Preferences for the measurement and supplementation of magnesium, phosphate and zinc in ICUs: The international WhyTrace survey

A Randomized Noninferiority Trial to Compare Enteral to Parenteral Phosphate Replacement on Biochemistry, Waste, and Environmental Impact and Healthcare Cost in Critically Ill Patients With Mild to Moderate Hypophosphatemia

OBJECTIVES

Hypophosphatemia occurs frequently. Enteral, rather than IV, phosphate replacement may reduce fluid replacement, cost, and waste.

DESIGN

Prospective, randomized, parallel group, noninferiority clinical trial.

SETTING

Single center, 42-bed state trauma, medical and surgical ICUs, from April 20, 2022, to July 1, 2022.

PATIENTS

Patients with serum phosphate concentration between 0.3 and 0.75 mmol/L.

INTERVENTIONS

We randomized patients to either enteral or IV phosphate replacement using electronic medical record-embedded program.

MEASUREMENT AND MAIN RESULTS

Our primary outcome was serum phosphate at 24 hours with a noninferiority margin of 0.2 mmol/L. Secondary outcomes included cost savings and environmental waste reduction and additional IV fluid administered. The modified intention-to-treat cohort comprised 131 patients. Baseline phosphate concentrations were similar between the two groups. At 24 hours, mean ( sd ) serum phosphate concentration were enteral 0.89 mmol/L (0.24 mmol/L) and IV 0.82 mmol/L (0.28 mmol/L). This difference was noninferior at the margin of 0.2 mmol/L (difference, 0.07 mmol/L; 95% CI, -0.02 to 0.17 mmol/L). When assigned IV replacement, patients received 408 mL (372 mL) of solvent IV fluid. Compared with IV replacement, the mean cost per patient was ten-fold less with enteral replacement ($3.7 [$4.0] vs. IV: $37.7 [$31.4]; difference = $34.0 [95% CI, $26.3-$41.7]) and weight of waste was less (7.7 g [8.3 g] vs. 217 g [169 g]; difference = 209 g [95% CI, 168-250 g]). C O2 emissions were 60-fold less for comparable phosphate replacement (enteral: 2 g producing 14.2 g and 20 mmol of potassium dihydrogen phosphate producing 843 g of C O2 equivalents).

CONCLUSIONS

Enteral phosphate replacement in ICU is noninferior to IV replacement at a margin of 0.2 mmol/L but leads to a substantial reduction in cost and waste.

Effects of magnesium, phosphate, or zinc supplementation in intensive care unit patients-A systematic review and meta-analysis

BACKGROUND

Low-serum levels of magnesium, phosphate, and zinc are observed in many intensive care unit (ICU) patients, but clinical equipoise exists regarding supplementation strategies. We aimed to assess the desirable and undesirable effects of supplementation with magnesium, phosphate, or zinc in adult ICU patients.

METHODS

We conducted a systematic review with meta-analysis of randomised clinical trials assessing the effects of supplementation with magnesium, phosphate, or zinc in adult ICU patients. Primary outcomes were mortality and duration of mechanical ventilation. We registered the protocol, followed the Preferred Reporting Items for Systematic Review and Meta-Analysis statement, used the Cochrane risk of bias 2 tool, and the grading of recommendations, assessment, development and evaluation (GRADE) approach for assessing the certainty of the evidence.

RESULTS

We identified no low risk of bias trials. For magnesium supplementation, we included three trials (n = 235); the relative risk (RR) for mortality was 0.54, 95% confidence interval (CI) 0.30-0.96 compared to no supplementation (very low certainty of evidence). For zinc supplementation, two trials were included (n = 168); the RR for mortality was 0.73, 95% CI 0.41-1.28 compared to control. No trials assessed the effects of phosphate supplementation on mortality. For outcomes other than mortality, only zero or one trial was available.

CONCLUSIONS

In adult ICU patients, the certainty of evidence for the effects of supplementation with magnesium, phosphate, or zinc was very low. High-quality trials are needed to assess the value of supplementation strategies in these patients.