Thiopental or etomidate for rapid sequence induction with rocuronium

We have assessed the effect of the choice of i.v. induction agent on intubation conditions, 60 s after administration of rocuronium 0.6 mg kg-1. We studied 60 adult patients, allocated randomly to one of two groups. Anaesthesia was induced with alfentanil 10 micrograms kg-1 followed by thiopental 5 mg kg-1 (AT-R group; n = 30) or etomidate 0.3 mg kg-1 (AE-R group; n = 30). Both groups received rocuronium 0.6 mg kg- 1. Laryngoscopy was started 60 s later and intubation conditions were evaluated according to a standard score, which considered ease of laryngoscopy, condition of the vocal cords and reaction to intubation. In the AT-R group, overall intubation conditions were scored as excellent in 20 patients, good in nine and fair in the remaining patient. In the AE-R group, overall intubating conditions were excellent in 24 and good in six patients. The difference between the two groups was not significant. Of the three components of the intubation score assessed, response to intubation stimulus was significantly less pronounced in group AE-R compared with group AT-R (P < 0.05): group AE-R, no reaction in 24 patients, slight diaphragmatic movement in five and mild coughing in one patient; group AT-R, no reaction in 13, slight diaphragmatic movement in 14, mild coughing in two and severe coughing in one patient. We conclude that etomidate as part of an induction regimen containing alfentanil and rocuronium attenuated the reaction to intubation to a greater extent than thiopental.      

Tracheal intubation without muscle relaxants using propofol and varying doses of fentanyl]

This study was designed to evaluate airway and intubating conditions without muscle relaxants after administration of fentanyl and propofol in 55 patients aged 20-60 years for elective surgery. Patients were randomly assigned to one of four groups to receive fentanyl 0, 2, 3, or 4 micrograms.kg-1, respectively. Three minutes after the administration of fentanyl, propofol (2 mg.kg-1) was given for induction of anesthesia. After the loss of consciousness, laryngoscopy and tracheal intubation, supplemented with topical anesthesia of lidocaine (2 mg.kg-1), were attempted. In control group, without administration of fentanyl, all patients were judged to provide poor intubating conditions. Increasing doses of fentanyl reduced the incidences of movement and persistent coughing on laryngoscopy and intubation in a dose-related manner. However, visualization of the vocal cord was significantly. (P < 0.05) more likely to be impossible in patients in 4 micrograms.kg-1 fentanyl group (40%) compared with patients in 2 micrograms.kg-1 fentanyl group (7%). There were no significant differences among groups receiving fentanyl with respect to vocal cord position. The vocal cords were closed in 26% of patients receiving fentanyl and propofol for intubation. Tracheal intubation without muscle relaxants is not recommended because of the potential unacceptable intubating conditions.     

Assessment of intubating conditions in adults after induction with propofol and varying doses of remifentanil

We have assessed intubating conditions in three groups of 60 ASA I or II patients after induction of anaesthesia with propofol 2 mg kg-1 and remifentanil 0.5, 1.0 or 2.0 micrograms kg-1. Tracheal intubation was graded according to ease of laryn-goscopy, position of the vocal cords, coughing, jaw relaxation and movement of the limbs. Intubation was successful in 80%, 90% and 100% of patients after remifentanil 0.5, 1.0 or 2.0 micrograms kg-1, respectively. Overall intubating conditions were regarded as acceptable in 20%, 50% and 80% of patients, respectively. All three groups had a decrease in arterial pressure after induction but there was no difference between groups. The decrease in arterial pressure was not regarded as clinically significant. Intubating conditions were best after induction with remifentanil 2 micrograms kg and propofol 2 mg kg-1.      

