Observations of hypophosphatemia and its management in nutrition support

Augmented Renal Clearance Following Traumatic Injury in Critically Ill Patients Requiring Nutrition Therapy

The intent of this study was to ascertain the prevalence of augmented renal clearance (ARC) in patients with traumatic injuries who require nutrition therapy and identify factors associated with ARC. Adult patients admitted to the trauma intensive care unit from January 2015 to September 2016 who received enteral or parenteral nutrition therapy and had a 24 h urine collection within 4 to 14 days after injury were retrospectively evaluated. Patients with a serum creatinine concentration > 1.5 mg/dL, required dialysis, or had an incomplete urine collection were excluded. ARC was defined as a measured creatinine clearance > 149 mL/min/1.73 m². Two hundred and three patients were evaluated. One hundred and two (50%) exhibited ARC. A greater proportion of patients with ARC were male (86% vs. 67%; p = 0.004), had traumatic brain injury (33% vs. 9%; p = 0.001), a higher injury severity score (30 ± 11 vs. 26 ± 12; p = 0.015), were younger (36 ± 15 vs. 54 ± 17 years; p = 0.001), had a lower serum creatinine concentration (0.7 ± 2 vs. 0.9 ± 0.2 mg/dL; p = 0.001) and were more catabolic (nitrogen balance of −10.8 ± 13.0 vs. −6.2 ± 9.2 g/d; p = 0.004). The multivariate analysis revealed African American race and protein intake were also associated with ARC. Half of critically ill patients with traumatic injuries experience ARC. Patients with multiple risk factors for ARC should be closely evaluated for dosing of renally-eliminated electrolytes, nutrients, and medications.

Guidelines for the Intravenous Management of Hypophosphatemia, Hypomagnesemia, Hypokalemia, and Hypocalcemia

Nutrition Support Consultant features issues pertinent to the clinical aspects of pharmacy nutritional support practice.

Refeeding Syndrome in the Intensive Care Unit

Nutrition Support Consultant features issues pertinent to the clinical aspects of pharmacy nutrition support practice.

A New Graduated Dosing Regimen for Phosphorus Replacement in Patients Receiving Nutrition Support

BACKGROUND

Hypophosphatemia is a common metabolic complication in patients receiving specialized nutrition support. We changed our previously reported dosing algorithm because the low dose no longer appeared to be effective at increasing serum phosphorus concentrations. The purpose of this study was to evaluate the safety and efficacy of a revised weight-based phosphorus-dosing algorithm in critically ill trauma patients receiving specialized nutrition support.

METHODS

Seventy-nine adult trauma patients with hypophosphatemia (serum phosphorus concentration < or = 0.96 mmol/L) receiving nutrition support received an IV dose of phosphorus on day 1 according to the serum concentration of phosphorus: 0.73-0.96 mmol/L (0.32 mmol/kg, low dose), 0.51-0.72 mmol/L (0.64 mmol/kg, moderate dose), and < or = 0.5 mmol/L (1 mmol/kg, high dose). The IV phosphorus bolus dose was administered at 7.5 mmol/hour. Generally, patients with a serum potassium concentration <4 mmol/L received potassium phosphate and patients with a serum potassium concentration > or = 4 mmol/L received sodium phosphate. Patients who still had hypophosphatemia on day 2 were dosed using the new dosing algorithm by the nutrition support service according to that day's serum concentration of phosphorus, or empirically by the trauma service.

RESULTS

Of the 79 patients studied, 57 were male and 22 were female with a mean age of 44.8 +/- 20.6 years. Mean Injury Severity Scores and APACHE-II scores were 27.1 +/- 11.6 and 15.2 +/- 6.8, respectively. There was no difference in baseline characteristics among the 3 dosing groups. Of the 79 patients, 34 received the low dose, 30 received the moderate dose, and 15 received the high dose of phosphorous. Mean serum phosphorous concentrations on day 2 were significantly increased in the moderate-dosed group (0.64 +/- 0.06 to 0.77 +/- 0.22 mmol/L, p < .05) and high-dosed group (0.38 +/- 0.06 to 0.93 +/- 0.32 mmol/L, p < .01), respectively, when compared with day 1. Mean serum phosphorus concentrations were normal in all 3 groups on day 3. Serum concentrations of magnesium, sodium, and potassium, as well as arterial pH, were stable across the study. Mean concentrations of ionized calcium were not significantly different in any of the 3 dosing groups across the study period.

CONCLUSIONS

This weight-based phosphorus-dosing algorithm is safe for use in critically ill patients receiving nutrition support. The moderate and severe-dose regimens effectively increase serum phosphorus concentrations.

