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PubMed1998

Comparison of time course of neuromuscular blockade in young children following rocuronium and atracurium.

In order to compare the neuromuscular effects following rocuronium 0.6 mg kg-1 and atracurium 0.5 mg kg-1 30 children aged from 18 to 67 months were studied under the same anaesthetic conditions. After induction of anaesthesia with etomidate and fentanyl, neuromuscular blockade was monitored by recording the electromyographic response of the adductor pollicis muscle to a supramaximal train-of-four (TOF) stimulation of the ulnar nerve at 2 Hz for 2 s at 20-s intervals. Intubation was performed when more than 90% muscle relaxation was achieved, thereafter anaesthesia was maintained with 70% nitrous oxide in oxygen and isoflurane 0.5% end-tidal. Mean onset of action was significantly faster following rocuronium (86 +/- 44.9 s) (mean +/- SD) compared with atracurium (126.3 +/- 61.0 s). Clinical duration with rocuronium was 22.8 +/- 5.31 min and thus significantly shorter than that of atracurium, which was 31.5 +/- 6.01 min. A statistically significant difference between rocuronium and atracurium also had been found for recovery of T1 to 50%, 75% and 90% as well as for the time taken to a TOF ratio of 70%. The recovery index for rocuronium and atracurium was not significantly different with 9.2 +/- 3.43 min and 10.9 +/- 2.65 min, respectively. Thus, rocuronium may be more advantageous than atracurium for short-lasting surgical procedures in young children.

Analysis of Variance↗

PubMed1991

Frequency-dependent neuromuscular blockade by textilotoxin in vivo.

The effect of stimulation frequency on the timecourse of neuromuscular blockade, following the administration of textilotoxin (20 micrograms/kg) or beta-bungarotoxin (50 micrograms/kg), was examined in the interdigital muscles of the hindlimb in anaesthetized mice. While the time of death was variable, neuromuscular blockade of the interdigital muscles occurred at the same time as respiratory failure with both textilotoxin and beta-bungarotoxin only at stimulation rates of 0.5 Hz and above. Textilotoxin (50 micrograms/kg) produced an increase in the heart rate prior to death but no change in the shape of the electrocardiogram.

Action Potentials↗

PubMed1997

Residual neuromuscular blockade after cardiac surgery: pancuronium vs rocuronium.

PURPOSE: To determine the incidence of residual neuromuscular blockade after cardiac surgery in patients receiving either rocuronium or pancuronium for muscle relaxation. METHODS: In a prospective, controlled, double-blind study, 20 patients undergoing coronary artery bypass were randomized to receive either rocuronium (n = 10) or pancuronium (n = 10) during surgery. Anaesthesia was induced with sufentanil, benzodiazepine and propofol or ketamine, and maintained with air/O2/sufentanil/isoflurane. Neuromuscular blockade was induced with 0.1 ml.kg-1 from blinded syringes containing recuronium (6 mg.ml-1) (Group R) or pancuronium (1 mg.ml-1) (Group P). Relaxants were administered according to clinical criteria and reversal agents were not given. After surgery, neuromuscular transmission was assessed by train-of-four stimulation of the ulnar nerve/adductor pollicis EMG (Datex Relaxograph). Mean values from three trains of stimuli were recorded and repeated 30 min later if TOF ratio was < 0.7. Time to extubation was recorded. RESULTS: On arrival in the ICU, nine of 10 patients in group R but only three of 10 patients in group P demonstrated four visible responses (P < 0.05). Mean TOF ratio in group P, 0.03 +/- 0.05, was less than in group R, 0.68 +/- 0.34 (P < 0.001). All patients in group P and 4 of 10 patients in group R had TOF ratio < 0.7 (P = 0.01). Time to extubation in group P (median 18, range 6-48 hr) was not statistically different from that in group R (14, 5-44 hr). CONCLUSION: Residual neuromuscular block, TOF ratio < 0.7, is common after cardiac surgery but the incidence is less when pancuronium is replaced by rocuronium.

