Suxamethonium pains: hypothesis and observation

Preoperative pregabalin prevents succinylcholine-induced fasciculation and myalgia: A meta-analysis of randomized trials

Succinylcholine is the gold standard neuromuscular blocker for rapid sequence induction; however, its use is associated with fasciculation and myalgia. We performed a systematic review and meta-analysis of randomized controlled clinical trials comparing gabapentinoids versus placebo for the prevention of fasciculations and succinylcholine-induced myalgias. Six randomized clinical studies were included with a total of 481 patients - 241 in the intervention group and 240 in the placebo group. Gabapentinoids reduced the incidence of succinylcholine-induced myalgia (RR=0.69, 95% CI 0.56-0.84, P<.001), which remained statistically significant for pregabalin (RR=0.71, 95% CI 0.54-0.93, P=.013) and gabapentin (RR=0.61, 95% CI 0.45-0.82, P=.001) separately. There was no difference in fasciculations between the groups (RR=0.92, 95% CI 0.82-1.03, P=.148). Preoperative use of gabapentinoids is associated with lower incidence of succinylcholine-induced myalgias within the first 24h of surgery.

Effect of Non-depolarizing Muscle Relaxants Rocuronium Versus Vecuronium in the Assessment of Post-Succinylcholine Complications in Surgeries Under General Anesthesia: A Randomized Double-Blind Study at a Tertiary Care Hospital

Background and objective

Several drugs have been used to prevent or attenuate succinylcholine-induced muscle fasciculations and myalgia. We designed the present study to evaluate the efficacy of rocuronium (ROC) and vecuronium (VEC) in preventing succinylcholine-induced fasciculations and postoperative myalgia (POM) in patients undergoing surgery under general anesthesia.

Materials and methods

After obtaining written informed consent, 125 patients were randomly selected to receive either ROC 0.06 mg/kg or VEC 0.01 mg/kg, with both diluted up to 2 ml, 90 seconds before the administration of propofol followed by succinylcholine. A standardized balanced anesthetic technique was used for all patients. The intensity of fasciculations and intubating conditions were assessed using a 4-point rating scale. All patients were evaluated up to the third postoperative day for the presence of POM, the severity of which was graded on a 4-point scale.

Results

The incidence of post-succinylcholine fasciculations during induction was nil in 74.58% of patients in the ROC group and 51.52% in the VEC group. Mild fasciculation was seen in 22.03% in the ROC group and 33.33% in the VEC group. Moderate fasciculation was seen in 3.39% and 15.15% in ROC and VEC groups respectively. When comparing both the groups, a significant decrease (p=0.015) in intraoperative fasciculation was observed in the ROC group than in the VEC group. Both drugs provided good intubating conditions without any statistical significance and with an overall intubating score of 8-9 in both groups as per Lund. On day one, 91.53% (n=54) of the ROC group and 65.15% (n=43) of the VEC group patients did not have any myalgia symptoms. Mild myalgia was observed in 8.47% (n=5) in the ROC group and 31.82% (n=21) in the VEC group, and only 1.8% had moderate myalgia in the VEC group. The results of the study showed that POM was significantly decreased in the ROC group than in the VEC group on day one (p=0.001). The incidence of POM on day two was significantly low in both groups. There was no statistical significance between the two groups based on Fisher's exact test (p=1.000). None of the patients had myalgia on day three.

Conclusion

Our results showed that the incidence and severity of fasciculations and POM were significantly decreased by pretreatment with ROC in contrast to that with VEC. Hence, ROC is a better option than VEC to combat succinylcholine-related complications like fasciculation and myalgia.

The Effect of Pregabalin on the Prevention of Succinylcholine-Induced Fasciculation and Myalgia

PURPOSE

This study evaluates the effect of pregabalin on fasciculation and myalgia after using succinylcholine.

DESIGN

This randomized double-blind prospective study was conducted among 100 patients aged 20 to 60 years old.