Influence of induction of anaesthesia on intubating conditions one minute after rocuronium administration: comparison of ketamine and thiopentone

We compared the effect of thiopentone and ketamine on intubating conditions after rocuronium 0.6 mg.kg-1 in two groups of patients (n = 16 each), aged 21-44 years, undergoing elective surgery. Premedication consisted of alprazolam 1 mg by mouth 1 h before surgery. All patients received midazolam 2 mg intravenously 2 min before intravenous administration of thiopentone 5 mg.kg-1 or ketamine 2.5 mg.kg-1. Muscle relaxation was provided by rocuronium 0.6 mg.kg-1. One minute after rocuronium administration, tracheal intubation was performed within 15 s by a skilled anaesthetist blinded to the treatment group assignment. Intubating conditions were graded as excellent, good, fair or poor on the basis of jaw relaxation, position of vocal cords and diaphragmatic response. Neuromuscular transmission was assessed at the adductor pollicis muscle using a TOF-GUARD monitor. Excellent and good intubating conditions were obtained in 100% of patients in the ketamine group and in 50% of patients in the thiopentone group (p = 0.002). Jaw relaxation was similar in both groups but vocal cord conditions were better and the diaphragmatic response less marked in the ketamine group compared with the thiopentone group (p = 0.002). The degree of neuromuscular block [% decrease of T1, mean (SD)] at the time of intubation was similar: 51.8 (25)% (ketamine group) and 54.3 (23.1)% (thiopentone group). We conclude that ketamine 2.5 mg.kg-1 provides better intubating conditions than thiopentone 5 mg.kg-1 1 min after administration of rocuronium 0.6 mg.kg-1.     

Rapid tracheal intubation with atracurium--a comparison of priming intervals

To determine the optimal interval between the administration of the priming dose and the intubating dose, atracurium was given to 44 patients either in a single dose of 0.5 mg X kg-1 or in an initial dose of 0.06 mg X kg-1 followed two, three or five minutes later with 0.44 mg X kg-1. When atracurium was given as a single bolus of 0.5 mg X kg-1 the time to 100 per cent twitch suppression (onset time) was 90.9 +/- 36 (mean +/- SD) seconds. When the priming interval was two minutes, the onset time of the intubating dose was 76.6 +/- 42.2 seconds (p = NS). But when the priming interval was three or five minutes, the onset times were 42.2 +/- 16.5 (p less than 0.01) and 52.6 +/- 28.8 (p less than 0.05) seconds respectively. Waiting for five minutes after the administration of the priming dose did not improve the intubating conditions. It is concluded that three minutes appears to be the optimal time interval for the administration of atracurium in divided doses. When a priming dose of atracurium is given three minutes before the intubating dose, it can provide an alternative to succinylcholine for rapid endotracheal intubation.     

Rapid induction sequence with vecuronium: should we intubate after 60 or 90 seconds?

The purpose of the study was to determine intubating conditions after administration of either succinylcholine or vecuronium in a rapid induction sequence. Patients received either succinylcholine 1.5 mg.kg-1 (Groups I and II) after d-tubocurarine 0.05 mg.kg-1 four minutes earlier, or vecuronium (Groups III and IV) in an initial dose of 0.01 mg.kg-1 followed four minutes later by 0.1 mg.kg-1. In Groups I and III an apnoeic delay of one minute was allowed before intubation whereas in Groups II and IV the delay was 90 sec. There was no significant difference in intubating conditions between Groups I and IV. Intubating conditions in Group III (vecuronium-delay of one minute) were statistically worse than in any of the three other groups. A delay of 90 sec after succinylcholine improved intubating conditions in male patients. Considering that intubating conditions obtained after 90 sec in patients given a priming sequence with vecuronium (Group IV) were not different from those obtained 60 sec after succinylcholine (Group I), the authors conclude that vecuronium is an acceptable alternative for rapid tracheal intubation. In the doses used in this study, intubating conditions 60 sec after vecuronium were unacceptable for rapid induction of anaesthesia.     

