Time course of rocuronium-induced neuromuscular block after pre-treatment with magnesium sulphate: a randomised study.
BACKGROUND
A previously published study suggested that pre-treatment with magnesium sulphate (MgSO(4)) had no impact on the speed of onset of rocuronium-induced neuromuscular block. We set out to verify this assumption.


METHODS
Eighty patients (18-60 years) were randomly allocated to MgSO(4) 60 mg/kg or placebo (saline). Study drugs were given intravenously for 15 min before induction of anaesthesia with propofol, sufentanil and rocuronium 0.6 mg/kg. Anaesthesia was maintained with a target-controlled propofol infusion. Neuromuscular transmission was measured using train-of-four (TOF)-Watch SX acceleromyography.


RESULTS
Onset was analysed in 37 MgSO(4) and 38 saline patients, and recovery in 35 MgSO(4) and 37 saline patients. Onset time (to 95% depression of T1) was on average 77 [SD=18] s with MgSO(4) and 120 [48] s with saline (P<0.001). The total recovery time (DurTOF0.9) was on average 73.2 [22] min with MgSO(4) and 57.8 [14.2] min with saline (P<0.003). The clinical duration (Dur25%) was on average 44.7 [14] min with MgSO(4) and 33.2 [8.1] min with saline (P<0.0002). The recovery index (Dur25-75%) was on average 14.0 [6] min with MgSO(4) and 11.2 [5.2] min with saline (P<0.02). The recovery time (Dur25%TOF0.9) was on average 28.5 [11.7] min with MgSO(4) and 24.7 [8.4] min with saline (P=0.28).


CONCLUSIONS
Magnesium sulphate given 15 min before propofol anaesthesia reduces the onset time of rocuronium by about 35% and prolongs the total recovery time by about 25%.
Czarnetzki
C
C
Division of Anaesthesiology, University Hospitals of Geneva, CH-1211 Geneva 14, Switzerland. christoph.czarnetzki@hcuge.ch
Lysakowski
C
C
Elia
N
N
Tramèr
M R
MR
D000759:Adjuvants, Anesthesia / Q000009:adverse effects; D000293:Adolescent; D000328:Adult; D000732:Androstanols / Q000009:adverse effects; D000762:Anesthesia Recovery Period; D000768:Anesthesia, General; D003627:Data Interpretation, Statistical; D004558:Electric Stimulation; D023381:Endpoint Determination; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008278:Magnesium Sulfate / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D009213:Myography; D019148:Neuromuscular Blockade / Q000009:adverse effects; D003473:Neuromuscular Nondepolarizing Agents / Q000009:adverse effects; D011292:Premedication; D000077123:Rocuronium; D013997:Time Factors; D055815:Young Adult
D000759:Adjuvants, Anesthesia; D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D008278:Magnesium Sulfate; D000077123:Rocuronium