bluuebunny/crossref_metadata_2025 huggingface dataset:
Clacton St. John's Primary School—a design study
Authors: King Brian
Published: September 2009

A project brief to design and build the first phase of a 240-place primary school with the potential to be extended to 420 places was accepted by the Architect's Department and further defined in that the solution should: (1) achieve a 50 per cent reduction in the applied energy requirements of the ‘standard’ school design as set out in Design Note 171, (2) meet the revised and improved environmental comfort standards, and (3) be achieved within normal budgetary allowances. In addition to the experience of the design team a powerful interactive dynamic thermal analysis computer program2 was used to test design options through from feasibility to control operation strategy. The optimised solution integrated building shape, fabric and energy system resulting in a solar selective building envelope of balanced thermal capacity utilising underfloor heating and controlled ventilation with heat recovery. Applied energy requirements being met through ground water-to-water heat pumps. Completed in April 1982 and now midway through a detailed monitoring programme, preliminary analysis indicates the school will meet educational requirements, energy targets and environmental standards.
Estimation of performance of prototype axial flow fan from model test
Authors: Salami L. A.
Published: September 2009

Scale formulae have been derived for the prediction of the performance of prototype fans from model tests for the prerotator-rotor and rotor-straightener type units based on the aerofoil characteristics of RAF 6-series which are available over a wide range of Reynolds number. Suitable formulae have also been derived for predicting the shift of the point of maximum efficiency towards the higher flow coefficient as the size of the prototype is increased. As assumptions have been kept to the minimum it is hoped that this method would be more realistic than any of the existing methods. The agreement between the prediction of the prototype from the formulae and the result of the prototype has been quite fair.
Group heating schemes
Authors: Levermore G. J.
Published: September 2009

This paper starts by establishing that, under certain conditions, a theoretical group heating scheme is just viable compared to individual heating of dwellings. The paper then examines the fuel consumption of one typical group heating scheme and finds that it uses slightly less energy than that calculated for individual heating of the dwellings, although the energy consumed in both cases could well be reduced by modern design. A further analysis, of the consumption data from 69 Inner London schemes, shows that domestic hot water generation is a source of inefficiency. It is proposed that this could be improved by individual generation in the dwellings with the group scheme providing space heating only.
Convection coefficients for stably stratified layers
Authors: Wright A. J.
Published: September 2009

The physics of heat transfer across stably stratified fluid layers adjacent to horizontal surfaces are examined. Different assumptions are found to lead to widely varying values for the convection coefficient, and this raises some doubt about the applicability of the present recommended values for horizontal building surfaces.
The effect of moisture on the thermal conductivity of aerated concrete
Authors: Stuckes Audrey D. , Simpson A.
Published: September 2009

The thermal conductivity (Λ) of five specimens of aerated concrete varying in density from 390 to 900 kg/m3 has been measured at several moisture contents between 0.2 and 7 per cent volume. Although the Λ-value increased with increasing moisture content, the change was less than that predicted by the Jakob factors. In general, the moisture factors were found to be density dependent and to increase with decreasing conductivity. A general expression has been derived relating the moisture factor to both density and moisture content by volume over the range 0 to 5 per cent.
Calculation of peak temperatures in multiple zones using the admittance method
Authors: Dow M. R.
Published: September 2009

The admittance method of calculating maximum summertime temperatures in buildings, as used in the CIBSE Guide, is the standard method in the UK. It was developed for manual calculations, where it is only feasible to consider one room or zone at a time, and is now used for calculating temperatures using a microcomputer. Other digital methods of calculating temperatures were developed originally with larger computers. This paper shows how the admittance method can be used to predict the temperature in multiple zones. A set of simultaneous equations relating the mean temperature in each room is derived, and these are solved by standard computer methods.
Thermal performance of mineral fibre insulation
Authors: Siviour J. B.
Published: September 2009

Experimental ‘U’-values have been derived for actual and simulated building components insulated with fibrous material. They cover a range of thicknesses from 90 to 360 mm and the values compare well with theoretical values calculated using CIBS methods. This rebutts earlier reports which suggested that thick layers of insulation perform less well than theoretically predicted.
Energy savings from secondary windows
Authors: Rayment R. , Morgan K.
Published: September 2009

This paper is one of a series of reports for an EEC Contract on field, laboratory and theoretical investigations of energy saving methods in dwellings. Here, specially prepared matched-house pairs have been used to investigate the energy savings obtained from fitting secondary windows. This forms part of an ongoing programme designed to examine a range of energy conservation measures. These particular results demonstrate a mean reduction in energy consumption of 12 per cent (3 per cent) for the secondary windows. The theoretical percentage reduction agrees well with that measured only if the air change rate is assumed to have been reduced by about one third. Energy consumption has been determined for a range of weather conditions which, from data gathered on the experimental houses in other heating seasons, should be representative of the average annual savings for this type of house and pattern of usage.
Correlation between daily diffuse and global irradiation for the UK
Authors: Saluja G. S. , Muneer T.
Published: September 2009

