Calcium phosphate precipitates can form in total parenteral nutrition (TPN) solutions. Infusion of these precipitates cause pulmonary microemboli with acute respiratory distress. Prevention of conditions favorable to precipitate formation and prompt recognition can reduce the risk to patients.


Symptoms of precipitates reaching the lung:

(1) acute respiratory distress

(2) interstitial pneumonia

(3) clinical suspicion of pulmonary embolism with no evidence of deep vein thrombosis


Prevention of formation:

(1) The solubility of added calcium and phosphate should be based on the volume of the solution at the time when they are added and not on the final volume.

(2) All sources of phosphate (buffering solutions, etc.) should be included in the calculation of the final phosphate concentration.

(3) If calcium and phosphate are added to the mixture, phosphate should be added first.

(4) The line should be flushed between additions of potentially incompatible components.

(5) While be prepared the TPN solution should be periodically agitated and inspected for precipitates.

(6) If stored at room temperature, the TPN solution should be administered within 24 hours of mixing. If refrigerated, the TPN solution should be administered within 24 hours of rewarming.

(7) The temperature of the TPN solution should be monitored during the infusion. Excessive warming of the solution favors formation of precipitates.

(8) A 3-to-1 lipid emulsion makes detection of precipitates difficult. If possible, infuse a 2-to-1 lipid emulsion and the remainder of the lipid requirements separately. If a 3-to-1 lipid emulsion must be infused, then the calcium should be added to the solution before the lipid and the solution observed for precipitates.

(9) If the amount of calcium and phosphate added could cause a precipitate, some of the calcium should be infused separately.

(10) Automated compounded devices should be operated and maintained according to the manufacturer's recommendations. The amount and sequence of each addition should be checked for potential incompatibility.

(11) A sample of the prepared TPN solution should be retained for reference if needed.


Prevention of precipitate infusion:

(1) The infusion solution should pass through a filter before reaching the patient. A 1.2 micron air-eliminating filter is recommended for a lipid-containing solutions and a 0.22 micron air-eliminating filter is recommended for nonlipid-containing solutions.

(2) The TPN solution should be inspected for precipitates prior to and during infusion.

(3) If infused at home, patients and caregivers should be instructed in proper handling techniques and on how to inspect the solution for precipitates.


Prompt response:

(1) If respiratory complications occur during infusion of a TPN solution, the infusion should be stopped immediately and the health care provider notified.

(2) The solution, filter and line should be immediately inspected for precipitates.


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