Speed and ease of tracheal intubation: priming with mivacurium compared with succinylcholine

This study examined the efficacy of mivacurium priming (0.015 mg · kg^?1) with five minutes between the priming and intubating doses by comparing the effects of one, two and three times the ED₉₅ dose (0.075 mg · kg^?1) of mivacurium after priming (Groups 1, 2 and 3, respectively), with a saline prime and 2 × ED₉₅ mivacurium (Group 4) or 1 mg · kg^?1 dose of succinylcholine (Group 5). The time from the intubating dose injection to intubation was measured and intubating conditions were rated on a five-point scale with 4 being optimal and 0 being failure. Mean times (± SEM) in seconds between the administration of the intubating dose and tracheal intubation were: 106.4 ± 5.1, 89.6 ± 6.7, 81.9 ± 2.7, 169.9 ± 7.8 and 82.9 ± 3.5 for Groups 1–5 respectively. The times for Group 2 (2 × ED₉₅ with priming), Group 3 (3 × ED₉₅ with priming) and Group 5 (succinylcholine with saline) were shorter than the times of Groups 1 (1 × ED₉₅ with priming) and 4 (2 × ED₉₅ with saline) P < 0.05. Mean intubating condition scores (± SD) for the five groups respectively were 3.1 ± 0.6, 3.4 ± 0.6, 3.5 ± 0.5, 3.2 ± 0.6 and 3.8 ± 0.4. Scores for Groups 2, 3 and 5 were higher than those of Group 1 (P < 0.05). The data demonstrated that (1) priming with mivacurium shortens the intubation time and is accompanied by good intubating conditions with doses 2× and 3× ED₉₅, and (2) intubating times and conditions similar to those achieved with succinylcholine can be obtained using mivacurium 2× (total dose 0.150 mg · kg^?1) or3 × ED₉₅ (total dose 0.215 mg · kg^?1) with a five-minute priming interval. Priming provides an alternative technique in those clinical circumstances where succinylcholine is contraindicated.     

Onset of vecuronium-induced neuromuscular block after a long priming interval

Purpose. We examined whether a new application of the priming principle, i.e., having the priming dose of vecuronium administered before the insertion of the epidural catheter, would hasten the onset of the neuromuscular block induced by the intubating dose of vecuronium. Methods. Forty-five adult female patients scheduled for general anesthesia combined with epidural anesthesia were studied. In group A (n = 15), the priming dose of vecuronium, 0.01 mg·kg⁻¹, was administered before insertion of the epidural catheter. The intubating dose of vecuronium, 0.09 mg·kg⁻¹, was given after the insertion of the epidural catheter. In group B (n = 15), the priming dose of vecuronium, 0.01 mg·kg⁻¹, was given 4 min before the intubating dose of vecuronium, 0.09 mg·kg⁻¹. In the control group (n = 15), no priming dose was given, and only the intubating dose of vecuronium, 0.10 mg·kg⁻¹, was administered. In all three groups, general anesthesia was induced with propofol 2.5 mg·kg⁻¹, and the trachea was intubated when T1/control value (control twitch height in response to train-of-four stimuli) was less than 0.1. Results. In group A, the priming dose was given 16 ± 3 min (mean ± SD) before the administration of the intubating dose. The times to onset of neuromuscular block in groups A and B, and the control group were: 145 ± 30, 184 ± 45, and 219 ± 23 s, respectively (P < 0.05 among the three groups). In all three groups, intubating conditions (graded on a four-point scale) were excellent (P = 0.59). Before the induction of anesthesia, symptoms of paralysis were observed in 5, 4, and 0 patients in groups A and B and the control group, respectively (P < 0.05 between group A or B vs control group). Conclusions. If the priming dose of vecuronium is given after a long priming interval (16 ± 3 min), the time to onset of the neuromuscular block caused by the intubating dose of vecuronium is markedly shorter than when the conventional priming interval of 4 min is employed. Received: March 5, 2001 / Accepted: October 4, 2001     