METHODS

Pregabalin (300 mg) and placebo (in capsule form) were placed in similar containers. The results were analyzed by SPSS 23 software, and statistical analysis consisted of χ² test and t test, and a P value less than .05 was considered significant.

FINDINGS

The mean pain score in the group receiving pregabalin was lower than the placebo group. According to the χ² test, there was a significant difference between the two groups in the frequency of fasciculation (P = .003). Mean fasciculation severity in the pregabalin group was lower than placebo group. According to t test, there was a significant difference in the mean fasciculation severity between the two groups (P = .002).

CONCLUSIONS

This study showed that 300 mg of pregabalin was effective in reducing postoperative fasciculation and myalgia in patients treated with succinylcholine.

A Randomized Controlled Trial to Compare Preemptive Analgesic Efficacy and Safety of Pregabalin and Gabapentin for Succinylcholine-Induced Myalgia

Background

Succinylcholine is a drug of choice for rapid induction of anesthesia but produces postoperative myalgia. Preemptive analgesia is intended to decrease perception of pain before exposure to painful stimuli. Pregabalin and gabapentin, analogs of the inhibitory neurotransmitter gamma aminobutyric acid, are effective in several models of neuropathic pain, incisional, inflammatory, and formalin-induced injury. However, the data available on their preemptive analgesic efficacy in succinylcholine myalgia are sparse. This study was designed to compare the preemptive analgesic efficacy and safety of pregabalin and gabapentin.

Materials and Methods

This randomized clinical trial included 120 surgical patients of either sex, between 18 and 70 years, and of American Society of Anesthesiologists-I/II grade. Patients were randomly allocated to control and test groups; received respective treatments 30 min before induction of anesthesia. Myalgia and pain scores were recorded using the myalgia scale and visual analog/facial rating scale at awakening at 6, 12, 18, and 24 h, respectively. Postoperative analgesic requirement over 24 h was recorded. Data were analyzed using OpenEpi (Andrew G. Dean and Kevin M. Sullivan, Atlanta, GA, USA) statistical softwares.

Results

Significantly lower pain scores were observed in the pregabalin group at 6, 12, and 24 h, and in gabapentin group at 24 h as compared to control and placebo (P < 0.05). They were however found to be equianalgesic when compared to each other (P > 0.05). Pregabalin-treated patients were more comfortable throughout with significantly less postoperative myalgia and analgesic requirement (P < 0.05).

Conclusions

Results strongly suggest the preemptive analgesic efficacy of a single oral dose of pregabalin and gabapentin over diclofenac in postoperative myalgia and pain management. However, on the basis of safety profile, pregabalin may be preferred over gabapentin in succinylcholine-induced myalgia.

Assessment of Mini-dose Succinylcholine Effect on FacilitatingLaryngeal Mask Airway Insertion

INTRODUCTION

Laryngeal Mask Airway (LMA) has gained wide acceptance for routine airway management and with increasing emphasis on day care surgery it is widely used. The aim of this study was to assess the effects of mini dose succinylcholine (0.1mg/kg) with semi-inflated cuff on facilitation of laryngeal mask airway insertion in order to achieve more satisfaction yet less complications .

METHODS

In a randomized double-blinded study, sixty ASA 1, 2 and 3 patients aged 20-60 years scheduled for urologic surgical procedures were included. Thirty patients received succinylcholine (Group S), and thirty received 0.9% sodium choride as a placebo (Group C).

RESULTS

Coughing occured in 33.3% of patients in the control group and there was no incidence in succ group (P=0.002). Head or limb movement occurred in 70% of the patients in the control group vs. 10% in succ group (P<0.001). Laryngospasm occurred in 36.6 % of the patients in the control group but there was no incidence in succ group (P=0.004). Additional propofol was required in 53% of the patients in control group vs. 10% for succ group (P=0.001). Ease of insertion and first successfull attempt of LMA were achieved in 93.3% and 90% of the patients respectively in group S (P<0.05). Myalgia and sore throat occurred in 66.7 % of patients in the group C in comparison with 33.3% in group S (P=0.06).

