Nutrition in clinical practice-the refeeding syndrome: illustrative cases and guidelines for prevention and treatment.

The refeeding syndrome is a potentially lethal complication of refeeding in patients who are severely malnourished from whatever cause. Too rapid refeeding, particularly with carbohydrate may precipitate a number of metabolic and pathophysiological complications, which may adversely affect the cardiac, respiratory, haematological, hepatic and neuromuscular systems leading to clinical complications and even death. We aimed to review the development of the refeeding syndrome in a variety of situations and, from this and the literature, devise guidelines to prevent and treat the condition. We report seven cases illustrating different aspects of the refeeding syndrome and the measures used to treat it. The specific complications encountered, their physiological mechanisms, identification of patients at risk, and prevention and treatment are discussed. Each case developed one or more of the features of the refeeding syndrome including deficiencies and low plasma levels of potassium, phosphate, magnesium and thiamine combined with salt and water retention. These responded to specific interventions. In most cases, these abnormalities could have been anticipated and prevented. The main features of the refeeding syndrome are described with a protocol to anticipate, prevent and treat the condition in adults.

Ethical and legal aspects of enteral nutrition.

European ethical and legal positions with regard to EN vary slightly from country to country but are based on a common tradition derived from Graeco Roman ideas, religious thought and events of the 20th century. The Hippocratic tradition is based on 'beneficience' (do good) and 'non-maleficience' (do no harm). Religious thinking is based upon the presumption of providing food and drink by whatever means unless burden outweighs benefit. The concept of 'autonomy' (the patients right to decide) arose following in the decades after the Second World War and is enshrined in Human Rights law. The competent patient has the right to participate in decision making and to refuse treatment although the doctor is not obliged to give treatment which he or she considers futile or against the patient's interests. The incompetent patient is protected by law. The fourth principle is that of 'justice' i.e. equal access to healthcare for all. The law regards withholding and withdrawing treatment as the same. It also defines the provision of food and drink by mouth as basic care and feeding by artificial means as a medical treatment. It requires doctors to act in the best interests of the patient.

Introductory to the ESPEN Guidelines on Enteral Nutrition: Terminology, definitions and general topics.

The ESPEN guidelines on enteral nutrition are the first evidence-based European recommendations for enteral nutrition. They were established by European experts for a variety of disease groups. During guideline development it became evident that terms and definitions in clinical nutrition have been used inconsistently depending on medical disciplines as well as regional and personal preferences. Therefore, to increase explanatory accuracy it was necessary to unify them. In this chapter terms and definitions used throughout all guidelines are explained. Additionally answers to more general questions, which might be important in most indications are dealt with, i.e. use of fibre containing and diabetes formulae.

Integrated nutrition.

There is no branch of medicine in which nutritional considerations do not play some part. Overnutrition, undernutrition or unbalanced nutrition are the major causes of ill health in the world. Conversely, illness causes important nutritional and metabolic problems. The spectrum from lack to excess of nutrients is seamless as a clinical and scientific discipline, the two extremes being linked by the Barker effect by which intrauterine malnutrition and low birth weight predispose to obesity, diabetes and CVD in later life. However, the teaching of nutrition in medical and nursing schools remains sparse. Nutritional care cannot be practised satisfactorily in isolation from other aspects of management, since factors such as drugs, surgery and fluid and electrolyte balance affect nutritional status. Nutritional treatment may also have adverse or beneficial effects according to the composition, amount and mode of delivery of the diet and the clinical context in which it is given. Any benefits of nutritional support may also be negated by shortcomings in other aspects of treatment and must therefore be fully integrated into overall care. One example of this approach is the enhanced recovery after a surgery protocol incorporating immediate pre-operative carbohydrate and early post-operative oral intake with strict attention to zero fluid balance, epidural analgesia and early mobilisation. Other examples include the deleterious effect on surgical outcome of salt and water overload or hyperglycaemia, either of which may negate the benefits of nutritional support. There is a need, therefore, to integrate clinical nutrition more closely, not just into medical and surgical practice, but also into the organisation of health services in the hospital and the community, and into the training of doctors and nurses. Societies originally devoted to parenteral and enteral nutrition need to widen their scope to embrace wider aspects of clinical nutrition.

Relationships between structural and functional measures of nutritional status in a normally nourished population.