The measurements of solar irradiation are available for relatively small number of locations. Again the stations recording diffuse as well as global irradiation are fewer. In the UK only seven stations record both components whereas the latter component is recorded at 26 stations. Hence a correlation is desired which would enable computation of daily diffuse component of global irradiation. The present study serves this need. The traditional method is to develop a correlation between daily diffuse ratio (ratio of diffuse to global irradiation) against clearness index (ratio of global to extraterrestrial irradiation). Hence correlations were first developed for five widespread locations in the UK using 3-year daily data. Comparison of these correlations showed their closeness to each other and hence the possibility for a single correlation for the entire United Kingdom. The correlation developed for the UK was checked by various statistical tests and was found to predict the diffuse component quite accurately.
Condensation in terrace housing: causes and cures
Authors: Byrd R. H.
Published: September 2009

This paper contains some results of an on-going project concerned with remedying surface condensation and mould growth in terrace housing. The project started in 1983 and was instigated by Coventry Churches Housing Association in response to complaints from tenants of ‘damp’ and mould. It was carried out in two phases. The first phase consisted of a detailed survey of a sample of houses and their occupants. This survey analysed the relationship of condensation with house plan type, the form and construction of the extensions, the orientation of the house, the moisture generated within the house, the amount of heating and the extent of ventilation. This, together with a theoretical analysis, indicated some of the most appropriate methods of remedying the problems. The second phase involved the implementation and monitoring of the remedial measures.
Energy routing through a controlled environmental space
Authors: Pfafflin James R. , Tompeck Mark A.
Published: September 2009

Responses to changes of energy input to an enclosure are exponential in nature. The time scales are characterised by active (heating) and cooling (passive) time constants. The time constants can be evaluated from room construction parameters. Heating and cooling paths are followed sequentially rather than simultaneously. A method for predicting heating and cooling trajectories is presented. Verification of the proposed procedure is through reproduction of time-temperature records of an environmental test room for which energy input was by skirting.
Areas in building heat loss calculations
Authors: Siviour J. B.
Published: September 2009

The areas used in building heat loss calculations are normally the plane areas calculated from the internal dimensions of each room. This excludes the areas of external walls, floor and ceiling which are covered by internal floors and walls, and also the effects of edges and corners. Some simple theory and infra-red experimental work suggests that together these would add around 15 per cent to the heat losses normally calculated for the walls, floor and roof, i.e. excluding the losses through windows and doors and by ventilation.
The use of thermal storage to improve commercial boiler plant operations
Authors: Gibson N. M. , Pattison J. R. , Wright G. F.
Published: September 2009

This paper describes operating experiences with a thermal storage heating system installed to heat an office complex. An existing single pipe radiator system was modified to include heat storage equipment, and the plant has been monitored since February 1983. It has been found that this unsophisticated installation gave a 10-25 per cent improvement in efficiency over the original boiler system and possibly 10-13 per cent improvement over a compensated system. These gains could be further increased by obvious modifications. The system offers further advantages in rapid heat-up times and the possibility of reducing peaks in the national gas supply pattern. A disadvantage was the capital cost of the thermal store, which was 30 per cent greater than the cost of the displaced boiler, but it was found that special store designs were not necessary to make the system work.
The prediction of air temperature variations in naturally ventilated rooms with convective heating
Authors: Howarth A. T.
Published: September 2009

A large proportion of heated rooms depend primarily on natural convection for the distribution of heat within the occupied zone. A method of predicting air temperature variations with height is presented. Using the heat and mass flow rates of the driving convection plume, along with the corresponding parameters of downward flowing air streams at cool surfaces, an estimation of the maximum (upper) temperature and the minimum (lower) temperature can be made. Points of entry of incoming air can be taken into account. It is shown that there are clear advantages of employing over-sized well controlled radiators.
What is the air temperature?
Authors: Fitzgerald D.
Published: September 2009

To calculate fabric heat losses the environmental temperature is often used, but for calculations about condensation the air temperature is needed. The note shows how the latter can be obtained from the former for a room surrounded by other rooms at different environmental temperatures.
Energy management of a large estate
Authors: Oughton R. J.
Published: September 2009

The paper outlines energy management of the PSA estate, which has been pursued since 1972. PSA's current expenditure on energy in buildings is <235M per annum (1983-84), and while energy management has been in operation the aggregate annual saving achieved across the civil and armed services estate is estimated at 33%. The development of energy management is described; the initial organisation concentrated on the existing estate. An Energy Database was generated for the whole of the civil estate and routine monitoring and targetting of consumption was instituted. Regional Energy Conservation Officers were appointed with responsibilities for energy management of defined areas of the estate and a headquarters group was set up to direct the campaign and determine policy. The funding of all energy efficiency applications depends on a favourable value analysis. The calculations used in establishing investment priorities were based on CIBSE methods. This was quickly followed by the introduction of design techniques to promote energy efficiency in new building work. The use of Design Energy Targets is a prominent feature. Over the period to date an in-house training programme in energy conservation has been established for technical staff involved in building design and operation and for general staff. An expanding range of in-house publications on energy efficiency is also available.
The effect of moisture on the thermal conductivity of lightweight aggregate concrete
Authors: Stuckes Audrey D. , Tinker J. A. , Simpson A.
Published: September 2009

