Rapid Induction Of Anaesthesia Research Articles

Comparison of suxamethonium and different combinations of rocuronium and mivacurium for rapid sequence induction of anaesthesia in children

Comparison of suxamethonium and different combinations of rocuronium and mivacurium for rapid sequence induction of anaesthesia in children

Prehospital emergency rapid sequence induction of anaesthesia.

OBJECTIVE: To determine the number of and reasons for rapid sequence inductions done by accident and emergency (A&E) doctors out of hospital as part of the activities of the MEDIC...

Attenuation of ocular and systemic responses to tracheal intubation by intravenous lignocaine

This study was undertaken to determine whether intravenous lignocaine could mitigate or prevent the ocular reactions and especially the acute increase in intraocular pressure associated with laryngoscopy and tracheal intubation. Two groups of children undergoing minor eye surgery under nitrous oxide-oxygen-halothane anaesthesia were examined. The experimental group (n = 17) received 2 mg/kg lignocaine and the controls (n = 18) an equivalent volume of saline. The incidence of local laryngeal and ocular reflexes was much lower in the lignocaine group. Pulse acceleration was significantly lower in the lignocaine group (p less than 0.025), and the maximal mean intraocular pressure was significantly less than in the control group (p less than 0.005). Other ocular reactions were recorded, and all were attenuated after lignocaine administration. The beneficial effects of lignocaine, a suppressant of autonomic reflexes, suggest that intraocular pressure, like the heart rate, rises after intubation as a result of autonomic stimulation. The use of intravenous lignocaine is thus recommended for children at risk, such as those needing an urgent operation because of lacerated eye injury under rapid sequence induction of anaesthesia.

Rapid inhalation induction in children: 8% sevoflurane compared with 5% halothane

Sevoflurane has a lower blood-gas solubility and a less pungent odour than halothane; this may allow more rapid induction of anaesthesia. In a randomized, blinded study, we compared the induction characteristics of maximum initial inspired concentration of 8% sevoflurane and 5% halothane using conventional vaporizers in children aged 3 months to 3 years. There was no statistically significant difference in induction times between the two groups: mean times to loss of consciousness were 1 min 12 s (SD 18 s, range 40 s-1 min 44 s) for sevoflurane and 1 min 16 s (SD 17 s, range 50 s-1 min 52 s) for halothane, although these times were shorter than in previous studies using a gradual increase in vapour concentration. A small number of complications were noted in both groups, although none interfered with induction of anaesthesia. Struggling scores were lower in the sevoflurane group than in the halothane group (chi-square for trends = 6.34, P < 0.02). A significant number (11 of 15) of parents of children in the sevoflurane group who had previous experience of halothane induction preferred sevoflurane (chi-square for trends = 4.03, P < 0.05). We conclude that with this technique, induction was rapid with both sevoflurane and halothane. Our assessment of patient struggling and parents' perceptions suggests that induction with sevoflurane was more pleasant than with halothane.

Comparison of Nicardipine, Diltiazem, and Verapamil for Controlling the Cardiovascular Responses to Tracheal Intubation

We have compared the efficacy of three calcium channel blockers, nicardipine, diltiazem and verapamil, in attenuating the cardiovascular responses to laryngoscopy and intubation in 60 normotensive patients (ASA I) undergoing rapid sequence induction of anaesthesia with thiopentone and fentanyl. We also examined whether or not these blockers inhibited catecholamine release induced by intubation. The patients were allocated to one of four groups (n = 15 for each): saline (control), nicardipine 30 micrograms kg-1, diltiazem 0.2 mg kg-1 or verapamil 0.1 mg kg-1. Verapamil and the three other drugs were administered 45 s and 60 s before the start of direct laryngoscopy, respectively, in a double-dummy design. Anaesthesia was induced with thiopentone 4 mg kg-1 i.v. and fentanyl 2 micrograms kg-1 i.v. Tracheal intubation was facilitated with vecuronium 0.2 mg kg-1. During anaesthesia, ventilation was assisted or controlled with 1% isoflurane and 50% nitrous oxide in oxygen. Laryngoscopy lasting 30 s was attempted 2 min after administration of thiopentone and vecuronium. Patients receiving saline exhibited significant increases in systolic and diastolic arterial pressures (AP), heart rate (HR) and plasma concentrations of catecholamines associated with tracheal intubation. The increase in AP was attenuated in patients treated with any calcium channel blocker. The greatest effect was elicited by verapamil, which attenuated the increase in HR, although nicardipine seemed to enhance tachycardia. All three drugs failed to suppress the increase in plasma catecholamine concentrations in response to tracheal intubation. These findings suggest that bolus injection of verapamil 0.1 mg kg-1 was a more effective method of controlling hypertension and tachycardia associated with intubation than diltiazem 0.2 mg kg-1 or nicardipine 30 micrograms kg-1, and that these prophylactic effects were not caused by inhibition of the catecholamine response.

