Significant hypophosphatemia following major cardiac surgery: incidence and consequences

Significant hypophosphayemia (SH) may be associated with respiratory and cardiac complications but has not been targeted as a reversible cause of these complications following cardiac surgery.

Patients and methods

We prospectively studied all patients (n = 566, males 388, females 178, mean age 65.5 [11.1] years) undergoing major cardiac surgery (coronary artery bypass grafting [CABG] 75.4%; aortic valve replacement 5.1%; aortic valve replacement + CABG 5.8%; mitral valve replacement 6.8%; other 6.9%) over a 6-month period. Phosphate levels were measured preoperatively, on admission to the ICU, and on the first postoperative day. Two groups were defined according to the ICU admission level: SH, level <0.48 mmol/l; and a control group, normal range 0.8–1.45 mmol/l. Preoperative, intraoperative and postoperative data were collected in all patients. SH was treated with intravenous sodium or potassium phosphate (0.08 mmol/kg) over 6–12 hours.

Results

SH was found in 34.3% (mean level 0.29 [0.13] vs 0.84 [0.11]). Preoperative data are presented in Table 1, and the postoperative course in Table 2. The phosphate level tended to be lower in the SH group on the first postoperative day (0.6 [0.15] vs 0.81 [0.10]), suggesting inadequate repletion.

Table 1

Table 2

Conclusions

As SH after cardiac surgery appears to be common and associated with major morbidity, levels should be routinely monitored.