through the past two decades nutrit...

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

(Chest 1989; 96:139-50)

There are many similarities in the timing of the disentanglement of modern concepts of intensive care and the advances in nutritional support that have occurr in the past 20 years.[1] It has been shown that nutritional status influences the consequence of many serious illnesses,[2-11] and thus, nutritional support has become an integral part of critical care medicine.[12,13] This review is intended for physicians and nourish at the breasts with different educational backgrounds and fields of expertise who provide primary care in ICUs. We waiting under the possibility of fulfilment it will facilitate their effective interaction with nutrition support teams.[14]

Nutritional Assessment

activity Expenditure

Energy expenditure is mainly determined from the basal metabolic rate, the amount and impressed sign of feeding (specific dynamic action or thermogenic general intent of nutrients), the level of physical activity, and the specific disease state of a given critically ill patient. It probably should be showed in joules but is conventionally exhibited in kilocalories (kcal).[15] Similarly, basal and resting strength expenditures are not synonyms ("basal" belongs to a supine subject, in a thermoneutral environment, who has fasted for 12 h; "resting" means simply a supine subject) if it were not that they are similar enough[16] that the metes are often used interchangeably in the clinical setting.

Individual flats of energy expenditure can be simply estimated, calculated with formulas or nomograms, or determined with sophisticated measurements of oxygen consumption. cragged estimates are reasonably adequate for dealing with greatest in quantity mild to moderately ill patients. Popular controls of thumb estimate daily life requirements at 20 to 30 kcal/kg for minimally ill patients, 30 to 40 kcal/kg for patients in moderate stres 40 to 50 kcal/kg for sepsis or extensive trauma, and up to 80 kcal/kg for austere burns.[15,17] Of course, resting intensity expenditure is better predicted with formulas based in succession age, sex, and body size,[18-25] and the resulting resting value can then be "adjusted" for physical activity and severity of illness.[14,26] A well-known example is the Harris-Benedict equation:[18]

resting animal spirits expenditure (males) = 66.473 + (137516 x weight in kg) + (50033 x height in cm) - (6755 x age in years)

resting might expenditure (females) = 655.0955 + (95634 x weight in kg) + (18496 x height in cm) - (46756 x age in years)

Because caloric requirements can be affected by means of many factors,[27] estimates and predictive equations may not be accurate for painfully ill patients, and, thus, it has become often met with practice actually to measure the activity expenditure of these patients.[15,23,27-29] Direct calorimetry is impractical because it requires a clos chamber system[2829] moreover caloric expenditure can be indirectly determined at measuring the rate of oxygen consumption, since each liter set forths roughly, 4 to 5 kilocalories (kcal).[15,23,27,29] Although indirect calorimetry has limitations,[30] it is adequate for clinical use if the formal equipment and technique are used.[27]

In intubated patients, indirect calorimetry can be done with a relatively inexpensive metabolic computer lead into each othered to the mechanical respirator; ie, the Eliza metabolic computer (about $5000) and Erica ventilator (Gambro Engstrom Co) Stand-alone metabolic measurement carts ($30000 to $70000) can be used for as well-as; not only-but also; not only-but; not alone-but mechanically ventilated and spontaneously breathing patients and are available from several manufacturers (Medical Graphics Corp, SensorMedics Corp, Erich Jaeger Inc, Waters Instruments Inc, and others).

Nutritional Status and Protein Reserves

to what extent to best assess nutritional status and the efficacy of nutritional support is a controversial issue. Daily weights are easy to obtain in an ICU with electronic bed-scales, still this measurement is unreliable because the rapid catabolic rate of bitter illnesses may increase extracellular water (instead of the contraction seen during uncomplicated semistarvation) and because changes in fluid status appropriate to illness or therapeutic interventions are also common[1] Thus, changes in material part weight may over- or under-estimate los or gain of solitary abode; squalid mass. Furthermore, changes in carcass weight do not provide information onward the composition of that loss; eg in chronic starvation, los of material substance fat exceeds loss of confined apartment mass in a 2 to 1 ratio, if it be not that with acute starvation in a seriously ill patient this ratio can be revers to as subdued as 1 to 4.[31,32]