Long-term Home Parenteral Nutrition Patients Research Articles

Cost-effectiveness of taurolidine locks to prevent recurrent catheter-related blood stream infections in adult patients receiving home parenteral nutrition: a 2-year mirror-image study

The use of long-term taurolidine locks (LTTL) seems to be effective in preventing catheter-related blood stream infections (CRBSI), especially in patients on home parenteral nutrition (HPN). This work targets the cost-effectiveness of LTTL in a cohort of adult HPN patients. A monocentric mirror-image design study was conducted in our referral centre among long-term HPN patients experiencing recurrent CRBSI. From 7th January 2011, LTTL were started after the third CRBSI episode within 12 months. CRBSI data was prospectively collected until 7th January 2013, in the same way as it had retrospectively been done before initiating LTTL. A cost-effective analysis was conducted to estimate the incremental costs and effects on CRBSI with LTTL. The efficacy of LTTL on CRBSI rate was assessed over 1000 days of catheter use. A total of 31,100 catheter days were analysed in 37 patients (median [interquartile range (IQR)]) aged 58 [42-68] years. The mean±SD proven CRBSI rate was 3.18±3.51 per 1000 catheter days before the introduction of LTTL and 0.39±1.50 per 1000 catheter days after its introduction (p<0.0001). Considering both proven and probable CRBSI requiring hospital management, LTTL reduced by (mean [bootstrap CI 95%])-2.63 [-3.26 to-2.06] infections per patient (from 2.89 [2.31 to 3.49] before to 0.26 [0.13 to 0.41] after) as well as incremental costs by-7 258 [-10 450 to -4 016] € (from 11 176 [8 004 to 14 968] € before to 3 918 [2 390 to 5 445] € after). Implementing LTTL to prevent recurrent CRBSI is cost-effective by dramatically decreasing their incidence.

Cardiac Changes in Patients on Long-Term Parenteral Nutrition.

Patients with short bowel syndrome (SBS) on long-term home parenteral nutrition (HPN) chronically receive high fluid volumes directly into the right atrium (RA) through the superior vena cava. We retrospectively evaluated cardiac function measured by routine transthoracic echocardiography (TTE) in a population of 26 SBS patients on long-term HPN and compared their data on echocardiograph-derived right heart structure and function, with those of a control group of 26 patients also bearing a central venous catheter (CVC) for other reasons. Results showed that body weight and BMI were significantly higher in the control group. The echocardiographic estimate of RA pressure was higher in HPN patients than in controls (p = 0.01). An increased estimate of RA pressure indicates the need to consider TTE in the follow-up of long-term HPN patients to detect functional impairment early.

Using Telemedicine to Identify Depressive Symptomatology Rating Scale in a Home Parenteral Nutrition Population.

Home parenteral nutrition (HPN) is a life-long daily 12-h intravenous nutrition infusion therapy that corrects for nutrient imbalances caused by a malfunctioning gastrointestinal tract outside a medical inpatient setting. Patients utilizing HPN face psychosocial challenges, particularly depression, that often goes undetected due to the lack of daily interactions with health care professionals. Telemedicine, as a mode of treatment, can assist health care professionals in the detection of depression by increasing accessibility to patients. Therefore, in the current study, we investigate the feasibility in assessing depressive symptomatology using telemedicine within a long-term HPN population. We hypothesized that telemedicine would be a viable mechanism by which trained health care professionals could monitor and identify depressive symptomatology within the long-term HPN population. Raters coded 25 facilitated group discussions with the modified Raskin scale (a 21-item observer rating scale; M = 3.28, SD = 3.46) and compared it to the Patient Health Questionnaire-9 (PHQ-9) at baseline (M = 7.88, SD = 5.46) and 4 months (M = 7.76, SD = 5.64). Our results suggest that the modified Raskin scale demonstrated evidence of poor concurrent validity the scale displayed strong predictive validity. Thus, the modified Raskin scale showed promise as a tool for health care professionals, who wish to use telemedicine as a treatment avenue to detect and monitor depression among long-term HPN patients.

The Prevalence of Vitamin D Insufficiency and Deficiency and Their Relationship with Bone Mineral Density and Fracture Risk in Adults Receiving Long-Term Home Parenteral Nutrition.

