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Biomedical subjects

S B Heymsfield

Publications and source records attributed to S B Heymsfield.

At least 235 records · Page 13Linked to original sources
PubMed1984

Nutrient bioavailability from nasojejunally administered enteral formulas: comparison to solid food.

The net absorption and retention of energy, fat, nitrogen, and six elements (potassium, phosphorus, calcium, magnesium, sodium, and chloride) from two intrajejunally infused enteral formulas were compared to solid food. Undernourished patients (group 1) underwent two consecutive 7-day balance studies on a predigested protein-low fat (elemental) formula and an intact protein-standard fat (polymeric) formula, the initial diet selected randomly. Periods were isocaloric and isonitrogenous, but differed in the amounts of remaining elements. The undernourished patients in group 2 ate a solid food standard hospital diet for the 7-day balance study in an amount equal in energy and protein to group 1. There were no major differences in the nutrient absorption between the three diets. Nitrogen balance was similar for the two formulas (mean +/- SD) (elemental 6.1 +/- 3.5 g/day; polymeric 4.8 +/- 3.2 g/day) and solid food (5.2 +/- 3.5 g/day), and the balance for the six remaining elements was approximately proportional to the amount supplied. Subjective tolerance of both formulas was good, with a tendency for superior tolerance of the polymeric formula. We conclude that for the nutrients investigated, 1) intrajejunally administered enteral formulas are capable of renourishing hospitalized patients with an efficacy similar to that of solid food, and 2) predigestion of the formula does not improve absorption.

Biological Availability↗
PubMed1984

Effect of meal size on myocardial oxygen requirements: implications for postmyocardial infarction diet.

The validity of the assumption that eating a small meal places less postprandial demands on the circulatory system than eating a large meal was examined in eight healthy volunteers. Five meal sizes that ranged from 15 to 75% of daily energy requirements were fed. There was a significant correlation between meal size (in percentage of daily caloric requirements) and peak percentage change in cardiac index (p less than 0.001) and stroke volume (p less than 0.05) (echocardiography); heart rate (p less than 0.001); an index of myocardial oxygen consumption (heart rate X mean blood pressure) (p less than 0.01); and whole body oxygen consumption (p less than 0.001). There was no significant correlation between meal size and peak percentage change in systolic and diastolic blood pressure. The duration of hemodynamic and metabolic changes that followed medium and large meals (greater than or equal to 35% of daily energy needs) exceeded smaller meals (less than or equal to 25% of energy needs). These results may have implications in the management of patients with ischemic heart disease.

Adolescent↗
PubMed1984

Respiratory, cardiovascular, and metabolic effects of enteral hyperalimentation: influence of formula dose and composition.

Respiratory, cardiovascular, and metabolic changes were monitored during balance studies in undernourished patients receiving continuous enteral formula feeding. The nutrient solutions, either high carbohydrate (83% of kcal) or high fat (50% of kcal), were administered at doses ranging from 2.7 to 6.0 X 10(-2) kcal X kg fat free body mass-1 X min-1. For both formulas, the observed physiological changes between fasting and the lower rates of energy infusion (ie, maintenance-slow growth) were either zero or relatively small. As formula dose was advanced into the rapid repletional range, physiological changes were more pronounced; there were linear increases in oxygen consumption, carbon dioxide production, minute ventilation, heat production, heat release, nitrogen balance, and change in heart rate from the base-line (all p less than 0.05 for both formulas). The rate at which carbon dioxide production, minute ventilation, and heat production increased with advancing energy infusion rate was also greater for the high carbohydrate formula relative to the high fat formula (p less than 0.02, less than 0.07, and less than 0.06, respectively). The physiological changes caused by continuous intragastric feeding are therefore a function of formula infusion rate and composition. Knowledge of these changes can be applied to patients treated for semistarvation who suffer respiratory or cardiac insufficiency.

Adult↗
PubMed1984

Myoglobinuria and acute renal failure associated with intravenous vasopressin infusion.

Myoglobinuria and acute renal failure were observed in two patients with vasopressin-treated gastrointestinal hemorrhage. Because there were no other obvious causes of renal failure in either patient, we propose that skeletal muscle ischemia developed during vasopressin infusion, followed by release of myoglobin and renal damage. This association should be considered in the period after vasopressin-treated gastrointestinal hemorrhage.

Acute Kidney Injury↗
PubMed1983

Measurement of muscle mass in humans: validity of the 24-hour urinary creatinine method.