Target controlled priming for rapid onset of intubation dose: A new approach

Purpose To determine the pattern of onset of the intubating dose when given at a monitored target priming block in either phase of the priming drug effect. Methods Sixty consenting ASA I and II patients were premedicated by intramuscular buprenorphine (5 μg·kg⁻¹) 1h before surgery. Neuromuscular junction monitoring was done by stimulating the ulnar nerve at the wrist using Myotest and recording the adductor pollicis response on Myograph-2000. After stabilization of the twitch tension at the titrated supramaximal stimulus (1 Hz), double-burst stimuli (DBS) were given to monitor the priming effect of vecuronium bromide (Vb) (0.015 mg·kg⁻¹). The DBS ratio (DBSr=D ₂/D ₁) was calculated for the DBS response, repeated at 20s. Depending on the target priming block level (DBSr 0.8, 0.6, or 0.5) and the phase of the priming block to give an intubating dose of Vb (0.8 mg·kg⁻¹) injection, all patients were randomly assigned to six study groups: group 1 (DBSr 0.8), group 3 (DBSr 0.6), and group 5 (DBSr 0.5) during the priming block progression phase (before peakD ₁ suppression), and group 2 (DBSr 0.8), group 4 (DBSr 0.6), and group 6 (DBSr 0.5) during the priming block regression phase (after peakD ₁ suppression). Anesthesia was induced by thiopental (5–7 mg·kg⁻¹) just before the intubating dose. The effect of the intubating dose on twitch stimuli (1 Hz) was monitored. Results We observed that in spite of significantly variable priming intervals for identical DBSr in two different phases, the onset time of the intubating dose to 0 response was identical in similar DBSr group patients; i.e., at 0.8 DBSr, 65.0±5.2s (group 1)vs 66.0±8.0s (group 2); at DBSr 0.6, 55.2±3.7s (group 3)vs 55.2±4.9s (group 4); and at DBSr 0.5, 43.5±4.8s (group 5)vs 43.5±4.2s (group 6). At 0 twitch response, the intubating conditions were comparable in patients of the six groups. Conclusion In conclusion, target controlled priming (DBSr) for administration of the intubating dose appears to be a useful double-vision sign to predict the onset of the effect of the intubating dose precisely.     

The agreement between adductor pollicis mechanomyogram and first dorsal interosseous electromyogram

The agreement between evoked adductor pollicis mechanomyogram and first dorsal interosseous evoked electromyogram (EMG) was evaluated during a pharmacodynamic study of rocuronium and vecuronium. In the first place the effective doses of rocuronium producing 50% and 90% block (ED₅₀ and ED₉₀, respectively) were established in 32 neurolept anaesthetized patients from the adductor pollicis mechanomyogram and the first dorsal interosseous EMG area and amplitude. Secondly, limits of agreement between the two methods were evaluated from the mean difference between methods 2 s.d. in 20 patients during onset of block following 2 × ED₉₀ of rocuronium and vecuronium, and during recovery from the last supplementary dose of 1/2 × ED₉₀. Limits of agreement show how much the EMG may be above or below the mechanomyogram. No differences were found between mechanomyographical and EMG based ED₅₀ (0.20 mg kg^-1) and ED₉₀ (0.30–0.32 mg kg^-1), respectively. The first EMG train–of–four (TOF) response overestimated block at 25% recovery and underestimated block at 75% and 90% recovery by only 3–7%. Limits of agreement suggested that the EMG may be 7–8% above or below the mechanomyogram during onset compared to 12–17% during recovery. The EMG TOF ratio lagged behind that of the mechanomyogram by 0.05 at TOF ratios below 0.50. No difference was found between methods at a TOF ratio of 0.75. Limits of agreement indicated that the EMG TOF ratio may be 0.12–0.15 above or below that of the mechanomyogram. Agreement between the amplitude and the area of the EMG were better than between the mechanomyogram and the EMG. Evaluation of the time courses of action showed that rocuronium had a faster onset of action than vecuronium (1.8 min compared to 2.8 min) while duration of action and reversal were similar. In conclusion, the first dorsal interosseous EMG amplitude and area can be used to assess rocuronium and vecuronium block.     

