Potential Aluminum Exposure from Parenteral Nutrition in Patients with Acute Kidney Injury

Background:

Patients' exposure to and potential toxicity from aluminum in parenteral nutrition (PN) formulations is an important concern of healthcare providers.

Objective:

To determine the potential for aluminum toxicity caused by PN in hospitalized adults who have risk factors of both acute kidney injury and PN.

Methods:

Adults who required PN and had a serum creatinine (SCr) level at least 1.5 times greater than the admission SCr on the first day of PN were studied in a retrospective fashion. Protein was administered based on whether hemodialysis was being used (0 6-1 g/kg/day without hemodialysis; 1.2-1.5 g/kg/day with hemodialysis). Aluminum exposure was determined for each patient by multiplying the volume of each PN component by its concentration of aluminum Unpaired f-tests, Fisher's exact test, and analysis of variance were used for statistical analysis. Data are presented as mean ± SD.

Results:

Thirty-six patients (aged 50.4 ± 20.4 y; weight 90.2 ± 32.8 kg) were studied. Initial serum urea nitrogen and SCr were 47 ± 23 and 3.3 ± 1.4 mg/dL. respectively. Twelve patients received hemodialysis. The mean aluminum exposure was 3.8 ± 2 μg/kg/day in the 36 patients, Of these, 29 had safe calculated aluminum exposure (<5 μg/kg/day) and 7 had high calculated aluminum exposure (>5 μg/kg/day), Patients with safe aluminum exposure had significantly higher SCr levels than did those with high aluminum exposure (3.5 ± 1.5 vs 2.2 ± 0.7 mg/dL; p < 0.04). Patients with high aluminum exposure received significantly more aluminum from calcium gluconate compared with those who had safe aluminum exposure (357 ± 182 vs 250 ± 56 μg/day; p < 0.02). Limitations of the study include its retrospective design, which resulted in calculated versus direct measurement of aluminum.

Conclusions:

Using our calculations, we believe that most patients with acute kidney injury who require PN do not receive excessive exposure to aluminum from the PN formulation, despite having 2 risk factors (acute kidney injury, PN) for aluminum toxicity,

Warfarin Resistance and Enteral Tube Feeding: An Old Problem with a New Solution

Nutrition Support Pharmacist features issues pertinent to the practice of clinical pharmacy in the area of metabolic support.

Low serum total calcium concentration as a marker of low serum ionized calcium concentration in critically ill patients receiving specialized nutrition support

BACKGROUND

The intent of this study was to ascertain to what extent serum total calcium concentration (tCa) <7 mg/dL reflects hypocalcemia (defined by ionized calcium concentration [iCa] of < or = 1.12 mmol/L) in critically ill patients receiving specialized nutrition support.

METHODS

Adult patients (> or = 18 years) admitted to the trauma, surgical, medical, burn, or neurosurgical intensive care units, trauma stepdown unit, or progressive care unit and referred to the nutrition support service were retrospectively identified for potential inclusion into the study. Serum chemistries, arterial blood gas measurements, nutrition markers, and serum iCa were simultaneously obtained from each patient approximately 1 day after initiation of specialized nutrition support. Patients with a serum creatinine > or = 2 mg/dL, hyperphosphatemia (> or = 6 mg/dL), severe hypomagnesemia (< or = 1.12 mg/dL), history of metabolic bone disease, or parathyroid disease were excluded from the analysis.

RESULTS

One hundred ninety-five patients (91% who had multiple trauma, with a mean Injury Severity Score 31 +/- 13) were enrolled into the study. Specialized nutrition support was initiated 2.8 +/- 1.8 days and calcium status was studied 4.2 +/- 3.1 days after hospital admission, respectively. The majority (28 of 33, or 85%) of patients with a tCa <7 mg/dL were hypocalcemic compared with 33% (22 out of 66) of patients with a tCa of 7-7.4 mg/dL, and 11% (11 of 96) of those with a tCa of 7.5-7.9 mg/dL (p < .001).

CONCLUSIONS

Critically ill patients with a serum total calcium concentration of <7 mg/dL have a high rate of hypocalcemia (iCa < or = 1.12 mmol/L). Hypocalcemia, defined as a serum iCa of < or = 1.12 mmol/L, occurs in 85% of acutely ill patients with a serum tCa <7 mg/dL.

