Continuous femoral nerve block enhances outcome of spinal anaesthesia in preventing perioperative cardiac complications in patients with cardiac risk

Background Elevated brain natriuretic peptide (BNP) is crucial to detect perioperative adverse cardiovascular events in patients with cardiac risk, even at low elevation of BNP level or when myocardial necrosis has not been already established. This study aims to compare between two anaesthesia methods in preventing perioperative myocardial infarction for patients having cardiac risk undergoing total knee arthroplasty (TKA). Patients and methods Fifty adult patients planned for TKA with risk factors as ischemic heart disease, diabetics, hypertensive, heavy smokers or body mass index >= 35 were categorized randomly into two groups. Group (S): received spinal anaesthesia followed by continuous ultrasound guided femoral nerve block once spinal motor blockade had been resolved. Group (G): received combined general and lumber epidural anaesthesia. BNP, cardiac troponins, pain severity, analgesic consumption, patients' satisfaction and adverse cardiac events were observed preoperatively and extended to 2 days postoperatively. Results Baseline readings of BNP and cardiac troponins were comparable in both members. At 24 and 48 hours postoperatively, it decreased significantly in group S compared to group G. Mean Visual analogue score was significantly lower in group S comparative to group G at all times except at 40 and 48 hours postoperatively. Morphine utilization was significantly lower in group S. Patients in group S were significantly more satisfied than those in group G. Conclusions The use of spinal anaesthesia with continuous femoral nerve block can reduce the prevalence of perioperative myocardial infarction in patients with cardiac risk undergoing TKA.