Sequestration of vecuronium bromide during extremity surgery involving use of a pneumatic tourniquet

Background: We hypothesized that sequestration of a neuromuscular blocking agent could occur during surgery involving use of an extremity tourniquet and cause changes in neuromuscular function after tourniquet release. Methods: Sixteen patients scheduled for total knee replacement were randomized to one of two groups. In Group 1,10 patients were administered O.lmg/kg of vecuronium 5 minutes prior to inflation of a pneumatic tourniquet; in Group II, 6 patients were administered O.lmg/kg of vecuronium after inflation of the tourniquet. The twitch (T₁) and train-of-four (TOF) were analyzed before and after release of the tourniquet, as was the rate of recovery of T₁ and TOF. Serial vecuronium plasma levels were drawn during the study. Results: The T₁ and TOF responses and the T₁ and TOF recovery rates were not significantly different between groups at tourniquet deflation. In Group I, after release of the tourniquet, Tj and TOF recovery rate decreased significantly over a 10-min period (10%±3 to 4%±4 and 0.12±0.06 to 0.06±0.04, mean±SD, respectively); in Group II, T₁ and TOF recovery rate increased significantly over a 10-min period following deflation of the tourniquet (10%±6 to 14%±7 and 0.10±0.03 to 0.18±0.02, respectively). Changes in pharmacodynamics were temporally associated with transient but statistically significant changes in vecuronium plasma levels. Overall pharmacokinetics during the study period were comparable between groups. After administration of neostigmine 30–40 μg/ kg i.v. all subjects in both groups showed complete TOF recovery within 15 min. Conclusions: Sequestration of a bolus dose of vecuronium, by a pneumatic tourniquet, causes transient changes in pharmacokinetics and pharmacodynamics. These changes are of limited clinical importance and do not affect reversibility of neuromuscular block.     

The effects of low-dose ephedrine on intubating conditions following low-dose priming with cisatracurium

Study ObjectiveTo determine whether low-dose ephedrine plus priming with low-dose cisatracurium improves intubating conditions.DesignProspective, randomized, double-blinded study.SettingOperating room.Patients124 ASA physical status I and II patients scheduled for elective surgery.InterventionsPatients were randomly assigned to 4 groups (n = 31): Group PE (priming + ephedrine), Group P (priming), Group E (ephedrine), and Group NPE (no priming, no ephedrine). All patients were induced with propofol two mg/kg and sulfentanil 0.15 μg/kg. In the priming groups, 0.005 mg/kg (10% ED₉₅) cisatracurium was given, followed three minutes later by 0.145 mg/kg of cisatracurium. In Groups E and NPE, a single dose of 0.15 mg/kg cisatracurium was given. Intravenous ephedrine 70 μg/kg was given in Groups PE and E. Tracheal intubation was attempted 60 seconds after the intubating dose of cisatracurium and was considered successful only if performed within 20 seconds.MeasurementsIntubating conditions were graded. Heart rate and non-invasive blood pressure, at one-minute intervals, were recorded during and 5 minutes after induction.Main ResultsThe tracheas of all patients in Group PE were successfully intubated within 20 seconds versus 74% in Group P, 77% in Group E, and 64% in Group NPE (P < 0.001 vs. Group PE). Intubating conditions were graded good to excellent in all PE patients, but in only 52% of Groups P and E, and 48% of NPE patients (P < 0.001). Hemodynamic variables were comparable among groups (P = ns).ConclusionsLow-dose ephedrine plus priming with low-dose cisatracurium before an intubating dose, significantly improved clinical intubating conditions at 60 seconds.     

Intubationsbedingungen nach Gabe von Atracurium und Vecuronium Bolusmethode vs. Primingtechnik