Treatment of moderate to severe acute hypocalcemia in critically ill trauma patients

BACKGROUND

Our recent data indicate that 21% of critically ill, adult, multiple-trauma patients receiving specialized nutrition support experience hypocalcemia. However, evidence-based methods for the treatment of moderate to severe acute hypocalcemia (ionized calcium concentration [iCa] <1 mmol/L) are lacking.

METHODS

The efficacy of an infusion of 4 g of calcium gluconate was evaluated in 20 critically ill, adult, multiple-trauma patients with moderate to severe hypocalcemia (iCa <1 mmol/L). The calcium gluconate was infused at a rate of 1 g/h in a small volume admixture. A serum iCa determination was obtained on the following day.

RESULTS

Calcium gluconate infusion significantly increased serum iCa from 0.90 +/- 0.08 mmol/L to 1.16 +/- 0.11 mmol/L (p < .001) on the following day. This dosage regimen was successful for achieving a serum iCa >1 mmol/L for 19 of 20 (95%) hypocalcemic patients and achieved a concentration >1.12 mmol/L in 14 (70%) of the patients. Two patients developed mild hypercalcemia (iCa of 1.34 mmol/L and 1.38 mmol/L) postinfusion.

CONCLUSIONS

A short-term infusion of 4 g of intravenous (IV) calcium gluconate for the treatment of moderate to severe hypocalcemia appears to be a promising regimen for critically ill, adult, multiple-trauma patients.

Dose-dependent characteristics of intravenous calcium therapy for hypocalcemic critically ill trauma patients receiving specialized nutritional support

OBJECTIVE

The purpose of this investigation was to evaluate the dose-dependent characteristics of intravenous calcium gluconate therapy for hypocalcemic critically ill patients.

METHODS

The dose-dependent characteristics of 2 g versus 4 g of intravenous calcium gluconate therapy were evaluated in 25 critically ill, adult multiple trauma patients with hypocalcemia. The calcium gluconate was infused at a rate of 1 g/h for both groups. Patients weighed within 90% to 120% of ideal body weight, had normal renal function, did not receive diuretic therapy, and did not have anasarca.

RESULTS

Fifteen patients with mild hypocalcemia (serum ionized calcium concentration [iCa] 1-1.12 mmol/L) were given 2 g of calcium gluconate. Ten patients with moderate to severe hypocalcemia (iCa <1 mmol/L) were given 4 g. Each dosage group had a significant (P < or = 0.001) increase in iCa (from 1.07 +/- 0.05 to 1.17 +/- 0.05 mmol/L and from 0.92 +/- 0.08 to 1.16 +/- 0.11 mmol/L, respectively). Each dosage group retained about half of the dose in the exchangeable calcium space (P = NS between groups), but the higher dosage group retained significantly more elemental calcium overall (81 +/- 38 versus 201 +/- 50 mg, respectively, P < or = 001). Serum ionized calcium concentrations achieved a plateau without a further decline in iCa by 10 h after completion of the infusion for each dosage.

CONCLUSION

About half of the administered elemental calcium dose was retained for each dosage group, with the higher dose (4 g) resulting in significantly more elemental calcium retention in the exchangeable calcium space. An iCa determination performed about > or =10 h after the completion of the calcium gluconate infusion should be sufficient time to ensure equilibration of iCa to assess the efficacy of the therapy. This mode of calcium therapy serves as an effective means for providing calcium to the acutely hypocalcemic, critically ill, multiple trauma patient.

Treatment of acute hypocalcemia in critically ill multiple-trauma patients

BACKGROUND

Recent data indicate that critically ill, adult multiple trauma patients receiving specialized nutrition support commonly experience hypocalcemia (ionized serum calcium [iCa] < or =1.12 mmol/L). However, validated methods for the treatment of acute hypocalcemia are lacking.

