Tonic Downward Movement of Eyes and Its Eccentric Positioning in Downgaze Under General Anaesthesia

Objectives. To summarize abrupt eccentric eye positioning in downgaze following the downward movement of eyes encountered in patients undergoing ophthalmic surgeries under general anesthesia (GA) and analyze the relationship between the fluctuation in the depth of anesthesia (DOA) and eccentric eye positioning in downgaze. Subjects and Methods. Patients undergoing ophthalmic surgeries under GA without nondepolarizing muscle relaxant between January 2018-December 2019 in a tertiary-eye-care who witnessed a sudden tonic hypo-tropic movement of eyes were included in the retrospective, cross-sectional study. Results. A total of 8 patients out of 199 were enrolled in this study with an average age of 1.13±0.40years. All cases (3 pediatric cataracts, 4 strabismus, and 1 pseudophakia with posterior capsular opacification) were performed under GA with sevoflurane as an inducing agent. Downward movement was seen before the start of surgery in 4 cases and during surgery in 4 cases. Downward drift of eyes appeared tonic as the strong tug was felt in an extreme downward eccentric position. It was preceded by an eccentric upward drift of eyes following which sevoflurane concentration was increased to optimize DOA when this downward drift was encountered (mean minimal alveolar concentration/MAC 1.63±0.25). Downward movement was quick but return movement of eyes to the central position was gradual (mean 1.55±0.48minutes) when DOA was decreased (mean MAC 1.3±0.09).Conclusions. Tonic-downward movement of eyes or its eccentric positioning in downgaze is not an uncommon entity in children under GA without muscle-relaxant and fluctuations in DOA should be avoided to circumvent inadvertent complications during ocular surgery.

Residual Paralysis in the PACU after a Single Intubating Dose of Nondepolarizing Muscle Relaxant with an Intermediate Duration of Action

Background Residual neuromuscular blockade remains a problem even after short surgical procedures. The train-of-four (TOF) ratio at the adductor pollicis required to avoid residual paralysis is now considered to be at least 0.9. The incidence of residual paralysis using this new threshold is not known, especially after a single intubating dose of intermediate-duration nondepolarizing relaxant. Therefore, the aim of the study was to determine the incidence of residual paralysis in the postanesthesia care unit after a single intubating dose of twice the ED(95) of a nondepolarizing muscle relaxant with an intermediate duration of action. Methods Five hundred twenty-six patients were enrolled. They received a single dose of vecuronium, rocuronium, or atracurium to facilitate tracheal intubation and received no more relaxant thereafter. Neuromuscular blockade was not reversed at the end of the procedure. On arrival in the postanesthesia care unit, the TOF ratio was measured at the adductor pollicis, using acceleromyography. Head lift, tongue depressor test, and manual assessment of TOF and DBS fade were also performed. The time delay between the injection of muscle relaxant and quantitative measurement of neuromuscular blockade was calculated from computerized anesthetic records. Results The TOF ratios less than 0.7 and 0.9 were observed in 16% and 45% of the patients, respectively. Two hundred thirty-nine patients were tested 2 h or more after the administration of the muscle relaxant. Ten percent of these patients had a TOF ratio less than 0.7, and 37% had a TOF ratio less than 0.9. Clinical tests (head lift and tongue depressor) and manual assessment of fade showed a poor sensitivity (11-14%) to detect residual blockade (TOF < 0.9). Conclusion After a single dose of intermediate-duration muscle relaxant and no reversal, residual paralysis is common, even more than 2 h after the administration of muscle relaxant. Quantitative measurement of neuromuscular transmission is the only recommended method to diagnose residual block.