49
50
suxamethonium regimen was 30.56 ± 5.95 sec this was higher than 23.30 ± 3.06 sec observed by Omosofe et al24 in their study using the same dose of propofol . It was, however, less than the 34.20 ± 3.45 sec obtained in the unmodified group in that same study. Though the optimal seizure duration remains unclear, report has shown that patients with seizure duration less than 10 seconds or greater than120 seconds had less favourable response to ECT.12 This suggests that seizure durations with either 0.5 mg/kg or 1.0 mg/kg suxamethonium obtained in this study is acceptable for clinical efficacy.
This study observed comparable times of onset of apnoea 62.15 ± 13.14 sec and 61.41
± 12.02 sec, respectively, following administration of 0.5 mg/kg suxamethonium and 1.0 mg/kg suxamethonium (p=0.785). The duration of apnoea was likewise comparable between the two doses (p=0.112). The mean duration of apnoea in this study was longer in the 1.0 mg/kg suxamethonium by 13 seconds (125.74 ± 35.40 vs 112.44 ± 31.24) when compared with 0.5 mg/kg suxamethonium. This was, however, smaller than a mean delay of 55 seconds in time to recovery from respiratory paralysis with 1.0 mg/kg suxamethonium when compared with 0.5 mg/kg suxamethonium reported by a previous study57. The duration of apnoea for the two doses in the present study were within normal limits and in agreement with a respiratory paralysis of two to four minutes following 1 mg/kg body weight of suxamethonium reported by Morgan55. This study shows that 1.0 mg/kg suxamethonium does not increase the duration of apnoea significantly when compared with 0.5 mg/kg suxamethonium; thus either regimen can be used without the fear of prolonged apnoea.
A dose of as low as 0.5 mg/kg of suxamethonium is thought to be effective in modifying motor activities associated with ECT because invasive airway manipulations are not required.60 In this study however, there was a significant difference in the quality of seizure. The modification score was more acceptable with the 1.0 mg/kg regimen than with 0.5 mg/kg regimen (p=0.016). A poor modification is characterized by vigorous convulsions
51
likened to those observed in straight ECT. This is associated with the risk of physical injury.
Unmodified ECT is no longer acceptable in present day clinical practice. The proportion of poor modification recorded in this study with the 0.5 mg/kg regimen (41 %) and 1.0 mg/kg (15 %) regimen were, however, less than those reported by Murali et al57 (48 % and 88 % respectively) using same dosages. This may be due to the anticonvulsant effect of thiopental used in the latter study on seizure threshold. Poor seizure modification characterized by violent motor seizure observed in 41 % of patients in 0.5mg/kg suxamethonium group is due to inadequate muscle relaxation.
Konarzewski et al59 reported better seizure modification in patients that received 50 mg suxamethonium compared with 15 mg suxamethonium. The dosage was, however, not based on kilogram body weight, making it unreliable. Also dose comparison was done between different patients; patient variability may thus have affected the result. A study by Omosofe et al24 in Nigeria using 0.5 mg/kg suxamethonium did not assess the extent of motor seizure modification. The current study showed that patients will experience less vigorous motor activities, that is, a better seizure modification with 1.0 mg/kg suxamethonium regimen than when 0.5 mg/kg of same is used to modify ECT. With well modified seizure there is less need for any physical restraint that gave ECT its sinister outlook in time past. Despite the difference in quality of seizure modification, seizure duration, the onset of apnoea and duration of apnoea were comparable between 0.5 mg/kg and 1.0 mg/kg regimens, (p values 0.498, 0.785 and 0.112 respectively).
Researchers24 have compared the effects of propofol and sodium thiopentone on seizure duration, recovery and haemodynamic changes during ECT. They reported a significantly shorter time to eye opening and obeying command as well as a reduction in seizure duration. There seems to be no report yet comparing the motor seizure modification effects of anaesthetics in our country. The effectiveness of ECT depends on the quality of
52
generalized seizure activity.24 Adequate but well controlled seizures are important in ECT because while cerebral seizure is required for treatment, its associated adverse physical effects like injury to bones, teeth and soft tissues must be modified and monitored without compromising the efficacy of treatment.
The cardiovascular changes associated with ECT are of clinical importance. The initial parasympathetic stimulation results in bradycardia, or rarely asystole which is often brief and likely unnoticed32. The sympathetic discharge that follows thereafter causes tachycardia, hypertension, and may lead to arrhythmias. The haemodynamic changes are self-limiting and resolved within 20 minutes19.