METHODS

The efficacy of a single dose of calcium gluconate using an empiric IV calcium gluconate graduated dosing regimen was evaluated in 37 patients. Patients with an iCa of 1-1.12 mmol/L (mild hypocalcemia) were provided 1-2 g of IV calcium gluconate. Patients with an iCa of <1 mmol/L (moderate to severe hypocalcemia) were given 2-4 g. The calcium gluconate was infused at a rate of 1 g/h in a small-volume admixture. Serum iCa determination was repeated on the following day.

RESULTS

One to 2 g of IV calcium gluconate was effective in normalizing iCa for 23 out of 29 patients (79%) with mild hypocalcemia and 2-4 g was effective for 3 of 8 patients (38%) with moderate to severe hypocalcemia. The individual response to calcium therapy (g/d) or when normalized to body weight (mg/kg/d) was highly variable.

CONCLUSIONS

One to 2 g of IV calcium gluconate were effective for most patients with mild hypocalcemia; however, treatment of moderate to severe hypocalcemia with 2-4 g of IV calcium gluconate was often unsuccessful. Further study with frequent serial ionized serum calcium and phosphorus determinations and electrocardiographic monitoring appears to be indicated for patients with moderate to severe hypocalcemia.

Metabolic Support of the Thermally Injured Patient

Nutrition Support Pharmacist features issues pertinent to the practice of clinical pharmacy in the area of nutritional support. The column is edited by Dr. Roland Dickerson, Professor of Pharmacy, University of Tennessee Health Science Center; Memphis, TN. Address correspondence to Dr. Roland N. Dickerson, University of Tennessee Health Science Center, 26 South Dunlap St., Memphis, TN 38163.

This article provides a summary of our approach to the nutritional management of the thermally injured patient. However, it must be pointed out that there are other alternative effective evidence-based approaches to managing this problematic patient population. There are numerous exceptions to the above outlined guidelines that the astute clinician must be able to identify. However, for the beginning reader, this approach will provide a sound foundation upon which to build their practice in the management of these difficult patients.

Morbid obesity and nutrition support: is bigger different?

Morbid obesity (body mass index >40 kg/m2 or >35 kg/m2 in the presence of an severe-obesity-related comorbid disease) is increasing in frequency in the United States and worldwide. This population has a variety of medical and surgical disorders that result in hospitalizations. It is not unexpected to encounter these patients on the nutrition support service. The obesity comorbid diseases that may increase complications related to nutrition support are present in greater frequency and severity in the morbidly obese population than in the nonobese population. To reduce these potential complications, strategies of hypocaloric nutrition have been advocated for obese patients, and this study focuses specifically on the morbidly obese subset.

Factors causing interrupted delivery of enteral nutrition in trauma intensive care unit patients

BACKGROUND

The intent of this study was to ascertain the adequacy of delivery of enteral nutrition (EN) to critically ill adult multiple trauma patients and to identify potential detrimental factors that affect EN delivery.

METHODS

Retrospective observational study. Trauma intensive care unit (TICU) in a university-affiliated hospital. Adult patients (>/=18 years of age) admitted to the TICU who received enteral feeding.

RESULTS

Fifty-six adult patients were enrolled for study. Patients received, on average, 67% +/- 19% of what was prescribed for 5.7 +/- 2.0 days. A total of 222 occurrences for temporary discontinuation of tube feeding were identified. Gastrointestinal intolerance, as defined by a gastric residual volume of >150 mL, abdominal pain, or >3 liquid stools per day, accounted for only 11% of the occurrences for discontinuation of feeding. Surgery (27%) and diagnostic procedures (15%) represented the majority of reasons for inadequate nutrient delivery. Minor factors for EN interruptions were mechanical feeding tube problems (8%), pharmacy delivery delay (4%), and miscellaneous factors (3%). Multiple and unknown reasons contributed to 14% and 18% of the occurrences, respectively.

CONCLUSIONS

Surgery and diagnostic procedures accounted for the largest factor in enteral feeding discontinuations in our critically ill trauma patients. Gastrointestinal intolerance contributed a minor role in the temporary discontinuation of enteral feeding.

Predicting total urinary nitrogen excretion from urinary urea nitrogen excretion in multiple-trauma patients receiving specialized nutritional support

OBJECTIVE

We investigated the accuracy of methods to estimate total urinary nitrogen (TUN) excretion from urinary urea nitrogen (UUN) excretion for patients who have multiple trauma and receive specialized nutritional support.

