Total parenteral nutrition with selective histidine depletion in man. II. Hematological, lipid, and hormonal responses.
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Biomedical subjects
Publications and source records attributed to H L Anderson.
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Effects of dietary histidine and arginine on nitrogen retention were compared in six young men consuming for 1 week, each of six semipurified diets containing eight indispensable amino acids proportioned as in casein and 6.3 g nitrogen daily. Nonspecific nitrogen was either A) a mixture of six dispensable amino acids and arginine (diet 1) or arginine and histidine (diet 2) in casein proportions, or B) an isonitrogenous mixture of glycine and diammonium citrate alone (diet 3), with histidine (diet 4), arginine (diet 5), or histidine and arginine (diet 6). Nitrogen retention was significantly greater when the nonspecific nitrogen source was dispensable amino acids, arginine and histidine (diet 2) than when it was glycine and diammonium citrate (diet 3). mean balances were positive only when diets contained histidine (diets 2, 4, and 6). Histidine with arginine (diets 2 and 6) significantly improved nitrogen retention compared to arginine alone, but the balance, although positive, was not significantly improved when histidine was fed without arginine (diet 4). Urinary urea nitrogen confirmed these data. Indicators of erythrocyte status, plasma enzyme activities and proteins, and creatinine clearance were unaffected by diet. In summary, histidine supplementation of the low nitrogen diet improved total nitrogen utilization when arginine was present in the diet.
The effects of dietary histidine and arginine on fasting and 1 and 2 hour postprandial plasma free amino acid and urea concentrations were studied in six young men. For 1 week each, they were fed six different diets containing 6.3 g of nitrogen daily. Each diet contained eight indispensable amino acids, cystine and tyrosine proportioned as in casein and a different mixture of dispensable nitrogen: A) six dispensable amino acids plus argine (diet 1) or plus histidine and arginine (diet 2) in the casein pattern, or B) an isonitrogenous amount of glycine and diammonium citrate alone (diet 3), with histidine (diet 4), with arginine (diet 5) or with histidine and arginine (diet 6). The fasting plasma concentrations of the seven indispensable amino acids assayed and their similar postprandial patterns were unaffected by the dietary treatments. Both fasting and postprandial plasma histidine concentrations were significantly lower when the histidine-low diets were fed than when the histidine-supplemented diets were fed. Histidine supplementation promoted a reduction in fasting plasma urea nitrogens. Proline concentrations were lowered significantly when proline was removed from the dietary amino acid mixtures, but plasma arginine concentrations were unaffected by arginine removal. Plasma histidine was maintained at lower concentrations in dietary histidine deficiency than when histidine was added to the low nitrogen diets.
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Selected aspects of total parenteral nutrition in man are reviewed with emphasis on carbohydrate, lipid, and hormonal interactions. In an experiment to test for the essentiality of a specific amino acid, a normal adult man received all major and minor nutrients, except lipids, by intravenous alimentation for 48 days. A chemical deficiency of essential fatty acids without clinical symptoms was promptly observed in four plasma lipid fractions and the phospholipid fraction of erythrocytes. With the glucose providing 2,600 kcal/day, blood glucose remained normal, but a hypertriglyceridemia was observed. Plasma insulin rose and cortisol fell. To meet the essential fatty acid and energy requirements of man, critical experiments are needed to define the safe utilization of lipid emulsions during prolonged intravenous nutrition.
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The authors designed and tested a 14F outside diameter thin-walled double lumen catheter (DLC) for neonatal venovenous (VV) extracorporeal membrane oxygenation (ECMO). In vitro tests with water and dye solution showed capacity of the drainage lumen was 1,096 ml/min at 100 cm siphon, and pressure drop across the perfusion lumen was 300 mmHg at 500 ml/min flow. Recirculation at 500 ml/min flow ranged from 5 to 29%, depending upon simulated cardiac output. The highest serum hemoglobin during 12 hour 400 ml/min flow VV bypass in five dogs was 49 mg/dl. Typical oxygen transport in four dogs was 25 cc/min at 400 ml/min flow. This catheter is well suited for clinical VV ECMO in neonates.
After satisfactory development and testing of a polyurethane 14 Fr double lumen catheter, we used this device for venovenous extracorporeal life support in neonates who had respiratory failure. This catheter was designed for single site cannulation of the internal jugular vein, thereby sparing the carotid artery from ligation. Cannulation was successful in 17 of 21 neonates, with 15 successful venovenous runs, whereas 2 of the 17 patients were converted to venoarterial bypass because of inadequate support. Oxygenation and CO2 removal were adequate in the remaining patients. Average time on bypass was 111 hours. All 15 patients survived, and exploration of the cannulation site for bleeding was required in three patients. Preoxygenator pressure, recirculation of oxygenated blood, and hemolysis were all within acceptable levels during each run. Venovenous extracorporeal life support with the double lumen catheter can replace venoarterial access in most cases of neonatal respiratory failure.
The efficacy of extracorporeal life support (ECLS, ECMO) in the management of severe adult cardiorespiratory failure remains controversial. The purpose of this review is to evaluate the authors' institutional experience with ECLS in adult patients. Between 1988 and 1993, 65 moribund patients with respiratory (n = 51) and cardiac (n = 14) failure were supported with ECLS. Criteria for initiation of ECLS were: 90% chance of mortality despite maximal conventional respiratory management, good potential for recovery, and age younger than 60 years. Venovenous bypass was used in 40 and venoarterial in 25 patients. Respiratory management included low rate, low pressure ventilation with an inspired oxygen fraction < or = 0.5 and tracheostomy tube placement. Continuous systemic heparinization was used, maintaining whole blood activated clotting time (ACT) between 180 and 200 sec. Survival data are summarized as follows: pneumonia (n = 25) 56%, adult respiratory distress syndrome (n = 24) 58%, airway support (n = 2) 100%, and cardiac support (n = 14) 29%. The most common complication was bleeding (68%), which was managed in most patients by reduction of anticoagulation or local measures such as packing. Data from survivors and nonsurvivors of ECLS in patients with respiratory failure were compared in an attempt to define prognostic indicators of improved survival. The only prognostic indicator of survival that could be identified was the period of time on the ventilator before the initiation of ECLS (survivors = 3.0 +/- 2.4 days, nonsurvivors = 6.1 +/9- 4.0 days, P < 0.005). It is concluded that ECLS can be a life saving modality for the management of severe adult cardiorespiratory failure. Earlier institution of ECLS in the course of cardiopulmonary failure may improve outcome.
Acute or adult respiratory distress syndrome (ARDS) contributes to mortality and morbidity in the intensive care environment. Appropriate application of microprocessor-controlled mechanical ventilatory support, pathophysiology of the disease, and new pharmacologic modalities are currently being investigated. Mechanical ventilation is usually begun when respiratory failure is caused by alveolar hypoventilation or hypoxia. Primary choices for this therapy are control-mode ventilation, assist-control ventilation, pressure-control ventilation, intermittent mandatory ventilation, and synchronized intermittent mandatory ventilation with the addition of positive end-expiratory pressure. Patients who deteriorate despite these interventions may require alternative modes of ventilation. Pharmacologic agents in ARDS is important due to the multifactorial pathophysiologic and pharmacodynamic processes that are part of the disease. Clinical studies will continue to determine advantageous agents. Unfortunately, no convincing data exist that any pharmacologic or nonpharmacologic strategy is superior for the support of these patients or results in a better outcome than others.