The optimal priming dose for atracurium

To determine the optimal priming dose for administration in divided doses, atracurium was given to 77 patients either in a single dose of 0.5 mg X kg-1 or in an initial dose of 0.04, 0.05, 0.06, 0.07, 0.08 or 0.09 mg X kg-1, followed three minutes later by the remainder of the 0.5 mg X kg-1 dose. Patients were anaesthetized throughout the study. When atracurium was given as a single bolus of 0.5 mg X kg-1, the mean time to complete neuromuscular block was 141.5 seconds. Administration in divided doses accelerated the onset time (p less than 0.01), that is the time from the intubating dose to the complete suppression of train-of-four (TOF) response. The TOF ratio decreased slightly but statistically significantly following the priming doses. When the priming dose was 0.05 mg X kg-1, the mean onset time was 70.9 seconds and priming with larger doses did not add any further advantage. It is concluded that 0.05 mg X kg-1 appears to be the optimal priming dose for the administration of atracurium in divided doses. When 0.05 mg X kg-1 is given three minutes before the intubating dose, tracheal intubation can be accomplished in less than 90 seconds.     

Alfentanil for intubation under halothane anaesthesia in children

Intubating conditions under halothane anaesthesia aided with alfentanil 20 micrograms.kg-1 were compared with suxamethonium 2 mg.kg-1 in 40 children presenting for day dental procedures. The condition of vocal cords, jaw relaxation and presence of movement and coughing were scored to give the overall intubating conditions. Successful intubation was achieved in 100% of the suxamethonium group and 94.7% of the alfentanil group. The cardiovascular response to intubation was attenuated in the alfentanil group. Some 43.7% of those receiving suxamethonium developed myalgia the day after surgery compared with 0% in the alfentanil group (P < 0.01).     

Rapid sequence induction using vecuronium

The purpose of this study was to determine the ideal priming and total dose of vecuronium when used as the relaxant during rapid sequence induction of anesthesia and tracheal intubation. Seventy patients were studied. Various priming and total dose schedules using vecuronium were compared with succinylcholine, 1.5 mg/kg. The mean onset times, intubating conditions, and mean duration times were compared. A priming dose of 10 micrograms/kg produced good intubation conditions with both 70 micrograms/kg and 150 micrograms/kg (total doses), but the mean onset times remained significantly longer than succinylcholine 1.5 mg/kg (P less than 0.05). A priming dose of 15 micrograms/kg of vecuronium with 100 micrograms/kg total dose, on the other hand, not only produced excellent intubating conditions but also resulted in a mean onset time not significantly different from succinylcholine, 1.5 mg/kg. This latter dose schedule of vecuronium is recommended for rapid sequence induction when succinylcholine is contraindicated. Vecuronium is preferable to pancuronium for rapid sequence induction because of its lack of cardiovascular side effects and short duration.     

Tracheal intubating conditions after induction with sevoflurane 8% in children. A comparison with two intravenous techniques

We studied tracheal intubating conditions in 120 healthy children, aged 3-12 years, in a blinded, randomised clinical trial. Children were randomly allocated to one of three groups: group PS, propofol 3 mg.kg-1 and succinylcholine 1 mg.kg-1 (n = 40); group PA, propofol 3 mg.kg-1 and alfentanil 10 microg.kg-1 (n = 40); group SF, sevoflurane 8% in 60% nitrous oxide in oxygen for 3 min (n = 40). Tracheal intubating conditions were graded according to ease of laryngoscopy, position of vocal cords, coughing, jaw relaxation and movement of limbs. Overall intubating conditions were acceptable in 39 of 40 children in the propofol/succinylcholine group, 21 of 40 children in the propofol/alfentanil group and 35 of 40 children in the sevoflurane group. Children receiving propofol and succinylcholine or sevoflurane had better intubating conditions overall than those given propofol and alfentanil (p < 0.01). In conclusion, anaesthetic induction and tracheal intubation using sevoflurane 8% for 3 min is a satisfactory alternative to propofol with succinylcholine in children.     