Comparison of induction and recovery between sevoflurane and halothane supplementation of anaesthesia in children undergoing outpatient dental extractions

We have compared sevoflurane and halothane in a double-blind controlled study for supplementation of nitrous oxide and oxygen anaesthesia in 80 children undergoing dental extraction as outpatients. Induction of anaesthesia was more rapid in those who received sevoflurane compared with those who received halothane (89 s compared with 127 s for loss of eyelash reflex). In both groups, mean duration of administration of anaesthesia was less than 4 min. Those who received sevoflurane were slower to awaken (167 s compared with 102 s), although discharge times from hospital were similar. The incidence of complications during induction and maintenance was low in both groups and return to normal appetite and activity occurred in the majority of children on the same day. More children who received halothane suffered nausea after leaving hospital. We conclude that sevoflurane is a suitable alternative to halothane, with more rapid induction of anaesthesia, but in these short procedures, awakening time was slower than after halothane.

Study of the safe threshold of apneic period in children during anesthesia induction

Study Objectives: (1) To investigate changes in arterial oxygen saturation via pulse oximeter (SpO 2) during apnea and after reinstitution of manual ventilation at SpO 2 of 95% or 90% following rapid sequence induction of anesthesia in children after 2-minute preoxygenation; (2) to determine whether the setting of a safe threshold of apneic period to an SpO 2 of 95% is appropriate in children during anesthetic induction; and (3) to evaluate the influences of age, body weight, and height on the time from the start of apnea to SpO 2 of 95%. Design: A clinical study of random design and comparison among groups. Setting: Operating room of a plastic surgery hospital of the Chinese Academy of Medical Sciences and Peking Union Medical College. Patients: 152 infants and children, ASA physical status I, aged 3 months to 12 years, scheduled for elective plastic surgery. Interventions: Patients were divided into three age groups: Group 1-infants 3 months to 1 year (n = 39); Group 2-children 1 to 3 years (n = 41); and Group 3-children 3 to 12 years (n = 72). Patients in each age group were randomly allocated again to Subgroups A and B. After a 2-minute preoxygenation, anesthesia was induced with thiopental 5 mg/kg, fentanyl 5 μg/kg, and suxamethonium 1.5 mg/kg. Patients were manually ventilated when SpO 2 decreased to 90% in Subgroups A and 95% in Subgroups B, respectively, during apnea. Measurements and Main Results: SpO 2 was measured continuously with a Datex pulse oximeter applied to the right index finger. During apnea, the times for SpO 2 to decrease to 99% (T 99) and 95% (T 95) in all children, and 90% (T 90) in Subgroups A were recorded. The time for SpO 2 to decrease from 95% to 90% (T 95 − 90) in Subgroups A was also measured. After reinstitution of manual ventilation, the time when SpO 2 continued to decrease (T 1) and the time from the end of apnea to recovery of SpO 2 baseline (T 2) were determined. In addition, the lowest value of SpO 2 after apnea was also recorded. The results showed that younger children were more susceptible than older children to the risk of hypoxemia during apnea. There were significant differences in T 99, T 95, T 90, and T 95 − 90 between the three age groups. T 1 and T 2 were significantly longer in Group 3 than in Groups 1 and 2. There were significant differences in the lowest values of SpO 2 following apnea among the three Subgroups A and between Subgroups A and B of each age group. During apnea, heart rate decreased gradually as SpO 2 decreased, showing a significant decrease at SpO 2 of 95%. Bradycardia was found in three children in Subgroups A. The apnea time to SpO 2 of 95% correlated well with age, weight, and height by linear regression analysis. Conclusions: The safe threshold of an apneic period setting to an SpO 2 of 95% was appropriate in children during anesthesia induction. Despite the same duration of preoxygenation, younger children were more susceptible than older ones to the risk of hypoxemia during apnea. The apnea time to Sp0 2 of 95% correlated with age, body weight, and height using linear regression analysis.

