The most common problem related to pharmaceutical preparation of PN formulations is day-to-day changes of patients' nutritional requirements following changing in their clinical and physiological conditions[16, 19–21]. Improving the quality of patients' metabolic supports can be achieved with adequate nutritional assessment using a standard protocol. This is especially important in the settings such as a referral teaching hospital with high prevalence of nutritional support complexities.
The ASPEN standards for nutritional support, recommend that all patients who are candidate for PN should undergo nutritional assessment at baseline before initiation of metabolic support. Baseline nutritional assessments include gathering of patients' demographic data such as age, gender, weight, height, nutritional history, physical examinations including anthropometric information, and biochemical parameters (Table1). These measurements can be used to differentiate between acute and chronic malnutrition and calculation of patients' nutritional requirements. These assessment were done somewhat for most of the patients during hospitalization course and had been recorded in their medical charts.
Based on the patients' baseline nutritional assessment, a metabolic support's plan for fluids, calories, protein, fat, and carbohydrate should be designed for each patient. We have used ASPEN criteria for evaluation of PN in the study. Approximately 21.1% of the patients received calorie goals, but we have not found any significant correlation between the patients' calorie intake and mortality. However sample size of the study was too small for evaluation of correlations between the parameters. Eighty percent of the patients received sufficient fluid (volume) and it seems that low calorie intake was not due to inadequate intake of volume.
Electrolytes, vitamins, minerals and other trace elements are necessary component of PN and metabolic complications can arise following inappropriate replacement of these nutrients[14, 21]. From these elements, calcium was frequently replaced inappropriately for the patients. Sufficient calcium replacement is necessary as there is a significant urine calcium loss in patients who receiving PN[13, 18].
Errors in replacement of vitamins were more frequent in the study and most of the patients did not receive nutritional goals with respect to these elements. Vitamin D is recommended for patients receiving PN as well as other human subjects. Metabolic complications such as hypocalcemia, hypercalciuria and negative calcium balance have been reported following long-term PN[23, 24]. Most of the patients received vitamin D more than their requirement, probably due to availability of one parenteral vitamin D preparation (300,000 IU) in our hospitals which contain more than even one week requirement of a patient.
Vitamin K (as phylloquinone or menaquinones) is an essential cofactor for coagulation cascade. Moreover, there are some evidences that show roles of vitamin K in the bone and vascular health. However the only generally accepted indication in the PN regimens is prevention of bleeding. The natural phylloquinone content of commercial PN products varies extensively depending on their fat sources. High levels of this element were reported in the PN formulations with soybean oil (150–300 μg per 100 g) fat origin. In year 2000, the US Food and Drug Administration (FDA) organization revised their guidelines and recommend that adult parenteral multivitamin preparations should supply 150 μg phylloquinone per day. In our study most of the patients did not receive vitamin K in their PN regimen.
Baseline laboratory and biochemical parameters should be assessed prior to initiation of PN. These parameters were assessed appropriately in 60% of the patients. Except sodium and potassium, other electrolytes such as calcium and magnesium were not evaluated at baseline for 89% of the patients. Vital signs (temperature, blood pressure, respiratory rate, pulse rate), weight, and fluid input and output, serum electrolytes (sodium, potassium, chloride, bicarbonate), BUN, serum creatinine and blood glucose are recommended to be monitored daily. In more than 80% of the patients these parameters were monitored semiweekly. It may be related to limited laboratory facilities, nursing staff workload, and patient's preferences[16, 27].
Complete blood count monitoring was performed semiweekly in most of the patients, but serum electrolytes levels were not monitored appropriately in more than 70% of the patients. Serum albumin levels and hepatic enzymes that are recommended to be monitored as weekly intervals were assessed more frequently in 35% of the patients. In another study conducted by Macfarlane et al. the same results were obtained. These differences may somewhat related to the recommendations. For example monitoring of these parameters as daily for 2 to 3 days, then every other day for 4 days, and then every week was recommended by another guideline. ASPEN guidelines recommend the weekly monitoring of these values as it is simple, less expensive and requires less-frequent blood sampling. This criterion should be changed if patient's clinical condition needs close monitoring[4, 16].
In this evaluation, we have found several deficiencies in assessment, establishing goals, and monitoring of the PN regimens in the medical and surgical wards. Complete nutritional assessments were performed only for 11% of the patients and many of them did not receive nutritional goals. About 25% of the patients received sufficient calorie and protein. Due to cost and availability issues of the parenteral trace elements products, approximately all of the patients did not receive their requirements.
This study has some limitations that must be considered. First, the data cannot be generalized to other teaching hospitals because of their different settings. Second, the study was retrospective and other factors such as exact nutrition status of the patients and effects of the patients' demographic data such as socio-economic status were not evaluated. Small sample size is another limitation of the study. Also we have not followed the patients for consequence of adequate or inadequate of the nutritional support.