An Institutional Change in Continuous Renal Replacement Therapy: Nutrition Support Team Resolves Resultant Severe Hypophosphatemia

BACKGROUND

Critically ill patients with acute kidney injury may require parenteral nutrition (PN) and continuous renal replacement therapy (CRRT). Introduction of a phosphate-free premixed renal replacement fluid without system-wide education in May 2011 resulted in increased incidence of hypophosphatemia, necessitating change in practice. Changes included (1) maximizing phosphate in PN, (2) modifying the CRRT order set, and (3) developing a CRRT competency evaluation for nutrition support team members. This study evaluates the effect of these changes on the incidence of hypophosphatemia.

METHODS

Phosphate levels and predicated probability of hypophosphatemia were evaluated for patients receiving PN and CRRT over 3 time periods: prior to implementing the changes (preimplementation), during change implementation (intermediate), and following implementation (postimplementation). Hypophosphatemia was defined as a serum phosphate level <2.5 mg/dL. Generalized linear mixed models were applied for statistical analysis.

RESULTS

The retrospective study includes 336 measures from 49 patients. Patients in the intermediate and postimplementation periods were not significantly different from each other and had significantly higher mean phosphate levels than patients in the preimplementation period (P < .0001). They were also less likely to develop hypophosphatemia compared with preimplementation patients (intermediate: odds ratio [OR], 0.07; 95% confidence interval [CI], 0.03-0.18, P < .0001; postimplementation: OR, 0.09; 95% CI, 0.03-0.27, P < .0001).

CONCLUSIONS

Modifications in phosphate dosing together with CRRT education reduced the incidence of hypophosphatemia in PN patients receiving CRRT. Communication of significant changes in clinical care should be shared with all services prior to implementation. Communication and planning between services caring for complex patients are necessary to prevent systems-based problems.

Prevention of hypophosphatemia during continuous renal replacement therapy-An overlooked problem

Hypophosphatemia is a common and potentially serious complication occurring during continuous renal replacement therapy (CRRT). Phosphate supplementation is required in the vast majority of patients undergoing CRRT, particularly beyond the first 48 hours. Supplementation can be provided either as a standalone oral or parenteral treatment or as an additive to CRRT solutions. Each approach has advantages and disadvantages, and clinicians must weigh the individual factors most relevant in their practice setting. Currently there are no consensus protocols for phosphate replacement in CRRT, and many centers replete phosphate in response to hypophosphatemia as opposed to pre-emptively. Repletion protocols have also been challenged in recent years by shortages in injectable phosphate solutions. More recently a commercially available phosphate-containing CRRT solution was approved in the United States, but there has been limited clinical experience with this product. In this review, we present recommendations for phosphate repletion in CRRT to prevent hypophosphatemia, and describe our experience using phosphate-containing CRRT solutions.

Effects of parenteral phosphorus dose restriction in preterm infants

BACKGROUND

In response to a national shortage of parenteral phosphorus solutions (2013), a hospital-wide phosphorus dose restriction strategies was implemented which included judicious use of phosphorus in preterm infants <1250 g birth weight and no parenteral phosphorus in preterm infants >1250 g birth weight unless they have a critically low phosphorus level.

OBJECTIVE

To study the effect of parenteral phosphorus dose restriction in preterm infants admitted to the neonatal intensive care unit.

METHODS

Preterm infants (≤35 weeks birth gestation and ≤2500 g birth weight) who received parenteral nutrition, survived >1 week and had no major congenital anomalies were studied. Clinical and laboratory data in the first 4 weeks of life of infants admitted during the parenteral phosphorus shortage (cases) were compared to infants who were admitted 6 months prior to the shortage (controls).

RESULTS

Twenty consecutive cases were compared to 40 consecutive controls. Cases had lower serum phosphorus levels, higher serum alkaline phosphatase levels, and need for greater inotropic support compared to controls. These differences were significant only in preterm infants with birth weight >1250 g, the group who received more parenteral phosphorus dose restriction while they were similar in preterm infants with birth weight <1250 g.

CONCLUSION

The modest effects of phosphorus dose restriction may become more clinically important if shortage is prolonged or severe or if it involves extreme preterm infants.

Use of Premixed Parenteral Nutrition During a Phosphate Shortage in a Non-Critically Ill Population

BACKGROUND

Drug shortages pose prescribing problems to clinicians. During fiscal year (FY) 2014, an acute shortage of intravenous potassium phosphate (K-Phos IV), a common supplement in parenteral nutrition (PN), prompted the use of premixed instead of individualized PN to conserve K-Phos IV. Here we quantify the K-Phos IV conserved by using premixed PN and the associated cost differences.

MATERIALS AND METHODS

Costs of preparing premixed PN vs individualized PN of equivalent composition were calculated for FY 2014 at a single-center tertiary care facility. Quantity and cost of K-Phos IV saved were calculated based on the number of premixed PN prescriptions. Costs for FY 2015 were projected based on drug costs from July 2014.