The thermal conductivity (Λ) of 13 specimens of lightweight concrete, incorporating either Lytag, Pellite or Aglite aggregates, varying in density from 1144–1424 kg/m3 have been measured at several moisture contents between 0.03 and 19.75 per cent by volume. Although the Λ-value increased with increasing moisture content, the change was much less than that predicted by the Jakob factors. In general, the moisture factors were found to be density dependent and to increase with decreasing conductivity. A general expression has been derived relating the moisture factor to both density and moisture content by volume over the range 0–4 per cent. A comparison has been made between Λ obtained up to 6.5 per cent moisture content, corrected to 3 per cent using this expression, and experimental results at 3 per cent moisture content. Close agreement was obtained. This expression has also been used to correct the Λ-values to 5 per cent moisture content by volume and reasonable agreement has been obtained with the limited experimental data obtained at this level.
Is there a minimum heating requirement for households?
Authors: Milbank Neil
Published: September 2009

This note arises from work to identify the effectiveness and cost of remedial treatments for condensation and mould problems in housing. Although the four factors-moisture generation, ventilation, insulation and heating-which control the likelihood of mould growths have long been established there has not been a straightforward way of showing their inter-relationship, particularly where energy costs are important. By treating the problem essentially as one of air conditioning the Note shows how the fabric heat loss of the house and the rate of moisture generation define a minimum heat requirement to limit mould growth.
BREDEM—The BRE domestic energy model: Testing the predictions of a two-zone version
Authors: Henderson G. , Shorrock L. D.
Published: September 2009

An earlier paper by Uglow1 describes a calculation method for determining energy use in dwellings. That model is now referred to as BREDEM-1 (BRE Domestic Energy Model 1). BREDEM-1 is a simple single-zone model designed for hand calculations; its predictive capabilities have been tested on a group of over forty dwellings2. Major extensions to the BREDEM-1 model to include two zones and also incorporating changes to the way in which internal and external temperatures are handled, resulted in BREDEM-23. Like its predecessor, BREDEM-2 is designed for hand calculations, although a number of closely related computer based versions have been developed. These are also called BREDEM and are given individual identification numbers. This paper tests the predictions of BREDEM-5 (also known as Energy Auditor) using the same sample as was used for BREDEM-1 testing. The two-zone model is found to be an improvement on BREDEM-1, there being less scatter in the results. Even so, the paper identifies potential areas for improvement.
Output of radiators at reduced flow rate
Authors: McIntyre D. A.
Published: September 2009

The heat output from conventional hot water radiators falls as the return temperature is reduced. Experimental results show a much lower heat output from a pressed steel radiator than that calculated using the conventional formula based on the mean of flow and return water temperatures. The fall in output is especially marked when using bottom, opposite end water connections to the radiator, as in conventional British practice. This reduction in output has implications for the design of systems which are designed to operate at low flow rates.
Summer condensation within dry lined solid walls
Authors: Southern J. R.
Published: September 2009

There have been recent reports of interstitial condensation forming on the back of vapour checks of dry lined solid walls. This usually occurred within south facing walls during hot weather. A possible explanation is that water evaporates from the inside surface of the masonry, travels through the insulation and condenses on the cooler internal vapour check. Similar condensation has been reproduced in experimental walls under natural weather conditions with a variety of insulants including highly permeable mineral fibre. In these tests it was found that condensation deposited over a period of a few hours can take several days to re-evaporate.
The BRE Low Energy Office—five years on
Authors: John R. W. , Salvidge A. C.
Published: September 2009

The BRE Low Energy Office (LEO) has already demonstrated, as part of a DEn Energy Efficiency Demonstration Scheme1, the very real opportunities for energy efficiency that can be incorporated into a building's design within normal cost limits. Five years of operating experience and monitoring of the LEO has highlighted a number of design, commissioning, and operating practices which led to unnecessary energy use and a failure to achieve design performance on a significant number of occasions. Lessons that have been learnt from the operating experience of the LEO are discussed. Because many of the problems identified in the LEO have also been found in other, more conventional, buildings, lessons learnt have an application beyond low energy designs. Over both the 1984/5 and 1985/6 heating seasons, the ‘BRESTART’ optimum start control algorithm was used, and its performance shown to be significantly better than the more conventional optimiser initially installed.
Simulation of HVAC components and systems
Authors: Hanby V I
Published: September 2009

