Single bolus dose of epidural magnesium prolongs the duration of analgesia in cardiac patients undergoing vascular surgeries

BACKGROUND AND AIMS: Magnesium, a physiological antagonist of calcium and N-methyl-d-aspartate, has a role in the prevention of pain in patients undergoing surgery for peripheral vascular diseases with cardiac comorbidities such as ischaemic heart disease and coronary artery disease. The objective of our study was assessment of effects of epidural magnesium in cardiac patients undergoing vascular surgery. METHODS: Sixty patients of either sex American Society of Anesthesiologists physical status III undergoing surgeries for peripheral vascular diseases were enrolled. The control group had 30 patients who received levobupivacaine 0.25% 10 ml with fentanyl 50 μg while 30 patients in study group received levobupivacaine 0.25% 10 ml with fentanyl 50 μg and magnesium 100 mg. The primary outcome was duration of analgesia. Sedation score, pain assessment using visual analogue scale (VAS), systolic blood pressure (SBP) and diastolic blood pressure (DBP), heart rate (HR), respiratory rate (RR) and fentanyl consumption were also recorded. Statistical analyses were performed using Minitab 15 statistical software. RESULTS: Both groups were similar demographically and with respect to baseline HR, SBP, DBP and RR. In the study group, compared to the control group, duration of analgesia was 4.17 ± 1.07 h versus 1.55 ± 0.47 h (P < 0.01), sedation score were\ better (P = 0.003) and the VAS scores was lower (P < 0.01). CONCLUSION: Epidural magnesium, added to levobupivacaine and fentanyl as a single bolus dose effectively prolongs the duration of analgesia in high-risk cardiac patients undergoing peripheral vascular surgery.