RESULTS

During FY 2014, prescribing premixed in lieu of individualized PN conserved 16,440 mmol K-Phos IV but increased the cost of PN by $4080.45. However, increases in K-Phos IV cost at the end of FY 2014 resulted in premixed PN as a relatively less expensive therapy than individualized PN for our institution. Cost savings of $7092.20 due to use of premixed PN is projected for FY 2015.

CONCLUSIONS

Prescribing premixed PN conserves K-Phos IV during shortages, but it increased direct drug spending in non-critically ill patients at our institution during FY 2014. Persistent shortages can drive market costs of K-Phos IV, however, necessitating frequent reconsideration of resource utilization.

Impact of an Intravenous Magnesium Shortage on Potassium Doses in Adult Surgical Patients Receiving Parenteral Nutrition

BACKGROUND

Shortages of parenteral nutrition (PN) components have been common in recent years. Effects on patient management and outcomes have not been well documented. This study aimed to determine the effect of a parenteral magnesium shortage, and an institutional decision to omit magnesium from adult PN, on magnesium and potassium doses and serum concentrations.

MATERIALS AND METHODS

This was a retrospective cohort study of adult surgical patients during two 6-month periods: prior to the magnesium shortage (2011) and during the shortage (2012). The relation between study period and electrolyte doses was evaluated by unadjusted and adjusted mixed models, while the relation between study period and hypokalemia and hypomagnesemia exposure was evaluated by Student's t tests and multiple linear regression.

RESULTS

During the shortage, patients received more supplemental magnesium (0.11-0.12 mEq/kg/d, P < .0001) but received less total daily magnesium (0.08-0.09 mEq/kg/d, P < .0001) and had greater exposure to hypomagnesemia (9.6-14.2 h·mcg/dL/h, P < .05 for all comparisons except multivariate analysis in a matched subpopulation). Patients received similar amounts of potassium in PN (0.06-0.08 mEq/kg/d less, P < .05 for full cohort but P > .05 for matched cohort), in supplemental doses (0.01-0.05 mEq/kg/d less, P > .05), and in total (0.07-0.14 mEq/kg/d less, P > .05), and they had similar exposure to hypokalemia.

CONCLUSION

Daily magnesium doses were lower and hypomagnesemia exposure was greater during the shortage, but the differences were numerically small and their clinical significance was questionable. Potassium doses and hypokalemia exposure were not higher during the shortage. This supports the strategy of omitting magnesium from PN of select patients and supplementing as clinically necessary.

A novel phosphorus repletion strategy in a patient with duodenal perforation

We describe a case in which a patient receiving parenteral nutrition (PN) developed hypophosphatemia. Due to lack of availability of parenteral phosphate supplements, we chose to restore phosphate using diluted hypertonic sodium phosphate enemas. Due to the recent shortages of parenteral minerals and vitamins, such an alternate means of repletion is of increasing importance. Diluted hypertonic sodium phosphate enemas are inexpensive, easy to administer, and effective since phosphate is readily absorbed across the rectal mucosa. We hope that through this type of repletion, life-threatening hypophosphatemia among patients receiving PN can be avoided.

Metabolic bone disease: a continued challenge in extremely low birth weight infants

BACKGROUND

Metabolic bone disease (MBD) is an important prematurity-related morbidity, but remains inadequately investigated in extremely low birth weight (ELBW) infants, the group most at risk. The objective was to describe the incidence and associated risk factors of MBD in ELBW infants.

METHODS

Retrospective analysis of all ELBW infants admitted between January 2005 and December 2010 who survived > 8 weeks. MBD was defined as the presence of osteopenia or rickets in radiographs.

RESULTS

Of the 230 infants included in the study, 71 (30.9%) developed radiological evidence of MBD (cases) of which 24/71 (33.8%) developed spontaneous fractures. MBD and fractures were noted at mean postnatal ages of 58.2 ± 28 and 100.0 ± 61 days, respectively. Compared with controls, cases were smaller at birth (664.6 ± 146 g vs 798.1 ± 129 g), more premature (25.0 ± 1.8 vs 26.4 ± 1.9 weeks), more frequently associated with mechanical ventilation, chronic lung disease, parenteral nutrition days, cholestasis, furosemide, postnatal steroids, and antibiotics use (all P < .01). Cases had lower average weekly intake of calcium, phosphorous, vitamin D, protein, and calories during the first 8 weeks of life compared with controls. Cases with MBD, compared with controls, had higher mortality (14.1 vs 4.4%) and longer hospital stay (140.2 ± 51 vs 101.0 ± 42 days; P < .01).

CONCLUSIONS

MBD remains an important morbidity in ELBW infants despite advances in neonatal nutrition. Further research is needed to optimize the management of chronic lung disease and early nutrition in ELBW infants.