LAUSR

Background and Aims: Residual neuromuscular block is a known postoperative complication. Even after train of four (TOF) ratio of >0.9, there is a possibility of neuromuscular blockade causing respiratory dysfunction. Primary objective was assessment of postoperative residual muscle weakness with dynamometer. Secondary objective was time of recovery to baseline strength. Methods: This was a single centre, prospective, observational study. We enroled 50 patients undergoing surgery under general anesthesia. The patients of Americal Society of Anesthesiologists physical status I-II, aged 18-60 years and undergoing surgery under general anaesthesia were included. The patients with surgery including fracture, deformity involving dominant upper limb and pre-existing neuromuscular diseases were excluded from the study. Baseline handgrip strength with dynamometer and peak expiratory flow rate (PEFR) were observed before induction of anaesthesia. Trachea was extubated with TOF ratio >0.9. Values monitored at 15 minutes after extubation,at regular intervals of 15 minutes until 1 hour, 30 minutes until 4 hours and hourly until 6 hours. Results: Muscle strength remained 50 to 60% of baseline at 15 minutes, 75% at 45 minutes and reached 100% of baseline at 210 minutes after endotracheal extubation. PEFR remained 50 - 60 % of baseline at 15minutes, 75% of baseline at 60 minutes and reached 100% of baseline at 180 minutes after endotracheal extubation (Table 1). Conclusion: A significant reduction in the postoperative muscle strength was detected using objective force dynamometer to measure handgrip strength even when TOF ratio had returned to 1 with no clinical signs of muscle weakness.Table 1 Difference in peak expiratory flow rate (PEFR) as change from baseline to postoperatively up to 300 min Time PEFR (mean±standard deviation) Percentage of baseline (%) P Baseline 234.82±78.30 100 15 min 139.25±52 59.30 0.000 30 min 150.75±53.30 64.20 0.000 45 min 163.14±56.50 69.50 0.000 60 min 174.85±58.40 74.50 0.000 90 min 188.3±61.80 80.20 0.000 120 min 208.63±61.80 88.80 0.000 150 min 221.95±67.30 94.50 0.000 180 min 233.30±73.65 99.30 0.003 210 min 245.57±72.28 105.00 0.043 240 min 236.78±72.50 101.00 0.070 300 min 256.00±91.00 109.00 0.400