CONCLUSION

The combination of propofol with mini dose succinylcholine, provided a significantly better method for LMA insertion, while reduced propofol doses were needed and number of attempts decreased.

The course of myalgia and headache after electroconvulsive therapy

BACKGROUND

Headache and myalgia seem to be common, though generally mild, complications of electroconvulsive therapy. Relatively little is known regarding the usual severity and time course of these complaints.

OBJECTIVE

This study examines the incidence, severity, and time course of myalgia and headache after electroconvulsive therapy.

METHODS

Patients rated severity of myalgia and headache immediately before treatment and again after recovery and at 2, 6, 12, and 24 hours posttreatment on a 10-point visual analog scale. Data were analyzed using random-effects linear models.

RESULTS

Severity of headache peaked 2 hours after treatment, returning to baseline by 24 hours and was relatively consistent within individuals between treatments. More severe posttreatment headache was reported by patients with a history of incapacitating headache and by those younger than 45 years. Headache was associated with increased duration of seizure. By contrast, myalgia was substantially more pronounced and lasted longer after the first treatment as compared with subsequent treatments. Severity of myalgia was not predicted by degree of fasciculations or motor activity, but was worse in patients younger than 45 years.

CONCLUSIONS

Posttreatment headache and myalgia are common but usually mild. Routine pretreatment using non-depolarizing agents is probably unnecessary in most cases but may have a role during the first treatment in a series. By contrast, preventive treatment may be warranted in those with history of severe headache and those who previously have had significant post-ECT headache.

Muscle relaxants

Studies on the toxic effects of muscle relaxants are difficult to design because of the need for mechanical ventilation and, consequently, concomitant administration of anaesthetic drugs which may influence the results. The following overview shows that muscle relaxants are weak toxic agents with regard to their teratogenicity, carcinogenicity and cytotoxic effects (including tissue- and organ-damaging effects). Moreover, this chapter presents other side-effects of muscle relaxants under the broad heading of toxicity: the succinylcholine-triggered cytotoxic effects on skeletal muscle cells with different aetiology, for example, or persistent muscle weakness after long-term administration of non-depolarizing muscle relaxants. Receptor stimulation in the central nervous system may cause acute excitement and seizures. Muscle relaxants and their metabolites may interact with muscarinic and nicotinic receptors in other organs and the ganglionic system, for example in the cardiovascular system. Direct stimulation of mast cells, with consequent release of histamine, after administration of muscle relaxants may clinically impose as toxic reactions.

Succinylcholine-associated postoperative myalgia

The subject of postoperative myalgia associated with the use of succinylcholine is reviewed. We discuss the mechanisms of succinylcholine-induced myalgia and the techniques available to prevent and treat the myalgia. In situations where patients are at risk of developing myalgia and succinylcholine is the neuromuscular blocker of choice, the use of a combination of techniques may prove to be a useful strategy.

Effects of pretreatment with cisatracurium, rocuronium, and d-tubocurarine on succinylcholine-induced fasciculations and myalgia: a comparison with placebo

STUDY OBJECTIVE

To evaluate the efficacy of cisatracurium, rocuronium, and d-tubocurarine in preventing succinylcholine-induced fasciculations and postoperative myalgia in patients undergoing ambulatory surgery.

DESIGN

Randomized, prospective, placebo-controlled trial

SETTING

Teaching hospital.

SUBJECTS

80 ASA physical status I and II patients scheduled for elective ambulatory surgery with general anesthesia.

INTERVENTION

A standardized balanced anesthetic technique was used for all patients.

