in NOLD was accentuated with time and did not reach plateau even after 6 h and indicated a prolonged carry-over effect for NOLD and Ra. This effect was not seen for leucine oxidation.

A double blind, randomised, controlled trial of glutamine supplementation in parenteral nutrition

BACKGROUND AND AIMS

To determine whether the inclusion of 20 g free glutamine as part of the nitrogen source of parenteral feeds reduces length of hospital stay or mortality.

METHODS

In a randomised, double blind, controlled trial in 168 patients clinically accepted for parenteral nutrition, standard feeds were compared with feeds in which 3.8 g of the total nitrogen was replaced with the equivalent 20 g glutamine. A minimum of 11 g nitrogen/day was used in all patients. Daily intakes of energy and nitrogen were determined using a validated computer protocol and were similar for the two groups. All feeds included trace elements, vitamins, electrolytes, and minerals.

RESULTS

A total of 85 patients received a median of eight (interquartile range 5-13) daily feeds containing glutamine while 83 received a median of eight (5-15) standard feeds. No difference between groups was detected for infective complications. Twenty control patients and 14 who had received glutamine died during their hospital stay (NS). Median length of stay was 32 (23-52) days on glutamine, which was not significantly different from the control value of 35 (25-55) days. Glutamine was associated with a significant (p<0.03) reduction in length of stay in surgical patients (45 days (range 29-81) versus 30 days (range 19-54)).

CONCLUSION

The benefit from glutamine supplementation of parenteral feeds as used in this trial has not been proved. Supplementation may have advantages in surgical patients and in haematological malignancy. Further trials are required.

The thiamin, riboflavin and pyridoxine status of patients on emergency admission to hospital

The aim of this study was to assess the prevalence of thiamin, riboflavin and pyridoxine deficiencies at admission to an acute hospital. One hundred and twenty adult patients were selected at random from those admitted via the Accident and Emergency department over 3 days. Comparisons were made with a group of 80 healthy blood donors sequentially attending a local transfusion centre. The alcohol intake of 500 patients admitted sequentially via the same Accident and Emergency department was also assessed. Erythrocyte transketolase (ETK), glutathione reductase (EGR) and aspartate aminotransferase (EAA) coenzyme activation assays were used to determine thiamin, riboflavin and pyridoxine deficiencies. The prevalences of deficiency states in the inpatient group were 21, 2.7 and 32% for thiamin, riboflavin and pyridoxine deficiencies respectively with 49.2% being deficient in one or more vitamin. The mean alcohol intake in the group of patients in whom this was assessed was 9.7 units per week compared with 10 units per week amongst blood donors.

Metabolic effects of adjuvant recombinant human growth hormone in patients with continuing sepsis receiving parenteral nutrition

BACKGROUND

Adjuvant growth hormone is advocated for treating the catabolism of prolonged sepsis not corrected by parenteral nutrition alone.

METHODS

An open study was performed in which eight patients whose postabsorptive resting energy expenditure was persistently elevated by a mean of 19% as a result of continuing sepsis were randomized to receive 0.03 or 0.06 mg/kg recombinant human growth hormone (rhGH) each evening for 7 days adjuvant to total parenteral nutrition. Plasma concentrations of growth hormone, insulin, insulin-like growth factors 1 and 2 (IGF-1 and -2) and their binding proteins IGFBP-1 and -3 were measured before and after rhGH, and their relationship with rates of whole-body protein turnover was determined in the morning in the postabsorptive state by using L-[1-13C]leucine.

