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Comparison of recovery after neuromuscular blockade by atracurium or pancuronium.

Thirty patients were randomly allocated to receive either atracurium or pancuronium for neuromuscular blockade during surgery. At the end of the operation residual paralysis was antagonized with neostigmine. Voluntary strength was assessed at intervals after the antagonism, by observing grip strength, maximum inspiratory and expiratory force, 5-s head lift and the presence or absence of double vision. Grip strength and maximum expiratory force recovered significantly more quickly in the atracurium group over the 2-h measurement period. Double vision was significantly more frequent at up to 1 h when pancuronium had been used. At no time was there any significant difference between the two groups in respect of the 5-s head lift or, after 30 min, in the measurement of inspiratory force.

Adolescent↗

[Neuromuscular blockade with vecuronium and its reversal with edrophonium during total intravenous anesthesia, neuroleptanalgesia and sevoflurane anesthesia].

The neuromuscular blocking effect of vecuronium and its reversibility ith edrophonium were studied under total intravenous anesthesia (TIVA) and compared with those under NLA or sevoflurane anesthesia (SA) in 30 surgical patients. The degree of neuromuscular blockade was evaluated by acceleration of thumb adduction in response to supramaximal stimulation of the ulnar nerve using Accelograph (Biometer). TIVA was induced with droperidol 0.25 mg.kg-1, fentanyl 2-4 micrograms.kg-1 and ketamine 2 mg.kg-1, and maintained with continuous infusion of ketamine 2 mg.kg-1.h-1 with 30-35% O2 in air. NLA was induced with droperidol 0.25 mg.kg-1 and fentanyl 5-10 micrograms.kg-1 and maintained with 66% nitrous oxide in oxygen. SA was induced with thiamylal 5 mg.kg-1 i.v. and maintained with 66% nitrous oxide in oxygen supplemented with sevoflurane (1 MAC). A single bolus intravenous injection of vecuronium 0.1 mg.kg-1 was used for paralysis and reversed with edrophonium 0.75 mg.kg-1 followed by atropine 0.015 mg.kg-1 when the TOF ratio returned to 25%. The times required from administration of vecuronium to completion of maximal block with TIVA, NLA and SA were 196.5 +/- 52.2 sec, 182.5 +/- 47.6 sec and 166.0 +/- 69.0 sec, respectively. There was no significant difference among them. The times from completion of maximal block to 25% recovery of the twitch height in TIVA and NLA were 39.5 +/- 11.0 min and 37.4 +/- 5.8 min without significant difference. Those values, however, were significantly shorter than 64.5 +/- 35.2 min of SA.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗

Self-tuning, microprocessor-based closed-loop control of atracurium-induced neuromuscular blockade.

A self-tuning, closed-loop computerized system was used to maintain atracurium-induced neuromuscular blockade in patients undergoing routine lower abdominal gynaecological surgery. The controller is based on a unique algorithm which utilizes a bi-exponential model wherein two of the variables are estimated on-line. This enables the system to optimize the sizes of subsequent bolus doses according to patient sensitivity. In this study an initial bolus of 0.3 mg kg-1 was given in a trade-off aimed at achieving earlier intubating conditions rather than taking control of relaxation ab initio and obtaining the pre-programmed setpoint of 15% single twitch response (STR) without overshoot. This was successful in all of the 11 patients studied, the mean time from injecting the bolus to intubation being 2.47 (SD 0.95) min and the drug maintenance requirement being 0.34 (0.07) mg kg-1 h-1. This provided a mean value of 10.26% STR with minimal oscillation about the setpoint (average standard deviation = 4.31 (2.53)) for up to 147 min.

Abdomen↗

Ventricular fibrillation related to reversal of the neuromuscular blockade in a patient with long QT syndrome.

The long QT syndrome (LQTS) is associated with syncopal attacks or even sudden death at a young age due to ventricular fibrillation. We report a patient with an undiagnosed LQTS who had an episode of cardiac arrest during the final part of general anesthesia, immediately after the drugs for reversal of the neuromuscular blockade were given. We suggest that the administration of glycopyrronium might have been the provoking factor in this patient.

