The effect of calcium chloride for the reversal of neuromuscular blockade during recovery of general anesthesia - A randomized controlled study

Abstract

Introduction: Ionized calcium plays an important role in neuromuscular transmission at both pre- and postsynaptic levels. The overall effect of ionized calcium at the neuromuscular junction is not yet evaluated in patients with nondepolarizing neuromuscular blockade. We hypothesized that administration of calcium chloride supplementary to acetylcholinesterase inhibitor could enhance the rate of neuromuscular recovery and reduce the incidence of residual neuromuscular blockade (RNMB) after surgery.

Methods: This single centre, randomized, controlled, double-blinded, parallel-group trial enrolled 58 patients scheduled for elective surgery lasting at least 60 minutes under general anesthesia. Patients were randomly allocated to receive 5 mg.kg-1 of calcium chloride (calcium group, n = 26) or the same volume of normal saline (control group, n = 27) with 25 μg.kg-1 of neostigmine and 15 μg.kg-1 of atropine at the end of surgery. Neuromuscular function was monitored using acceleromyography with the TOF-Watch SX®. The primary endpoint was the time from neostigmine administration to recovery of a train-of-four ratio (TOFr) to 0.9. Secondary end points included TOFr after 5, 10, and 20 min after neostigmine administration, TOFr at the arrival of postanesthesia care unit (PACU), the incidence of RNMB. Results: The time from neostigmine administration to recovery of TOFr to 0.9, was significantly faster in the calcium group than in the control group (5.0 [3.0-7.0] vs. 6.7 [5.7-10.0] min

P = 0.007). TOFr 5 min after neostigmine administration was significantly higher in the calcium group than in the control group. (87 [74-100] vs. 68 [51-81] %

P = 0.002) There were no differences between the two groups with respect to TOFr at PACU, TOFr after 10 and 20 min from neostigmine administration. The incidence of RNMB at 5 min following neostigmine administration was significantly lower in calcium group than in control group (13 [50%] vs. 22 [81.5%]

P = 0.016). All patients were extubated in the operating room. During PACU stay, all patients did not show any clinical sign of residual neuromuscular blockade or recurarization.

Conclusion: The use of calcium chloride at the reversal of nondepolarizing neuromuscular blockade enhances neuromuscular recovery at early recovery period. Further studies are required on the relationship between the calcium administration and clinical outcomes.