Aged↗

PubMedDate not supplied

Neuromuscular blockade does not change the incidence or severity of pharyngolaryngeal discomfort after LMA anesthesia.

PURPOSE: Positive pressure ventilation using a laryngeal mask airway (LMA) has gained increased popularity. This study examined the influence of neuromuscular blockade on the incidence and severity of pharyngolaryngeal discomfort after positive pressure ventilation using a LMA. METHODS: 130 patients were included in this prospective, double-blind, randomized two-centre study. Anesthesia was induced with remifentanil and propofol and maintained using remifentanil and sevoflurane in 30% oxygen and 70% air. Patients were mechanically ventilated at 15 breaths.min(-1) with tidal volumes to maintain Petco(2) 30-40 mmHg. Patients were randomly assigned to receive no neuromuscular blocking agent (NOBLOCK group) or cisatracurium prior to LMA insertion (BLOCK group). Prior to the end of surgery, morphine 3 to 5 mg iv were injected. The ease of insertion of the LMA, cuff pressure, and inspiratory pressure were recorded. Patients were asked immediately after two hours, and 24 hr after surgery to rate sore throat, dysphonia, or dysphagia as absent, minimal, moderate or severe. Continuous and categorical data were compared using t test and Chi-squared test, respectively. RESULTS: 68 and 62 patients were randomized to the NOBLOCK and BLOCK groups, respectively. Successful insertion on first attempt were 89% and 92% in the NOBLOCK and BLOCK groups, respectively. Mean intracuff and inspiratory pressures were 85 +/- 35 mmHg and 13 +/- 3 mmHg for the NOBLOCK group, and 96 +/- 34 mmHg and 15 +/- 2 mmHg for the BLOCK group. The immediate, two and 24 hr postoperative incidences and severity of sore throat, dysphonia, and dysphagia did not differ significantly between the two groups. CONCLUSION: Neuromuscular blockade does not influence the ease or rate of success of LMA insertion nor the incidence and severity of pharyngolaryngeal discomfort after positive pressure ventilation using a LMA.

Adult↗

PubMed1991

Vecuronium neuromuscular blockade at the adductor muscles of the larynx and adductor pollicis.

The differences between neuromuscular blockade of the adductor muscles of the vocal cords and the adductor pollicis were examined in 20 adult women anesthetized with fentanyl and propofol. Vecuronium 0.04 or 0.07 mg/kg was given as a single bolus by random allocation. The force of contraction of the adductor pollicis was recorded. Laryngeal response was measured as pressure changes in the cuff of the tracheal tube positioned between the vocal cords. Train-of-four stimulation was applied to the recurrent laryngeal nerve at the notch of the thyroid cartilage and to the ulnar nerve at the wrist. Neuromuscular blockade had a faster onset, was less intense, and recovered more rapidly at the vocal cords. With 0.04 mg/kg, maximum blockade of first twitch (T1) was 55 +/- 8 (mean +/- standard error of the mean [SEM]) and 88 +/- 4% at the vocal cords and the adductor pollicis, respectively (P = 0.006). Onset time was 3.3 +/- 0.1 and 5.7 +/- 0.2 min, respectively (P = 0.000001), and time to 90% T1 recovery was 11.3 +/- 1.6 and 26.1 +/- 1.8 min, respectively (P = 0.001). With 0.07 mg/kg, onset time was unchanged; maximum blockade was more intense, being 88 +/- 4 and 98 +/- 1%, respectively (P = 0.04 between muscles); and time to 90% T1 recovery was 23.3 +/- 1.8 min at the vocal cords versus 40.3 +/- 2.9 min at the adductor pollicis (P = 0.001). Approximately 1.73 times as much vecuronium was required at the larynx compared with the dose required at the adductor pollicis for the same intensity of blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗

PubMed1989

Neostigmine after spontaneous recovery from neuromuscular blockade. Effect on depth of blockade monitored with train-of-four and tetanic stimuli.