It has been demonstrated that low bone mass and vitamin D deficiency occur in adult patients receiving home parenteral nutrition (HPN). The aim of this study is to determine the prevalence of vitamin D insufficiency and deficiency and its relationship with bone mineral density (BMD) and fracture risk in long-term HPN patients. Methods: A retrospective chart review of all 186 patients in the HPN registry followed by the Northern Alberta Home Parenteral Nutrition Program receiving HPN therapy >6 months with a 25 (OH) D level and BMD reported were studied. Results: The mean age at the initiation of HPN was 53.8 (20–79) years and 23 (37%) were male. The mean HPN duration was 56 (6–323) months and the most common diagnosis was short bowel syndrome. Based on a total of 186 patients, 62 patients were categorized based on serum vitamin D status as follows: 1 (24.2%) sufficient, 31 (50%) insufficient and 16 (25.8%) deficient. Despite an average of 1891 IU/day orally and 181 IU/day intravenously vitamin D, the mean vitamin D level was 25.6 ng/mL (insufficiency) and 26.2 ± 11.9 ng/mL in patients with the highest 10-year fracture risk. Conclusion: Suboptimal vitamin D levels are common among patients on long-term HPN despite nutrient intake that should meet requirements.

Peripherally Inserted Central Catheter Experience in Long-Term Home Parenteral Nutrition Patients

Parenteral nutrition is administered through a central venous catheter(CVC). Peripherally inserted central catheters (PICC) are appropriate for home parenteral nutrition (HPN). The objective of this study was to examine a group of HPN patients with a PICC in place for more than six months, and the complications associated with PICC removal. Medical records from one home infusion pharmacy were retrospectively reviewed for PICC characteristics and complications leading to removal. Nineteen adult HPN patients had 26 PICC placements. Total PICC days were 22,262 with a mean of 856 (265-2500) days. Seven PICCs were in place for 3 to greater than 5 years. The overall complication rate was 0.58/1000 CVC days. Catheter related bloodstream infection (CRBSI) was the main cause of PICC removal. There was no evidence of symptomatic thrombosis. Patients experienced no infusion related complications. The PICCs were 88% polyurethane, 65% double lumen, and 54% were 5 Fr. No patient received alcohol or antibiotic lock therapy, and 8 patients had successful alteplase administered at least one time. All patients needed caregiver assistance for site care and dressing changes, but were independent in HPN infusion and flushing. This group of patients demonstrated that PICCs are a viable option HPN administration. The PICC overall complication rate was very low, and the most frequent complication leading to removal was CRBSI. The infection rate of 0.36/1000 CVC days is considered very low in an HPN population. This is the only HPN infusion study to date reporting 7 PICCs lasting 3 or more years, with 2 lasting greater than 5 years without complications resulting in removal. Patients received their prescribed therapy reliably and without interruption with this device. Larger studies are needed to confirm the efficacy of maintaining a PICC for very long-term HPN administration.

Evaluation of Ethanol Lock Therapy in Pediatric Patients on Long‐Term Parenteral Nutrition

Pediatric home parenteral nutrition (PN) patients present a unique challenge with risks of catheter-associated bloodstream infections (CABSIs), sometimes requiring subsequent catheter removal. Recurrent infections can lead to line removal and potential loss of venous access in the future. Demonstrate that weekly ethanol lock therapy decreases CABSIs in long-term home PN patients and decreases line removals due to infections. Beginning August 2007, patients receiving PN with a history of multiple previous CABSIs were started on ethanol lock therapy. Seventy percent ethanol solution was instilled into the central venous catheter (CVC) for 2 hours weekly. Episodes of CABSIs and catheter removal due to infection were documented in patients prior to and after ethanol lock therapy. Fourteen patients were followed for an average of 690 days after ethanol lock therapy was initiated. These patients were found to average 9.8 CABSIs per 1000 catheter days prior to starting ethanol lock therapy and only 2.7 CABSIs per 1000 catheter days after ethanol lock therapy (P < .001). Prior to ethanol lock therapy, the group averaged 4.3 catheter removals per 1000 catheter days but only 1.0 catheter removal per 1000 catheter days after ethanol lock therapy. Our group of patients showed a 73% reduction in CABSIs and a 77% reduction in catheter removal due to infection after ethanol lock therapy. In our patient population, weekly ethanol lock therapy for 2 hours is an effective technique to reduce CABSIs and catheter removal in long-term home PN patients.