RESULTS AND CONCLUSIONS

Before rhGH, the patients were hyperinsulinemic (mean, 44.4 mU/L) but had growth hormone levels within the normal range (< 10 mU/L). After the seventh dose of rhGH, nocturnal growth hormone concentrations rose to a mean of 35.3 +/- 26.1 and 61.3 +/- 21.05 mU/L for the low and higher dose groups, respectively. Morning IGF-1 concentrations showed a small increase during treatment, rising from a mean of 241.3 +/- 99.0 to 301.7 +/- 167.3 ng/mL for the low-dose group and from 214.5 +/- 74.6 to 294.1 +/- 116.9 ng/mL for the higher-dose group. IGF-2 increased slightly by 89 +/- 39 and 75 +/- 49 ng/mL for the low and higher doses, respectively. IGFBP-1 and -3 and insulin did not change. The balance between nitrogen input and urinary urea nitrogen increased after rhGH by a mean of 5.3 g/d with no differences between the two dosage groups (4.74 +/- 1.56 g/d for the higher dose, 5.94 +/- 3.70 g/d for the lower). No significant changes were observed in whole-body protein turnover after a 1-week course of rhGH.

A placebo controlled investigation of the effects of tryptophan or placebo on subjective and objective measures of fatigue

OBJECTIVE

To examine the effect of L-tryptophan administration on subjective and objective measures of fatigue in healthy volunteers.

SUBJECTS

Six healthy volunteers (4M:2F) were recruited from staff and students at the College.

SETTING

Department of Human Nutrition, St. Bartholomews and the Royal London School of Medicine and Dentistry.

DESIGN

Subjects were tested for central and peripheral fatigue using a visual analogue scale, flicker fusion frequency, grip strength, reaction time and wrist ergometry. In addition, plasma free tryptophan concentrations and Trp:LNAA ratio were determined. Measurements were made before, and at 1, 2, 3 and 4 h after drinking one of two test drinks. The drinks were of either caffeine free diet Coca-Cola (placebo) or caffeine free diet Coca-Cola plus L-tryptophan (30 mg/kg: active drink). Each of the six subjects was tested after placebo and active drink with a one week washout period between test days.

RESULTS

Subjective fatigue was significantly increased following tryptophan compared to placebo (P < 0.002), and objective measures of central fatigue were significantly increased by tryptophan compared to placebo (flicker fusion frequency: P < 0.001; reaction time P < 0.001). No significant changes in grip strength were found following tryptophan compared to placebo, but a significant increase in ergometric work output was seen (P < 0.001).

CONCLUSION

Tryptophan ingestion in the quantity 30 mg/kg leads to increased subjective and central fatigue. Increases in work output observed following tryptophan may be as a result of a reduced perception of discomfort during ergometry.

Nutritional support: a course for developing multidisciplinary clinical teams. Education Committee, British Association for Parenteral and Enteral Nutrition

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Post-prandial changes in measures of fatigue: effect of a mixed or a pure carbohydrate or pure fat meal

OBJECTIVES

To assess the changes in measures of fatigue after meals of varying composition, and to compare the relation of the fatigue with changes in the plasma tryptophan:large neutral amino acids (Trp:LNAA) ratio.

SUBJECTS

Sixteen healthy volunteers were recruited from staff and students at the College.

DESIGN

Subjects were tested for central and peripheral fatigue using a visual analogue scale, flicker fusion frequency, grip strength, reaction time and wrist ergometry. In addition, plasma amino acid concentrations and Trp:LNAA ratio were determined. Measurements were made before, and at 1, 2, 3 and 4 h after drinking one of three liquid test meals. The meals were isoenergetic (1672 kJ) and were of mixed carbohydrate, fat and protein, or of pure carbohydrate or pure fat.

SETTING

Department of Human Nutrition.

RESULTS

Subjects consuming the pure carbohydrate meal reported more subjective feelings of fatigue and had slower reaction times. Aspects of central fatigue were greater in subjects consuming a pure fat meal. The Trp:LNAA ratio was depressed in those consuming a pure fat or mixed meal and raised only after pure carbohydrate.

CONCLUSIONS

Central and subjective fatigue may be influenced by raised plasma free tryptophan to competitor amino acid ratios induced by carbohydrate intake but other aspects of central arousal are affected by fat intake.