The effect of neostigmine on neuromuscular function was examined after spontaneous recovery from an atracurium-induced neuromuscular blockade, which reached a train-of-four ratio of either 0.5 or 0.9. Two doses of neostigmine 2.5 mg were given 5 minutes apart. Neuromuscular recovery was assessed with train-of-four and tetanic stimuli. The first dose of neostigmine antagonised the neuromuscular blockade. The second dose diminished tetanic height and increased tetanic fade. The train-of-four measured mechanically was adversely affected to a small degree, but when measured with the electromyograph no significant change occurred. Neostigmine may adversely affect neuromuscular function after spontaneous recovery from a non-depolarising block. This is unlikely with a single modest dose and any effects are probably short-lived.

Adolescent↗

PubMed2006

Analgesia, sedation and neuromuscular blockade in mechanically ventilated cardiac intensive care unit patients. Part I: Analgesia.

This article reviews relevant clinical issues regarding sedation, analgesia and neuromuscular blockade in the cardiac intensive care unit, including monitoring tools and available therapeutic options. The pathophysiologic implications of pain, agitation, anxiety and delirium in the ventilated patient are also discussed. Although guidelines for sedation, analgesia and neuromuscular blocking drugs in critical care have recently been published, there is great variability in clinical practice. The complexity of the environment and associated pathologies makes it difficult to implement universally applicable therapeutic regimens. Knowledge of pharmacologic mechanisms is an important tool in the development of dynamic protocols adapted to each unit. Strategies that include monitoring resources are essential for the optimization of sedation, analgesia and neuromuscular blockade.

Analgesia↗

PubMed1992

Effect of partial neuromuscular blockade on intraoperative electromyography in patients undergoing resection of acoustic neuromas.

Intraoperative electromyographic monitoring of the facial nerve during acoustic neuroma excision provides early detection of nerve injury and improved outcome. To determine whether a useful level of peripheral neuromuscular blockade could be achieved without compromise of facial electromyographic monitoring, we studied 10 patients undergoing resection of acoustic neuroma. Facial nerve monitoring was accomplished by placement of wire electrodes in the orbicularis oris, orbicularis occuli, and mentalis muscles. Peripheral neuromuscular blockade was assessed by recording unprocessed hypothenar compound muscle action potentials (CMAPs). After induction of anesthesia, an infusion of atracurium (1.0 micrograms.kg-1.min-1) accompanied by a bolus dose of 50 micrograms/kg was administered. The infusion was then increased in increments of 0.5 micrograms.kg-1.min-1 until a 50% reduction in hypothenar single-twitch CMAP was obtained. Facial nerve function was continuously monitored by comparison of facial CMAPs produced by stimulation of the nerve proximal and distal to the tumor bed. The mean (+/- SD) infusion rate of atracurium was 2.55 +/- 0.75 micrograms.kg-1.min-1. Decrements in facial nerve CMAPs were detected in 6 of 10 patients, and all demonstrated moderate to severe facial nerve dysfunction. In no patient was an unexpected deficit present postoperatively. Moderate degrees of peripheral neuromuscular blockade can be achieved without compromising facial nerve electromyographic monitoring.

Action Potentials↗

PubMed2006

Analgesia, sedation and neuromuscular blockade in mechanically ventilated cardiac intensive care unit patients. Part II--sedation.

Analgesia↗

PubMed1989

Comparison of the effects of botulinum toxin in adult and neonatal rats: neuromuscular blockade and toxicity.