MEASUREMENTS AND MAIN RESULTS

Patients were randomized to receive cisatracurium 0.01 mg/kg, rocuronium 0.06 mg/kg, d-tubocurarine 0.05 mg/kg, or saline, 3 minutes prior to intravenous (i.v.) succinylcholine 1.5 mg/kg. The intensity of fasciculations and intubating conditions were assessed using a four-point rating scale. In addition, the severity of myalgia was assessed using a four-point rating scale in the postanesthesia care unit and at 24 hours postoperatively. No patient complained of any side effects after the administration of the study drug. Fasciculations were observed less frequently (p < 0.05) in the d-tubocurarine and rocuronium groups compared with the placebo and cisatracurium groups. However, there was no difference between the d-tubocurarine group and the rocuronium group (21% vs. 10%, respectively). Although fasciculations occurred less frequently in the cisatracurium group than in the placebo group (59% vs. 85%, respectively), this difference did not reach statistical significance. There was no difference among the four groups in the intubating conditions or the incidence of postoperative myalgia.

CONCLUSION

Pretreatment with rocuronium and d-tubocurarine was superior to cisatracurium in preventing succinylcholine-induced fasciculations. However, pretreatment did not have any effect on the incidence of myalgia after ambulatory surgery.

EMG spike trains of succinylcholine-induced fasciculations in myalgic patients

Single spike activity from the surface electromyogram (EMG) of fasciculations induced by succinylcholine (Sch) were studied from limb muscles (biceps, triceps, anterior tibialis and gastrocnemius) in 100 female patients. About 2/3 of them (n = 72) also received nondepolarizing neuromuscular pretreatment (atracurium or vecuronium). We observed from 20% of EMG records in the myalgic (but not in the nonmyalgic) patients, sustained spike trains (mean duration 1.47 s) that resembled motor units firing at physiologically high rates (mean 21.7 spikes/s). The finding reflects Sch's distal actions at the muscle spindle. The implications for myalgia and the possible involvement of micro damage at the extrafusal muscles are discussed.

A comparison of the effect of propofol or thiopentone on the incidence and severity of suxamethonium-induced myalgia

We conducted a prospective, randomised single-blind study in 48 adult women undergoing laparoscopic gynaecological surgery to assess the incidence of suxamethonium-induced myalgia. Anaesthesia was induced with either thiopentone or propofol. All other aspects of clinical care were standardised between the groups. The propofol group had a significantly lower incidence of suxamethonium myalgia (19%) compared with the thiopentone group (63%) (P < 0.05). The mechanism of this effect is not understood.

Serum potassium and sodium levels following intravenous suxamethonium in pediatric dental anesthesia

The effects of rectally administered midazolam (.35 mg/kg), diazepam (.70 mg/kg), and placebo used as preanesthetic medications on serum levels of potassium after intravenous suxamethonium in children undergoing dental extractions under halothane anesthesia were examined. Ninety patients between the ages of 2 and 7 years were randomly allocated into three groups in this double-blind parallel study. Blood samples were taken immediately after induction with halothane (Pre-S) and at 1, 3, 5, 10, and 15 minutes after administration of suxamethonium (Post-S). Serum from these samples was analyzed in duplicate for potassium and sodium and the data analyzed statistically. The results showed that mean serum potassium levels tended to remain higher in the two groups that had received a benzodiazepine than in the controls at 5, 10, and 15 minutes Post-S. Although the increases in plasma potassium differed significantly from Pre-S at the various times within each patient group, no significant intergroup differences could be shown except at the 15 minute Post-S stage, when the mean serum potassium level of the placebo group was significantly closer to its Pre-S value than that of the diazepam group. At all stages Post-S the mean serum sodium levels for each of the three groups showed statistically significant decreases from their Pre-S values. However, no statistically significant intergroup differences could be shown.