Propofol and Alfentanil Prevent the Increase in Intraocular Pressure Caused by Succinylcholine and Endotracheal Intubation During a Rapid Sequence Induction of Anesthesia

The increase in intraocular pressure (IOP) associated with succinylcholine (Sch) has made its use in patients with open globe injuries controversial.Studies that have examined techniques to prevent the increase in IOP due to Sch have shown a larger increase in IOP from the stimulus of laryngoscopy and endotracheal intubation. The purpose of our study was to examine whether the combination of propofol and alfentanil would prevent the increase in IOP due to Sch as well as endotracheal intubation during a rapid sequence induction of anesthesia. Sixty patients were randomized to receive either thiopental 5 mg/kg and Sch 1.5 mg/kg (Group I), propofol 2 mg/kg and Sch 1.5 mg/kg (Group II), or propofol 2 mg/kg, alfentanil 40 micro gram/kg, and Sch 1.5 mg/kg (Group III). The IOP was measured continuously from baseline awake (control) values until 15 s after successful intubation. All three groups had a significant decrease in IOP with the induction of anesthesia. Succinylcholine produced a consistant increase in IOP from the postinduction low in Groups I and II, but this increase was not significantly higher than baseline. The postintubation IOPs in Groups I and II were significantly higher than baseline (P < 0.001). During the entire study period, the IOP in Group III never increased above baseline. The IOP in Groups I and II had already begun to decline by 15 s postintubation, suggesting that laryngoscopy and intubation have the greatest effect on increasing IOP. We conclude that the combination of propofol and alfentanil prevents the increase in IOP from Sch as well as the increase associated with endotracheal intubation during a rapid sequence induction of anesthesia. (Anesth Analg 1996;83:814-7)

Rapid Induction with 7% Sevoflurane Inhalation???Not the Single-Breath Method

The usefulness of the rapid anesthesia induction method with 7% sevoflurane, not the single-breath method, was investigated in 88 patients with ASA physical status 1. Anesthesia was induced with 3 l·min−1 nitrous oxide in 3 l·min−1 oxygen and sevoflurane 7% for 3 min (group A), 7% for 5 min (group B), 7% for 7 min (group C), and 5% for 7 min in conventional induction (group D). There were 22 patients in each group. Each sevoflurane concentration was given at the same time as the start of nitrous oxide inhalation except for group D. The changes in blood pressure and heart rate were the smallest in group A. The time for the loss of consciousness was shorter in groups A (47.2 s), B (44.9 s), and C (49.8 s) than in group D (73.4 s). During induction, body movements were seen in 18.2% in group A and 13.6% in the other 3 groups, but no other complications such as coughing, breath holding, or laryngospasm were seen in any group. In conclusion, the anesthesia induction method with 3 min of 7% sevoflurane inhalation was useful for rapid induction.

A comparison of sevoflurane with halothane in outpatient adenotomy in children with mild upper respiratory tract infections

Study Objective: To investigate the efficacy and safety of sevoflurane compared with halothane in pediatric outpatient ear-nose-throat (ENT) surgery during the induction, maintenance, emergence, and recovery of anesthesia. Design: Prospective, randomized, comparative, open-label study. Setting: ENT operating room and postoperative recovery room at a university medical center. Patients: 41 ASA status I and II children between the ages of 2 to 10 years, with mild upper respiratory tract infection (URI). Interventions: Induction and maintenance of anesthesia with either sevoflurane or halothane for outpatient adenotomy, otomicroscopy, and myringotomy. Measurements and Main Results: Induction (means ± SEM) was significantly shorter in the sevoflurane group (2.6 ± 0.2 minutes) than in the halothane group (3.2 ± 0.2 minutes). There was no difference between the two groups with regard to complications that occurred during the induction and maintenance period. The time to emergence and recovery was significantly shorter with sevoflurane than with halothane (means ± SEM; time to extubation 9.9 ± 0.98 minutes vs. 13.4 ± 1.06 minutes, time to eye opening 12.9 ± 1.6 minutes vs. 24.5 ± 1.8 minutes, command response time 20.7 ± 2.5 minutes vs. 36.4 ± 2.8 minutes). No difference in the incidence of complications during emergence and recovery was found. Evaluation of recovery as assessed by a modified Aldrete score showed that children who had received sevoflurane reached higher scores in the first 30 minutes following the discontinuation of the anesthetic. The Pain/Discomfort Scale demonstrated a difference in the sevoflurane group, with more children being agitated and restless. Conclusion: Sevoflurane provides a safe and rapid anesthetic induction with no differences in complications during the induction, maintenance, and emergence period. With sevoflurane, the time of emergence and recovery was significantly shorter. The characteristics of sevoflurane as evaluated in the present study make it a suitable anesthetic in pediatric outpatient surgery even in the presence of mild URI.