A single dose of botulinum toxin (BoTX) was injected subcutaneously to induce neuromuscular blockade in the triceps surae muscles of the hindlimbs of neonatal and adult rats. The efficacy of the toxin in producing complete neuromuscular blockade of the lower limb muscles, assessed by blockade of (a) postural and flexor reflexes and (b) muscle contraction in response to nerve stimulation, was dose dependent at all ages over a BoTX dose range of 10-60 ng/kg. However, BoTX was dramatically more toxic in adult animals resulting in a decline in body weight and lethal consequences in 25% of adult animals 1 week after administration of BoTX doses as low as 40 ng/kg. In contrast, neonatal animals, given the same dosage, continued to grow and no mortalities were observed. The differences in toxicity of BoTX in adult and neonatal rats are readily accounted for by the short duration of effect in the younger animals, which, in turn, is probably the result of more rapid generation of new and functional nerve terminals.

Aging↗

PubMed1997

Role of bedside electroencephalography in the adult intensive care unit during therapeutic neuromuscular blockade.

BACKGROUND: Size, weight and technical difficulties limit the use of ponderous strip chart electroencephalographs (EEGs) for real time evaluation of brain wave function in modern intensive care units (ICUs). Portable, computer processed, bedside EEGs provide real time brain wave appraisal for some brain functions during therapeutic neuromuscular blockade when the visual clues of the cerebral function disappear. RESULTS: Critically ill ICU patients are frequently placed in suspended animation by neuromuscular blockade to improve hemodynamics in severe organ system failure. Using the portable bedside EEG monitor, several cerebral functions were monitored continuously during sedation of selected patients in our ICU. CONCLUSIONS: The processed EEG is able to continuously monitor the end result of some therapeutics at the neuronal level when natural artifacts are suppressed or eliminated by neuromuscular blockade. Computer processed EEG monitoring may be the only objective method of assessing and controlling sedation during therapeutic musculoskeletal paralysis.

Journal Article↗

PubMed2003

Evaluation of intense neuromuscular blockade caused by rocuronium using posttetanic count in male and female patients.

STUDY OBJECTIVE: To establish the relationship between train-of-four (TOF) nerve stimulation and the number of posttetanic twitches (posttetanic count [PTC]) during neuromuscular blockade caused by rocuronium in males and females. DESIGN: Prospective, observational, clinical comparison. SETTING: Operating room of a university hospital. PATIENTS: 60 ASA physical status I and II patients (30 women and 30 men), aged 18 to 60 years, who were scheduled for elective orthopedic surgery and ear, nose, throat surgery with a planned duration of 2 hours. INTERVENTIONS; During fentanyl, propofol, and nitrous oxide (N(2)O) anesthesia, neuromuscular blockade was evaluated with accelerometry of the thumb using TOF and posttetanic twitch stimulation (PTTS) of the ulnar nerve in patients who received rocuronium 1 mg.kg(-1). MEASUREMENTS AND MAIN RESULTS: The first responses to PTTS were seen at mean times of 34.9 and 37.7 minutes after rocuronium injection in male and female patients, respectively (NS). The average interval between the appearance of a posttetanic response and the first response to TOF stimulation (T1) was not significantly different between male and female patients (15.4 +/- 4.8 min (SD) vs. 15.9 +/- 4.9 min, respectively). There was a significant negative correlation between PTC and the time to first response to TOF nerve stimulation (r = -0.83; p = 0.0001). Gender did not have a statistically significant effect on this relation (F = 0.9; p = 0.34). The intervals from administration of rocuronium to the first appearances of T1 and T2 were not significantly different between the two groups, but the intervals to the first appearances of T3 and T4 were significantly longer in female patients. CONCLUSIONS: Even though the times from initial administration of rocuronium 1 mg.kg(-1) to the first appearances of T3 and T4 are significantly longer in female patients, the intervals to the first detectable responses to PTTS and TOF are not significantly different between females and males. Gender has no significant effect on the relation between PTC and the time to T1.

Adolescent↗

PubMed1990

Atracurium administration, as an infusion, to induce neuromuscular blockade in clinically normal and temporarily immune-suppressed cats.