Our study observed significant mean increases in systolic, mean arteria and diastolic blood pressures with 0.5 mg/kg suxamethonium which were similar to findings by Takada et al42 who used the same dose of suxamethonium following induction with etomidate. However the 52% increase in mean heart rate observed by Takada et al42 was significantly higher than what is found in neither 0.5 mg/kg nor 1.0 mg/kg suxamethonium groups in this study.
Etomidate which was used by Takada et al42, has a more stable haemodynamic effect than propofol. The study was conducted among individuals above 50 years of age as against a mean age of 34.9 years of subjects in the current study. Therefore, the observed haemodynamic changes may be due to age-related reduction in tonic cardiac vagal inhibition of heart rate and cardiac output in the elderly as compared to young people 34. The minimum arterial oxygen saturation observed in this study was 92% seen in 4% of patients. In contrast, Bansal et al44 reported a 27 % incidence of arterial oxygen desaturation during recovery from anaesthesia following modified ECT. Body mass index (BMI) which has been recognised as an important variable that can affect saturation35 was similar with the two studies. Although
53
atropine was used by Bansal and colleagues unlike in the present study, the incidence of desaturation they observed cannot be explained by its anticholinergic effects38.
Changes in haemodynamic parameters from the baseline values following ECT were significant with either 0.5 mg/kg or 1.0 mg/kg regimen. These changes were however comparable.
The muscle activities that characterize induced seizures in ECT as well as fasciculations that accompany suxamethonium may contribute to increase in serum potassium during the procedure. There was a significant difference between the Pre-ECT and Post-ECT serum potassium for both 0.5 mg/kg and 1.0 mg/kg suxamethonium groups (p ˂0.001). The results agree with the findings of McCleane and Howe63 who likewise reported a significant rise in serum potassium following administration of 0.5 mg/Kg suxamethonium and ECT with values of 4.1 mmol/L and 4.4 mmol/L respectively before and after the procedure (p<0.001).
The maximum rise in serum potassium of 0.4 mmol/L reported by McCleane and Howe63 was seen in two patients during ECT with 0.5 mg/kg suxamethonium in the present study. A rise in serum potassium of 0.5 mmol/L was observed in three patients with 1.0 mg/kg suxamethonium regimen. Bali et al61 reported a rise in serum potassium of 0.25 mmol/L following administration of 1.0 mg/kg suxamethonium; the same value was observed with the use of 1.0 mg/kg in this study. A higher increase of 0.5 mmol/kg potassium was however observed when the same dose of suxamethonium was used with halothane induction for ECT by Bali et al61. Halothane nevertheless is not a choice anaesthetic for induction in ECT. While a significant increase in serum potassium was observed with both 0.5 mg/kg and 1.0 mg/kg suxamethonium in modified ECT the present study has shown that the changes were comparable between the two doses (p=0.192): Thus 1.0 mg/kg suxamethonium regimen
54
will not likely cause a higher increase in serum potassium than 0.5 mg/kg when either is used as relaxant in modified ECT.
Prolonged apnoea, dental injury, tongue laceration, status epilepticus and headache have been reported following ECT.6, 77 The electrical current provokes unique haemodynamic changes in systemic and cerebral circulation which manifest as headache 15, 32. Muscle pain following ECT is due to muscle fasciculations as well as the motor activities following induced seizures.
Five patients in this study complained of muscle pain following ECT with 0.5 mg/kg while four had similar complaint with 1.0 mg/kg suxamethonium (p= 0.133). Two patients complained of headache with 1.0 mg/kg regimen and one with 0.5 mg/kg suxamethonium;
these also showed no statistical significance (p= 0.353). They were treated with oral Paracetamol.
Delayed recovery, prolonged seizures or vomiting that may make ECT procedure worrisome for patients and caregivers were not observed in this study. From these findings the incidence of the common side effects of ECT are comparable when either 0.5 mg/kg or 1.0 mg/kg suxamethonium is used for seizure modification. This also confirms the report of an overview of ECT done in Nigeria about three decades ago by Odejide et al22 which conclude that complications associated with ECT were relatively few.
55
CONCLUSION
This study has shown that 1.0 mg/kg suxamethonium regimen provides better modification of motor seizure activities than 0.5 mg/kg suxamethonium when used as muscle relaxant for electroconvulsive therapy without increasing the known common side effects associated with the procedure.
56
LIMITATION OF THE STUDY
Electroencephalography (EEG) device was not available to monitor seizures. It definitely measures the duration of cerebral seizure which may not all manifest with motor activities.
57
RECOMMENDATION
Suxamethonium at a dose of 1.0 mg/kg controls motor seizures optimally and better than 0.5 mg/kg in electroconvulsive therapy. The dose should be recommended especially in patients that are susceptible to complications that may accompany violent convulsions during the procedure.
58