The role of Intralipid in prolonged parenteral nutrition. I. As a caloric substitute for glucose.

Three stable patients were studied in order to assess the role of intravenous fat solutions (Intralipid) in long-term home parental nutrition. The standard source of nonprotein calories (NPC) in these patients was 60% glucose. Replacing 40% of NPC by Intralipid was effective in maintaining nitrogen balance and allowed total infusion time to be reduced from 12 hr to 8 hr. The serum triglyceride level was significantly elevated when glucose was used as the sole source of NPC, whereas serum cholesterol was significantly elevated when 40% of NPC were supplied by Intralipid.

Blood pressure control in dialysis patients: importance of the lag phenomenon.

Failure by the world dialysis community to understand and use the dry-weight method of blood pressure (BP) control has resulted in an increasing incidence of treatment-resistant hypertension, which remains the principal cause of cardiovascular morbidity and mortality. This failure may in part be because the relationship between the extracellular volume (ECV) and BP is not simple and linear, but complex, because of a lag of several weeks between the normalization of the time-averaged ECV and the decrease in BP. Another cause for this failure may be the unwillingness to taper and stop all antihypertensive medications during the transition from hypertension to normotension. In this report, we describe in detail the lag phenomenon, document its presence during treatment in other populations, and describe how this knowledge is used in the application of the dry-weight method of drug-free BP control in the dialysis population.

Whole blood trace element concentrations during total parenteral nutrition.

Samples of whole blood in eight patients on long-term total parenteral nutrition (TPN) and in four who served as controls were analyzed for trace element concentrations of Au, Br, Cu, Mn, Cr, Sb, Fe, Zn, Co, Hg, Rb, and Se. The concentrations of essential elements in the patients deviated significantly from those in the control group. The Mn concentration in blood was consistently higher in patients, owing to the high Mn concentration in the nutrient solutions. A reciprocal relationship between Cu and Zn was demonstrated in one patient. Some trace element concentrations are correlated with the duration of malabsorption and the amount of oral intake during TPN. This study shows that patients on TPN may have abnormal trace element profiles and that TPN currently does not supply the necessary concentrations of trace elements.

Evolution of the technique of home parenteral nutrition.

Experience with use of the artificial kidney in the home led to the concept of self-infusion of parenteral nutrients at home. Originally called an artificial gut, the term has been changed to home parenteral nutrition. The original method proposed for circulatory access, a side-arm on an A-V shunt, failed and forced the development of a right atrial catheter which proved to be both safe and longlasting. A safe and rapid self-mix system of nutrient preparation was developed which made the patient independent of the hospital pharmacy. A wearable infusion device proved workable but was abandoned because it was unnecessary and greatly interfered with patient rehabilitation. A portable infusion system has been developed which facilitates patient mobility during infusions as well as patient travel.

Creatinine production rate measured by whole body counting of 40K.

The creatinine production rate in dialysis patients was measured by potassium-40 whole body counting and carbon-14 creatinine injection. The correlation coefficient for the two methods was 0.96, p less than 0.005. An equation predicting whole body potassium (WBK) for normal subjects was found to accurately predict the WBK of dialysis patients as well. Two equations predicting creatinine production from WBK were compared with measured production rates and were found to agree within experimental error. It is thus possible to use the predictive equations to accurately estimate creatinine production without resorting to experimental measurements. These findings should simplify the use of computer models of the patient-artificial kidney system where accurate estimations of creatinine production rates are essential.

Creatinine degradation. II: Mathematical model including the effect of extra-renal removal rates.

Previous models of the patient-artificial kidney system have neglected the contribution of creatinine degradation as a pathway for creatinine removal. Creatinine degradation can remove significant amounts of creatinine from dialysis patients, and models which neglect this mechanism are susceptible to error in predicting creatinine concentrations. In this study three models of the patient-artificial kidney system have been developed. The single pool model is the easiest to use since it requires a minimum of patient information, but it is the least accurate in predicting creatinine plasma concentrations. A two-pool model predicts experimental data within 5 percent, and appears to be the most useful model from the consideration of ease of use and accuracy. A three-pool model was derived that is suitable for use on a mini-computer or programmable calculator providing the device is capable of inverting a 3 x 3 matrix. The three-pool model predicts the measured plasma concentrations with 0.5 percent. These models provide a means to account for creatinine degradation and accurately predict creatinine concentrations in dialysis patients.

Creatinine degradation I: the kinetics of creatinine removal in patients with chronic kidney disease.

The existence of an alternative route of excretion for creatinine in subjects with chronic renal failure has been demonstrated. The data presented in this study confirm the hypothesis that creatinine is converted into other metabolites, probably by action of the gut flora. Creatinine degradation was quantitated in a group of subjects that spanned a wide range of kidney functions from normal to no renal function. Five patients were analyzed who were on maintenance dialysis, five were predialysis and two subjects were normal with respect to kidney function. Creatinine degradation expressed as a percentage of production varied from 13.9 to 27.7% in the dialysis patients, 0 to 42.3% in the pre-dialysis patients and was 0% in the controls. Creatinine degradation was correlated with plasma creatinine degradation was correlated with plasma creatinine levels in predialysis (r = 0.73, p less than 0.01), but not in dialysis patients. No correlation was found between creatinine degradation and production in either group. It is concluded that significant amounts of creatinine are degraded in dialysis patients, and this removal mechanism must be accounted for in models of the patient-artificial kidney system.