Sevoflurane

Sevoflurane is an ether inhalation general anaesthetic agent with lower solubility in blood than isoflurane or halothane but not desflurane. The low solubility and the absence of pungency facilitate rapid mask induction; the low blood solubility also expedites "wash-out' and therefore recovery from anaesthesia. Sevoflurane produces dose-dependent CNS, cardiovascular and respiratory depressant effects that generally parallel those of isoflurane. Sevoflurane is degraded by carbon dioxide absorbents to nephrontoxic (in rats) haloalkenes, although renal toxicity has not been observed in humans. Compared with other inhalation anaesthetics, negligible quantities of carbon monoxide are generated from degradation of sevoflurane by carbon dioxide absorbents. Sevoflurane has negligible airway irritant effects, which facilitates a "smooth' induction, even in comparison with halothane in paediatric patients, and makes sevoflurane especially amenable to rapid induction of anaesthesia in adults and children. Emergence, orientation an postoperative cognitive and psychomotor function recovery of paediatric outpatients is singnificantly more rapid from sevoflurane than from halothane anaesthesia. In adult inpatients and outpatients, emergence and orientation are significantly faster after sevoflurane than after isoflurane but not desflurane anaesthesia. Other recovery parameters (e.g. times to sitting, ambulation) occur at similar times after either sevoflurane or desflurane anaesthesia. Recovery of psychomotor function occurs at generally similar times after sevoflurane, isoflurane or desflurane. Compared with propofol, sevoflurane facilitates more predictable extubation times and significantly better postoperative modified Aldrete scores in outpatients, although cognitive and psychomotor recovery occurs at similar times for both agents. As a supplement to opioid anaesthesia during coronary bypass graft surgery or in those at risk for myocardial ischaemia, sevoflurane is comparable to isoflurane. Limited data suggest that it is also as useful as isoflurane for the maintenance of anaesthesia during neurosurgical or obstetric procedures. Sevoflurane is well tolerated by adult and paediatric patients during induction of anaesthesia, with a low incidence of mild airway complications (breath-holding, coughing, excitement and laryngospasm). During rapid induction, it is particularly better tolerated than isoflurane or halothane. Sevoflurane has a lower potential for hepatic injury than halothane. Unlike methoxyflurane, sevoflurane undergoes minimal intrarenal defluorination, which may account for the lack of fluoride ion-induced nephrotoxicity in humans, despite elevated plasma fluoride levels after its use. In summary, sevoflurane provides for a rapid and smooth induction of, and recovery from, anaesthesia. These features combined with its favourable cardiovascular profile should make sevoflurane the agent of choice for inhalation induction in adult and paediatric anaesthesia. Although further clinical evaluation will define the role of this agent relative to that of propofol and desflurane, sevoflurane should also prove to be a valuable alternative anaesthetic agent for adults in both outpatient and inpatient surgery.

Sevoflurane-a long-awaited volatile anaesthetic

In evaluating any newly introduced anaesthetic, it is worth comparing its properties with those of a theoretical “ideal” volatile agent which would have a low solubility in blood to allow for rapid equilibration between delivered concentration and the effect site in the central nervous system (CNS). This would facilitate rapid induction of anaesthesia, allow easier titration of anaesthetic dose to the desired effect during the maintenance period and permit rapid emergence and recovery at the end of anaesthesia. An ideal anaesthetic should also be easy to deliver and devoid of perioperative side effects and toxicity. Desflurane (Suprane) was the last new volatile anaesthetic introduced into clinical practice in 1992. Although relatively insoluble and easy to titrate during the maintenance period, desflurane is not a practical induction agent because of its irritant effects on the airway. The theoretically improved control over depth of anaesthesia during the maintenance period afforded by desflurane is complicated by its tendency to induce cardiovascular stimulation when the delivered concentration is increased rapidly [16, 85). In addition, desflurane requires unusually complex vaporizer technology for its administration. Sevoflurane has been in clinical use in Japan since 1990 and has recently gained approval for use in Great Britain, the United States and much of the rest of the world. This review considers the clinical properties of sevoflurane in relation to existing volatile anaesthetics (table 1) and the “ideal” volatile agent.