Catheter-Related Complications in Long-Term Home Parenteral Nutrition Patients with Chronic Intestinal Failure

Home Parenteral Nutrition is a therapeutic option to improve quality of life in chronic intestinal failure. To describe frequency of complications both in cancer and noncancer patients. This study was performed on 270 adult patients (52% with cancer, 48% without cancer) followed for a total of 371 years of treatment. Mean duration of therapy was 191±181 for cancer and 830±1168 days/patient for noncancer. The treatment was administered by a competent, dedicated provider. Patients received our prescribed "all-in-one admixtures" at their homes. Catheter-related complications/1000-days-catheter was 1.40; mechanical complications were comparable in cancer (0.82) and noncancer (0.91) patients while a statistically significant difference was observed between cancer (0.71) and noncancer (0.46) patients for sepsis. Bacterial infections were more frequent in noncancer, mycotic infections primarily affected cancer patients. In our experience 49% of the patients were readmitted, with a low incidence rate of 0.89/1000 days-catheter. The incidence of hepatobiliary complications in our population was 65%. The degree of liver damage was related to short bowel syndrome and to length of treatment. This study indicated that cancer patients are more vulnerable to CVC-related infections during Home Parenteral Nutrition and that a safer Home Parenteral Nutrition protocol should be adopted in order to contain CVC-related complications.

Dosing and Monitoring of Trace Elements in Long‐Term Home Parenteral Nutrition Patients

Trace elements (TEs) dosing and monitoring in home parenteral nutrition (PN) patients vary with their underlying conditions. This retrospective observational study evaluated parenteral TE dosing, serum TE concentrations and monitoring, and dose-concentration relationships between TE doses and serum TE concentrations in 26 adult and adolescent home PN patients. There was a total of 40,493 PN days. Average parenteral zinc doses of 9.1 mg/d and 7.6 mg/d resulted in the majority of serum zinc concentrations (90%) within normal range in patients with and without short bowel syndrome (SBS), respectively. Selenium at about 70 mcg/d resulted in about 60% of serum selenium concentrations within normal range, with 38% of values below normal in patients with and without SBS alike. Copper at 1 mg/d resulted in 22.5% of serum copper concentrations above the normal range. The majority of serum manganese (94.6%) and chromium (96%) concentrations were elevated. Serum TE concentrations were infrequently monitored. Significant relationships existed between doses and serum concentrations for zinc (P < .0001), manganese (P = .012), and chromium (P < .0001) but not for selenium or copper. TE doses in home PN should be individualized and adjusted based on regular monitoring of TE status. In long-term home PN patients, higher zinc and selenium doses may be necessary to maintain their normal serum concentrations. Lower copper doses and restrictions of manganese and chromium supplementation may be needed to avoid their accumulation. Relationships between TE doses and serum TE concentrations vary for each TE and underlying clinical conditions.

The Clinical and Psychometric Validation of a Questionnaire to Assess the Quality of Life of Adult Patients Treated With Long‐Term Parenteral Nutrition

Home parenteral nutrition (HPN) is an established treatment for the management of patients with chronic intestinal failure. No quality-of-life assessment tools have been developed and validated specifically for this patient population, and previous studies have used generic instruments or techniques not validated in HPN. The assessment of quality of life (QOL) should produce clinically relevant data reflecting patients' issues. The HPN-QOL was designed to assess the QOL of HPN patients. The purpose of this study was to test the hypothesized scale structure of the questionnaire with regard to reliability and validity in a sample of patients. A provisional questionnaire was prepared following recognized guidelines and then subjected to field testing. The questionnaire was administered to 100 adult patients receiving HPN. Psychometric tests examined the reliability and validity of the questionnaire, and patients' debriefing comments were analyzed. The provisional questionnaire was adapted using evidence from quantitative and qualitative analysis. Multitrait scaling analysis and face validity refined the questionnaire to 48 items. Compliance rates were high, and the questionnaire was well accepted. A method of objectively assessing the QOL of patients treated with HPN has been developed. The HPN-QOL has been rigorously prepared and demonstrates psychometric and clinical validity to assess the QOL of long-term HPN patients.

Manganese in Parenteral Nutrition: Who, When, and Why Should We Supplement?