Phenytoin reduces suxamethonium-induced myalgia

A prospective, randomised trial was undertaken in 60 healthy adults to determine the efficacy of intravenously administered phenytoin in doses of 5 mg.kg-1 for the prevention of suxamethonium-induced fasciculations, a rise in serum K+ and myalgia. This was compared with tubocurarine pretreatment and no pretreatment (control group). Phenytoin pretreatment significantly reduced myalgia from 45% (nine patients) in the control group to 10% (two patients) (p less than 0.05). It also decreased the duration and mean intensity of fasciculations. Incidentally, phenytoin was also found to decrease significantly mean serum Na+ levels (p less than 0.001) both at 5 and 20 min after administration. Tubocurarine pretreatment (3 mg) resulted in a significant decrease in fasciculations, but myalgia, which occurred in five patients, remained the same. No significant correlation was found between muscle fasciculations, postoperative myalgia and K+ changes, but patients with myalgia had a significant decrease in mean serum Na+ levels at 5 and 20 min after suxamethonium (p less than 0.01).

Comparison of high and low doses of suxamethonium

In a double-blind study, 67 young adult patients undergoing anaesthesia for dental extractions were allocated at random to receive either 0.5 mg/kg or 1.5 mg/kg suxamethonium. A greater increase in arterial pressure was seen following induction in the 1.5 mg/kg group, although overall intubating conditions were similar in the two groups. Suxamethonium-associated muscle pains were significantly more common in the group which received the larger dose (p less than 0.05).

Prevention of succinylcholine-induced myalgia with lidocaine pretreatment

We studied the effects of 3 mg.kg(-1) lidocaine iv on the succinylcholine (SCh)-induced myalgia in 94 unpremedicated ambulant patients undergoing dilatation and curettage of the uterus. The post-SCh myalgia was confirmed through interview by telephone. The data were correlated with the degree of fasciculation and changes in the serum electrolytes and creatine kinase (CK) levels following SCh administration. Pretreatment with lidocaine, 3 mg.kg(-1) iv, significantly reduced the incidence of myalgia from 40.4% of control group to 12.8% lidocaine-treated group, but not the CK levels. The severity of myalgia was not related to the intensity of fasciculation assessed by visual observation. The pretreatment with lidocaine had no untoward effect on the circulation, although the peak arterial and peak venous lidocaine levels achieved were 29.6 +/- 23 micro g.ml(-1) and 10.1 +/- 3.3 micro g.ml(-1) respectively. These finding indicated that the pretreatment with lidocaine, 3 mg.kg(-1) iv, was effective in prevention of SCh-induced myalgia.

Attenuation of suxamethonium myalgias. Effect of midazolam and vecuronium

We studied the incidence of fasciculations and postoperative myalgias in 100 female outpatients who had laparoscopy under thiopentone, N2O, isoflurane anaesthesia. Four groups of 20 patients each were pretreated with saline (group 1), tubocurarine 0.05 mg/kg (group 2), vecuronium 0.006 mg/kg (group 3), or midazolam 0.025 mg/kg (group 4), followed by suxamethonium 1.5 mg/kg. Group 5 received only vecuronium 0.1 mg/kg as relaxant (no suxamethonium). Fasciculations were graded, and postoperative myalgias rated on the first and third postoperative days. In groups 1-5 the incidence of fasciculations was 95, 15, 25, 95 and 0%; the incidence of myalgias on the first day after operation was 70, 45, 65, 75 and 60%, and on the third day after operation 20, 5, 20, 20, and 5%, respectively. We conclude that pretreatment with vecuronium, but not midazolam, decreases the incidence of fasciculations after suxamethonium (p less than 0.05) and that in this patient population, postoperative myalgias appear to be unrelated to the use of suxamethonium.