Measuring muscle mass is an important component of the nutritional assessment examination and a suggested index of this body space is the 24-h urinary excretion of creatinine. The method originated from studies in a variety of animal species in whom early workers found a parallelism between total body creatine and urinary excretion of creatinine. Assuming that nearly all creatine was within muscle tissue, that muscle creatine content remained constant and that creatinine was excreted at a uniform rate, an obvious "corollary" was that urinary creatinine was proportional to muscle mass. The so-called "creatinine equivalence" (kg muscle mass/g urinary creatinine) ranged experimentally from 17 to 22. One of the limiting factors in firmly establishing this constant and its associated variability was (and is) the lack of another totally acceptable noninvasive technique of measuring muscle mass to which the creatinine method could (or would) be compared. An improved understanding of creatine metabolism and a variety of clinical studies in recent years has tended to support the general validity of this approach. However, specific conditions have also been established in which the method becomes either inaccurate or invalid. While creatinine excretion may serve as a useful approximation of muscle mass in carefully selected subjects, there remains a need for accurate and practical indices of muscle mass for use in the individuals in whom the method cannot be reliably applied.

Adult↗
PubMed1983

Home nasoenteric feeding for malabsorption and weight loss refractory to conventional therapy.

Two patients with malabsorption syndrome and weight loss refractory to conventional pharmacologic and dietary therapy were evaluated on a metabolic ward. Baseline studies indicated moderate to severe protein-energy malnutrition, and severe energy, fat, and nitrogen malabsorption. Metabolic balance studies on low-fat elemental formulas infused nasoenterally over 18-hour periods indicated improved retention of nitrogen, phosphorus, calcium, magnesium, and energy when compared with a solid food diet. Because this dietary modification appeared to correct their malabsorption, both patients learned to insert the nasoenteral tube themselves, and a low-calorie solid-food diet combined with nocturnal tube feedings was continued at home. During the next 9 to 12 months, both patients had increases in body weight, and in the mass of fat-free tissue, skeletal muscle, and fat. This therapeutic approach may correct life-threatening semistarvation in selected patients.

Body Weight↗
PubMed1982

Increased ureagenesis and impaired nitrogen use during infusion of a synthetic amino acid formula: a controlled trial.

In a controlled trial conducted to assess the biologic value of High Nitrogen Vivonex, we compared this "elemental" diet with predigested protein--Product MJ7041--and with solid food during eight-day balance periods. Each formula was evaluated in three patients with malabsorption and one without it, by measuring apparent absorption of nitrogen and energy, nitrogen balance, and blood and urinary urea nitrogen. Overall energy and nitrogen absorption in the patients with malabsorption was better with either special diet than with solid food; net intestinal uptake of Vivonex tended to be higher but not consistently so in al patients. However, nitrogen balance differed consistently during the three diets; with solid food and MJ7041, retention of absorbed nitrogen was respectively, nine and 16 times greater than with Vivonex. Moreover, institution of each Vivonex period led to a prompt increase in urea nitrogen--a trend quickly reversed by the alternative diets. Although the mechanism for the impairment of nitrogen use caused by High Nitrogen Vivonex is unknown, its low biologic value and tendency to cause azotemia should be kept in mind.

Adult↗
PubMed1982

Biochemical composition of muscle in normal and semistarved human subjects: relevance to anthropometric measurements.

Anthropometric methods aimed at assessing muscle size in undernourished subjects assume a constant proportionality between the mass (i.e., size) and composition (specifically protein-energy content) of this tissue. This assumption was examined in three autopsy groups: controls (n = 11, sudden traumatic death), early semistarvation (n = 6), acute preterminal disease), and chronic semistarvation (n = 34, severe weight loss over time). Results of semistarved groups were expressed relative to respective control value. Early semistarvation produced no detectable change in muscle mass, protein, or total energy content (per gram wet weight), although RNA and glycogen were -50 to -70% of control value (p less than 0.05). Chronic semistarvation caused muscle atrophy (-54.2%), but not all measured constituents were reduced to the same degree. The results were H2O--52.9%, collagen--46%, noncollagen proteins--65.3%, total lipids--40%, DNA--54.1%, RNA--81.7%, glycogen--90.3%, and total energy--59.6%. Muscle per unit mass in chronic semistarvation thus reflects relatively more H2O and less protein and energy when compared to normal tissue. About 85 to 95% of muscle protein-energy loss can be detected by anthropometric measurements of muscle size; the remaining 5 to 15% depletion of protein and energy is masked by muscle compositional changes. Proper interpretation of anthropometric data requires an understanding of these unmeasured but important compositional differences in normal and semistarved muscle.

Anthropometry↗
PubMed1982

Anthropometric measurement of muscle mass: revised equations for calculating bone-free arm muscle area.