Interest in simulation of the performance of HVAC components and systems has increased considerably in recent years, generated by the possibility of producing integrated plant/building models for energy studies, and investigating the performance of operational plant with a view to improving the design of installed systems. The paper presents an overview of the various approaches to this simulation problem in three sections: component models, linking protocols (networking) and methods for solving the component model equation sets. Probable avenues of future development in both research and design oriented applications are discussed.
A simplified thermal response model
Authors: Crabb J A , Murdoch N , Penman J M
Published: September 2009

The observed dynamic thermal response of intermittently occupied buildings can usually be described by one or two time constants. This suggests that much of the complexity in detailed computer thermal response models may not always be necessary. Simplified thermal response models may be adequate for many purposes, and ought to have cost advantages, both in setting up and run time. The paper describes the basis of a simplified microcomputer model of building thermal response. Model predictions of internal temperature variation in a working school are shown to agree well with observations. The model is intended for professional use and user interface is being developed in consultation with an architectural practice.
How accurate are the predictions of complex air movement models?
Authors: Holmes M J , Whittle G E
Published: September 2009

The validation of computer predictions of physical processes is still a topic of concern, particularly in relation to dynamic thermal simulation modelling. However, far more complex computer programs are now being introduced into the building services industry. These new programs solve the conservation equations of momentum, energy and mass to simulate air movement in and around buildings. The validation task is potentially more difficult than that encountered to date. This paper discusses some of the problems associated with the application and validation of these codes and suggests how a user can ensure that the physical processes are being modelled realistically.
Air movement in a partitioned industrial environment
Authors: Pitts A C
Published: September 2009

A study of the effects of air movement within a complex factory building is described. Air conditioning systems operated to alleviate discomfort in some parts of the factory, and to satisfy product requirements in another. The interaction of the various air conditioning systems and potential overcapacity were considered to offer scope for improvement. Environmental investigations included the use of a tracer gas to examine air transfers. It was concluded that air transfers between adjacent partitioned areas were low, enabling the adoption of a more sophisticated control strategy which would reduce the demand for conditioned air.
Ionic microclimate within buildings
Authors: Jokl Miloslav V , Hapl Ladislav
Published: September 2009

From experiments in buildings of different construction it is concluded that the ionic microclimate inside depends on that outdoors and on the partial vapour pressure of water indoors, that the lowest level of ionisation occurs in winter and the highest in spring and summer, and that by contrast with buildings built from concrete panels, in traditional buildings (brick, wood) and in buildings with lightweight external cladding, the lightweight negative ion concentration and unipolarity quotient evolve in concert with those outdoors.
Time lags in a two-zone air movement model
Authors: Waters J R
Published: September 2009

Multi-zone models of air movement in buildings usually assume that there is no time lag in the flows between zones. Nevertheless, such time lags could have a significant effect on the pattern of contaminant distribution throughout a building. This note shows how such effects can be evaluated by examining theoretically a two-zone model with time lags. The results have implications for the interpretation of tracer decay measurements.
Room internal heat exchange: New design method
Authors: Davies M G
Published: September 2009

The paper reviews the approach taken by the present CIBSE Guide as it handles convective and radiant exchange in an enclosure through the use of the room index temperature, ‘environmental temperature’. Certain difficulties in handling radiant exchange are identified. The paper goes on to show how the rigorous but intractable radiant exchange pattern in an enclosure can be simplified with good accuracy to a more amenable form centred on a radiant star temperature T1. It is shown that if the radiant energy from an internal heat source is taken as input at T1, it generates a (necessarily fictitious) temperature which proves to be a satisfactory approximation to the average value of the radiant temperature observable over the enclosure volume. The emissivities of the separate surfaces are included explicitly in this formulation. Further heat inputs may act at the surface nodes, T1, T1. … Convectively input heat is taken to act at the mean air temperature, T1. The temperature response of the enclosure to the various heat inputs is illustrated using this model and is compared with the results of two simpler models. In the first model (that discussed above) convective and radiant heat inputs are handled separately, as physically speaking they must. The method is conceptually simple, logical, flexible and accurate but may require the solution of simultaneous equations. In the second model convection and radiation inputs are simply lumped at an ‘air temperature node’. The method is computationally very simple but is illogical in a number of respects. It is commonly used. In the third model convective and radiant inputs are partly lumped and input at a node Tc. The model has a logical basis of a kind, but the basis is too restrictive to afford the method full credibility. Its conductances, heat flows and Tc itself are conceptually recondite through combining the two heat flow mechanisms. For preliminary and crude estimates of heat needs, the second, traditional model is suitable. For accurate assessment, the first model is needed. The third model, closely akin to the present CIBSE Guide method, provides a possible but unattractive approach.
Legionnaires' Disease in refrigeration and associated equipment
Authors: Oughton R J
Published: September 2009