Micronutrient requirements are not fully understood. Parenteral nutrition (PN) usually contains the trace element (TE) manganese (Mn) from fixed-concentration TE supplements. Multiple TE formulations may not be optimal in pediatric and home PN. Moreover, most PN products contain Mn as a ubiquitous contaminant. Excessive Mn can lead to Parkinson-like symptoms resulting from hypermanganesemia. A survey of 40 Australasian hospitals that contributed data on 108 patients to the annual home PN register and a systematic review of the literature were conducted to establish the scope of the potential problem of Mn toxicity in PN patients. Exposure to Mn doses 5-6 times current daily requirements, together with the TE contamination that is reported in PN products, can lead to neurotoxicity. Whole-blood levels are more accurate for monitoring and correlate well with signal intensity of magnetic resonance imaging. Current TE formulations restrict prescribing options. The regulatory mechanisms of Mn homeostasis are bypassed via the parenteral route so elimination via the hepatobiliary system is impaired, resulting in tissue or brain accumulation. Published dosage recommendations may be excessive and official guidelines require revision. Variability in clinical practices necessitates that individual TE additives are more widely available and multiple TE products reformulated. More frequent monitoring for any brain accumulation is recommended. The scarcity of PN-associated Mn deficiency, plus the growing evidence for Mn toxicity, leads to the conclusion that it is unnecessary for Mn to be prescribed routinely for pediatric or long-term PN patients.

Iron and Parenteral Nutrition

There is ample evidence that iron is an essential trace element, but assessment of iron status and decisions on the amounts needed and the means of delivery in patients on parenteral nutrition (PN) have been unclear. Although iron requirements may diminish during acute illness, the frequent concurrence of blood loss and iron deficiency argue strongly for maintenance of levels of delivery in line with basal requirements. Maintenance of iron delivery has not been thought likely to present risk, but new data are questioning this. The needs of menstruating, pregnant, and lactating women are greater than those of adult men. The evidence favors an intravenous dose of around 1 mg of elemental iron per day in adult men and postmenopausal women. Doses of 1.5 mg/d [DOSAGE ERROR CORRECTED] in menstruating women and 2.0 mg/d [DOSAGE ERROR CORRECTED] for those in the later stages of pregnancy or lactating can be supported. A calibrated response is required in the growing child. Continued monitoring of iron status is recommended. Iron is an essential component for most PN regimens. The quantity of iron to be included should take account of predicted requirements.

Zinc: An Essential Trace Element for Parenteral Nutrition

Zinc is an essential trace element for human nutrition that is an integral part of many enzyme systems, including DNA polymerase complex. Zinc deficiency has been associated with stunting of growth and sexual immaturity. In children, deficiency causes a fatal condition called acrodermatitis enteropathica. The same syndrome has been observed in patients on total parenteral nutrition (TPN) who do not receive zinc. In TPN the requirements have been estimated by balance studies to be 3 mg/d in patients without gastrointestinal losses and a mean of 12 mg/d in patients with diarrhea and fistula losses.

Is manganese an essential supplement for parenteral nutrition?

To summarize the role of the essential trace element, manganese, its potential toxicity, monitoring methods and dosage recommendations for nutrition support. Parenteral nutrition usually contains manganese as part of a fixed concentration multiple trace element supplement. Recent literature identifies potential problems in this approach and reports toxic symptoms resulting from hypermanganesaemia in paediatric and long-term home patients. Elimination by the hepatobiliary system is frequently impaired, and parenteral administration bypasses the regulatory mechanisms of homeostasis. Together with occasional oral intake and product contamination, this can lead to brain accumulation and neurotoxicity, with individual responses to supplementation difficult to predict. Regular monitoring is recommended, but plasma and serum analyses are poor indicators of body stores. Whole blood concentrations are more accurate and correlate with signal intensity of MRI. We have identified a need for individual trace element additives to be more widely available and for multitrace element products to be reformulated. There is now a persuasive argument for not routinely adding manganese to parenteral nutrition admixtures. High intravenous doses of manganese can lead to neurotoxicity. Current dosage guidelines and trace element formulations need revision. Frequent monitoring to identify tissue accumulation is recommended for paediatric and long-term home parenteral nutrition patients.

Intestinal Failure–Associated Liver Disease: What Do We Know Today?

