A COMPARISON OF TWO DOSES OF SUXAMETHONIUM CHLORIDE IN MODIFIED ELECTROCONVULSIVE THERAPY IN A NIGERIAN TEACHING HOSPITAL

Abstract

Background: The goal of anaesthesia for electroconvulsive therapy (ECT) is to
ensure a calm patient with satisfactory seizure modification and minimal side effects without
compromising the therapeutic benefits of ECT. Suxamethonium remains the most commonly
used muscle relaxant to reduce the intense muscle contractions associated with ECT-induced
seizure activity. This study compared the quality of seizure modification, haemodynamic
changes, serum potassium levels and side effects profile; when either 0.5 mg/kg or 1.0 mg/kg
was administered at two consecutive treatment sessions in the same patient within a course of
ECT.
Methodology: In a prospective randomized crossover study, the effects of
suxamethonium at a dose of 0.5 mg/kg and 1.0 mg/kg were compared in the first two
treatment sessions of modified ECT in 27 patients aged 19-62 years in a total of 54 ECT
sessions. Patients were randomized to have either 0.5 mg/kg or 1.0 mg/kg suxamethonium as
muscle relaxant at the first treatment session. Patients who had 0.5mg/kg suxamethonium
regimen at the first treatment session had 1.0 mg/kg regimen at the second session and vice
versa. The two sessions took place 48 hours apart. Intravenous propofol was used as
induction agent at a dose of 1 mg/kg. Seizure modification pattern was scored; duration of
seizure as well as onset and duration of apnoea were recorded. Haemodynamic parameters
were monitored every three minutes. Blood samples were taken before and after procedure to
determine serum potassium levels. These were compared between the two ECT sessions in all
the patients recruited.
Results: Sixteen patients (59 %) had acceptable seizure modification with 0.5 mg/kg
suxamethonium while 23 patients (85 %) had acceptable seizure modification with 1.0 mg/kg
suxamethonium. Seizure modification was poor in 11 (41%) patients with 0.5 mg/kg
suxamethonium and 4 (15 %) patients with 1.0 mg/kg suxamethonium, (p = 0.016; Fisher’s
exact test). There was no statistically significant difference in seizure duration between 0.5
mg/kg and 1.0 mg/kg doses (30.26 ± 5.95 sec vs 29.00 ± 7.83 sec respectively. p = 0.498).
Onset of apnoea was 62.15 ± 13.14 sec and 61.41 ±12.02 sec respectively (p= 0.798).
Duration of apnoea was 30.26 ± 5.95 sec and 29.00 ± 7.83 (p = 0.112). While there was
significant change in haemodynamic parameters when either 0.5 mg/kg suxamethonium
regimen or 1.0 mg/kg was used, these differences were not statistically significant. The mean
serum potassium levels pre and post ECT respectively were 3.52 ± 0.32 mmol/L and 3.72 ±
0.32 mmol/L (p = 0.000) for 0.5 mg/ kg suxamethonium and 3.67 ± 0.27 mmol/L and 3.92 ±
0.32 mmol/L (p = 0.000) for 1.0 mg/kg. Increases in serum potassium were comparable for
the two doses. Five patients complained of muscle pain with 0.5 mg/kg while four
complained of same with 1.0 mg/kg. The incidence of headache for the two doses was 1 (4%)
and 2 (7 %) respectively.
Conclusion: The study showed that patients experienced a better modification of
motor seizure and less violent convulsions during ECT with 1.0 mg/kg than 0.5 mg/kg
suxamethonium with comparable changes in haemodynamic parameters and incidences of
side effects.