The paper outlines the nature of Legionnaires' Disease (LD) and its origins. The nature of the bacterium and the four features in the chain of infection are discussed and the essentials of its treatment are outlined. The typical incidence of Legionella Pneumophila in building services is dealt with and UK case histories of outbreaks are used to illustrate the ubiquity of contamination. Susceptible equipment and applications relevant to refrigeration are reviewed and extensive reference is made to Part 1 of the Badenoch Inquiry which, although this referred to hospitals, was very much concerned with refrigeration plant components. The main part of the paper deals with design, operation and maintenance of plant to offer the minimum risk of LD concentrations in carry-over from evaporative cooling equipment, water treatment, including filtration, access, cleaning and drainage arrangements and plant location. The paper concludes that the lessons learned indicate that, while standards seem to be appropriate to minimum risk, more dedication is required to their application. Views expressed in this paper are those of author and do not necessarily represent the policy of the Property Services Agency.
Air leakage measurements on full-scale construction
Authors: PhD Paul Baker BScTech , BSc Gilbert Valentine
Published: September 2009

A technique for identifying and measuring air leakage through the fabric of buildings is presented. The leakage characteristics of a few selected full-scale building details are illustrated. The data derive from both laboratory and real-world buildings, and indicate the importance of design detailing and construction of junctions to control air leakage.
Expert systems: Their application to the building services industry
Authors: Dunn A
Published: September 2009

Expert systems are defined and explained, the way in which they differ from conventional software is highlighted and the areas in which they are being currently exploited are indicated. Many areas of application within the building services industry are suggested and the potential problems and dangers are discussed. The experience of building an expert system to assist in the selection of air conditioning systems for buildings is described, explaining the various stages through which the project passed from inception to final implementation. The paper concludes that expert systems represent a valuable cost-effective tool that can and should be used to increase the efficiency of a wide range of activities within the building services industry.
Hourly diffuse and global solar irradiation: Further correlation
Authors: Muneer T
Published: September 2009

Following the correlation equations between hourly diffuse and global irradiation established in an earlier study(1) the work has been extended by analysing data for a further six locations. Plots of hourly diffuse ratio (ratio of diffuse to global irradiation) against clearness index (ratio of global to extra terrestrial irradiation) were obtained in the first instance for eleven UK sites. The plots were further examined for seasonal trends by plotting separately data for winter, summer and autumn/spring and also obtaining regression curves. While the plots for summer and autumn/spring showed definite trends, the winter plots showed more scatter. Some factors which cause this scatter have been identified. Plots of the regressed curves for the three seasons showed the summer and winter curves lying at the top and bottom respectively with the autumn/spring curve intermediate. This behaviour has been traced to the higher and lower turbidities during the summer and winter months. An error analysis was carried out for the seasonal model developed for each location. This exercise confirmed the adequacy of the model. The seasonal curves for different locations when superimposed disproved a latitude trend. The curves for Lerwick and Stornoway departed from the rest. Furthermore, the two locations were found to have almost identical characteristics. Finally equations were obtained for the summer and the rest of the year period for the UK by pooling data from all mainland locations and carrying out regression analysis. Statistical analysis of these models confirmed their validity. The model established in the earlier study based on data from only five locations proved satisfactory for the prediction of the diffuse ratio for all additional mainland locations.
Latent thermal storage for air conditioning
Authors: Arnold David
Published: September 2009

The advantages of thermal storage as part of an installation that provides intermittent temperature conditioning are obvious: the peak power requirement is reduced; this peak can be shifted to a lower tariff time of day; chilling plant can operate at close to 100% capacity, i.e. maximum efficiency; and the maximum electrical demand can be reduced significantly, further reducing running costs. Unfortunately the space required, using sensible thermal storage, is usually too great to provide anything more than a buffer to prevent chillers starting too frequently. To overcome this space problem system designers are now resorting to latent thermal storage. Commercially available equipment can be divided into that based on ice and that based on the use of encapsulated eutectic mixtures (phase change materials). For the air conditioning designer the systems can be further subdivided into pressurised and atmospheric storage. Both types rely on the latent heat of fusion to reduce to a third or a quarter the storage volume necessary, but there are important differences in the satisfactory application of the various methods. The note examines and discusses the basic principles relevant to system design, describes the range of ice-based equipment available including ice builders, ice tanks and ice harvesters. The range of phase change materials and associated equipment is then discussed and analysed in the context of suitable air conditioning applications. It is concluded that both ice systems and phase change materials can offer advantages and savings but that they must be carefully matched to the air conditioning system design if their full benefits are to be realised.
Nutritional Support in Cancer Patients
Authors: Barrera Rafael
Published: September 2009