Intubating conditions after vecuronium and atracurium given in divided doses (the priming technique)

Intubating conditions have been assessed at 60 s following administration of vecuronium 0.1 mg kg-1 or atracurium 0.5 mg kg-1 given either as a single dose after induction of anaesthesia with thiopentone or in divided doses; vecuronium 0.015 mg kg-1 followed 4 or 6 min later by 0.085 mg kg-1, or atracurium 0.075 mg kg-1 followed 4 or 6 min later by 0.425 mg kg-1. In the divided dose groups the smaller initial (priming) dose was given prior to induction of anaesthesia. Onset and duration of clinical relaxation were assessed using a peripheral nerve stimulator. The intubating conditions at 60 s improved significantly, with the use of relaxants in divided doses being acceptable in 80 and 70% of patients, respectively, with vecuronium and atracurium, but the conditions are not as good as those commonly found using suxamethonium. Priming at 6 min has no advantage over priming at 4 min. The onset of complete block was accelerated with priming, but the difference was not significant. The duration of clinical relaxation of vecuronium was significantly prolonged by giving it in divided doses. Unpleasant awareness of muscle weakness was observed in 15 patients, requiring early induction of anaesthesia in five of them.     

Low-dose sufentanil and lidocaine supplementation of general anaesthesia

This randomized double-blind study compared the effects of: (1) saline infusion (C); (2) sufentanil alone (1.0 micrograms.kg-1) (S); and (3) low-dose sufentanil (0.5 micrograms.kg-1) in combination with lidocaine (1.5 mg.kg-1) (LS): on the cardiovascular responses to tracheal intubation and on postoperative ventilation as monitored by respiratory inductive plethysmography in day-care surgical procedures of approximately 60 min duration. Thirty healthy, unpremedicated patients were studied. Thiopentone requirements were reduced by 40 and 28 per cent in the S and LS groups respectively compared with control (P less than 0.001). Both treatments suppressed HR and BP responses (P less than 0.005) to intubation. Postoperatively, PaCO2 was elevated (P less than 0.05) in group S. Dose-related respiratory depression was observed. The incidence of postoperative apnoea was significantly higher in both S and LS groups than compared with control (P less than 0.05). However, only patients in group S showed higher apnoea index and mean apnoea duration over the initial 10-20 min after surgery compared with control (P less than 0.005). In addition, group S showed slower respiratory frequency and prolonged expiratory time (P less than 0.005). In conclusion, an induction dose of sufentanil (1 microgram.kg-1) used in balanced anaesthesia of less than 70 min duration was associated with significant respiratory depression, particularly during the initial 10-20 min after surgery, whereas low-dose sufentanil (0.5 micrograms.kg-1) with lidocaine (1.5 mg.kg-1) had minimal postoperative respiratory depression and comparable attenuation of pressor responses to intubation.     

Effects of ephedrine on intubating conditions following priming with rocuronium

BACKGROUND: Onset of action of muscle relaxants is influenced by cardiac output and muscle blood flow. Ephedrine reduces the onset time of rocuronium. Onset is also shortened by priming. Accordingly, we hypothesized that priming combined with ephedrine is superior to either technique used separately. METHODS: Four groups of randomly allocated patients (n = 31), ASA I - II, were induced with propofol 2.5 mg kg(-1). In groups I and II, 0.04 mg kg(-1) of rocuronium was followed by a 3-min priming interval. Induction was followed by an intubation dose of 0.04 mg kg(-1). Then a 30-s intubation was attempted. In groups III and IV the same sequence was repeated except for sham priming and an intubation dose of 0.44 mg kg(-1). In groups I and II, ephedrine (210 microg kg(-1)) was injected before propofol. In groups II and V, an equivalent volume of normal saline was injected. Jaw relaxation, vocal cord position, and diaphragmatic response were used to assess intubating conditions. RESULTS: All patients of group I were intubated 30 s after the intubating dose and within a 20-s interval compared with 74% of patients in groups II and III, and 84% of patients in group IV. Intubating conditions were graded good to excellent in all patients in group I compared with 42% of those in group II, 35% in group III and 52% in group IV (P < 0.01 vs. group I). During the priming interval, no adverse effects were observed or reported. CONCLUSIONS: Ephedrine in combination with propofol significantly improved clinical intubating conditions at 30 s following priming with rocuronium compared with priming with ephedrine without priming.     