Prompted by the ongoing discussion of the pros and cons of using succinylcholine, this study was conducted to compare the responses to bolus injections of atracurium or vecuronium with those after sequential injection of these drugs (priming principle). We evaluated the earliest possible intubation times, intubating conditions, and the onset times (i.e. times from the end of injection to the maximum blockade) under conditions approaching real use as closely as possible. Methods. The randomized and double-blind study was carried out with 80 ASA risk class 1 and 2 patients. Approval of the institutional ethics committee was obtained, and each patient gave informed consent. Patients were randomly allocated to four study groups of 20 patients each. Isotonic saline was administered to those patients assigned to the atracurium or vecuronium bolus groups, whereas the patients assigned to the other two groups received a priming injection of either atracurium (0.05 mg/kg) or vecuronium (0.01 mg/kg). We observed the patients for signs of incipient muscular weakness before the induction of anaesthesia. Anaesthesia was induced with thiopental 3.5 min after the first injection (5 mg/kg and 50–100?mg before intubation). After a further 1 min during which adequate mask ventilatin with oxygen was assured, corresponding to a priming interval of 4.5?min, 0.5 mg/kg of atracurium or 0.1 mg/kg of vecuronium was administered to the patients in the bolus groups and 0.45 mg/kg of atracurium or 0.09 mg/kg of vecuronium as intubating doses to those in the priming groups. Intubation was attempted at 90, 120, 150 and 180?s thereafter. Intubating conditions were evaluated on the basis of laryngoscopy, vocal cord movement and coughing or bucking of the patients. Neuromuscular function was monitored via accelerometry at the adductor pollicis muscle (TOF stimulation of the ulnar nerve every 15?s). Results. The priming doses did not diminish the elicited twitches of the adductor pollicis muscle, but led to heavy eyelids and double vision in 35% of the atracurium patients and 47% of the vecuronium patients; these symptoms were well tolerated by the patients. At the time of intubation the adductor pollicis muscle was relaxed to approximately the same degree in all groups (mean±SD for the TOF ratios in the bolus groups was 0.46±0.37 for atracurium, 0.45±0.4 for vecuronium; in the priming groups 0.52±0.39 for atracurium, 0.53±0.36 for vecuronium). The administration of the relaxants in divided doses significantly shortened the intubating time after atracurium (100 vs 124?s) and improved the intubating conditions of vecuronium (good vs tolerable), but had no effect on the time course of the neuromuscular blockade (onset times in the bolus groups 224±84?s for atracurium and 209±64 s for vecuronium; in the priming groups 249±112?s for atracurium and 205±52 s for vecuronium). Conclusions. The priming technique presented here is clinically superior to the bolus method and therefore should be preferred in all elective cases and in those patients in whom succinylcholine is contraindicated.     

Comparison of sensitivity of neuromuscular monitoring tests: twitch versus tetanic test

Purpose The study was planned to compare the sensitivity of a twitch neuromuscular monitoring test, the train-of-four (TOF), with a tetanic test, double-burst stimulation (DBS), during a subclinical dose of vecuronium. Methods Twenty consenting. ASA I patients (16 to 65 years of age) of both sexes were studied. The ulnar nerve was stimulated at the wrist through surface electrodes by Myotest-DBS, and the adductor pollicis response was recorded on Myograph-2000. After stabilization of the twitch tension at titrated supramaximal stimuli (1 Hz), patients were randomly allocated into groups. In group 1 (n=10), the TOF test was monitored; in group 2 (n=10), the DBS test was monitoral. All patients received a priming dose of vecuronium (0.015 mg·kg⁻¹); parameters such asT ₁ and TOF ratio (TOFr) (T ₄/T ₁) were noted in group 1, andD ₁ and DBS ratio (DBSr) (D ₂/D ₁) were noted during the vecuronium effect. Results The DBS test showed a wider range of change (from control 1.00 to 0.62±0.19 forD ₁ and to 0.37±0.14 for DBSr) at a faster rate (0.07±0.04 min⁻¹ forD ₁ and 0.08±0.02 min⁻¹ for DBSr) during the block progression phase than the TOF test parameters (T ₁ and TOFr). The tetanic fade or DBSr showed peak onset later than peak twitch suppression. The rate of recovery of the DBS test was also slower than that of the TOF test after the peak effect. Conclusions DBS is a more sensitive test than TOF to quantify the subclinical dose effect of vecuronium, and among the studied parameters (T ₁, TOFr,D ₁ and DBSr), DBSr, measuring tetanic fade, was the most sensitive single parameter.     

Optimum priming dose of vecuronium for tracheal intubation

To determine the optimum priming dose of vecuronium, we divided 173 surgical patients into five groups according to priming dose (0, 2.5, 5.0, 7.5, and 10 μg·kg⁻¹). For endotracheal intubation, we administered a priming dose of vecuronium, and then after 4 min, the remainder was injected for a total dosage of 0.15 mg·kg⁻¹. Onset time was determined by a 95% depression of twitch height as shown by electromyography (EMG) of the hypothenar muscles. This was measured by repeating the train-of-four (TOF) stimulation. An increased priming dose shortened the onset time; however, this shortening rate diminished when the dosage was above 7.5 μg·kg⁻¹. In the zero priming dose group there was a significant correlation between onset time and age, and between onset time and body mass index (BMI) in women (r=0.62 and −0.45, respectively); however, this correlation was not observed in men. A priming dose of 10 μg·kg⁻¹ showed a decrease of TOF ratio to 95% or less in 1 out of 25 cases. Although one-third of the patients in the 5 and 7.5 μg·kg⁻¹ groups complained of clinical symptoms such as ptosis, this was clinically allowable. We conclude that the optimum priming dose of vecuronium is 7.5 μg·kg⁻¹; however, in obese patients, a smaller dosage would be recommended.     