This article will summarize the current nutrition strategies in cancer patients. A review of relevant studies dealing with nutrition in cancer patients is presented. Basic recommendations for feeding patients with malignancy are suggested. Early nutrition evaluation, assessment, and support should be instituted in the appropriate clinical setting. Use of specialized nutrition support is not indicated in well‐nourished cancer patients undergoing surgery, chemotherapy, or radiotherapy in whom adequate oral intake is anticipated. Severely malnourished patients need early nutrition support preoperatively. Postoperative nutrition support has to be initiated in a timely fashion depending on the disease process. An algorithm for decisions regarding administration of specialized nutrition support is proposed. (Journal of Parenteral and Enteral Nutrition26:S63—S71, 2002)
Risk Factors for Aspiration
Authors: Metheny Norma A.
Published: September 2009

Background: There are numerous risk factors for aspiration in tube‐fed critically ill patients. However, there is confusion about the extent to which these factors actually contribute to aspiration. The purpose of this literature review was to summarize findings from selected research studies. Methods: A nonexhaustive literature search was conducted to identify risk factors for aspiration in tube‐fed, critically ill patients. The most commonly cited factors were decreased level of consciousness, supine position, presence of a nasogastric tube, tracheal intubation and mechanical ventilation, bolus or intermittent feeding delivery methods, high‐risk disease and injury conditions, and advanced age. Results: Many studies of aspiration risk factors have relatively small sample sizes and used equivocal definitions of aspiration. Although some addressed aspiration as an outcome, others considered gastroesophageal reflux or pneumonia as outcomes. Despite these variations, authors almost uniformly agree that a decreased level of consciousness and a sustained supine position are major risk factors for aspiration. There is less agreement regarding the effect of a nasogastric tube (or its size) on aspiration and on the effect of various formula delivery methods. Conclusions: A decreased level of consciousness is a major risk factor for aspiration, as is a sustained supine position. Although some authors favor using small‐bore feeding tubes to prevent aspiration, there seems to be insufficient data to warrant this action. Although strong data are lacking regarding feeding delivery methods, there are more data to support continuous feedings than bolus/intermittent feedings in high‐risk patients. (Journal of Parenteral and Enteral Nutrition26:S26‐S33, 2002)
Future Considerations in Aspiration Pneumonia in the Critically Ill Patient: What Is Not Known, Areas for Future Research, and Experimental Methods
Authors: DiSario James A.
Published: September 2009

The medical literature supports the use of enteral feeding to provide nutrition and improve patient outcomes. A major complication of enteral feeding is aspiration and associated morbidity and mortality. Many knowledge gaps exist that inhibit our ability to define and diagnose aspiration, identify patients at risk, and develop prevention techniques. Several areas of inquiry should be explored to help us define and prevent the disorder—for instance, standardized criteria should be developed for diagnosing aspiration pneumonia and for differentiating it from other types of pneumonia, and accurate tests should be devised for detecting it. Research also is needed to evaluate the influence of (1) various enteral feeding sites on aspiration risk, (2) the effects of risk reduction techniques such as selective decontamination and use of promotility agents, and (3) potential benefits of immunonutrition. Current parameters used in decisions about when to initiate enteral feeding in critically ill patients are defined. (Journal of Parenteral and Enteral Nutrition 26:S75‐S79, 2002)
Creatinine Excretion as a Measure of Protein Nutrition in Adults of Varying Age
Authors: Walser Mackenzie
Published: September 2009

The use of the creatinine height index (CHI) as a measure of protein nutrition is reviewed. Any such cross‐sectional measurement is inherently limited. Using published values for urinary creatinine excretion per kilogram body weight in adult subjects of varying age and values for “ideal” weight as a function of height, we have derived normal values for expected creatinine excretion in men and women of varying height. These permit the derivation of an age‐corrected CHI. Possible explanations for the normal decrease in creatinine excretion with age include (1) decreasing lean body mass with age, (2) decreasing proportion of muscle in lean body, and (3) lower meat intake in older persons. Diet has an important influence if meat intake is substantial of if consumption of a creatine‐free diet is prolonged. Creatinine metabolism and extrarenal excretion are minor, except in subjects with reduced renal function. Application of a correction for constant extra‐renal clearance of creatinine in patients with chronic renal failure probably is not valid. Further observations of creatinine excretion in normal subjects of varying age and height are needed. (Journal of Parenteral and Enteral Nutrition 11:73S‐78S, 1987)
Uses and Limitations of the Balance Technique
Authors: Kopple Joel D.
Published: September 2009

Classical balance techniques are a powerful, sensitive, and usually accurate technique for assessing the nutritional or metabolic response to changes in nutritional intake or to metabolic or physiological perturbations. Balances are particularly sensitive for examining transient or short‐term responses to nutritional or metabolic stimuli. A major factor responsible for the precision and sensitivity of this technique is the precise control of the activities and environment of an individual during a classical metabolic balance study (eg, the carefully defined dietary intake, degree of exercise, and environmental temperature to prevent sweating); these same factors may enhance the precision and sensitivity of other metabolic or nutritional investigations that may be carried out concurrently with a balance study. Finally, for nitrogen balance studies, the measurement of nitrogen (eg, by the Kjeldahl technique) can be very accurate and sensitive.