Nutrition support in advanced cancer

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Four years' experience of an undergraduate medical nutrition course

In 1992 the medical colleges of The Royal London and St Bartholomew's hospitals launched a new curriculum in which basic medical sciences were to be integrated with early exposure to clinical medicine in the first phase. The curriculum was to be modular and integrative, combining clinical and medical-science-based teaching of body systems, rather than the traditional teaching by departmental discipline. We describe the inception, content and evaluation of a 7-day course on nutrition which was developed as part of this curriculum. It was rated highly by the students, whose feedback led to important modifications. The programme works well in practice, and could provide a useful guide for other schools about to set up nutrition courses for medical students.

Transposition of the anorectum to the abdominal wall

A unique procedure is described in which the anorectum is mobilized on the inferior mesenteric vascular pedicle and transposed to the anterior abdominal wall. The aim is to preserve maximal intestinal length in patients with short bowel syndrome and intractable diarrhoea. Unique physiological data provided by the second case demonstrate that the specialized sensory functions of the rectum reside in the rectal wall and are subserved by an autonomic nervous supply that is independent of the pudendal nerves.

Physical measures of recovery from anorexia nervosa during hospitalised re-feeding

OBJECTIVE

To examine the relationship between weight gain, changes in body composition and physiological characteristics of fitness during the recovery from anorexia nervosa.

DESIGN

Longitudinal over eight weeks of intensive inpatient re-feeding (Wk 0-8).

SETTING

The London Hospital Medical College.

SUBJECTS

Ten female patients who agreed to participate. Seven completed the protocol.

INTERVENTIONS

Dual-energy X-ray absorptiometry (dexa) and skinfold thickness measures at Wk 0 and 8. Weekly measures of peak expiratory flow rate and cycle ergometry (several variables relating to aerobic work recorded at rest and during cycling at low loads (0-60 W)). Blood samples for lactate and potassium measures, taken during cycling at Wk 0, 4 and 8 only.

RESULTS

(1) Body composition: Mean weight gain over eight weeks was 9.6 kg, dexa and skinfold measures showing fat gain to contribute 62% and 54%, respectively. Both methods showed significant changes in percentage body fat with refeeding (P < 0.01 and P < 0.001, respectively), however there were significant differences in results between methods before (P < 0.01) but not after (P = 0.2) refeeding. (2) Physiological function: Between weeks 0 and 8, mean peak expiratory flow rate rose to 85% of predicted values, cycle ergometry performance improved in six subjects (three never reached 60 W load), mean respiratory exchange ratio (RER) during cycling fell at 0 W and 20 W loads (both P < 0.05), and oxygen pulse increased at rest and 0 W load cycling (both P < 0.05), Wk 8 values being well below normal. Oxygen uptake at rest and all loads increased in line with body weight gain only. No significant changes were seen in heart rate or blood lactate and potassium levels.

CONCLUSIONS

(1) Lean body and fat mass increased significantly during eight weeks of refeeding. The methodological difference in initial body fat measurements requires further investigation. (2) The women had severely impaired physiological function. Variables studied were only slowly improving with refeeding, and work capacity was still well below normal.

Protein Turnover, Energy Expenditure and Body Composition in Patients with Acute Leukaemia Undergoing Chemotherapy

1. Measurements of whole body protein turnover using the (13)C-leucine tracer technique, of body composition using anthropometric measurements and DEXA scanning, and of resting energy expenditure (REE) assessed by indirect calorimetry were made in 8 patients with acute leukaemia undergoing a single course of chemotherapy. Measurements were made in the post absorptive state immediately before chemotherapy and were repeated close to the time of discharge from hospital (mean days in hospital 31 ± 4.3, range 22-35), a mean of 23 ± 4.8 days after completion of chemotherapy. 2. The mean weight loss was 3.63kg (P < 0.001) with significant reductions in the mean non dominant mid arm circumference (1.29cm, P < 0.01), biceps (0.7mm, P < 0.01) and triceps (1.9mm, P < 0.05) skinfold thicknesses. DEXA scanning showed a reduction of mean body fat (1.22kg, P < 0.05) and lean tissue (1.85kg, P < 0.01). 3. There was a reduction in whole body leucine flux (Q) by 35% (P < 0.01) and synthesis (S) by 40% (P < 0.001) with no change in catabolism (C) over the course of admission. 4. There were no significant changes in REE.