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.     

Is the priming principle both effective and safe?

This study determined the priming dose of vecuronium (V), pancuronium (P) and atracurium (A) that resulted in the most rapid onset of neuromuscular blockade (NMB) in 150 patients given either V 0.08 mg/kg, P 0.1 mg/kg or A 0.6 mg/kg. Patients were further divided (n = 10 per group) to receive no prime or 5%, 10%, 15% or 20% of the total dose as a prime followed 5-7 minutes later by the remaining (intubating) dose. A further 10 patients received 0.04 mg/kg d-tubocurarine followed by 1.5 mg/kg succinylcholine (S). Priming significantly shortened the onset of NMB. The priming doses producing the most rapid onset were 0.012 mg/kg for V, 0.015 mg/kg for P and 0.09 mg/kg for A. The S resulted in significantly greater NMB at 60 sec than any priming dose of A, V or P. There was no difference between the three nondepolarizing neuromuscular blockers in shortening the onset of NMB produced by priming. To evaluate both the effect of the "optimal" priming dose in awake patients and the effect of increasing intubating doses on NMB an additional 40 patients were given V 0.012 mg/kg followed by V 0.08, 0.1, 0.12 or 0.15 mg/kg. Increasing the intubating dose did not improve onset of NMB. The "optimal" priming dose, however, resulted in a high incidence of symptoms of muscle weakness. We conclude that priming shortens the onset of NMB similarly between V, P and A but the priming dose producing the most rapid onset of NMB also results in a high incidence of side effects and therefore the priming principle should be used with caution.     

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.     

Ketamine, but not priming, improves intubating conditions during a propofol–rocuronium induction

Purpose

Both ketamine and priming may shorten the onset time of rocuronium. This study investigates the effects of ketamine and priming as components of a propofol induction on intubating conditions and onset of neuromuscular block.

Methods

This prospective randomized double-blind study was performed in 120 American Society of Anesthesiologists (ASA) I–II patients who were assigned to one of four groups of 30 patients each: control, priming, ketamine, and ketamine-priming. Ketamine 0.5 mg ? kg^?1 or saline was given before priming and induction. Rocuronium 0.06 mg ? kg^?1 or saline was injected 2 min before propofol 2.5 mg ? kg^?1. This was followed by rocuronium 0.6 mg ? kg^?1 or by rocuronium 0.54 mg ? kg^?1 if priming was given. Intubation was performed one minute later. Intubating conditions were graded as excellent, good, or poor. Heart rate, noninvasive blood pressure, and train-of-four (TOF) response were monitored.

Results

Intubating conditions were graded excellent in 20% of the control group, 30% of the priming group, 47% of the ketamine group, and 57% of the ketamine-priming group. Analysis using forward stepwise regression indicated that ketamine improved intubating conditions (P = 0.001) but priming did not (P = 0.35). Time to reach a TOF count of zero was shortened by ketamine (P = 0.001) but not by priming (P = 0.94): 216 ± 20 s in the control group, 212 ± 27 s in the priming group, 162 ± 18 s in the ketamine group, and 168 ± 22 s in the ketamine-priming group.

Conclusion

A low-dose ketamine used with a propofol–rocuronium induction improved intubating conditions and shortened onset time. Priming did not influence intubating conditions or onset time.     

Sevoflurane and isoflurane impair edrophonium reversal of vecuronium-induced neuromuscular block

Purpose

A dose-response relationship study for edrophonium to examine the modification of volatile anaesthetics on reversal of vecuronium block.

Methods

One hundred and twenty ASA (I–II) patients were anaesthetized with sevoflurane, isoflurane (I minimum alveolar anaesthetic concentration [MAC] end-tidal concentration), or fentanyl-diazepam anaesthesia, in combination with 66% nitrous oxide (n = 40 for each group). The evoked electromyogram (EMG) response of the abductor digiti minimi was monitored at 20 sec intervals following train-of-four (TOF) stimulation of the ulnar nerve. The initial neuromuscular block was produced by vecuronium 100 μg · kg^?1. When the amplitude of the first response (T₁) had spontaneously recovered to 10% of the control, edrophonium (0, 125, 400, 700 or 1000 μg · kg^?1; eight patients each) was randomly administered, and the ratio of the fourth TOF to the first response (TOFR ) was monitored at one minute intervals for 10 min.