Despite these advantages, there are important limitations and errors that are inherent in the balance technique. The errors tend to overestimate intake and underestimate output, thereby leading to erroneously positive balances. These errors include losses of food on cooking and eating utensils and dishware, losses of feces or urine on toilet paper or in collection containers, and losses through sweat, exfoliated skin, hair and nail growth, saliva, menses, blood sampling, toothbrushing, semen, and, for nitrogen, from flatus and respiration. Cumulative balance measurements are particularly likely to be falsely positive. The magnitude of unmeasured losses vary among healthy individuals, with the magnitude of the nitrogen intake (for nitrogen), in altered environmental conditions (eg, with sweating), and possibly in disease states. Balance studies are also expensive and time consuming. Finally, the fate and intermediary metabolism of the compounds ingested or infused into the subject and the sources of the output of nitrogen or minerals are poorly defined by the balance technique. Balances are probably most helpful when they are performed in conjunction with other techniques for studying nutrition or metabolism, when the intake is not too high (eg, equal to or less than 12–15 g/day for nitrogen), and when the same individual is studied before and after a perturbation in their nutritional or metabolic status. Classical balance techniques are so complicated and expensive that they are primarily of value for research studies. (Journal of Parenteral and Enteral Nutrition 11:79S‐85S, 1987)
Measurement of Energy Expenditure in Clinical Nutritional Assessment
Authors: Jequier Eric
Published: September 2009

Indirect calorimetry with the ventilated‐hood open circuit is a useful and accurate technique to measure energy expenditure in acutely ill patients. This approach should be useful to evaluate the energy and the nutrient needs of a patient under acute conditions. The measurement of energy expenditure is of obvious importance in assessing protein‐calorie malnutrition. A better understanding of energy balance and nitrogen balance in critically ill patients is needed to determine the best caloric and nutrient intake to avoid tissue depletion. It is foreseen that this method will become more widely used when reliable equipment is made available. (Journal of Parenteral and Enteral Nutrition11:86S‐89S, 1987)
Parameters for Evaluation of Lipid Metabolism
Authors: Carpentier Y.A. , Thonnart N.
Published: September 2009

The influence of the clinical condition and the intravenous intake on parameters of fat metabolism has been analyzed. Compared to normal subjects, the correlation between plasma concentrations and the turnover rate of glycerol and free fatty acids varies in the opposite direction in nutritionally depleted and severely injured patients. The significance of plasma concentrations as an index of fat mobilization should be interpreted in relation to the clinical condition. Kinetic measurements are particularly interesting in hypermetabolic patients. Plasma triglyceride and cholesterol concentrations are markedly affected by surgical procedures. Any delay (in treatment) following the injury and the type of intravenous regimen used have an important influence on plasma lipid levels and should be taken into account when groups of patients are studied. The infusion of exogenous fat emulsions significantly affects not only plasma triglyceride levels but also phospholipid and cholesterol concentrations and will modify the plasma lipoprotein pattern. Measurements of plasma clearance and oxidation of fat can be used to evaluate individual tolerance and the metabolic utilization of lipids, but these procedures cannot be easily applied in routine clinical practice. Regular monitoring of plasma triglyceride, cholesterol, and phospholipid concentrations during and after cessation of fat infusion is recommended for each patient who is receiving daily fat infusions so that the safe rate of infusion for that individual can be determined. (Journal of Parenteral and Enteral Nutrition 11:104S‐108S, 1987)
Glutamine Metabolism and Its Physiologic Importance
Authors: Smith Robert J.
Published: September 2009

The amino acid glutamine has important and unique metabolic functions. It is the most abundant free amino acid in the circulation and in intracellular pools and a precursor for the synthesis of amino acids, proteins, nucleotides, and many other biologically important molecules. It is the most important precursor for ammoniagenesis in the kidney, the major end product of ammonia‐trapping pathways in the liver, a substrate for gluconeogenesis, and an oxidative fuel in rapidly proliferating cells and tissues. Glutamine also may have a number of important regulatory roles, increasing protein synthesis and decreasing protein degradation in skeletal muscle and stimulating glycogen synthesis in the liver. The demonstration that glutamine concentrations decrease and tissue glutamine metabolism increases markedly in many catabolic, stressful disease states has led to a reconsideration of the classification of glutamine as a nonessential amino acid and to the alternative hypothesis that glutamine may be a conditionally essential nutrient. This hypothesis has been supported by recent studies that have shown trophic effects of glutamine‐supplemented diets on the growth of specific tissues and on total body nitrogen balance. These observations form the basis for current efforts to define the clinical usefulness of glutamine‐supplemented nutrition. (Journal of Parenteral and Enteral Nutrition14:40S‐44S, 1990)
Safety and Metabolic Effects of L‐Glutamine Administration in Humans
Authors: Ziegler Thomas R. , Benfell Kathleen , Smith Robert J. , Young Lorraine S. , Brown Elaine , Ferrari‐Baliviera Elisabetta , Lowe Daniel K. , Wilmore Douglas W.
Published: September 2009