Adult↗

Effects of high-dose gentamicin sulfate on neuromuscular blockade in halothane-anesthetized horses.

OBJECTIVE: To evaluate effects of a single high dose of gentamicin on neuromuscular function in horses anesthetized with halothane. ANIMALS: 6 healthy adult horses. PROCEDURE: Halothane-anesthetized horses were positioned in left lateral recumbency, and the right hind limb was immobilized in a reusable fiberglass cast fixed to a steel frame. The hoof was attached to a force transducer, and resting tension of 0.93 +/- 0.16 kg was maintained. A supramaximal train-of-four stimulus of 2 Hz for a duration of 0.25 millisecond was applied to the superficial peroneal nerve every 20 seconds by a square-wave stimulator. The force of the evoked digital extensor tension was recorded to determine first muscle twitch tension, compared with the baseline value (T1%) and the ratio of the force of the fourth twitch to the first twitch (T4/T1). Data were recorded at 5, 10, 15, 30, and 60 minutes after i.v. administration of vehicle or gentamicin (6 mg/kg of body weight). RESULTS: There was a significant (P = 0.04) treatment-time interaction for the effect of gentamicin on T1%; T1% associated with vehicle decreased from 100% to 92% during the 60- minute study period, but no decrease was associated with gentamicin. For T4/T1, there was no significant effect of treatment or time or treatment-time interaction between gentamicin and vehicle. CONCLUSIONS: Gentamicin did not cause a decrease in initial muscular strength, nor did it impair the muscles' ability to sustain strength. CLINICAL RELEVANCE: A single high dose of gentamicin does not cause significant neuromuscular blockade when administered alone to healthy horses anesthetized with halothane.

Analysis of Variance↗

High-performance liquid chromatography as a diagnostic tool in prolonged neuromuscular blockade.

We report the use of high-performance liquid chromatography (HPLC) to identify the cause of prolonged neuromuscular blockade in a child who had received 2 mg.kg-1 of succinylcholine. Upon analysis by HPLC the syringe was found to contain succinylcholine (10 mg.ml-1) and also atracurium (5 mg.ml-1), so that a diagnosis was established. In situations where medication errors are suspected, we recommend saving syringe contents for analysis for confirmation of the agent.

Anesthesia, Intravenous↗

A continuous quality improvement approach to improving clinical practice in the areas of sedation, analgesia, and neuromuscular blockade.

BACKGROUND: Practice concerns associated with the medical prescription and nurses' administration and monitoring of sedatives, analgesics, and neuromuscular blocking agents were identified by the clinical nurse specialist within a surgical intensive care unit of a large, tertiary-care referral center. These concerns were identified using a variety of needs assessment strategies. Results of the needs assessment were used to develop a program of care, including a teaching initiative, specific to these practice areas. METHODS: The teaching initiative incorporated principles of andragogy, the theory of adult learning. Educational techniques included inservice education, bedside instruction using "teaching moments," competency-based education modules, and integration of instruction into critical care orientation. Content and approach were based on the background and level of experience of participants. RESULTS: Educational program outcomes included increased consistency in monitoring neuromuscular blockade by clinical assessment and peripheral nerve stimulation. A second outcome was more accurate patient assessment leading to the provision of drug therapy specific to the patients' clinical states, including anxiety or pain. CONCLUSION: The continuous quality improvement approach offers a model for improving patient care using individualized needs assessment, focused educational interventions, and program evaluation strategies.

Analgesia↗

Post-tetanic count and profound neuromuscular blockade with atracurium infusion in paediatric patients.

In 38 paediatric surgical patients given atracurium by infusion, the degree of neuromuscular blockade was monitored using the post-tetanic twitch response. This was assessed by counting the number of visible responses when single twitch stimulation was applied at 1 Hz for 30 s after a 5-s tetanic stimulation at 50 Hz. A post-tetanic count of less than 10 correlated with a single twitch height of less than 5% of control, and ensured adequate paralysis. Once the count was greater than 15, the blockade could be antagonized readily.