Comparison of nicardipine, diltiazem and verapamil for controlling the cardiovascular responses to tracheal intubation

We have compared the efficacy of three calcium channel blockers, nicardipine, diltiazem and verapamil, in attenuating the cardiovascular responses to laryngoscopy and intubation in 60 normotensive patients (ASA I) undergoing rapid sequence induction of anaesthesia with thiopentone and fentanyl. We also examined whether or not these blockers inhibited catecholamine release induced by intubation. The patients were allocated to one of four groups (n = 15 for each): saline (control), nicardipine 30 micrograms kg-1, diltiazem 0.2 mg kg-1 or verapamil 0.1 mg kg-1. Verapamil and the three other drugs were administered 45 s and 60 s before the start of direct laryngoscopy, respectively, in a double-dummy design. Anaesthesia was induced with thiopentone 4 mg kg-1 i.v. and fentanyl 2 micrograms kg-1 i.v. Tracheal intubation was facilitated with vecuronium 0.2 mg kg-1. During anaesthesia, ventilation was assisted or controlled with 1% isoflurane and 50% nitrous oxide in oxygen. Laryngoscopy lasting 30 s was attempted 2 min after administration of thiopentone and vecuronium. Patients receiving saline exhibited significant increases in systolic and diastolic arterial pressures (AP), heart rate (HR) and plasma concentrations of catecholamines associated with tracheal intubation. The increase in AP was attenuated in patients treated with any calcium channel blocker. The greatest effect was elicited by verapamil, which attenuated the increase in HR, although nicardipine seemed to enhance tachycardia. All three drugs failed to suppress the increase in plasma catecholamine concentrations in response to tracheal intubation. These findings suggest that bolus injection of verapamil 0.1 mg kg-1 was a more effective method of controlling hypertension and tachycardia associated with intubation than diltiazem 0.2 mg kg-1 or nicardipine 30 micrograms kg-1, and that these prophylactic effects were not caused by inhibition of the catecholamine response.

Manual compared with target-controlled infusion of propofol

We studied 160 ASA I-II patients, anaesthetized with propofol by infusion, using either a manually controlled or target-controlled infusion system. Patients were anaesthetized by eight consultant anaesthetists who had little or no previous experience of the use of propofol by infusion. In addition to propofol, patients received temazepam premedication, a single dose of fentanyl and 67% nitrous oxide in oxygen. Each consultant anaesthetized 10 patients in sequential fashion with each system. Use of the target-controlled infusion resulted in more rapid induction of anaesthesia and allowed earlier insertion of a laryngeal mask airway. There was a tendency towards less movement in response to the initial surgical stimulus and significantly less movement during the remainder of surgery. Significantly more propofol was administered during both induction and maintenance of anaesthesia with the target-controlled system. This was associated with significantly increased end-tidal carbon dioxide measurements during the middle period of maintenance only, but recovery from anaesthesia was not significantly prolonged in the target-controlled group. With the exception of a clinically insignificant difference in heart rate, haemodynamic variables were similar in the two groups. Six of the eight anaesthetists found the target-controlled system easier to use, and seven would use the target-controlled system in preference to a manually controlled infusion. Anaesthetists without prior experience of propofol infusion anaesthesia quickly became familiar with both manual and target-controlled techniques, and expressed a clear preference for the target-controlled system.