BACKGROUND AND AIMS: Both anthropometric and functional measurements have been used in nutritional assessment and monitoring. Hand dynamometry is a predictor of surgical outcome and peak expiratory flow rate has been used as an index of respiratory muscle function. This study aims to measure in normal subjects the relationship between anthropometric measurements, voluntary muscle strength by hand grip dynamometry and respiratory muscle function by peak expiratory flow rate. METHODS: Ninety-eight subjects (46 male, 52 female) with a mean age of 45.9 years were studied. Hand grip strength was measured in the dominant and non-dominant hands with a portable strain-gauge dynamometer. Peak expiratory flow rate was measured using a mini-Wright peak flow meter. Three readings were taken, each 1 min apart, and the average recorded. Midarm muscle circumference (MAMC) was derived from triceps skin fold thickness and midarm circumference (MAC) using standard anthropometric techniques. Statistical relationships were measured with Pearson's coefficient of correlation. RESULTS: In both sexes there was significant correlation between hand grip strength in the dominant and non-dominant hands and peak expiratory flow rate (P<0.001). In men, there was a positive correlation between MAMC, hand grip strength (P<0.001) and peak expiratory flow rate (P<0.001). In women muscle function correlated with height (P<0.001) but not MAMC (P>0.05). CONCLUSIONS: In normal subjects bedside tests of skeletal and respiratory muscle function correlated with each other in both sexes, and with muscle mass in men but not in women.

A practical posture for hand grip dynamometry in the clinical setting.

BACKGROUND & AIMS: The optimal testing position for hand grip strength, which is a useful functional measure of nutritional status, is open to debate. We therefore examined the systematic difference between different postures in order to establish a methodology that is clinically relevant, easy to perform and reproducible. METHODS: Grip strength was measured in the dominant and non-dominant hands with a strain gauge dynamometer in three positions: lying at 30 degrees in bed with elbows supported, seated in an armchair with elbows supported and in a chair with elbows unsupported. The average of three readings made in each position, each 1 min apart, was recorded. RESULTS: 55 normally nourished subjects (26 male) were studied. Mean (95% CI) grip strengths measured in the dominant hand with the subject in bed, sitting in an armchair and sitting in a chair were 45.7 (42.3-49.2), 46.3 (42.9-49.8) and 48.5 (45.4-51.7) kg, respectively for males. Corresponding values for females were 29.4 (27.0-31.8), 29.3 (26.8-31.9) and 31.6 (28.8-34.3) kg. There was no significant difference (Student t-paired test) between measurements made in bed and on an armchair (P = 0.49), but the measurements made in a chair were significantly higher than those made in bed (P = 0.001) and in an armchair (P = 0.004). No statistical difference was present, comparing the three separate measurements in each position (Student t-paired test). CONCLUSIONS: Measurement of grip strength using hand dynamometry is reproducible and consistent. As all patients are not able to sit in a chair with elbows unsupported, in clinical practice it is more practicable to perform hand dynamometry with the elbows supported in a bed or armchair.

ESPEN guidelines for nutrition screening 2002.

AIM: To provide guidelines for nutrition risk screening applicable to different settings (community, hospital, elderly) based on published and validated evidence available until June 2002. NOTE: These guidelines deliberately make reference to the year 2002 in their title to indicate that this version is based on the evidence available until 2002 and that they need to be updated and adapted to current state of knowledge in the future. In order to reach this goal the Education and Clinical Practice Committee invites and welcomes all criticism and suggestions (button for mail to ECPC chairman).

The effect of an oral glucose load on sodium and water excretion after rapid intravenous infusion of 0.9% (w/v) saline.

BACKGROUND & AIMS: Previous studies have suggested that oral or intravenous glucose enhances salt and water retention following a saline load. To test this, we studied the effects of an oral glucose load on urinary sodium and water excretion and serum biochemistry in response to a 2l intravenous infusion of 0.9% saline in normal subjects. METHODS: A crossover study was conducted on six male volunteers. On one occasion, they received 2l 0.9% saline intravenously over 1h. A week later, they were given 100ml 50% dextrose orally prior to the same infusion. Subjects passed urine before start of the infusion. Body weight, haematocrit and serum biochemistry were recorded preinfusion and hourly for 6h. Urine was collected for 6h postinfusion and analysed for sodium, potassium and osmolality. RESULTS: The six subjects had a mean (SE) age of 20.9 (0.4) years and BMI of 22.7 (0.2). Median (IQR) water balance over 6h was 1462 (1005-1650)ml after saline and 1203 (989-1735)ml after glucose and saline (NS). Urinary sodium and potassium excretion on the two occasions over 6h were 76 (69-111) vs 74 (92-174)mmol and 31 (29-40) vs 30 (20-36)mmol, respectively (NS). Using repeated measures testing, there was no significant difference in body weight, haematocrit, serum albumin, sodium, potassium, chloride, osmolality and blood glucose measured at hourly intervals on the two occasions. CONCLUSIONS: In contrast to previous literature, in normal subjects, an additional oral glucose load does not appear to have an effect on urinary sodium excretion or serum biochemistry after a rapid 2l infusion of 0.9% saline. This does not preclude an effect under conditions of prior starvation or injury.