METHODS

Fifty-five critically ill, adult patients who had multiple trauma and were receiving specialized nutritional support were evaluated. A 24-h urine collection for urea nitrogen and total nitrogen was performed 4.4 +/- 2.6 d after admission to the trauma intensive care unit. Patients with significant renal impairment, liver dysfunction, or obesity (>150% of ideal body weight) were excluded from study entry. Eight publications that examined the relation between TUN and UUN were evaluated for bias and precision in estimating TUN from UUN.

RESULTS

TUN was 20.8 +/- 10.8 g/d with an average difference of 3.8 +/- 2.8 g/d between TUN and UUN. Linear regression analysis comparing TUN with UUN indicated a significant correlative relation (TUN = 1.1 x UUN + 2; r = 0.958, P < 0.001). The difference between TUN and UUN varied based on UUN: for UUN lower than 10 g/d, TUN minus UUN was 1.5 +/- 1.0 g/d; for UUN 10 to 20 g/d, TUN minus UUN was 4.1 +/- 3.2 g/d; and for UUN higher than 20 g/d, TUN minus UUN was 5.3 +/- 1.9 g/d (P < 0.001). Six methods were biased toward underpredicting TUN, one method was unbiased, and one was biased toward overpredicting TUN. A practical method for estimating TUN from UUN was developed: TUN = UUN + 2 for those with UUN lower than 10 g/d and TUN = 1.1 x UUN + 2 for those with UUN of at least 10 g/d.

CONCLUSIONS

Our method, the modified Velasco method, UUN/0.84, and UUN/0.85 provided reasonable estimates of TUN from UUN in critically ill, adult patients who had multiple trauma and were receiving specialized nutritional support; however, our method requires further validation.

Accuracy of methods to estimate ionized and "corrected" serum calcium concentrations in critically ill multiple trauma patients receiving specialized nutrition support

BACKGROUND

The purpose of this study was to determine the accuracy of 22 published methods to estimate serum ionized calcium (iCa) and "corrected" total serum calcium (totCa) concentrations in critically ill, multiple trauma patients. Seven of these formulas estimated iCa and 15 were directed toward predicting a "corrected" totCa.

METHODS

Adult patients admitted to the trauma intensive care unit who received specialized nutrition support were consecutively recruited for study. Patients who received blood products, i.v. calcium, or therapeutic doses of heparin within 24 hours before the laboratory measurements or had a history of cancer, bone disease, parathyroid disease, hyperphosphatemia (> or = 6 mg/dL), hyperbilirubinemia (> 3.5 mg/dL), or renal failure requiring dialysis were excluded. The 22 published methods were analyzed for sensitivity, specificity, percentage false negatives, and percentage false positives for predicting hypocalcemia or hypercalcemia.

RESULTS

One hundred patients were studied 4.9 +/- 3.3 days postinjury and were receiving enteral nutrition (n = 81), parenteral nutrition (n = 18), or both (n = 1) at the time of study. Twenty-one patients were hypocalcemic (iCa < or = 1.12 mmol/L) and 6 were hypercalcemic (iCa > or = 1.32 mmol/L). The mean sensitivity of the 22 methods for assessing hypocalcemia was 25% +/- 32% and the specificity was 90% +/- 18%. Although the average percentage of false positives for assessing hypocalcemia was 10% +/- 18%, the mean percentage of false negatives was inordinately high at 75% +/- 32%. The most common method for determination of "corrected" totCa concentration ["corrected" calcium = totCa + (0.8 x (4-serum albumin concentration))] had a sensitivity of only 5%. The McLean-Hastings nomogram method, the most common method for estimating serum iCa concentration, had a sensitivity of 67% but unfortunately also had a significant false-positive rate of 27%. Serum totCa correlated modestly with iCa (r2 = .334, p < .001). Those patients with a serum albumin < or = 2 g/dL (n = 43) had a significantly higher prevalence of hypocalcemia than those with a higher serum albumin concentration (37% incidence of hypocalcemia vs 10%, respectively, p < .002).