Atracurium besylate, a nondepolarizing neuromuscular blocking agent, was administered by infusion to 10 cats that were anesthetized with isoflurane and oxygen to allow transplantation of a myocutaneous flap. Five of the cats were given cyclosporine (20 mg/kg of body weight, PO q 12 h in divided doses) for 2 days prior to anesthesia, and prednisolone (0.25 mg/kg, PO) on the morning of surgery. The other 5 cats were not given either drug. Neuromuscular blockade was assessed, using the train-of-four stimulation, and throughout surgery, the infusion rate was adjusted to maintain the first-twitch response (T1) at 90 to 95% depression from baseline. At completion of surgery, atracurium was discontinued, and the infusion rate and the time for recovery (the time for the train-of-four ratio to increase from 50 to 75%) were recorded. Once the train-of-four ratio had been stable for 10 minutes, edrophonium (0.5 mg/kg), a cholinesterase inhibitor, was administered IV, and neuromuscular blockade was monitored for another 10 minutes. Mean (+/- SD) duration of the atracurium infusion was 302.1 +/- 70.5 minutes for the control group and was 323.9 +/- 61.7 minutes for the cats given cyclosporine and prednisolone. In the cats of the control group, the infusion rate required to induce 90 to 95% T1 depression from baseline was 3.7 +/- 0.7 micrograms/kg/min. This rate was not significantly different from that of 2.8 +/- 1.2 micrograms/kg/min in cats given cyclosporine and prednisolone. Significant difference in recovery time was not evident between the control group and the treated group (6.4 +/- 4.5 minutes vs 6.2 +/- 2.5 minutes).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

[Risk of secondary neuromuscular blockade after autotransfusion of blood drawn from the patient following curare administration].

A secondary neuromuscular blockade can occur after transfusion of autologous blood withdrawn after injection of muscle relaxants. In this study time course of muscle relaxation after transfusion of blood withdrawn before or after administration of atracurium (A) or vecuronium (V) was assessed. Forty adults undergoing haemorrhagic urologic surgery were included in the study. After induction of general anaesthesia and intubation of the trachea facilitated by local lidocaine, they were divided into 4 groups. In groups A1 and V1 the blood units were withdrawn before injection of atracurium 0.5 mg.kg-1 or vecuronium 0.1 mg.kg-1. In group A2 and V2 the blood units were withdrawn after administration of muscle relaxants. Haematocrit was decreased to 0.30. The last bolus of these muscle relaxant was injected 30 min before the end of surgical procedure. Autologous blood was transfused when train of four (T4R) recovered to 0.80. Electromyographic elicited responses to T4R stimulation were obtained every minute during the 4 first minutes after the beginning of transfusion (T1 to T4), thereafter every minute during the 5 first minutes after the end of transfusion (T5 to T9), and finally every 5 minutes for 10 minutes (T10 and T11). There was a secondary neuromuscular blockade in patients of groups A2 and V2. The intensity of blockade was more important after vecuronium than after atracurium (p < 0.01 from T2 to T11 between groups A2 and V2). In group A2, the T4R had not reached the control level at the end of the procedure (0.78 at T11 vs 0.80 at T0). These data emphasize the importance of withdrawing blood units before administration of muscle relaxants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2003

Effects of partial neuromuscular blockade on facial nerve monitorization in otologic surgery.

OBJECTIVE: Neuromuscular blockade (NMB) is administered as part of a general anesthetic in order to keep the patient immobilized during surgery and has been known to hinder intraoperative neuromonitorization. The aim of this study was to determine the effects of different levels of NMB on electrical stimulation thresholds of the facial nerve during otologic surgery. MATERIAL AND METHODS: Intraoperative facial nerve monitorization was performed in 29 patients with advanced middle ear disease. Electromyographic (EMG) responses were recorded by insertion of needle electrodes into the orbicularis oris and orbicularis oculi muscles. Minimal facial nerve stimulations causing EMG responses in the facial musculature were measured during full recovery from the effects of muscular relaxants and with 25%, 50%, 75% and 100% levels of NMB. These defined NMB levels were maintained by the administration of a drip infusion of atracurium and were assessed objectively by recording the hypothenar muscle action. RESULTS: All of the patients had detectable EMG responses of the facial musculature at the 50% and 75% levels of NMB in response to the electrical stimulation of the facial nerve. The corresponding mean stimulation thresholds were 0.10 +/- 0.08 and 0.11 +/- 0.09 mA, respectively. No responses were measured in 31% of the patients when the level of peripheral NMB was 100%. CONCLUSION: This study suggests that a regulated 50% level of peripheral NMB provides reliable intraoperative EMG monitoring of the facial musculature in response to electrical stimulation and adequate anesthesia, with full immobilization of the patient.