Train-of-four fade of non depolarizing muscle relaxants: an insight into the mechanism of precurarization

This study was carried out to assess the prejunctional effect of non depolarizing muscle relaxants during the onset of neuromuscular blockade using the train-of-four ratio (TR). The prejunctional effect was compared with previous results concerning the ability of the relaxants to prevent suxamethonium-induced fasciculations. Fifty-three adult patients were relaxed with small incremental doses of either alcuronium (0.03 mg.kg-1), atracurium (0.04 mg.kg-1), pancuronium (0.01 mg.kg-1), d-tubocurarine (0.05 mg.kg-1) or vecuronium (0.01 mg.kg-1) during anaesthesia with thiopentone, fentanyl and nitrous oxide in oxygen. The muscle relaxant was given after recovery from an initial suxamethonium blockade needed for tracheal intubation. The evoked integrated EMG response to supramaximal train-of-four (2 Hz) stimulation was recorded every 20 s. TR % was calculated at different first twitch (T1) levels during the onset of neuromuscular blockade. Significant changes occurred at the 100% and 90% T1 levels, alcuronium having the lowest mean TR values. Atracurium, pancuronium and vecuronium gave similar TR values. Results with d-tubocurarine placed it between alcuronium and the others. These train-of-four ratio results were compared with the ability of non depolarizing muscle relaxants to prevent fasciculations. In conclusion, the stronger the train-of-four fade, the greater was the ability of the relaxant to prevent suxamethonium-induced fasciculations. This supports the theory that the blockade of prejunctional cholinergic receptors is the mechanism of action of precurarization.

Myalgia and biochemical changes following intermittent suxamethonium administration. Effects of alcuronium, lignocaine, midazolam and suxamethonium pretreatments on serum myoglobin, creatinine kinase and myalgia

One hundred gynaecological patients for laparoscopy divided into five groups were studied to determine the effects of a number of pretreatments on serum myoglobin, creatinine kinase and myalgia following intermittent suxamethonium administration. One group acted as controls, while the other groups were given intravenous pretreatments of alcuronium 2 mg, midazolam 0.15 mg/kg, lignocaine 1.5 mg/kg and suxamethonium 7 mg. Serum myoglobin was determined by radio-immunoassay. The mean increases in the control group were 167 micrograms/litre myoglobin at 20 minutes and 196 IU creatinine kinase at 24 hours; 13 out of 20 patients responded with a marked increase of serum myoglobin at 20 minutes and of creatinine kinase at 24 hours. Only alcuronium pretreatment prevented myoglobin increase at 20 minutes, abolished creatinine kinase increase at 24 hours and reduced 24-hour myalgia. The other pretreatments slightly reduced myoglobin increase at 20 minutes and 24-hour creatinine kinase but did not reduce myalgia. Only one patient in the whole study had markedly elevated serum myoglobin at 24 hours. We conclude that only non-depolarising relaxant pretreatment is effective in the reduction of some of the adverse effects of suxamethonium administration.

Biochemical changes following suxamethonium. Serum myoglobin, potassium and creatinine kinase changes before commencement of surgery

Forty patients were investigated for serum myoglobin changes following induction of anaesthesia but before the commencement of surgery. Blood was drawn for potassium, creatinine kinase and serum myoglobin immediately prior to and 5, 10 and 20 minutes after administration of thiopentone 4 mg/kg and suxamethonium 1.2 mg/kg. Twenty patients were given either 2 mg alcuronium or 20 mg gallamine as pretreatment 2 to 3 minutes before the suxamethonium to reduce the fasciculations. Anaesthesia was maintained with artificial ventilation and alcuronium, or spontaneous ventilation with halothane. Serum myoglobin was assayed by radioimmunoassay. All pre-induction myoglobin levels were within the normal range. Of the 20 patients who were not pretreated, six showed a marked rise of serum myoglobin within 5 minutes, increasing to 150-200 micrograms/litre at 20 minutes. The remaining 14 patients had no such rise. No patients in the pretreatment group had any significant rise in serum myoglobin, suggesting that although the fasciculations were not completely abolished, there was protection against one of the effects of suxamethonium on the muscle. Although there was no clear relationship between intensity of fasciculations and increase in serum myoglobin, there was no marked rise in serum myoglobin values in any patient who did not have muscle fasciculations. There were no consistent changes in potassium or creatinine kinase in any group during the period of study.

