Perioperative Tracking of Intravenous Iron in Patients Undergoing On-Pump Cardiac Surgery: A Prospective, Single-Center Pilot Trial.

BACKGROUND

Preoperative intravenous iron administration is a frequently used patient blood management procedure. If the timeframe of intravenous iron administration before surgery is short, (1) the concentration of the intravenous iron compound might still be high in patients' plasma when undergoing surgery and (2) this iron in patients' plasma is at risk to be lost due to blood loss. The aim of the current study was, therefore, to track the iron compound ferric carboxymaltose (FCM) before, during, and after cardiac surgery requiring cardiopulmonary bypass, with an emphasis on intraoperative iron losses in shed blood and potential recovery through autologous cell salvage.

METHODS

Concentrations of FCM were analyzed in patients' blood using a hyphenation of liquid chromatography and inductively coupled plasma-mass spectrometry to distinguish between pharmaceutical compound FCM and serum iron. In this prospective, single-center pilot trial, 13 anemic and 10 control patients were included. Anemic patients with hemoglobin levels ≤12/13 g/dL in women and men were treated with 500 milligrams (mg) intravenous FCM 12 to 96 hours before elective on-pump cardiac surgery. Patients' blood samples were collected before surgery and at days 0, 1, 3, and 7 after surgery. One sample each was taken of the cardiopulmonary bypass, the autologous red blood cell concentrate generated by cell salvage, and the cell salvage disposal bag.

RESULTS

Patients who had received FCM <48 hours before surgery had higher FCM serum levels (median [Q1-Q3], 52.9 [13.0-91.6]) compared to ≥48 hours (2.1 [0.7-5.1] µg/mL, P = .008). Of 500-mg FCM administered <48 hours, 327.37 (257.96-402.48) mg were incorporated compared to administration ≥48 hours with 493.60 (487.78-496.70) mg. After surgery, patients' plasma FCM concentration in the FCM <48 hours group was decreased (-27.1 [-30 to -5.9] µg/mL). Little FCM was found in the cell salvage disposal bag (<48 hours, 4.2 [3.0-25.8] µg/mL, equivalent to 29.0 [19.0-40.7] mg total; equivalent to 5.8% or 1/17th of the 500 mg FCM initially administered), almost none in the autologous red blood cell concentrate (<48 hours, 0.1 [0.0-0.43] µg/mL).

CONCLUSIONS

The data generate the hypotheses that nearly all FCM is incorporated into iron stores with administration ≥48 hours before surgery. When FCM is given <48 hours of surgery, the majority is incorporated into iron stores by the time of surgery, although a small amount may be lost during surgical bleeding with limited recovery by cell salvage.