Induction characteristics of thiopentone/suxamethonium, propofol/alfentanil or halothane alone in children aged 1-3 years.

The aim of this study was to compare the effect of three different induction techniques, with or without neuromuscular block, on tracheal intubation, haemodynamic responses and cardiac rhythm. Ninety children, aged 1-3 years, undergoing day-case adenoidectomy were randomly allocated to three groups: group TS received thiopentone 5 mg kg-1 and suxamethonium 1.5 mg kg-1, group H 5 Vol.% halothane and group PA alfentanil 10 micrograms kg-1 and propofol 3 mg kg-1 for induction of anaesthesia. No anti-cholinergics were used. Holter-monitoring of the heart rate and rhythm was started at least 15 min before induction of anaesthesia and continued until 3 min after intubation. Tracheal intubation was performed by an anaesthetist blinded to the induction method and judged as excellent, moderate or poor according to ease of laryngoscopy, position of vocal cords and incidence of coughing after intubation. Tracheal intubation was successful at the first attempt in all children in groups TS and H and but only in 80% in group PA (P = 0.001). Intubating conditions were excellent in 22 (73%), 22 (73%) and one (3%) of the patients in groups TS, H and PA, respectively (P = 0.001). Cardiac dysrhythmias (supraventricular extrasystole or junctional rhythm) occurred in two (7%) patients in groups PA and H each (NS). Bradycardia occurred in 0 (0%), four (14%) and six (21%) children in groups TS, H and PA, respectively (P = 0.007 PA vs. TS, P = 0.03 H vs. TS). In conclusion, induction of anaesthesia with propofol 3 mg kg-1 and alfentanil 10 micrograms kg-1 without neuromuscular block did not provide acceptable intubating conditions in children 1-3 years, although it preserved arterial pressure better than thiopentone/suxamethonium or halothane. Cardiac dysrhythmias were few regardless of the induction method.     

A comparison of spinal and epidural anaesthesia for hip arthroplasty

Spinal and epidural anaesthesia were compared in 65 patients undergoing hip arthroplasty, with regard to the degree of sensory and motor blockade, cardiovascular effects, operating conditions, the dose of propofol required to produce satisfactory hypnosis, and complications. Epidural anaesthesia was successful in 30 patients using an initial dose of 15 ml of 0.5% bupivacaine, and spinal anaesthesia in 32 patients, using 4 ml 0.5% isobaric bupivacaine. The two techniques were similar with regard to the level of sensory blockade (T8), degree of hypotension and perioperative haemorrhage. Differences occurred in the degree of motor blockade (mean Bromage score of 1 in the spinal group vs 3.86 in the epidural group) (P less than 0.05), time to achieve maximal cephalad spread (13 min in the spinal group vs 21 min in the epidural group) (P less than 0.05) and the dose of propofol required to produce adequate hypnosis (1.95 mg.kg-1.hr-1 in the spinal group vs 2.89 mg.kg-1.hr-1 in the epidural group) (P less than 0.05). Only seven patients required urethral catheterization in this spinal group compared with 14 in the epidural group (P less than 0.05). Spinal anaesthesia also proved advantageous by providing better operating conditions for the surgeon, with a lower incidence of patient movement.     