Oral dantrolene prevents rise of myoglobin due to suxamethonium

Forty patients were studied in a randomised trial to investigate the effect of pre-operative oral dantrolene on the increase of serum myoglobin and creatinine kinase due to suxamethonium administration. Twenty patients in the treatment group were given 1.5 mg/kg dantrolene orally 4 hours pre-operatively. Blood was drawn immediately pre-induction and 5, 10 and 20 minutes after suxamethonium 1.2 mg/kg administration, following which surgery could commence. Myoglobin was measured by radioimmunoassay. The increase in mean myoglobin values was greatly reduced following suxamethonium in the treatment group (10.6 micrograms/litre at 20 minutes) compared to the control group (54.8 micrograms/litre at 20 minutes), (p less than 0.01). Total fasciculation score was not significantly reduced by the dantrolene pretreatment. No increase in creatinine kinase values occurred in any patient and the changes in mean potassium values in both groups were negligible. The only side effect attributed to dantrolene was pre-operative nausea in two patients. No interference with the action of suxamethonium, or difficulty with reversal was noticed. Oral dantrolene may be almost as effective as pretreatment with non-depolarising neuromuscular blocking drugs in preventing suxamethonium-induced increase in myoglobin with less interaction with other anaesthetic agents.

Pain-reducing effect of self-taming suxamethonium

The effect was evaluated of a small "self-taming" dose of suxamethonium (0.1 mg/kg) on fasciculations and postoperative muscle pain following a normal intubating dose of suxamethonium (1.0 mg/kg). Forty outpatients undergoing bronchoscopy were randomly allocated to pretreatment with either sodium chloride or suxamethonium 0.1 mg/kg. The pretreatment dose was followed in 60 s by suxamethonium 1.0 mg/kg. Visual rating and mechanical registration of muscle fasciculations were done separately. Muscle pain was found in 74% and in 26% of the patients following pretreatment with sodium chloride and suxamethonium 0.1 mg/kg, respectively (P less than 0.01). No significant relationship was found between pain and muscle fasciculations. It is concluded that self-taming with suxamethonium has a marked pain-reducing effect; and this technique may be used as an alternative to pretreatment with a non-depolarizing relaxant.

Five non-depolarizing muscle relaxants in precurarization

Five different non-depolarizing muscle relaxants and a control solution of saline were studied as precurarization agents. Two hundred and twenty-two surgical patients (ASA I-II) were allocated in a double-blind fashion to one of the following groups: d-tubocurarine 0.05 mg/kg, alcuronium 0.03 mg/kg, pancuronium 0.01 mg/kg, gallamine 0.25 mg/kg, ORG NC-45 (vecuronium) 0.01 mg/kg and saline solution 0.005 ml/kg. Pretreatment was performed 4 min before administering a 1.5 mg/kg bolus of succinylcholine (SCh). Fasciculations, intubation conditions, duration of neuromuscular blockade after SCh, serum potassium changes and postoperative myalgias (in 60 patients) were recorded. All the drugs studied prevented fasciculations significantly (P less than 0.05) more than in the control group. d-Tubocurarine and alcuronium were superior to the others in this respect. Intubation conditions were best in the control and pancuronium groups, but there was no significant difference between the pancuronium and d-tubocurarine or between the d-tubocurarine and alcuronium groups. Pancuronium pretreatment prolonged the SCh block significantly, whereas other agents shortened the duration of the SCh block. The antagonism of the SCh block apparently also affected intubation conditions, although intubation remained satisfactory. A statistically significant rise in serum potassium level was measured only in the control and pancuronium groups. In the control and pancuronium groups, four patients out of 10 had postoperative myalgias, whereas in the other groups only one or none out of 10 had them (0/10 vs. 4/10; 0.10 greater than P greater than 0.05). In conclusion, d-tubocurarine and alcuronium seem to have advantages over pancuronium, ORG NC-45 and gallamine for precurarization.