Adolescent↗

PubMedDate not supplied

Cross-resistance to both atracurium- and vecuronium-induced neuromuscular blockade in a critically ill patient.

A previously healthy 33-year-old woman received neuromuscular blocking agents during treatment of severe adult respiratory distress syndrome secondary to pneumococcal pneumonia and septic shock. Atracurium infusion rates were progressively increased, preceded by repeated loading doses up to a maximum of 3.57 mg/kg/hour, but produced inadequate neuromuscular blockade as assessed by clinical and ventilatory parameters as well as train-of-four (TOF) monitoring. Atracurium was discontinued and vecuronium infusions of 2.3 mg/kg/hour finally produced adequate paralysis for 7 days. Increasing vecuronium requirements then prompted discontinuation of neuromuscular blockade. Atracurium was reinstituted 2 days later because of worsening pulmonary function. Infusion rates of 3.04 mg/kg/hour were again required, together with high-dose midazolam and fentanyl, to achieve adequate oxygenation with acceptable airway pressures; however, TOF monitoring showed an unacceptable level of paralysis. Cross-resistance among chemically dissimilar neuromuscular blocking agents poses a difficult patient management problem and supports a pharmacodynamic basis of resistance to these agents.

Adult↗

PubMed1986

Vecuronium induced neuromuscular blockade. The effect of increasing dose on speed of onset.

The speed of onset of neuromuscular blockade was measured for increasing doses of vecuronium. Onset times were found to be shorter with larger doses, up to a limit of ED95 X 3 (0.15 mg/kg). Thereafter, increasing the dose, even up to ED95 X 8 (0.4 mg/kg), did not appreciably shorten the time to full neuromuscular blockade. The clinical implications of, and pharmacokinetic basis for, these findings are discussed.

Adult↗

PubMed1995

[Continuous administration of mivacurium for short procedures. Delayed onset and recovery from neuromuscular blockade].

OBJECTIVE: To assess the delays of onset and spontaneous recovery from neuromuscular block produced by mivacurium administered by continuous infusion for short procedure requiring a deep relaxation. STUDY DESIGN: Prospective open non comparative study. PATIENTS: Twenty-nine class ASA I and II adults undergoing a stomatological procedure of short duration were included in the study. METHOD: General anaesthesia was obtained with a continuous infusion of propofol, supplemented with alfentanil and N2O-O2 mixture. Neuromuscular blockade, assessed with electromyography of the adductor pollicis muscle, was obtained with mivacurium (150 micrograms.kg-1). After restoration of 5% of neuromuscular transmission, mivacurium was administered by continuous infusion in order to maintain a blockade between 91 and 99%. RESULTS: The delay for decreasing twitch height by 95% was 2.9 +/- 1.0 min. The mean dose for maintenance of blockade was 10.9 +/- 1.5 micrograms.kg-1.min-1. The delay of spontaneous recovery from blockade was 10.2 min, 16.6 min and 21.3 min for obtaining 25, 75 and 95% twitchs respectively. The delay for the twitch increase from 25 to 75% was 6.6 min. DISCUSSION: Mivacurium in continuous infusion provides rapidly a deep and stable neuromuscular blockade followed by a rapid spontaneous restoration of neuromuscular transmission in patients with normal pseudocholinesterases.

Adult↗