Adolescent↗

The impact of implementation of neuromuscular blockade monitoring standards in a surgical intensive care unit.

The purpose was to determine whether implementation of standards for peripheral nerve monitoring could decrease the incidence of neuromuscular dysfunction related to the administration of paralytic agents. Over a 2-year period, consecutive patients admitted to a surgical intensive care unit who received continuously-infused or >6 daily doses of neuromuscular blocking agents were subjected to train-of-four (TOF) monitoring of the adductor pollicis. Therapy was titrated to the maintenance of one to two twitches at all times. The incidence of prolonged (>12 h) paralysis after drug discontinuation was documented in these patients and compared to that in patients treated in the previous 12 months. The presence of electrolyte abnormalities, organ dysfunction, and concomitant medications was also recorded. Chi-square analysis with Yates correction was employed. Before implementation of routine TOF monitoring, there were five instances of paralytic-associated neuromuscular dysfunction (5/43). After implementation of the TOF protocol, no instances of paralytic-associated neuromuscular dysfunction occurred (0/90), despite the same incidence of risk factors (100%) (P < 0.05). A protocol for neuromuscular blockade monitoring is efficacious in preventing paralytic-associated neuromuscular dysfunction. This can be a cost-effective measure, minimizing the prolonged mechanical ventilation and intensive rehabilitation required secondary to unmonitored use of neuromuscular blocking agents.

Aged↗

A comparative study of the orbicularis oculi muscle to the adductor pollicis muscle during vecuronium neuromuscular blockade.

This study compared the orbicularis oculi muscle to the adductor pollicis muscle during vecuronium blockade. The orbicularis oculi muscle was found to be more resistant to and recovered from vecuronium neuromuscular blockade faster than the adductor pollicis muscle. Thus, caution should be utilized when assessing neuromuscular block with the orbicularis oculi muscle.

Adolescent↗

Effect of neuromuscular blockade on oxygen consumption and energy expenditure in sedated, mechanically ventilated children.

OBJECTIVE: To quantify the effects of neuromuscular blockade (NMB) on energy expenditure for intubated, mechanically ventilated, critically ill children. DESIGN: A prospective, unblinded clinical study. Each subject was studied twice, before and after establishment of NMB. SETTING: A tertiary care pediatric intensive care unit. PATIENTS: Critically ill children undergoing mechanical ventilation and receiving ongoing sedation were eligible, if they had a cuffed endotracheal tube and were physiologically stable. INTERVENTIONS: A total of 20 children (age, 1 to 15 yrs) were studied in an unblinded, crossover fashion. All were mechanically ventilated via a cuffed endotracheal tube, with ventilator rate and tidal volume adequate to provide complete ventilation, and F(IO2) <0.6. Absence of gas leak around the endotracheal tube was assured, and all patients were sedated using continuous infusions of midazolam and/or fentanyl; no changes in ventilator settings, nutritional input, or inotropic drug dose were permitted during the study period. Each patient underwent indirect calorimetry immediately before establishment of NMB. NMB was then induced, and indirect calorimetry was repeated. Complete blockade was verified using a peripheral nerve stimulator. In each case, the two sets of measurements were completed within a 1-hr period. MEASUREMENTS AND MAIN RESULTS: Data analyzed included identifying and diagnostic information, oxygen consumption, and carbon dioxide production. Energy expenditure was calculated using standard formulas. Oxygen consumption and energy expenditure values obtained before and after the establishment of NMB were compared by using paired Student's t-test. NMB reduced oxygen consumption from 6.54+/-0.49 mL/kg/min to 5.90+/-0.40 ml/kg/min, and energy expenditure was reduced from 46.5+/-3.7 kcal/kg/24 hrs to 41.0+/-2.8 kcal/kg/24 hrs (p < .001 in each case). The reduction in oxygen consumption was 8.7+/-1.7%, and that in energy expenditure 10.3+/-1.8%, of pre-NMB values, respectively. CONCLUSION: NMB significantly reduces oxygen consumption and energy expenditure in critically ill children who are sedated and mechanically ventilated; the degree of reduction is small.