Lignocaine pretreatment for suxamethonium. A clinicobiochemical study

Lignocaine pretreatment (2 mg/kg) significantly restricted the increase in serum potassium and decrease in serum calcium caused by suxamethonium. Suxamethonium muscle pains occurred in only 8% of patients who received lignocaine just before induction of anaesthesia. The incidence of muscle pains was 45% in those patients who were not given lignocaine.

Diazepam and suxamethonium muscle pain (a dose-response study)

Postoperative muscle pain occurred in 17.2% of patients given diazepam intravenously 5 minutes prior to suxamethonium. The incidence of muscle pain was 48% in those patients who were not given diazepam before suxamethonium. The difference is statistically significant (p less than 0.01). Five mg diazepam reduced the incidence of pain but not significantly (p = 0.30); 10 mg diazepam significantly reduced the incidence (p less than 0.05); while 15 and 20 mg diazepam showed better effects (p less than 0.01). Diazepam pretreatment also reduced the severity, frequency and duration of muscle pain. The incidence of fasciculations was significantly reduced but there was no correlation between the incidence of fasciculations and the occurrence of muscle pains.

Mixed neuromuscular block: the effect of precurarization

The effects of precurarisation, with small doses of pancuronium, curare or gallamine, on the neuromuscular blockade following suxamethonium, 1 mg/kg, were studied using train-of-four stimulation. The duration of the block was reduced by pretreatment with d-tubocurarine and gallamine but increased with pancuronium. The degree of competitive neuromuscular blockade, both after administration of the precurarising dose and at full recovery from suxamethonium was mild and was insufficient to be a cause of postoperative muscle weakness.

The influence of thiopentone and alfathesin on succinylcholine-induced fasciculations and myalgias

Thiopentone doses corresponding to 5.238 mg x kg-1, that is 2UD95 (UD95:unconsciousness dose 95) inhibit the intensity of succinylcholine-induced fasciculations compared with UD95. Alfathesin doses corresponding to 0.570 mg x kg-1, also 2UD95 (calculated as alphaxalone at a concentration of 9 mg/ml in alfathesin), do not have any greater effect on the degree of fasciculations compared to UD95. Furthermore, neither induction agent influences the incidence, distribution and duration of succinylcholine-induced myalgias. The inhibition of the degree of fasciculations caused by thiopentone is believed to be a consequence of a postsynaptic depressant effect of thiopentone at the neuromuscular junction. The evaluation of the degree of succinylcholine-induced fasciculations must take into consideration the dose of thiopentone administered at induction of anaesthesia.

Suxamethonium fasciculations: a topographical study

It has been found in a group of 455 gynaecological patients that not all the voluntary muscles of the body respond to suxamethonium in the same way. One group of muscles (e.g. biceps) which is sensitive to suxamethonium, responds by fasciculating in almost every individual. A second, resistant, group of muscles (e.g. pectoralis major) is almost totally unresponsive to suxamethonium. A third muscle group (e.g. triceps) shows fasciculations in about 60% of cases and appears intimately associated with the development of suxamethonium pains, for if fasciculations do occur then suxamethonium pains are likely to ensure, but not necessarily involving all the fasciculating muscles. A theory to account for these different groups has been proposed involving the known variation in distribution of red and white muscle fibres throughout the body.

Methohexitone and etomidate for bronchoscopy

General anaesthesia for bronchoscopy has been provided with either methohexitone or etomidate, with and without fentanyl. Recovery was faster following methohexitone and there was no statistically significant difference in the incidence of complications. Inclusion of fentanyl in the technique did not confer any benefits with either drug.

Anaesthesia for electroconvulsive therapy

The results of a prospective study of 3,500 Anaesthetics for electroconvulsive therapy is presented. Minimal differences were observed between thiopentone and methohexitone. Propanidid and Diazepam were found to be unsuitable induction agents. Other findings included minimal serum potassium elevation and a low incidence of post treatment muscle pains. The place of the single-handed operator and the place of unmodified electroconvulsive therapy is questioned as being unacceptable practice.