Arm muscle area (AMA, cm2) is currently calculated from triceps skinfold thickness (TSF, cm), and midarm circumference (MAC, cm). In assessing the accuracy of the current equation by comparison to AMA measured by computerized axial tomography, error in each of the four approximations made was found to result in a 20 to 25% overestimate of AMA. Two correctible error sources were: a 10 to 15% overestimation caused by assuming a circular midarm muscle compartment and a 5 to 10% overestimation due to inclusion of midarm cross-sectional bone area. Corrected AMA equations for men and women were respectively: [(MAC - pi x TSF)2/4 pi] - 10, and [MAC - pi x TSF)2/4 pip] - 6.5. With two additional study groups, the overall improved accuracy of the new equations was confirmed, although the average error for a given patient was 7 to 8%; the relationship between corrected AMA and total body muscle mass was established [muscle mass (kg) = (ht, cm2) (0.0264 + 0.0029 x corrected AMA)]; and the minimal range of corrected AMA values compatible with survival (9 to 11 cm2) was defined. Bedside estimates of undernutrition severity and prognosis can therefore be calculated from two simple measurements, TSF and MAC.

Adult↗
PubMed1981

Decreased myocardial taurine levels and hypertaurinuria in a kindred with mitral-valve prolapse and congestive cardiomyopathy.

In a 46-member kindred with consanguineous ancestry, eight progeny in two generations had congestive cardiomyopathy and markedly elevated urinary taurine levels (range, 411 to 536 mg per gram of creatinine [normal +/- S.D., 89 +/- 32]). Ten other family members had late or holosystolic mitral-valve prolapse, and elevated urinary taurine values (range, 215 to 265 mg). In two with mitral-valve prolapse, congestive cardiomyopathy eventually developed while the amounts of urinary taurine doubled. One member with mitral-valve prolapse died suddenly; histologic examination revealed myocardial fibrosis in the papillary muscles and myocardial taurine values of 16.9 +/- 3.0 mumol per gram of protein (normal +/- S.E., 33.2 +/- 3.6). Four other family members with congestive cardiomyopathy had myocardial fibrosis at autopsy or biopsy and mean myocardial taurine levels of 9.2 +/- 2.2 mumol. We conclude that hypertaurinuria and depressed levels of taurine in the myocardium may be associated with one type of mitral-valve-prolapse syndrome and a rapidly progressive form of congestive cardiomyopathy.

Adolescent↗
PubMed1981

Energy malabsorption: measurement and nutritional consequences.

Fecal energy (FE) loss was measured using bomb calorimetry in 30 patients; 14 had a history of malabsorption, while 16 had no history of intestinal dysfunction. Average digestibility (and range) of energy and FE loss were 73% (48 to 91%) and 493 kcal/day (177 to 927 kcal/day) in the group with malabsorption, compared to 96% (89 to 99%) and 74 kcal/day (8 to 146 kcal/day) in the group without malabsorption, respectively. Metabolizable energy supplied by the diet (intake kcal -- (fecal kcal + urinary kcal) was below the calculated daily energy requirement in five of seven patients with malabsorption; in three of these five subjects the combination of decreased energy intake and increased FE loss produced negative energy balance, while in the remaining two patients malabsorption alone caused negative energy balance. Inadequate metabolizable energy in these five patients was associated with weight loss and protein-energy malnutrition. The usual clinical laboratory tests applied to the study of malabsorption, including fecal fat, fecal nitrogen, and stool weight, were poor predictors of FE loss. These tests were also of limited value in assessing the effects of dietary modification on energy malabsorption. Contrastingly, bomb calorimetry provided a simple and accurate alternative in quantitatively assessing FE loss in the patient with malabsorption.

Calorimetry↗
PubMed1981

Hemodynamics of LeVeen shunt pulmonary edema.

In order to characterize the circulatory changes which may lead to pulmonary edema following the surgical placement of a LeVeen peritoneovenous shunt, intraoperative hemodynamic studies were performed on five consecutive patients without clinical evidence of cardiac disease undergoing shunt insertion. Within 30 minutes after opening the peritoneovenous shunt, there was a marked increase in pulmonary capillary wedge pressure, cardiac output, and stroke work index, and a sharp decline in both pulmonary and systemic vascular resistances. In three patients, pulmonary edema did not occur; in one patient, pulmonary edema occurred transiently but responded to furosemide administration. In these four patients, systemic vascular resistance continued to drop over the ensuing hours and the elevated pulmonary capillary wedge pressure also decreased appropriately with furosemide. The fifth patient developed persistent pulmonary edema. In this subject, systemic vascular resistance continued to rise and the elevated pulmonary capillary wedge pressure did not respond to intravenous furosemide. This study suggests that uncomplicated LeVeen peritoneovenous shunt insertion may result in a drop in systemic vascular resistance which lowers left ventricular afterload, and, thus, may protect most patients from pulmonary edema. In contrast, a continued rise in systemic vascular resistance and afterload may contribute to pulmonary edema refractory to diuretic therapy and should probably be treated with a parenteral afterload-reducing agent.

Ascites↗