Intestinal failure-associated liver disease develops in 40% to 60% of infants who require long-term total parenteral nutrition (TPN) for intestinal failure and 15% to 40% of adults on home parenteral nutrition. The clinical spectrum includes hepatic steatosis, cholestasis, cholelithiasis, and hepatic fibrosis. Progression to biliary cirrhosis and the development of portal hypertension and liver failure occurs in a minority but is more common in infants and neonates than in adults. The pathogenesis is multifactorial. In infants it is related to prematurity, low birth weight, duration of PN, short bowel syndrome requiring multiple laparotomies, and recurrent sepsis. Other important mechanisms include lack of enteral feeding, which leads to reduced gut hormone secretion; reduction of bile flow and biliary stasis, which leads to the development of cholestasis; and biliary sludge and gallstones, which exacerbate hepatic dysfunction. In adults, IFALD is less common and related to age, length of time on PN, total caloric intake, and lipid or glucose overload. In preterm infants, a deficiency of taurine or cysteine may play a role, whereas in both adults and children, choline deficiency may exacerbate IFALD. Lipid emulsions, choline deficiency, and manganese toxicity are associated with both hepatic steatosis and cholestasis in adults and children. Management strategies for the prevention of intestinal failure-induced liver disease include early enteral feeding, a multidisciplinary approach to the management of parenteral nutrition, and aseptic catheter techniques to reduce sepsis. The addition of choline, taurine, and cysteine to PN solutions may also play a role. Oral administration of ursodeoxycholic acid may improve bile flow and reduce gallbladder stasis. Survival after either isolated small bowel or combined liver and small bowel transplantation is approximately 50% at 5 years, making this an acceptable therapeutic option in adults and children with irreversible liver and intestinal failure.

Hypermanganesemia in an Acute Care Setting

Hypermanganesemia has recently been reported in long-term home parenteral nutrition patients receiving routine trace element supplementation. Because the regulation of manganese involves intestinal absorption and biliary excretion, patients receiving parenteral nutrition, especially those with hepatic dysfunction, may be at risk for manganese toxicity. This case study describes a patient in an acute care setting who had been receiving parenteral nutrition for 7 months. When neurologic symptoms developed, she was found to have a whole blood manganese level almost 3 times normal. Manganese was eliminated from the trace element solution, and a whole blood level was rechecked 3 months later, showing a significant decrease and a marked improvement in facial paralysis and headaches.

Intestinal transplantation for gut failure

In recent years, we have witnessed increasing clinical experience with intestinal transplantation at selected centers. Although early results with this therapy were poor, several important advances have led to improved outcomes. These improvements prompted the Centers for Medicare and Medicaid Services to issue a memorandum on October 4, 2000, according federal reimbursement for intestinal transplantation at selected centers and for selected indications.1 The Centers for Medicare and Medicaid Services stipulated that, to qualify for transplantation, patients must meet a specific definition of intestinal failure and have experienced failure of parenteral nutrition (Table 1). In addition, the Centers for Medicare and Medicaid Services set forth centerspecific criteria for reimbursement, including 1-year patient survival rates of at least 65% and minimum center volume of at least 10 transplants performed per year. Only 4 centers in the United States currently meet these criteria (Mount Sinai Medical Center, University of Pittsburgh Medical Center, University of Miami, and University of Nebraska Medical Center). Thus, intestinal transplantation is currently at a crossroads, transitioning from its historical status as an experimental therapy to standard care for patients with appropriate indications. Presently, appropriate indications, timing of referral, and outcomes of intestinal transplantation are not well recognized among physicians caring for patients who may be candidates for this therapy. Definitions of terms such as “intestinal failure” and “failure of parenteral nutrition” are not standard, and there is no accepted algorithm for integrating parenteral nutrition, intestinal rehabilitation, and transplantation for patients with intestinal failure. Herein we review (1) the applicability of intestinal transplantation for patients with intestinal failure, (2) the current state of medical practice in intestinal transplantation with an emphasis on recent improvements, and (3) current results of this therapy. We also offer for the general gastroenterologist or gastrointestinal surgeon a rational approach to managing intestinal failure and integrating intestinal rehabilitation, parenteral nutrition, and transplantation.2 Brief History

Evaluating the Effectiveness of a Micronutrient Assessment Tool for Long‐Term Total Parenteral Nutrition Patients