CONCLUSIONS

Aberrations in calcium homeostasis are frequent (27%) in postresuscitative critically ill multiple trauma patients. Methods for predicting hypocalcemia lack sensitivity and are often associated with an unacceptable rate of false negatives. Predictive methods for estimating ionized or corrected serum concentrations should not be used. Direct measurement of serum iCa concentration is indicated for assessing calcium status for this population.

Hypocaloric feeding of obese patients in the intensive care unit

PURPOSE OF REVIEW

Given the increased awareness of the detrimental complications of overfeeding, particularly hyperglycemia, the safety and efficacy of specialized nutritional support for the critically ill obese patient is of major concern. The intent of this review is to provide the scientific foundation, supporting and conflicting literature, for the implementation of hypocaloric, high-protein specialized nutritional support for acutely ill, hospitalized patients with obesity.

RECENT FINDINGS

Similar anabolic equivalencies can be achieved with hypocaloric, high-protein nutritional support compared with a more traditional higher calorie, lower protein regimen. The provision of additional calories worsens hyperglycemia, results in a further accumulation of fat mass, and increases the potential for overfeeding without significant net protein anabolism gain.

SUMMARY

The current literature indicates that hypocaloric, high-protein enteral or parenteral nutrition is promising as the standard of practice for the metabolic support of the critically ill obese patient. The achievement of net protein anabolism and the avoidance of overfeeding complications are the primary goals, with fat weight loss a welcome secondary benefit.

Energy requirements of non-ambulatory, tube-fed adult patients with cerebral palsy and chronic hypothermia

OBJECTIVES

We investigated the energy requirements of non-ambulatory patients with severe neurodevelopmental disabilities and chronic hypothermia.

METHODS

Six adult patients with a permanent ostomy for tube feeding were studied. Otic temperature was taken before the indirect calorimetry measurements. Prescribed tube-feeding intake and nutrient prescription changes were evaluated for 4 y for each patient. Monthly body weights and periodic anthropometric body fat assessments were measured for assessment of the need for weight gain, loss, or maintenance. The prescribed caloric intake was compared with the measured energy expenditure when normothermic, the Harris-Benedict equations, and the Arlington Developmental Center equation for non-ambulatory adult patients with severe neurodevelopmental disabilities (estimated resting energy expenditure [kcal/d] = [22.3 x fat-free mass [kg]] - [9.4 x age [y]] + 557).

RESULTS

Mean energy expenditure was 783 +/- 81 kcal/d or 29.0 +/- 10.9 kcal. kg(-1)d(-1) when normothermic versus 606 +/- 11 kcal/d or 19.5 +/- 8.5 kcal. kg(-1)d(-1) (P < 0.05) when hypothermic (36.9 degrees C +/- 0.4 versus 35.5 degrees C +/- 0.4; P < 0.02), respectively. Prescribed caloric intakes to achieve weight gain, maintenance and loss were 138 +/- 13%, 105 +/- 15%, and 74 +/- 11% of the measured energy expenditure when normothermic (P < 0.001); 107 +/- 19%, 86 +/- 18%, and 56 +/- 3% of the Harris-Benedict equations (P < 0.02); or 130 +/- 23%, 100 +/- 19%, and 75 +/- 11% of the Arlington Developmental Center equation (P < 0.02).

CONCLUSIONS

Measured energy expenditure when the patient is normothermic significantly overestimated actual caloric needs. The energy intake necessary to achieve desired weight changes are restrictive when compared with the basal energy expenditure, Arlington Developmental Center equation, or measured energy expenditure when normothermic.

Management of Hyperglycemia in Patients Receiving Specialized Nutritional Support

Nutritional Support Consultant features issues pertinent to the practice of clinical pharmacy in the area of nutritional support. The column is edited by Dr. Roland Dickerson, Associate Professor of Pharmacy, University of Tennessee Health Science Center; Memphis, TN.

Procalcitonin and enteral nutrition tolerance in critically ill patients

BACKGROUND

Serum procalcitonin concentrations have been reported to be elevated in patients with bacterial infection. Early enteral nutrition (EN) has been shown to decrease infections in trauma patients. The purpose of this study was to characterize procalcitonin and other serum proteins during EN of trauma patients based on EN tolerance and presence of infection.

