191COMPLICATIONS ASSOCIATED WITH REVERSAL OF RESIDUAL NEUROMUSCULAR BLOCKResidual neuromuscular blockade can be defined by inadequate neuromuscular recovery as measured by objective neuromuscular monitoring. It is also referred to as residual paralysis, residual curarisation, and residual neuromuscular block. More specifically, recent opinion suggests a definition of inadequate train of four recovery of less than 0.9 (TOF <0.9). With advances in monitoring and continued studies, a TOF <0.9 is now considered as residual neuromuscular blockade. As part of anesthesia management, a neuromuscular blocking agent (NMBA) is often administered to induce muscle relaxation, facilitate airway management, and minimize the risk for laryngeal trauma during tracheal intubation. Implications of residual neuromuscular blockade include physiological changes like impaired muscle tone and coordination and clinical implications like symptoms and signs of muscle weakness, immediate critical respiratory events in postanesthesia care unit (PACU) and later respiratory events. The use of anticholinesterases to reverse residual neuromuscular block at the end of surgery became routine practice in the 1950s. These drugs could only be used when recovery from block was established [two twitches of the train-of-four (TOF) count detectable] and concern was expressed about their cholinergic side-effects. By the 1990s, it was recognized that failure to reverse residual block adequately to a TOF ratio (TOFR) >0.7 was associated with increased risk of postoperative pulmonary complications (POPCs) following the long-acting non-depolarizing neuromuscular blocking drug (NDNMBD) pancuronium. By 2003, and the introduction of acceleromyography, a TOFR ≥0.9 was considered necessary to protect the airway from aspiration before tracheal extubation. It was also considered that four, not two, twitches of the TOF should be detectable before neostigmine was given. Use of any NDNMBD was subsequently shown to be associated with increased risk of POPCs, but it was thought that neostigmine reduced that risk. Recently, there has been conflicting evidence that use of neostigmine might increase the incidence of POPCs. Although sugammadex has been shown to rapidly reverse profound neuromuscular block from aminosteroidal agents, there is currently no evidence that sugammadex is superior to neostigmine in its effect on POPCs. Other new antagonists, including cysteine to degrade CW002 and calabadion 1 and 2 to antagonize aminosteroidal and benzylisoquinolium NDNMBDs, are being studied in preclinical and clinical trials. Quantitative neuromuscular monitoring is essential whenever a NDNMBD is used to ensure full recovery from neuromuscular blockdrrajugmc1@gmail.comResearch822018Residual neuromuscular blockade, Reversal, Complications, anticholinesterases S. Umamaheswara RajuS. Umamaheswara Raju