Abstract No.: ABS3480 : Dynamometer based hand grip strength as a clinical tool for objective assessment of post-operative residual muscle weakness

Abstract

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 1Difference in peak expiratory flow rate (PEFR) as change from baseline to postoperatively up to 300 minTimePEFR (mean±standard deviation)Percentage of baseline (%) P Baseline234.82±78.3010015 min139.25±5259.300.00030 min150.75±53.3064.200.00045 min163.14±56.5069.500.00060 min174.85±58.4074.500.00090 min188.3±61.8080.200.000120 min208.63±61.8088.800.000150 min221.95±67.3094.500.000180 min233.30±73.6599.300.003210 min245.57±72.28105.000.043240 min236.78±72.50101.000.070300 min256.00±91.00109.000.400