Results

Sevoflurane and isoflurane impaired the edrophonium-assisted TOFR recovery in an edrophonium dose and time dependent manner. The dose-response curves at 10 min exhibited a greater shift to the right in the sevoflurane and isoflurane groups than in the fentanyl-diazepam-nitrous oxide group (P < 0.05). Higher ED₅₀ values (the edrophonium dose required to obtain TOFR value of 50%) in the sevoflurane (> 1000 μg · kg^?1) and isoflurane groups (851 · μg · kg^?1) were observed than in the fentanyl-diazepam-nitrous oxide group (339 μg · kg^?1) (P < 0.05).

Conclusion

One MAC sevoflurane and isoflurane anaesthesia impair edrophonium reversal of vecuronium block to a similar degree.     

Rapid-sequence orotracheal intubation: a comparison of three techniques

The authors compared tracheal intubating conditions using three techniques for rapid-sequence orotracheal intubation. Sixty patients were randomly assigned to one of three groups: priming with vecuronium (0.01 mg/kg priming dose, 4-min priming interval, 0.14-mg/kg intubating dose along with thiopental 4-6 mg iv); timing with vecuronium (0.15-mg/kg intubating dose given before thiopental and timed to weakness of hand grip); and succinylcholine (1.5 mg/kg). Blinded intubators graded intubating conditions 60 s after the induction of anesthesia with thiopental. Intubation scores in the succinylcholine group were significantly better than in the priming group (P = 0.009). Intubation scores of the succinylcholine and the timing groups were not significantly different. Use of the timing principle for rapid-sequence orotracheal intubation is a reliable alternative in cases where succinylcholine is contraindicated.     

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)     

The effect of age on the dose of remifentanil for tracheal intubation in infants and children

Introduction: This study aimed to determine the age‐specific bolus dose of remifentanil (ED₅₀) to facilitate tracheal intubation without the use of neuromuscular blocking agents. Methods: ASA 1–2 subjects were recruited into three groups of 0–3 months (group I), 4–12 months (group II), and 1–3 years (group III) of age. A sequential up‐and‐down design determined the remifentanil bolus dose, which was initially started at 3 mcg·kg^?1 and adjusted in 1 mcg·kg^?1 increments (range 1–6 mcg·kg^?1). Following pretreatment with glycopyrrolate 10 μg·kg^?1 and an induction dose of propofol 5 mg·kg^?1, remifentanil was administered with a blinded study investigator commencing tracheal intubation after 60 s. After tracheal intubation, the time to return of spontaneous ventilation was measured. Logistic regression was used to predict the ED₅₀ and ED₉₅ of remifentanil. Results: Sixty‐four subjects were recruited. Tracheal intubation was successful at first attempt in over 90% of subjects in each age group. Satisfactory intubating conditions were achieved in 85%, 63%, and 75% of subjects in groups I, II, and III, respectively. The logistic regression results for ED₅₀ (95% CI) were 3.1 (2.5–3.8), 3.7 (2.0–5.4), and 3.0 (2.1–3.9) mcg·kg^?1, and ED₉₅ (95% CI) were 5.0 (3.0–7.0), 9.4 (1.5–17.4), and 5.6 (2.9–8.4) mcg·kg^?1 in groups I, II, and III, respectively. Infants aged 4–12 months (group II) showed a marked variability in dose response; however, the mean ED₅₀ and ED₉₅ were not different to groups I and III. Older children had a longer duration of apnea than infants, 331 vs 180 s (P < 0.05). Discussion: The ED₅₀ of remifentanil for tracheal intubation was higher in all age groups than previously reported. Ideal intubating conditions were achieved in 50% of subjects with remifentanil doses of 3.1–3.7 mcg·kg^?1. Higher doses will be required for higher success rates and with anticholinergic pretreatment, doses of up to 6 mcg·kg^?1 were tolerated, without adverse effects, in two patients. Further investigation of the variability in dose response in infants and assessment of the safety this technique is warranted.     