Monitoring parameters for patients receiving long-term home parenteral nutrition (HPN) should include assessment of micronutrient status to avoid deficiencies and potential excesses of any micronutrient. This evaluation examined the effectiveness of a standardized micronutrient assessment tool administered semiannually to long-term HPN consumers, for identifying signs/symptoms of a suspected deficiency or excess. All patients assessed were receiving long-term HPN from a single home-infusion provider. Of the 275 micronutrient assessments evaluated, 30 patients were found to have a suspected deficiency. Laboratory tests were ordered for 13 patients: deficiencies were confirmed in 6 patients, no deficiency was found in 4 patients, and 1 patient was not deficient in the suspected micronutrients but was found deficient in others. The micronutrient assessment tool is effective in determining the suspected presence of micronutrient deficiencies. All long-term HPN patients should receive ongoing monitoring by a home care clinician, including an assessment of micronutrient status, to ensure adequacy of the nutrition support regimen.

Clinical, social and rehabilitation status of long-term home parenteral nutrition patients: results of a European multicentre survey

Background: Home parenteral nutrition (HPN) is a lifesaving treatment in patients with intestinal failure. Dependency of nutritional support becomes permanent for the majority of patients who had received HPN for at least 2 years. The alternative to long term HPN in selected patients is intestinal transplantation.Aims: To study some of the clinical, social and rehabilitation aspects of long-term HPN treatment.Methods: A survey was performed in nine European HPN centres. The questionnaire covered epidemiologic data, underlying diseases, intestinal anatomy, nutritional support and status, marital status, rehospitalization rate, HPN complications, rehabilitation score, drugs use, coexistent diseases and interest in intestinal transplantation. For some items, data were collected within 12 months prior to the evaluation.Results: This survey included 228 patients with a median age of 49 years. The median duration of HPN was 7 years (range 2–24 years). Short bowel length less than 100 cm was reported in 65% of patients with a predominance of end-jejunostomy or jejuno-colonic anastomosis. Global subjective nutritional status was normal in 79% of the patients, who were supplied with a mean number of 5.6 bags of parenteral nutrition weekly. Rehospitalizations within the 12 months prior to evaluation accounted for a mean period of 23 days and were due to HPN complications in half of the cases. Catheter-related sepsis was the most frequent HPN-complication. Bone metabolism disorders, which seemed to be more common than liver diseases, were directly related to HPN duration. One-third of the HPN patients was regularly consuming analgesics or opiates. HPN impair complete rehabilitation status but may improve the status of patients who had a very low rehabilitation score before starting HPN. An interest of intestinal transplantation was noted in only 10% of medical teams and in 8% of HPN patients.Conclusions: This study is the largest European survey on long-term HPN patients with long standing or permanent intestinal failure. Data enlighten clinical, social and rehabilitation aspects of patients who could face the option of intestinal transplantation in the future.

P.90 Ascorbic acid and dehydro-ascorbic acid in long-termhome parenteral nutrition patients

P.90 Ascorbic acid and dehydro-ascorbic acid in long-termhome parenteral nutrition patients

Serum amino acid concentrations in patients receiving total parenteral nutrition with an amino acid plus dextrose mixture.

The results of monitoring the serum amino acid concentrations during three infusion regimens using a 5:4 mixture of 70% glucose and the synthetic L-amino acid solution, Synthamin 17 (Travasol) are reported. Twelve stabilized patients received continuous total parenteral nutrition (TPN), eight of whom were subsequently placed on a second regimen of cyclical feeding. A separate group of five patients was infused with amino acids, both with and without simultaneous glucose. The serum amino acid concentrations indicated that the supply of valine, leucine, isoleucine, lysine, and histidine, and the synthesis of taurine from the infused methionine was suboptimal, particularly if the period of TPN was prolonged. The synthesis of tyrosine from phenylalanine appeared to be inversely proportional to the infusion rate of the TPN mixture, in particular the glucose component, resulting in depressed tyrosine and increased phenylalanine concentrations in serum during continuous iv nutrition. Cyclical infusions, on the other hand, permitted the tyrosine and phenylalanine concentrations to return to normal during the noninfusion stage of the cycle. Amino acid measurements enabled us to design an amino acids additive mixture which normalized the serum concentrations in three long-term home parenteral nutrition patients. As a result of these investigations serum amino acid measurements are used routinely to monitor the efficacy of TPN and accommodate any specific amino acid requirements of individual patients.