METHODS

Twenty traumatized patients received a high-protein enteral formulation within 5 days of injury. Serum for procalcitonin, C-reactive protein, and prealbumin was analyzed on days 1 and 7 of EN. The procalcitonin/prealbumin and C-reactive protein/prealbumin ratios were calculated the same days. Patients who were infected during the study were compared with those not infected, and enteral-tolerant patients were compared with enteral-intolerant patients using these measurements.

RESULTS

In the 20 trauma patients, procalcitonin (10.35 +/- 27.87 versus 1.03 +/- 1.24 ng/mL, p < .001) and procalcitonin/prealbumin ratio (1.70 +/- 4.20 versus 0.18 +/- 0.28, p < .01) decreased significantly over the 7-day period of EN. In the 12 patients who had infection, procalcitonin (16.33 +/- 35.31 versus 1.37 +/- 1.41 ng/mL, p < .004) and procal- citonin/prealbumin ratio (2.74 +/- 5.31 versus 0.26 +/- 0.33, p < .01) decreased significantly over the 7-day period of enteral nutrition. There were no significant changes in the measurements for 8 patients without infection. In the 15 patients who were enteral-tolerant, procalcitonin (12.56 +/- 32.84 versus 1.07 +/- 1.23 ng/mL, p < .004) and procalcitonin/prealbumin ratio (2.03 +/- 4.93 versus 0.20 +/- 0.29, p < .01) decreased significantly.

CONCLUSION

Procalcitonin serum concentrations decrease significantly during EN in enteral-tolerant, critically ill patients with infection.

The effect of sepsis during parenteral nutrition on hepatic microsomal function in rats

STUDY OBJECTIVE

To investigate the effect of sepsis during parenteral nutrition on hepatic cytochrome P450 (CYP) activity in rats.

DESIGN

Prospective, randomized, controlled study.

SETTING

University-based animal research laboratory.

ANIMALS

Twenty adult male Sprague-Dawley rats.

INTERVENTION

The animals were cannulated intravenously and randomized to receive parenteral nutrition (PN), intravenous live Escherichia coli 4 x 10(8) colony-forming units/100 g body weight for 2 consecutive days with PN (PNEC), or chow (CH).

MEASUREMENTS AND MAIN RESULTS

Both PN alone and PNEC resulted in a progressive decline in hepatic CYP concentration compared with CH (0.53 +/- 0.10, 0.41 +/- 0.17, and 0.35 +/- 0.14 nmol/mg microsomal protein, respectively, p < 0.05). Parenteral nutrition alone was associated with a 57% decrease in isoenzyme ethoxycoumarin-O-deethylase activity (ECOD) compared with CH, but sepsis did not further decrease ECOD activity any more than PN alone (0.103 +/- 0.049, 0.044 +/- 0.018, and 0.050 +/- 0.020 nmol/mg microsomal protein/min, respectively, p < 0.05).

CONCLUSION

Hepatic CYP concentration declines with PN and is further decreased when compounded by sepsis. The disproportional decrease in ECOD activity relative to CYP concentration with PN is unchanged by sepsis, indicating a selective alteration in hepatic isoenzymes by PN.

Effect of upper extremity posturing on measured resting energy expenditure of nonambulatory tube-fed adult patients with severe neurodevelopmental disabilities

PURPOSE

To ascertain the effect of upper extremity posturing on measured resting energy expenditure (MEE) for patients with severe neurodevelopmental disabilities.

METHODS

Twenty-four nonambulatory adult patients with severe neurodevelopmental disabilities referred for evaluation of enteral tube feeding and who had a steady-state MEE performed were studied. Steady-state indirect calorimetry measurements were done through a canopy system. Patients were stratified according to the topography of their neuromotor impairment and motor function as having either fixed upper extremity contractures (Fixed UE) or with preservation of limited functional and nonfunctional upper extremity movement (Preserved UE).