Sufentanil: the effect on cardiocirculatory parameters and intubation conditions on administration of pancuronium or vecuronium

A lack of uniform methodology used in the assessment of moderate doses of sufentanil in combination with non-depolarizing neuromuscular blocking drugs formed the basis of the current study which compared under randomized conditions the effects of sufentanil-pancuronium versus sufentanil-vecuronium on hemodynamics, intubating conditions and chest wall rigidity during induction of anesthesia. MATERIAL and METHODS. One hundred and twenty ASA physical status I and II patients aged between 20 and 40 years of age who were undergoing elective urological surgery were included in the study. Premedication consisted of 0.15 mg kg-1 diazepam, given orally 60 min prior to induction of anesthesia. Patients were randomly divided into eight groups of 15 each to receive 0.5 microgram kg-1 sufentanil or placebo in combination with pancuronium (groups I-IV) or vecuronium (groups V-VIII) Within each group, patients were randomly allocated to receive the relaxant either as a single bolus dose of 0.095 mg kg-1 pancuronium or 0.1 mg kg-1 vecuronium, or in divided doses (the priming principle), the smaller priming dose (0.015 mg kg-1 pancuronium or 0.015 mg kg-1 vecuronium) being administered 2 min before induction of anesthesia with 5 mg kg-1 thiopentone, followed by the second intubating dose of 0.080 mg kg-1 pancuronium or 0.085 mg kg-1 vecuronium. To maintain blind study conditions in the groups, the patients given the relaxants in one dose were given an equivalent volume of saline 2 min prior before 5 mg kg-1 thiopentone. Intubating was attempted 60 s after administration of the main dose of the relaxant, and conditions were assessed on a four-point scale: excellent, satisfactory, fair, or poor. Neuromuscular transmission was monitored with the Datex Relaxograph, a neuromuscular transmission analyzer, that utilizes the integration of the EMG response. Producing train-of-four (TOF) stimuli, with a pulse width of 100 microseconds and a frequency of 2 Hz every 20 s the following parameters were recorded by the Datex Relaxograph: The percentage of first twitch amplitude compared with the reference (T1), and the train-of-four (TOF) ratio, i.e., the ratio of last twitch height to first height. Measurements were taken after premedication in the operating room, the value which served as a baseline (t0), 1 min after sufentanil or placebo (t1), 1 min after priming or placebo (t2), 1 min after thiopentone (t3), and 1 min after intubation (t4).(ABSTRACT TRUNCATED AT 400 WORDS)     

Intubating conditions and neuromuscular block after divided dose mivacurium or single dose rocuronium

Purpose

To evaluate the tracheal intubating conditions and neuromuscular blocking charactenstics of divided dose mivacurium or single dose rocuronium.

Methods

Thirty-two patients undergoing elective surgery were studied. Anaesthesia was with propofol 2 mg · kg^?1, followed by an infusion of l50 μg · kg^?1 · min^?1. Patients were randomized to receive either mivacurium-0.15 mg · kg^?1 followed 30 sec later by 0.1 mg · kg^?1, or rocuronium-0.9 mg · kg^?1, followed 30 sec later by placebo. Tracheal intubating conditions were assessed 90 sec after the initial dose of relaxant by an anaesthetist who was unaware of patient group. The electromyographic (EMG) response of the first dorsal interosseus muscle to ulnar nerve train-of-four was measured.

Results

Successful tracheal intubation was performed in all patients after both mivacurium and rocuronium. Intubating conditions (jaw relaxation, open visible vocal cords) were judged to be good-excellent in all but one patient before insertion of the tracheal tube. However, patients receiving mivacunum were more likely to experience coughing and bucking after tracheal tube insertion (10/16 patients) than those receiving rocuronium (3/16 patients, P < 0.05). No patient in the rocuronium group experienced moderately vigorous coughing and bucking after insertion of the tracheal tube vs six patients in the mivacurium group (P < 0.05). Time to 10 and 25% recovery of neuromuscular function was faster (P < 0.05) after divided dose mivacunum (20 ± 1 and 23 ± 1 min, respectively) than after rocuronium (45 ± 5 and 57 ± 8 min, respectively).

Conclusion

The results suggest that, during conditions of the study, divided dose mivacurium is not recommended for a 90-sec tracheal intubation in patients where moderate coughing and bucking is deemed unacceptable.     