Adolescent↗

Sleep during neuromuscular blockade in cats.

The purpose of the experiment was to determine whether normal sleep patterns can occur during neuromuscular blockade. Electrographic variables for determining the states of sleep and wakefulness, the electrocorticogram, lateral geniculate nucleus potentials, and dorsal hippocampal potentials, were recorded before, during and after the administration of gallamine triethiodide to cats with chronically implanted electrodes. When respiratory muscles became paralyzed, artificial ventilation commenced through a chronic tracheal fistula. The electrographic wave forms of the states (wakefulness, NREM sleep and REM sleep) in paralyzed cats were indistinquishable by visual observation from those of freely moving animals. As compared to freely moving cats, paralyzed cats had more wakefulness at the expense of both states of sleep (about 33% NREM and 3% REM compared to 45% NREM and 15% REM respectively). REM sleep wasdemonstrated to occur, albeit increase across repeated session in the same cats nor was the distribution uneven within the average session. Large percentages of REM sleep with respect to total recording time were associated with large percentages of NREM sleep (correlation coefficient = 0.58). The sequence of sleep states was like that of freely behaving animals. The main conclusion is that this preparation, depsite low amounts of REM sleep, is useful in neural studies of sleep and wakefulness.

Animals↗

The effect of epidural bupivacaine on vecuronium-induced neuromuscular blockade in children.

The effect of epidural bupivacaine on potency and duration of action of vecuronium-induced neuromuscular blockade (NMB) was evaluated in 30 general surgical paediatric patients (ASA I-II) of three to ten years of age. Premedication was midazolam 0.5 mg kg-1 orally (max 15 mg). In addition to general anaesthesia, 15 of the children received a lumbar epidural block with 0.5% bupivacaine 2.5 mg kg-1. Anaesthesia was induced and maintained with N2O:O2 (2:1), propofol and alfentanil. NMB was monitored by adductor pollicis EMG with the train-of-four stimulus every 20 sec. Thirty minutes following the epidural bupivacaine injection (mean plasma concentration 0.86 micrograms ml-1) or induction of anaesthesia a cumulative dose-response curve of vecuronium was established to achieve a 95% depression of the twitch response. Thereafter, NMB was allowed to recover spontaneously. ED doses of vecuronium were 19-22% greater in the control group than in the epidural group. ED50 doses were 33.8 (s.e. mean 1.3) micrograms kg-1 and 28.4 (2.2) micrograms kg-1, respectively (P < 0.05). There were no differences in recovery times from NMB between control and epidural group, the recovery index (time of twitch height to recover from 25 to 75%) being 6.4 (0.4) min and 7.0 (0.9) min, respectively. However, a negative correlation was found between bupivacaine plasma concentration and an ED50 dose of vecuronium (P = 0.01). Our results indicate that vecuronium is slightly more potent in children with bupivacaine epidural block than in children without it.

Alfentanil↗

Concomitant assessment of depth of sedation by changes in bispectral index and changes in autonomic variables (heart rate and/or BP) in pediatric critically ill patients receiving neuromuscular blockade.