RESULTS

Despite a similar age, weight, height, and gender distribution between groups, those patients with Fixed UE (n = 13) had a significantly lower MEE than those with Preserved UE (n = 11): 893 +/- 91 versus 1144 +/- 262 kcal/d (p < .01), respectively. The Harris-Benedict equations' predicted energy expenditures were similar to MEE for patients with Preserved UE (1212 +/- 156 versus 1144 +/- 262 kcal/d, respectively, p = N.S.). Patients with Fixed UE had a significantly lower MEE than predicted by the Harris-Benedict equations (893 +/- 91 versus 1128 +/- 123 kcal/d, respectively, p < .01)

CONCLUSIONS

Patients with fixed upper extremity contractures have a significantly lower MEE than those with preserved upper extremity movement. MEE for nonambulatory tube-fed adult patients with severe neurodevelopmental disabilities and fixed upper extremity contractures is significantly lower than predicted by the Harris-Benedict equations.

Endotoxin-mediated hepatic lipid accumulation during parenteral nutrition in rats

OBJECTIVE

To assess the effect of endotoxemia on hepatic lipid content during parenteral nutrition (PN) in rats.

METHODS

Twenty male Sprague-Dawley rats (185-230 gm) were randomized to receive PN (n=9) or PN plus a continuous infusion of E. coli 026:B6 lipopolysaccharide (LPS; n= 11). All animals received isocaloric (170 kcal/kg/day), isonitrogenous (1.1 g N/kg/day), glucose-based PN for the next 78 hours. After 30 hours of adaptation to TPN, the animals were randomized to receive PN or PN plus LPS at 6 mg/kg/day for the remaining 48 hours of study. The animals were euthanized and the livers were harvested.

RESULTS

Liver weight increased significantly (by 60%) from 7.5+/-0.6 g to 12.1+/-2.4 g (p < or = 0.01) in the animals who received PN versus LPS, respectively. The proportion of liver water remained the same for PN and LPS groups (72.9+/-3.2% versus 72.3+/-3.8%, respectively, p = N.S.). However, liver fat increased disproportionately (by about 130%) from 0.20+/-0.05 g to 0.46+/-0.20 g (p < or = 0.01) total fat weight or from 9.6+/-1.8% to 13.6+/-4.1% (p < or = 0.02) lipid content (g/g) of the dry liver weight for the PN and LPS groups, respectively.

CONCLUSION

Endotoxin, when given concomitantly with parenteral nutrition, increases hepatic lipid accumulation and thus augments the development of parenteral nutrition-associated fatty liver in rats.

Validation of a new method for estimating resting energy expenditure of non-ambulatory tube-fed patients with severe neurodevelopmental disabilities

OBJECTIVE

We assessed the bias and precision of the Arlington Developmental Center (ADC) equations derived from our previous study and the Harris-Benedict equations for estimating resting energy expenditure in non-ambulatory, tube-fed patients with severe neurodevelopmental disabilities.

METHODS

Fifteen non-ambulatory patients with neurodevelopmental disabilities referred to the nutrition consult service for evaluation of enteral tube feeding via a permanent ostomy who had a steady-state resting energy expenditure measurement performed by indirect calorimetry were included in the study. The predicted energy expenditure values were compared with the measured resting energy expenditure values and evaluated for bias and precision.

RESULTS

Both ADC equations were more precise (95% confidence interval [CI]: 9-22% and 10-18% error, respectively) for the total population than the Harris-Benedict equations (95% CI: 17-40% error). The ADC-2 equation was precise (95% CI: 7-15% error) and unbiased (95% CI: -5 to 139 kcal/d) in contrast to the Harris-Benedict equations (95% CI: 23-54% error; bias, +230 to 365 kcal/d) for patients with cerebral palsy and fixed upper extremity contractures. The Harris-Benedict equations were precise and unbiased (95% CI: 3-14% error; bias, -182 to 39 kcal/d) for patients with cerebral palsy with preservation of upper body movement, whereas the ADC equations were biased toward underprediction and associated with greater error (95% CI: -367 to -73 kcal/d and 7-26% error; 95% CI: -379 to -109 kcal/d and 9-27% error, respectively).

CONCLUSIONS

The ADC-2 equation was unbiased and more precise in non-ambulatory adult patients with severe neurodevelopmental disabilities and fixed upper extremity contractures, whereas the Harris-Benedict equations were more precise and unbiased for those with preservation of limited functional and non-functional upper extremity movement.