Percutaneous endoscopic gastrostomy (PEG): change in practice since 1988.

BACKGROUND AND AIMS: We previously reported a 30-day mortality following percutaneous endoscopic gastrostomy (PEG) of 8% (1988-92). Concerns over increasing mortality rates prompted us to survey current practice compared with 1988-92: assess case mix, outcome, risk factors for early death, and review practice guidelines. METHODS: 78 consecutive adults were referred for PEG over 7 months. Baseline characteristics, including age and functional status (Barthel Index), and outcome at 30 and 180 days were prospectively evaluated. RESULTS: 74 patients. Median age 69 years; male 55%. Major underlying diagnoses: cerebrovascular disease 42%, head and neck tumours 19%, motor neurone disease 4% (33%, 16% and 27% in 1988-92). Mortality rates at 30, 90 and 180 days were 19%, 35% and 42% respectively (8%, 20% and 37% in 1988-92). Univariate analysis showed that age >75 years, Barthel Index <1 and Glasgow Coma Scale < or =10 were significant risk factors for death at 30 days: odds ratios (95% confidence intervals) 3.9 (1.1-13), 5.9 (1.4-25) and 4.4 (1.2-15) respectively. CONCLUSIONS: 30-day mortality was increased from 8% to 19% between 1988-92 and 1998-99 reflecting a change in referral patterns: more elderly with cerebrovascular disease and fewer with motor neurone disease. Age and functional status should be considered when advising on PEG feeding.

Peri-operative fluid and electrolyte management: a survey of consultant surgeons in the UK.

BACKGROUND: Current peri-operative fluid and electrolyte management in the UK may be suboptimal. We assessed the attitudes of consultant surgeons to fluid and electrolyte prescribing and gathered suggestions for improvement in education on the subject. METHODS: A postal questionnaire survey was sent to 1091 Fellows of the Association of Surgeons of Great Britain and Ireland. Of the 730 (67%) replies, 20 were invalid or incomplete, and 710 (65%) questionnaires were analysed. Outcome measures included provision of guidelines and teaching to junior staff on fluid and electrolyte prescribing, appropriateness of fluid management and suggestions to improve standards. RESULTS: Junior staff were given written guidelines in 22% of instances. Only 16% of respondents felt that their preregistration house officers (PRHOs) were adequately trained in the subject before joining the firm; 15% also stated that PRHOs did not receive much training on their firm. 65% felt that fluid balance charts were accurately maintained, nursing shortages being the commonest reason for inaccuracies. Only 30% felt that postoperative patients were receiving appropriate amounts of water, sodium and potassium. Respondents who had been consultants for > 5 years were more likely to prefer erring on the side of under-replacement of fluid than those who were consultants for 5 years (63% versus 47%, P < 0.0005). Suggestions for improvement in education included problem-oriented ward rounds, written guidelines, and discussion of patient scenarios. CONCLUSIONS: Consultant surgeons feel that present practice in peri-operative fluid management is unsatisfactory. Higher standards within clinical governance and risk management may be achieved by focused practical training combined with formal written guidelines.

Reproducibility and normal ranges for gastric emptying in normal volunteers using a test meal designed for post-operative patients.

Scintigraphy is the current gold standard for the quantification of gastric emptying; however, results vary with meal composition. We modified a dual phase meal for administration to patients in the early post-operative period and aimed to test the reproducibility of the method, to obtain normal ranges and to compare these with previous data. Twenty healthy volunteers (10 male, 10 female), studied prospectively, were compared with 10 historical male volunteers. Each volunteer was studied twice (Test 1 at day 0 and Test 2 at day 7-10). After an overnight fast, subjects had Meal A consisting of a 60 g pancake labelled with 3 MBq of non-absorbable 99mTc-ion exchange resin and 100 ml of water labelled with 0.5 MBq of non-absorbable 111In-diethylenetriamine pentaacetic acid (111In-DTPA). Anterior and posterior gamma camera images of the stomach were obtained every 20 min for 3 h. The time for 50% emptying (T50) was derived from time-activity curves. Data obtained for males were compared with historical data using a similar technique with Meal B, consisting of two pancakes and a 200 ml milkshake labelled with identical amounts of radioisotopes. The mean (95% CI) T50 values for solid phase emptying for males and females using Meal A, and for historical males using Meal B, were 51.1 min (44.1-58.1), 58.6 min (52.7-64.5) and 128.9 min (112.8-145.1), respectively. Corresponding figures for the liquid phase were 33.2 min (26.1-40.3), 50.2 min (38.4-62.1) and 30.7 min (21.4-39.9). Bland-Altman plots for each phase showed good agreement between Tests 1 and 2 for Meal A. The modified test meal gave reproducible results in healthy volunteers; however, solid phase emptying was significantly faster than that of the bulkier test meal in historical subjects.

