Rate of Termination of Premixed Parenteral Nutrition (PN) in Surgical Patients Secondary to High Serum Electrolytes

Introduction: Various commercial premixed parenteral nutrition (PN) solutions have been introduced to clinical practice in 3-compartment large volume bags. Olimel N9E is the formulary premixed PN formula at King Faisal Specialist Hospital and Research Centre (KFSH \& RC). The commercial premixed PN was associated with a significant cost reduction compared to the compounded PN, with lower incidence of infectious complications, compared to the compounded PN formula. Electrolyte irregularities are commonly encountered with PN use. Patients who develop high serum potassium, magnesium or phosphate levels while receiving premixed PN are shifted to a compounded PN with lower electrolyte content. This study aims to describe the incidence of shifting of premixed PN to a compounded PN secondary to high serum electrolytes in surgical patients receiving commercial premixed PN. Methods: This is a prospective, cohort, study, to be conducted at KFSH \& RC, Riyadh. This study is proposed to commence after obtaining the approval of the Research Ethical Committee at KFSH \& RC. Patients enrolment will start after the approval at KFSH \& RC, by data collection phase, that might extend for a suspected 6-month until achieving the target sample size of 55 patients. The analysis phase will follow and elapse for 2 months. This is followed by 2 months to get the initial abstract. All patients will have their potassium, magnesium, calcium and phosphorus levels assessed daily in the morning for the first 7 days of PN initiation. After the first week of PN support, according to the routine laboratories, electrolytes will be assessed at a minimum of three times a week thereafter while on PN. There will be no extra laboratory work obtained for the study purpose. The incidence of shifting from premixed PN to compounded PN will be assessed and reported. A description of the characteristics of patients who develop high serum level of electrolytes will be undertaken using regression analysis.

Methods Study design and centres This is a prospective, cohort, multi-centre study, to be conducted at King Faisal Specialist Hospital and Research Centre, (KFSH \& RC), Riyadh. The study has been approved by KFSH\&RC Office of Research Affairs representing the institutional review board (IRB). Subjects: Sample Size Sample size has been calculated using Raosoft website based on the total surgical patients who receive PN support on monthly bases, which is 20 patients per month, and the duration of the data collection is expected to elapse 6 months. This makes the field population represented by 120 patients. According to a previous study that assessed need for bolus of electrolytes, 7% of the eligible patients are expected to have the outcome. Allowing for 5% margin of error and 95% confidence level the target sample size will be 72 patients from KFSH\&RC. Collaborating centers withdrew from this study due to insufficient eligible patients given the COVID-19 pandemic. Protocol Surgical patients starting PN will be screened for the inclusion and exclusion criteria by the investigators of the study. Eligible patients will be asked to sign a consent form. All patients will start PN after normalization of the following electrolytes potassium, magnesium, and phosphorus according to standard. Premixed PN formula, Olimel N9E will be started at a rate of 45 mL per hour for all patients on day 1 of PN support. After the routine assessment by pharmacists, the PN rate will be increased at an increment of 10 mL per hour on daily basis, representing the target goal of protein of 2 gm per kg according to the ideal body weight (IBW) , is achieved. Patients enrolled in the study will be followed while on PN support until cessation of PN or after 30 days of support have elapsed. All patients will get their potassium, magnesium, and phosphorus levels assessed daily in the morning for the first 7 days of PN initiation. After the first week of PN support, electrolytes will be assessed at a minimum of three times a week thereafter while on PN. High electrolyte levels that develop on the following day of their respective low levels and corrected with bolus will not be considered as induced by PN. Patients who develop hyperphosphatemia, hypermagnesemia, hyperkalaemia will get their PN stopped immediately and replaced with dextrose 10% water solution to run at 50 mL per hour till 21:00.Premixed PN will commence again at the same rate of the corresponding day. Patients who develop a second episode of any hyperphosphatemia, hypermagnesemia, or hyperkalaemia on the preceding day obtained from a blood sample will be shifted to the compounded PN.