In this episode, I’ll discuss oral vs IV phosphate replacement for critically ill patients with mild to moderate hypophosphatemia.
IV phosphate is frequently used to replace low serum phosphate levels in critically ill patients. However this often requires the administration of significant amounts of IV fluid, which can complicate the management of many critical illnesses and is more time consuming and costly than oral administration. Because approximately two-thirds of phosphate administered orally is bioavailable, there is reason to believe that oral phosphate replacement might be adequate for critically ill patients with enteral access and functioning GI tracts.
Since there are no expert guidelines on phosphate replacement for critically ill patients, a group of authors carried out a study to determine whether oral phosphate replacement was non-inferior to IV replacement for critically ill patients with mild to moderate hypophosphatemia.
The authors randomized patients to either enteral or IV phosphate replacement and analyzed data from 131 critically ill patients with a serum phosphate concentration between 0.3 and 0.75 mmol/L.
The enteral group received effervescent 500 mg sodium phosphate tablets dissolved in 80–100 mL of water, and administered via a nasogastric tube or ingested. The IV group received sodium or potassium phosphate 10–20 mmol, diluted in 100–250 mL of either sodium chloride 0.9% or glucose 5%, and administered over 1–4 hours.
The primary outcome was serum phosphate concentration 24 hours after randomization and a noninferiority margin of 0.2 mmol/L was chosen a priori based on local expert consensus.
At 24 hours after randomization, the mean serum phosphate concentrations were 0.89 mmol/L and 0.82 mmol/L in the enteral and IV groups, respectively. This met the pre-specified level for non-inferiority.
The enteral group received a median of 2 replacements for a total median dose of 2 grams of enteral sodium phosphate, equivalent to 64 mmol. The Iv group also received a median of 2 replacements for a total median dose of 20 mmol.
Although the IV group did require a mean of 408 mL of fluid to administer the IV dose, the daily fluid intake and daily fluid balance were similar between the two groups.
The mean cost per patient was 10 times greater in the IV group at $37 vs just $3.70 in the enteral group.
The authors concluded:
In patients admitted to the ICU who develop mild or moderate hypophosphatemia, replacement with enteral phosphate, when compared with IV replacement, appears as effective at correcting serum phosphate concentrations. Furthermore, enteral replacement reduces cost with substantially less environmental impact than IV replacement.
To access my free download area with 20 different resources to help you in your practice, go to pharmacyjoe.com/free.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.
Leave a Reply