Phosphate-containing dialysis solution prevents hypophosphatemia during continuous renal replacement therapy

BACKGROUND

hypophosphatemia occurs in up to 80% of the patients during continuous renal replacement therapy (CRRT). Phosphate supplementation is time-consuming and the phosphate level might be dangerously low before normophosphatemia is re-established. This study evaluated the possibility to prevent hypophosphatemia during CRRT treatment by using a new commercially available phosphate-containing dialysis fluid.

METHODS

forty-two heterogeneous intensive care unit patients, admitted between January 2007 and July 2008, undergoing hemodiafiltration, were treated with a new Gambro dialysis solution with 1.2 mM phosphate (Phoxilium) or with standard medical treatment (Hemosol B0). The patients were divided into three groups: group 1 (n=14) receiving standard medical treatment and intravenous phosphate supplementation as required, group 2 (n=14) receiving the phosphate solution as dialysate solution and Hemosol B0 as replacement solution and group 3 (n=14) receiving the phosphate-containing solution as both dialysate and replacement solutions.

RESULTS

standard medical treatment resulted in hypophosphatemia in 11 of 14 of the patients (group 1) compared with five of 14 in the patients receiving phosphate solution as the dialysate solution and Hemosol B0 as the replacement solution (group 2). Patients treated with the phosphate-containing dialysis solution (group 3) experienced stable serum phosphate levels throughout the study. Potassium, ionized calcium, magnesium, pH, pCO(2) and bicarbonate remained unchanged throughout the study.

CONCLUSION

the new phosphate-containing replacement and dialysis solution reduces the variability of serum phosphate levels during CRRT and eliminates the incidence of hypophosphatemia.

Influence of traumatic brain injury on potassium and phosphorus homeostasis in critically ill multiple trauma patients

OBJECTIVE

The intent of this study was to ascertain whether multiple trauma patients with traumatic brain injury (TBI) had lower serum concentrations of potassium and phosphorus and required more aggressive supplementation than multiple trauma patients without TBI.

METHODS

Ventilator-dependent adult patients without renal impairment who were admitted to the trauma intensive care unit or neurosurgical intensive care unit and who received enteral nutrition were evaluated for the first 14 d after hospital admission. Patients were grouped according to the presence or absence of TBI. Target serum concentrations for potassium and phosphorus were 4 mEq/L and 4 mg/dL, respectively. Electrolyte repletion therapy was given according to the nutritional support service guidelines.

RESULTS

Fifty trauma patients (25 with and without TBI) were studied. Daily serum potassium concentrations were consistently lower for those with TBI (P < or = 0.001), whereas the mean net potassium intake was greater (1.3 +/- 0.5 versus 0.7 +/- 0.3 mEq x kg(-1) x d(-1), respectively, P < or = 0.001). Serial serum phosphorus concentrations were similar between groups (P = NS) except for a significantly lower serum phosphorus concentration for trauma patients with TBI on day 3 after hospital admission (2.5 +/- 0.5 versus 2.9 +/- 0.7 mg/dL, respectively, P < or = 0.05). However, the mean net phosphorus intake was significantly greater for trauma patients with TBI (0.65 +/- 0.25 versus 0.45 +/- 0.17 mmol x kg(-1) x d(-1), P < or = 0.001).

CONCLUSION

Potassium and phosphorus requirements are greater for multiple trauma patients with TBI compared with those without TBI.

Severe Refeeding Hypophosphatemia in a CAPD Patient: A Case Report

Refeeding syndrome is defined as severe electrolyte and fluid shifts associated with metabolic abnormalities in malnourished, refeeding patients. Hypophosphatemia is its predominant concern, though its occurrence is unusual in uremic patients due to the concomitant hyperphosphatemia. This case study reports a 56-year-old woman on continuous ambulatory peritoneal dialysis (CAPD) therapy who was admitted for peritonitis. Ileus and diarrhea developed during admission; enteral feeding was given initially and then shifted to total parenteral nutrition (TPN) because of poor digestion. A lower concentration of phosphate was administered in the TPN formula initially due to high initial serum phosphate level. However, severe hypophosphatemia (0.3 mg/dL) developed on the second day after TPN supplementation. Continuous intravenous phosphate (total 6 mmol of phosphate) was supplied immediately. Unfortunately, the sudden onset of conscious loss and cardiac arrest happened on the third day of TPN. It should be emphasized that severe refeeding hypophosphatemia can also develop early in uremic patients with hyperphosphatemia.

Metabolic, Electrolytes, and Nutritional Concerns in Critical Illness

This article discusses metabolic, electrolyte, and nutritional concerns in critical illness.

Metabolic complications associated with parenteral nutrition

Parenteral nutrition is an accepted medical therapy for individuals with gastrointestinal tract dysfunction. It also uses one of the most complex intravenous solutions, which contains all the nutrients needed for a patient's nutritional requirements. Metabolic complications may result from intolerance of glucose, overfeeding, electrolyte shifts, and fluid imbalances. This article describes how to anticipate, identify, and treat such complications so they do not become life threatening.

