Are the perioperative changes of serum magnesium in lung surgery arrhythmiogenic?

To prospectively study the perioperative changes in serum magnesium (sMg) after major lung resections and their effect to the generation of cardiac dysrhythmias, and to present a brief review of the literature surrounding this phenomenon.

We studied 33 patients with non small cell lung cancer (NSCLC), scheduled for major pulmonary resection. Three patients were excluded from the study due to preoperative medication with beta-blocker and calcium (Ca) antagonists. Pneumonectomy was performed in 10 patients and lobectomy in 20. Heparinized arterial blood samples for the assessment of sMg, potassium (K) and Ca concentration were obtained before surgery, on arrival to the High Dependency Unit (HDU), and on the morning of the first and the second postoperative day. No patient had evidence of cardiac disease.

Atrial fibrillation occurred in 3 (10%) patients. There was no statistically significant association between sMg and dysrhythmias. A statistically significant difference after adjusting for age was found between sMg concentration, just after the operation and the first post-operative day and the baseline measurement (before the operation). The type of surgical procedure was not found to be associated with the sMg concentration or the appearance of dysrhythmia. The serum K and Ca concentration for all samples was within normal range.

Serum concentration of Mg decreases significantly within the first 24 hours of major lung resection. Although our study didn't demonstrate a relationship between decreases in sMg and the generation of arrhythmias, this link is well established in other fields and thus we support the prophylactic MgSO(4) administration in their prevention in such cases whilst we await further larger studies.