Bronchospasm During Pneumoperitoneum

Bronchospasm During Pneumoperitoneum

A New Endotracheal Tube with a Cuff Impervious to Nitrous Oxide

A New Endotracheal Tube with a Cuff Impervious to Nitrous Oxide

The Bullard Laryngoscope for Emergency Airway Management in a Morbidly Obese Parturient

The Bullard Laryngoscope for Emergency Airway Management in a Morbidly Obese Parturient

Aufwachzeiten, Kreislaufverhalten und unerwünschte Wirkungen bei Anwendung von Sevofluran und Enfluran - Eine offene, randomisierte, vergleichende Phase III-Studie

Sevoflurane is a "new" volatile inhaled anaesthetic currently undergoing phase III clinical trials in Europe and USA. Owing to the low blood solubility, rapid induction of anaesthesia and emergence from anaesthesia would be expected. In this study, we compared emergence times and haemodynamics in patients receiving either sevoflurane or enflurane. Furthermore, all adverse experiences were recorded, and the relationship to the drug administered was rated. Thirty ASA physical status I and II patients were studied in an open, prospective and randomised clinical trial. Anaesthesia was induced with fentanyl, thiopentone and vecuronium for facilitating endotracheal intubation. Anaesthesia was maintained with sevoflurane or enflurane, 60% nitrous oxide in oxygen and additional doses of fentanyl (1-2 micrograms/kg/h). ECG, blood pressure (non-invasive), inspiratory and end-tidal concentrations of sevoflurane or enflurane were monitored continuously. At the end of surgery, administration of sevoflurane or enflurane and nitrous oxide stopped without tapering and emergence times were recorded. All adverse experiences which occurred until the third postoperative day were recorded and the relationship to the inhaled anaesthetic was rated as "none", "unlikely", "possible", "probable" or "highly probable". With the exception of the end-tidal concentration at the end of surgery and the mean inspiratory and end-tidal concentrations, which were higher for sevoflurane, the two patient groups were comparable. Pulmonary elimination was significantly faster and emergence time was significantly shorter (5 vs. 9 minutes) with sevoflurane. Emergence time did not correlate with the duration of anaesthetic exposure (MAC hours) for sevoflurane. There was no difference in the time courses of heart rate and mean arterial blood pressure between sevoflurane and enflurane. No adverse experiences with a "probable" or "highly probable" relationship to the inhaled anaesthetic were observed. Emergence time after inhalation anaesthesia depends on (alveolar) ventilation, blood-gas solubility coefficient and, at least for enflurane and isoflurane, on the dose applied (MAC hours). There is no positive correlation between emergence time and dose applied for sevoflurane. Due to the lower blood-gas solubility coefficient (0.6-0.7 for sevoflurane vs. 1.8 for enflurane) pulmonary elimination is faster and emergence time is shorter with sevoflurane. Supplementing inhalation anaesthesia with fentanyl, there is no difference in the time courses of heart rate and mean arterial blood pressure between sevoflurane and enflurane.

Acute Management of Unsuspected Subglottic Stenosis by Tracheal Dilation

Acute Management of Unsuspected Subglottic Stenosis by Tracheal Dilation

Interaction of magnesium sulphate with vecuronium-induced neuromuscular blockt

We have investigated the interaction between magnesium sulphate 40 mg kg-1 i.v. and vecuronium. First, we determined the effect of pretreatment with magnesium on the potency of vecuronium using a single bolus dose-response technique. In addition, we compared the time course of vecuronium-induced neuromuscular block (vecuronium 100 micrograms kg-1) with and without magnesium pretreatment. For both parts, neuromuscular block was assessed by electromyography. In addition, the effect of magnesium pretreatment on vecuronium-induced neuromuscular block was investigated in the context of rapid sequence induction of anaesthesia. We found that the neuromuscular potency of vecuronium was increased by pretreatment with magnesium sulphate. The ED50 and ED90 of vecuronium with MgSO4 were 25% lower than without MgSO4 (ED50: 21.3 vs 26.9 micrograms kg-1; ED90: 34.2 vs 45.7 micrograms kg-1; P < 0.05 for both). Mean onset time was 147.3 (SD 22.2) s in the MgSO4-vecuronium group vs 297.3 (122) s for controls (P < 0.05). Clinical duration was prolonged (MgSO4-vecuronium 43.3 (9) min vs 25.2 (5.1) min for controls; P < 0.05). This was also true for the recovery index (20.1 (6.6) min vs 10.6 (3.4) min; P < 0.05) and duration to 75% recovery (63.4 (9.9) min vs 35.8 (6.9) min; P < 0.05). In the context of rapid sequence induction, pretreatment with MgSO4 improved the intubating score of vecuronium compared with vecuronium without MgSO4, reaching the same quality as that with suxamethonium 1 mg kg-1. We conclude that magnesium pretreatment increased the neuromuscular potency of vecuronium, in addition to modifying the time course of its neuromuscular block.