[Evaluation of residual neuromuscular block and late recurarization in the post-anesthetic care unit.].

BACKGROUND AND OBJECTIVES: Residual postoperative paralysis impairs airway patency increasing the risk for postoperative complications. Anti-cholinesterase agents improve neuromuscular transmission by acetylcholine build up in the endplate. However, when there is no longer neostigmine effect, 'recurarization' is theoretically possible since the antagonist agent does not displace neuromuscular blocker from its action site. This study aimed at determining the degree of residual neuromuscular block in the Post Anesthetic Care Unit (PACU) and at observing whether patients receiving neostigmine presented the late 'recurarization' phenomenon.

METHODS: Participated in this study 119 adult patients who received neuromuscular blockers for different procedures. At PACU arrival, neuromuscular transmission has been quantified by acceleromyography, with stimulating electrodes placed over the ulnar nerve at the wrist, the train of four (TOF) was used with electrical current of 30mA at 15-minute intervals for a period of 120 minutes. Residual neuromuscular block was considered T4/T1 ratio below 0.9. Clinical symptoms suggesting residual neuromuscular block and vital signs were also recorded in the PACU. Descriptive measures, such as mean and absolute frequency were used for statistical analysis.

RESULTS: Patients receiving pancuronium had a higher incidence of residual block, especially the elderly. Patients receiving neostigmine also presented an expressive percentage of residual curarization. There has been no late recurarization in both groups.

CONCLUSIONS: The incidence of residual block was significantly higher in the pancuronium group. There has been no case of recurarization with neostigmine suggesting that this phenomenon has no clinical significance when patients have no signs of organ failure or co-morbidity impairing neuromuscular transmission.