Bed rest decreases whole-body protein turnover in post-absorptive man

1. Whole-body protein turnover was measured using the [15N]glycine tracer technique in 10 post-absorptive healthy volunteers during normal daily activities and a period of bed rest. 2. Bed rest reduced whole-body protein turnover (25%), synthesis (26%) and breakdown (25%), but short-term urinary nitrogen excretion remained unchanged.

Review article: artificial nutritional support for improved patient care

Malnutrition is common and undiagnosed in the majority of affected hospital patients; it is associated with impaired organ function, morbidity, and increased length of hospital stay. Artificial nutritional support in malnourished patients leads to improvement in nutritional status and clinical outcome. Nutritional support is required in malnourished patients, patients who are unable to take normal diet and patients with intestinal failure. Gastroenterologists are required to supervise patients with intestinal failure, to insert endoscopic feeding devices, and increasingly to participate in, or lead, nutritional support teams. Major developments in nutrient delivery have included percutaneous endoscopic feeding devices, the recognition that enteral feeding is possible in patients with gastric stasis, and that nutrient needs can be met by peripheral parenteral nutrition. There is much interest in the use of new substrates, or substrates delivered in pharmacological doses such as glutamine and arginine, to manipulate the response to disease. Many hospitals lack an organized approach to artificial nutritional support. Patients continue to suffer from a lack of treatment or the consequences of inappropriate or inadequate treatment. This article reviews the current status of artificial nutritional support and provides guidelines for patient management.

Malnutrition: incidence, diagnosis, causes, effects and indications for nutritional support

Various methods for the diagnosis of malnutrition, and some of the physical signs commonly associated with it, are discussed. The incidence and possible causes of malnutrition and its effects are then addressed. Finally, the indications for nutritional support, using either the enteral or the parenteral route, are examined.

Whole-body protein turnover in response to hyperinsulinemia in humans postabsorptively with [15N]glycine as tracer

Studies using stable isotopes to determine the effect of insulin on whole-body protein turnover have given conflicting results. The precursor approach to studying healthy subjects in a postabsorptive state shows reductions in breakdown and oxidation; with end product methods in parenterally fed patients no such changes are seen. To explain these discrepancies, we measured protein turnover with and without euglycemic hyperinsulinemic clamping postabsorptively in nine healthy subjects by using single-dose [15N]glycine with calculations based on ammonia and urea end product excretion. With and without clamping, respectively, insulin reduced nitrogen (22.1 and 48.2 mg.kg-1.9 h-1, P < 0.01) and urea (15.8 and 37.5 mg.kg-1.9 h-1, P < 0.05) but increased ammonia (7.7 and 5.0 mg.kg-1.9 h-1, P < 0.05) excretion. Although the urea end product method suggested that insulin tended to reduce both protein breakdown and synthesis, the protein metabolism changes detected with the ammonia end product method tended to be in the opposite direction. The [15N]glycine ammonia end-product method may be inappropriate for studies during insulin infusion because of insulin's effect on ammonia excretion.

Nutritional support in patients with low volume chylous fistula following radical neck dissection

One of the well known complications of radical neck dissection is a chylous fistula, which results from injury to the thoracic duct as it enters the left subclavian vein. Such fistulae may cause considerable increased morbidity to a patient who is already debilitated by malignancy and by the increased catabolic response to surgery. Further surgery may be appropriate for those with a high fistula output but conservative therapy is normally advocated for the remainder. Nutritional and electrolyte support for these patients is essential and poses potential problems in management. We present three such patients. One was fed parenterally and two enterally and in all cases the fistulae closed spontaneously. We examine the known physiological stimuli to chyle production and conclude that the enteral feedings of these patients with fat or an isomolar enteral feed does not, contrary to current belief, increase chyle flow or delay the healing of these fistulae.

