Background and Goal of Study: Contemporary anesthesia is considered safe because mortality related to anesthesia is decreased and there is an increased emphasis on expeditious recovery without morbidity.However postoperative residual curarization (PORC) following the use of neuromuscular blockers(NMBs) without neuromuscular monitoring remains a clinical problem although intermediate-acting NMBs are used.The aim of this study was to survey the PORC and critical respiratory events(CREs) in the recovery room.
Materials and Methods: In this study,415 patients(ASA I-III) who received general anesthesia with intermediate-acting NMBs were enrolled.Anesthetists were blinded to the study.Neuromuscular monitoring(TOF-Watch-S) was performed at arrival in the recovery room by assessing the fade in response to submaximally TOFstimulation of the ulnar nerve.A TOF< 0.7 and between 0.7-0.9 at arrival was classified as severe and mild-moderate PORC respectively.CREs was defined by airway requirement, SpO2< 90%(severe hypoxemia) and 90-93%(mild-moderate hypoxemia) while receiving 3L/min nazal O2, respiratory rate>20 breaths per minute, difficulty in breathing and swallowing, use of accessory muscles and reintubation requirement.
Results and Discussion: TOF less than 0.7 and 0.9 were observed in 61(14.7%) and 179(43.2%) patients, respectively. TOF< 0.9 was significantly higher patients in females, ASAIII, who underwent laparoscopic and abdominal surgery and who received supplement NMBs dose. Patients with TOF< 0.9 also significantly had an older avarage age, shorter duration of anesthesia and interval from last NMBA injection or antagonism of block to TOF recording(p< 0.05).This result may be associated with lowest mean dose of neostigmine (0.02mg/kg±0.01mg) in patients who receive reversal medication[272(66%)]. The incidence of PORC(TOF< 0.9) while receiving 3L/min nazal O2 in patients with severe(SpO2< 90%) and mild to moderate(SpO2: 90-93%) hypoxemia was significantly higher than patients with SpO2>93%;14/17(82.4%),60/96(6 2.5%) and 105/302(34.8%); respectively(p< 0.05).
Conclusion(s): PORC remains a clinical problem despite use of intermediateacting NMBs. Older patients, female gender, ASA III, shorter surgery, short interval from the last NMB dose to TOF recording and early extubation after reversal of neuromuscular blockade may be at risk of PORC and CREs. The optimal antagonism of NMBs and objective neuromuscular monitoring needs to be performed to ensure patient safety.