A comparison of renal phosphorus regulation in thermally injured and multiple trauma patients receiving specialized nutrition support

To compare phosphorus intake and renal phosphorus regulation between thermally injured patients and multiple trauma patients, 40 consecutive critically ill patients, 20 with thermal injury and 20 with multiple trauma, who required enteral tube feeding were evaluated. Phosphorus intakes were recorded for 14 days from the initiation of tube feeding which was started 1 to 3 days postinjury. Serum for determination of phosphorus concentrations was collected at days 1, 3, 7, and 14 of the study period. A 24-hour urine collection was obtained during the first and second weeks of nutrition support for urinary phosphorus excretion, fractional excretion of phosphorus, renal threshold phosphate concentration, and phosphorus clearance. Average total daily phosphorus intake during the 14-day study for thermally injured patients and multiple trauma patients was 0.99+/-0.26 mmol/kg/d vs 0.58+/-0.21 mmol/kg/d, respectively, p < .001. Serum phosphorus concentration on the third day of observation was significantly lower in the thermally injured group than those with multiple trauma (1.9+/-0.8 mg/dL vs 3.0+/-0.8 mg/dL, p < or = .01). A trend toward hypophosphatemia in the thermally injured group persisted by the seventh day of feeding (2.7+/-1.2 mg/dL vs 3.3+/-0.6 mg/dL, p < or = .04). Differences in urinary phosphorus excretion was not statistically significant between the thermally injured and multiple trauma groups (271+/-213 mg/d vs 171+/-181 mg/d for week 1, and 320+/-289 mg/d vs 258+/-184 mg/d for week 2, respectively). Urinary phosphorus clearance, fractional excretion of phosphorus, or renal threshold phosphate concentrations were also not significantly different between thermally injured and multiple trauma patients. During nutrition support, serum phosphorus concentrations are lower in thermally injured patients compared with multiple trauma patients despite receiving a significantly greater intake of phosphorus. Renal phosphorus regulation does not significantly contribute to the profound hypophosphatemia observed in thermally injured patients when compared with multiple trauma patients during nutrition support.

Treatment of hypophosphatemia in patients receiving specialized nutrition support using a graduated dosing scheme: results from a prospective clinical trial

OBJECTIVE

To determine the safety and efficacy of a graduated dosing scheme of phosphorus replacement therapy in patients with hypophosphatemia receiving specialized nutrition support.

DESIGN

Prospective clinical trial.

SETTING

A 455-bed tertiary care institution, with Level I trauma designation.

PATIENTS

Seventy-eight adult patients, followed and co-managed by a multidisciplinary Nutrition Support Service, with a serum phosphorus concentration of < 3 mg/dL (< 0.97 mmol/L) and no evidence of renal insufficiency, calcium or parathyroid disorders, or obesity.

INTERVENTIONS

Patients were enrolled into one of three categories based on their serum phosphorus concentration: mild hypophosphatemia (2.3 to 3 mg/dL [0.74 to 0.97 mmol/L]), moderate hypophosphatemia (1.6 to 2.2 mg/dL [0.52 to 0.71 mmol/L]), or severe hypophosphatemia (< 1.5 mg/dL [< 0.48 mmol/L]). Each patient received one intravenous phosphorus bolus dose, based on the assigned category of hypophosphatemia, according to a graduated dosing scheme: 0.16 mM/kg (mild), 0.32 mM/kg (moderate), or 0.64 mM/kg (severe). Serum/blood concentrations of phosphorus, calcium, albumin, magnesium, urea nitrogen, and creatinine were measured for three consecutive days.

MEASUREMENTS AND MAIN RESULTS

Sixty-seven patients completed the protocol. There were 31 patients with mild hypophosphatemia, 22 patients with moderate hypophosphatemia, and 14 patients with severe hypophosphatemia. Serum phosphorus concentrations increased significantly (p < .001) in all groups after the phosphorus bolus: 2.6 +/- 0.6 to 3.3 +/- 0.6 mg/dL (0.84 +/- 0.19 to 1.1 +/- 0.19 mmol/L) for the mild group; 1.9 +/- 0.6 to 2.7 +/- 0.6 mg/dL (0.61 +/- 0.19 to 0.87 +/- 0.19 mmol/L) for the moderate group; 1.3 +/- 0.8 to 2.3 +/- 0.8 mg/dL (0.42 +/- 0.26 to 0.74 +/- 0.26 mmol/L) for the severe group. There were no clinically significant changes in serum/blood calcium, albumin, urea nitrogen, or creatinine concentrations and no adverse reactions to the phosphorus regimens throughout the 3-day study period.

CONCLUSION

The graduated dosing scheme of phosphorus replacement therapy is both safe and efficacious in patients receiving specialized nutrition support.