A series of dose‐response studies was conducted to evaluate the clinical safety, pharmacokinetics, and metabolic effects of L‐glutamine administered to humans. Initial studies in normal individuals evaluated the short‐term response to oral loads of glutamine at doses of 0, 0.1, and 0.3 g/kg. A dose‐related increase in blood glutamine occurred after oral loading and elevation of amino acids known to be end products of glutamine metabolism occurred (including alanine, citrulline, and arginine). No evidence of clinical toxicity or generation of toxic metabolites (ammonia and glutamate) was observed. Glutamine was infused intravenously in normal subjects over 4 hr at doses of 0.0125 and 0.025 g/kg/hr. In addition, glutamine was evaluated as a component of parenteral nutrition solutions (0.285 and 0.570 g/kg/day) administered for 5 days to normal subjects. Intravenous administration of glutamine was well tolerated without untoward clinical or biochemical effects. Subsequent studies in patients receiving glutamine‐enriched parenteral nutrition for several weeks confirmed the clinical safety of this approach in a catabolic patient population. In addition, nitrogen retention appeared to be enhanced when glutamine was administered at a dose of 0.570 g/kg/day in a balanced nutritional solution providing adequate calories (145% of basal) and protein (1.5 g/kg/day). Nitrogen balance in patients receiving lower doses of glutamine (0.285 g/kg/day) was similar to that in patients receiving standard formulations. Further controlled clinical trials of the metabolic efficacy, tolerance, and dose response of glutamine in other patient groups are necessary to determine the appropriate use of glutamine enrichment of nutrient solutions. (Journal of Parenteral and Enteral Nutrition14:137S‐146S, 1990)
Metabolic Response to Chemotherapy in Colon Cancer Patients
Authors: Tayek John A. , Chlebowski Rowan T.
Published: September 2009

The goal of this investigation was to identify the metabolic abnormalities in a group of colon cancer patients before and during 5‐fluorouracil chemotherapy. Twenty‐two colon cancer patients were prospectively enrolled into a Clinical Research Center for measurement of counter regulatory hormones, fasting hepatic glucose production (HGP), intravenous glucose tolerance test, plasma leucine appearance (LA), and leucine oxidation (LO). Both the cancer group and the normal volunteers were matched for nutrition status (109 ± 5% of ideal body weight us 104 ± 4%, mean ± SEM, respectively) and history of weight loss (6.3 ± 2.6 kg vs 4.4 ± 4.8). Plasma growth hormone was significantly elevated in the colon cancer patients (3.22 ± 0.62 ng/mL us 0.73 ± 0.18, p <.05) despite the fact that insulin‐like growth factor‐1 levels were not different. Plasma glucose, insulin, cortisol, glucagon, epinephrine, and norepinephrine levels were not significantly different than those of the normal volunteers. Fasting HGP rates were slightly but not significantly elevated in the group of colon cancer patients compared with the normal volunteers (2.09 ± 0.11 mg/kg per minute us 1.79 ± 0.10, p =.10). Plasma LA was not significantly elevated in the colon cancer group (63.3 ± 3.0 μmol/kg per hour vs 57.7 ± 4.2; p =.25). Five days of continuous 5‐fluorouracil chemotherapy was associated with a significant elevation in both the fasting glucose level (97 ± 3 mg/dL vs 106 ± 5, p <.05), and HGP (2.09 ± 0.11 mg/kg per minute us 2.27 ± 0.10; p <.05). The increased fasting glucose value was associated with an increase in the insulin response to the intravenous glucose tolerance test. LA was not affected by the chemotherapy infusion (63.3 ± 3.0 μmol/kg per hour us 58.4 ± 3.0). In contrast, LO was significantly increased (11.5 ± 1.1 μmol/kg per hour us 13.0 ± 1.0, p <.05) and leucine incorporation into protein was significantly decreased (51.2 ± 2.7 μmol/kg per hour us 45.4 ± 2.7, p <.05) while the patients received chemotherapy. Evaluating all the the counter‐regulatory hormone measurements demonstrated a significant correlation between the mean HGP and growth hormone levels (r =.446; p <.05). Twenty‐four‐hour growth hormone pulse frequency in a patient with diffuse carcinoma was 2.5 times the normal rate compared with a sex‐and weight‐matched normal volunteer. The HGP rate was increased from 1.7 mg/kg per minute to 2.12 mg/kg per minute in the cancer patient. Further work is in progress to identify the possible association between growth hormone physiology and the elevation in fasting HGP observed in cancer patients. (Journal of Parenteral and Enteral Nutrition 16:675–71S)