High lipid parenteral nutrition improves portasystemic encephalopathy

We have conducted a randomized double crossover study over 4 days in six parenterally fed patients with portasystemic encephalopathy (PSE) in which the nonprotein energy source of otherwise identical feeds was alternately all glucose or predominantly fat. Concentrations of plasma branched chain amino acids (BCAA), plasma insulin, and blood glucose were measured after an initial fast and subsequently after each of the four 24-hr periods of isonitrogenous feeding. The grade of PSE was assessed clinically and by the number connection test, BCAA concentrations were significantly lower during the glucose infusion than during fasting or the lipid infusion. PSE was significantly less with the lipid than with the glucose infusion. Trials testing the effect of infused BCAA must take account of the opposing effect on BCAA concentrations of simultaneous glucose infusion. A high lipid feed may have advantages in the short-term treatment of PSE.

Reproducibility of whole-body protein turnover measurements in an 'ideal' metabolic subject

Whole-body protein turnover measurements using the single dose 15N-glycine technique have been made in a patient completely paralysed by the Guillaine-Barré syndrome. Variation (difference x 100/mean) between the results of the studies was better than 0.75 per cent for protein flux, better than 0.85 per cent for protein breakdown, and better than 5 per cent for protein synthesis.

Protein metabolism in inflammatory bowel disease

Major loss of body protein mass in inflammatory bowel disease is much less common than weight loss, which is often attributable to losses of other body, particularly water and fat. It does occur, however, in a few patients, especially in those with compromised food intake. It is due principally to the combined effects of diminished intake and excessive intestinal losses of amino nitrogen. Nitrogen metabolism is influenced not only by protein nutritional state and net nitrogen intake but also by disease activity. There is some evidence for abnormally low secretion of growth hormone in adolescents with inflammatory bowel disease and growth failure. Low serum albumin concentrations are not necessarily related to protein undernutrition and are the combined result of relatively reduced albumin synthesis, increased intestinal losses, and maldistribution between intravascular and extravascular spaces. Concentrations in the plasma of IgG and acute phase reactants may be raised despite increased losses into the bowel lumen. The prevention of total body protein depletion is achieved principally by maintaining adequate and often not supranormal intakes of a balanced source of amino nitrogen in a balanced diet given orally, enterally, or parenterally, combined with a medical or surgical approach to reduce disease activity: supranormal energy intakes are not beneficial.

Controlled trial of bowel rest in the treatment of severe acute colitis

In a prospective, randomised clinical trial, 47 patients with severe, acute, non-infective colitis treated with 60 mg intravenous prednisolone daily, received either bowel rest with parenteral nutrition or oral diet. Although those who received 'bowel rest' experienced a reduction in daily stool weight, there were no differences in the operation or mortality rates between the groups. Fourteen of the 27 patients with ulcerative colitis, but none of the 16 patients with Crohn's disease required urgent surgery. Bowel rest did not affect the outcome in severe ulcerative colitis treated with intravenous prednisolone. Ulcerative colitis and Crohn's colitis behaved differently in the acute attack.

The effect of insulin infusion on whole-body protein metabolism in patients with gastrointestinal disease fed parenterally

The effect of insulin infusion on whole-body protein metabolism was studied in six non-diabetic patients with gastrointestinal disease receiving constant total parenteral feeding, with each patient as his own control. Insulin added to the parenteral feed significantly raised the plasma insulin concentration and lowered the blood glucose. With insulin infusion there was a significant increase in the rates of urea output and ammonia excretion, but no change in 3-methylhistidine excretion or in the urinary 3-methylhistidine/creatinine ratio. Studies of whole-body protein turnover were performed with a tracer injection of 15N-glycine and both urea and ammonia as end products. Without insulin urea as end product gave an estimate of flux 18 per cent greater than that given by ammonia. With both end products rates of whole-body protein synthesis were significantly greater than rates of breakdown. When insulin was infused the estimate of flux from ammonia increased significantly, resulting in close agreement with the estimate from urea, and there was no longer a significant difference between rates of whole-body protein synthesis and breakdown. Our data, taken with the results of other studies, suggest that insulin infusion is not beneficial as a means of increasing nitrogen retention in non-diabetic parenterally-fed patients.