Body water compartment measurements: a comparison of bioelectrical impedance analysis with tritium and sodium bromide dilution techniques.

BACKGROUND AND AIMS: This study was undertaken to assess the comparability of body water compartment estimates in healthy volunteers using single and dual frequency bioelectrical impedance analysis (BIA) with established reference methods of tritium and NaBr dilution. METHODS: Total body water (TBW) was estimated in 10 healthy volunteers using single frequency (50 kHz) BIA (Bodystat 1500), dual frequency (5 and 200 kHz) BIA (Bodystat Dualscan 2005) and tritium dilution. Extracellular water (ECW) was measured with dual frequency BIA and NaBr dilution. BIA was performed using distal tetrapolar electrodes in the supine position. Venous blood was sampled for measurement of background concentrations of tritium and NaBr using a beta counter and high performance liquid chromatography respectively. 10 ml tritiated water (3.7 MBq) and 50 ml 5% NaBr solution were then injected intravenously and blood samples taken from the opposite arm every 45 min for 4.5 h for estimation of concentrations of tritium and NaBr. RESULTS: There was good correlation (r(2)=0.76) between estimates of ECW using dual frequency BIA and NaBr dilution, with the former overestimating ECW by approximately 1 L. However, this difference varied systematically with body weight. Although TBW measurements obtained by single and dual frequency BIA correlated well with estimates using tritium dilution (r(2)=0.96 and 0.95 respectively), single frequency BIA underestimated TBW by approximately 1 L and dual frequency BIA by approximately 5 L compared to tritium dilution. CONCLUSION: TBW measurements obtained using the single frequency BIA device were more accurate than those obtained using the dual frequency BIA device. Dual frequency BIA provided a reasonably accurate estimate of ECW.

Dilution and redistribution effects of rapid 2-litre infusions of 0.9% (w/v) saline and 5% (w/v) dextrose on haematological parameters and serum biochemistry in normal subjects: a double-blind crossover study.

Although hypoalbuminaemia after injury may result from increased vascular permeability, dilution secondary to crystalloid infusions may contribute significantly. In this double-blind crossover study, the effects of bolus infusions of crystalloids on serum albumin, haematocrit, serum and urinary biochemistry and bioelectrical impedance analysis were measured in healthy subjects. Ten male volunteers received 2-litre infusions of 0.9% (w/v) saline or 5% (w/v) dextrose over 1 h; infusions were carried out on separate occasions, in random order. Weight, haemoglobin, serum albumin, serum and urinary biochemistry and bioelectrical impedance were measured pre-infusion and hourly for 6 h. The serum albumin concentration fell in all subjects (20% after saline; 16% after dextrose) by more than could be explained by dilution alone. This fall lasted more than 6 h after saline infusion, but values had returned to baseline 1 h after the end of the dextrose infusion. Changes in haematocrit and haemoglobin were less pronounced (7.5% after saline; 6.5% after dextrose). Whereas all the water from dextrose was excreted by 2 h after completion of the infusion, only one-third of the sodium and water from the saline had been excreted by 6 h, explaining its persistent diluting effect. Impedances rose after dextrose and fell after saline (P<0.001). Subjects voided more urine (means 1663 and 563 ml respectively) of lower osmolality (means 129 and 630 mOsm/kg respectively) and sodium content (means 26 and 95 mmol respectively) after dextrose than after saline (P<0.001). While an excess water load is excreted rapidly, an excess sodium load is excreted very slowly, even in normal subjects, and causes persistent dilution of haematocrit and serum albumin. The greater than expected change in serum albumin concentration when compared with that of haemoglobin suggests that, while dilution is responsible for the latter, redistribution also has a role in the former. Changes in bioelectrical impedance may reflect the electrolyte content rather than the volume of the infusate, and may be unreliable for clinical purposes.