Intubating conditions and onset of neuromuscular block of rocuronium (Org 9426); a comparison with suxamethonium

The intubating conditions and neuromuscular blocking profile following 600 micrograms.kg-1 rocuronium (Org 9426) have been investigated in patients under various experimental conditions. They were compared with conditions following 1.5 mg.kg-1 suxamethonium, preceded by a precurarising dose (10 mg) of gallamine, and with those in a control group in the absence of a muscle relaxant. Rocuronium produced good to excellent intubating conditions at 60 as well as at 90 s after administration, even though there was only a partial blockade of the adductor pollicis muscle. Intubating conditions following suxamethonium were comparable with those after rocuronium. Half of the control patients could be intubated. The clinical duration and the recovery time of 600 micrograms.kg-1 of rocuronium were 24(4) and 9(3) min (mean(s.d.)), respectively. Rocuronium may have a major advantage over existing non-depolarising muscle relaxants due to the early presence of excellent intubating conditions. The results indicate that rocuronium may replace suxamethonium in procedures in which rapid sequence induction is required.     

Effects of ephedrine on the onset time of neuromuscular block and intubating conditions after cisatracurium: preliminary results

We studied the effects of intravenous ephedrine on the onset time and the intubating conditions 2 min after a bolus dose of cisatracurium (0.15 mg kg-1). Thirty patients anaesthetized with sufentanil and propofol were randomly divided in 2 groups to receive either ephedrine (70 micrograms.kg-1) or saline, 5 s before propofol. Cisatracurium was administered after loss of consciousness. Neuromuscular block was assessed at the adductor pollicis using accelography. Tracheal intubation was performed 2 min after cisatracurium injection and rated as excellent, good, poor or bad. At intubation, neuromuscular block (% height of control T1) was greater in patients receiving ephedrine (36.1 +/- 25.8% vs 57.9 +/- 25.1%) (mean +/- SD). The frequency of excellent intubating conditions was higher after ephedrine (86.6%) than after saline (40.0%). The onset time of cisatracurium was shorter after ephedrine (167 +/- 64.8 s vs 234.9 +/- 63.1 s). Thus, a low dose of ephedrine given before induction of anaesthesia improves the intubating conditions 2 min after 0.15 mg kg-1 cisatracurium and this effect likely relates to a quicker onset of neuromuscular block.     

Facilitation of rapid endotracheal intubations with divided doses of nondepolarizing neuromuscular blocking drugs

The authors sought to determine whether prior administration of a small, subparalyzing dose of nondepolarizing muscle relaxant would shorten the onset time of an intubating dose of muscle relaxant. Initially, in 60 anesthetized patients, twitch response of adductor pollicis to ulnar nerve stimulation was studied after a small dose of pancuronium 0.015 mg . kg-1, metocurine 0.03 mg . kg-1, or d-tubocurarine 0.04 mg . kg-1, followed 3 min later by pancuronium 0.08 mg . kg-1 or atracurium 0.4 mg . kg-1 administered iv. After 60 s, the minimum neuromuscular block, in all patients was 79.0 +/- 5.0%. A 95% depression or twitch tension occurred between 59.1 +/- 5.3 and 86.1 +/- 5.9 s. In another 60 patients, intubating conditions under similar regimen were studied, except the small dose of muscle relaxant was given immediately prior to induction of anesthesia. At the end of 60 s, good to excellent intubating conditions were present in 100% of the patients following the second dose of pancuronium and in 83% of the patients following atracurium. In 17% of the patients, after atracurium intubating conditions were fair. When nondepolarizing neuromuscular blocking drugs are administered in divided doses, neuromuscular blockade adequate for endotracheal intubation is achieved in less than 90 s. This facilitates rapid endotracheal intubation in a time comparable to using succinylcholine, without undesirable effects of the depolarizing neuromuscular blocking drugs.