Kardiovaskuläre Effekte nach Bolusapplikation von Cisatracurium

Cisatracurium – one of the ten stereoisomers of atracurium – is an intermediate long-acting non-depolarizing neuromuscular blocking agent. Cardiovascular reactions have been described after administration of cisatracurium or vecuronium in surgical patients. Methods. After approval by our institutional review board, 62 patients (ASA I–II) were randomly assigned to three groups to either receive 3×ED₉₅ or 5×ED₉₅ of cisatracurium or 3×ED₉₀ of vecuronium prior to intubation as a bolus. After oral premedication with 2?mg lormetazepam anaesthesia was induced with thiopental (4–12?mg/kg) and maintained with O₂/N₂O and isoflurane (1.5%–2%). Six minutes after administration of thiopental, patients received the muscle relaxant. Six minutes later 0.1–0.2?mg fentanyl was given and the trachea was intubated. Heart rate (HR) and blood pressure (BP) were monitored every minute. Changes of heart rate or blood pressure?>20% compared to baseline were defined as clinically significant. Results. After application of the study drug, median values of blood pressure and heart rate were stable. For each muscle relaxant, there were several patients who had statistically significant cardiovascular changes. After 3×ED₉₅ cisatracurium, 3 of 21 patients exhibited haemodynamic changes?>20% (2 exhibited hypotension and 1 tachycardia), while in the high-dose cisatracurium group 2 of 21 patients demonstrated a tachycardia that was predetermined to be statistically but not clinically significant. In the vecuronium group, 2 of 20 patients sustained statistically significant hypotension and 1 patient had statistically significant tachycardia. The frequency of all individual cardiovascular changes after the application of the muscle relaxant was not dose-dependent. Conclusion. After the administration of cisatracurium in two different doses (3×ED₉₅ and 5×ED₉₅) or vecuronium (3×ED₉₀) only minor cardiovascular changes were observed. Both drugs proved to be safe for use during induction of anaesthesia in patients ASA I–II. With regard to its cardiovascular effects, cisatracurium shares with vecuronium the requirements of an ideal muscle relaxant.     

The influence of alfentanil on the intubating conditions after priming with vecuronium

The ability of alfentanil 15 micrograms kg-1 or 30 micrograms kg-1 to improve intubating conditions was studied in four groups of 25 ASA class 1 patients. Induction of anaesthesia was with thiopentone 5 mg kg-1. Neuromuscular blockade was induced with vecuronium using the priming principle. The priming dose, priming interval and intubating dose were 0.01 mg kg-1, 4 min, and 0.1 mg kg-1, respectively. Intubation was attempted 1 min after the intubating dose. Intubating conditions were judged unacceptable in about 30% of the patients belonging to the control groups. Alfentanil 15 micrograms kg-1, when administered 65 s before intubation, reduced the incidence of coughing and diaphragmatic movement (P less than 0.05) but did not reduce the incidence of overall unacceptable intubating conditions. Alfentanil 30 micrograms kg-1, however, reduced the incidence of vocal cord movement (P less than 0.005) as well as coughing and diaphragmatic movement (P less than 0.002). Alfentanil 30 micrograms kg-1 reduced the incidence of unacceptable intubating conditions from about 30% to 4% (P less than 0.02).     

Rocuronium in infants, children and adults during balanced anaesthesia

We studied 20 infants, 20 children and 20 adults during balanced anaesthesia to compare the neuromuscular blocking effects of rocuronium in these age groups. Neuromuscular function was recorded by adductor pollicis emg and a cumulative log-probit dose-response curve of rocuronium was established. Thereafter, full spontaneous recovery of the neuromuscular function was recorded. Onset time of the first dose of rocuronium was shorter in children than in infants or adults. The potency of rocuronium was greatest in infants and least in children; the ED₅₀ doses (mean ± SD) being 149 ± 36 μg˙kg^?1 in infants, 205 ± 52 μg˙kg^?1 in children and 169 ± 47 μg˙kg^?1 in adults (P<0.05 between infants and children) and the ED₉₅ doses being 251 ± 73 μg˙kg^?1, 409 ± 71 μg˙kg^?1 and 350 ± 77 μg˙kg^?1, respectively (P<0.05 between all groups). The emg recovery following an average 94.5 ± 4.8% neuromuscular blockade established by rocuronium was roughly similar in all study groups. Thus, one ED₉₅ dose of rocuronium, unlike vecuronium, acts as an intermediate-acting agent in all age groups.