Abstract: |
Purpose: Supraventricular dysrhythmias (SVD) after non-cardiac thoracic surgery occur in 10%-25% of patients and have been attributed to acute decrements in serum magnesium (Mg+2). Actual data on alterations in serum Mg+2 concentrations after lung resection are sparse. Methods: We studied 16 patients scheduled for major pulmonary resection. Excluded were patients receiving β-blockers or Ca+2-antagonists. Heparinized arterial blood samples for serum Mg+2 and Ca+2 (for comparison) were obtained before surgery (PRE), on arrival to the post-anesthesia care unit (PACU) and on the morning of postoperative day (POD) 1. Data (mean±SD) were analyzed using a Student t-test and P <0.05 was considered significant. Results: Of the 16 patients (8M/8F) aged 65±15 yr., 15 had undergone a lobectomy and one a pneumonectomy. When compared to baseline, there were no significant differences in serum magnesium or calcium postoperatively (Table). PRE PACU POD1 Mg+2 (mmol/L) 0.8±0.1 0.7±0.1 0.8±0.1 Ca+2 (mmol/L) 2.2±0.1 2.1±0.1 2.1±0.1 Conclusions: Serum concentrations of Mg+2 and Ca+2 did not change significantly within 24h of major thoracic surgery. These preliminary data do not support an important contribution of decreases in serum Mg+2 to SVD generation. However, because SVD often occur 24-48 hours after thoracic surgery, future studies may explore whether Mg+2 alterations later in the postoperative period are associated with an increased incidence of SVD. |