OBJECTIVE: We evaluated whether or not changes in bispectral index (BIS) are associated with concomitant changes in autonomic variables that are in agreement with the different level of sedation that the changes in BIS indicate. DESIGN: A retrospective chart review. SETTING: A pediatric ICU of a children's hospital. METHODS AND MAIN RESULTS: Charts of patients who were receiving mechanical ventilation and IV sedation, neuromuscular blockade, and continuous BIS monitoring were enrolled in the study. Changes in BIS values > or = 30% from previous readings were evaluated to determine whether or not concomitant changes of > or = 10% in autonomic variables, in the same direction, coexisted. Forty-seven patients (35 male and 12 female) were enrolled in our study; ages ranged from 10 days to 18 years (mean, 4.2 +/- 6.2 years [+/- SD]). Twenty-five patients were < 1 year of age (53%). All patients were sedated and pharmacologically paralyzed. Overall, 387 BIS readings (15%) showed a > or = 30% change from the previously documented BIS number. These BIS changes were in agreement with heart rate (HR) changes, mean arterial pressure (MAP) changes, and both HR and MAP changes in 10.6%, 23.8%, and 5.7% of the time, respectively. The same analysis of agreement was done for patients < or = 1 year old, and results were no different from those of older patients. Among 21 patients who were not receiving any vasoactive drugs (alpha- and/or beta-adrenergic agonists) during the study period, 157 BIS recordings (15%) showed a > or = 30% change from the previously documented BIS number. The percents of agreement with HR, MAP, and HR and MAP for these patients were 14.6%, 17.2%, and 7.6%, respectively. In 26 patients who were receiving vasoactive medications during the study, 230 BIS recordings (15%) showed a > or = 30% change from the previously documented BIS number. For these patients, the percentages of agreement were 7.8%, 28.3%, and 4.3%, respectively. Agreement with MAP was significantly better than with HR for this group of patients (p < 0.05; Fisher Exact Test). SUMMARY: While significant changes in BIS are thought to reflect significant changes in depth of sedation, they have a very low rate of agreement with changes in vital signs. In the absence of BIS, the level of sedation of chemically paralyzed pediatric patients can be better guided by changes in MAP than in HR, particularly in patients receiving vasoactive drug treatment.

Adolescent↗

[Clinical significance of posttetanic count (PTC) during onset and spontaneous offset of neuromuscular blockade induced by vecuronium].

To compare the clinical difference of posttetanic count (PTC) during onset and spontaneous offset, the changes of PTC during an intense neuromuscular blockade induced by vecuronium (0.08 mg.kg-1, i.v.) were measured using a neuromuscular transmission analyzer in 64 adult patients anesthetized with nitrous oxide and halothane. Furthermore, intubation score was evaluated when zero PTC was obtained. The obvious movement of diaphragm associated with endotracheal intubation was observed in 9 out of 20 patients (45%) even when it was performed after obtaining zero PTC. The difference of PTC responses between the onset and the offset was found. The difference was that, during the onset, a tetanic response was observed obviously and the height of the posttetanic single twitch was low, and during offset, even when no response was observed, the height of a posttetanic single twitch response was high with the same PTC. These facts indicate that the same PTC has different clinical significance during onset and offset.

Adult↗

Neuromuscular blockade of fazadinium bromide (AH 8165) in renal failure patients.

Fazadinium bromide (AH 8165) is a new non-depolarizing neuromuscular blocking agent with rapid onset of action and intermediate duration of effect. The characteristics of the neuromuscular blockade induced were compared in normal and renal failure patients by monitoring the mechanical responses of thumb adductor muscle to ulnar nerve stimulation. The data suggest that renal failure, even in anephric patients, does not influence the depth of neuromuscular relaxation when judged from the identical dose-effect curves in both groups of patients. Moreover, the duration of the neuromuscular block was not significantly increased in end-stage kidney failure patients, whether the initial or late phases of the spontaneous recovery of neuromuscular transmission were considered, and this occurred over the entire therapeutic range. However, additional incremental injections of fazadinium bromide should be used cautiously, as evidence appeared of prolonged duration of action. This agent, fazadinium bromide, may therefore present useful advantages to other non-depolarizing neuromuscular blocking agents as to clinical safety and effects in patients with renal insufficiency.

Adolescent↗

Pattern of change of bronchomotor tone following reversal of neuromuscular blockade. Comparison between atropine and glycopyrrolate.

Specific airways conductance (s.Gaw) was measured using the forced airflow oscillation method, to study the effect of two regimens, commonly used for the reversal of neuromuscular blockade, on bronchomotor tone. Patients who had received neuromuscular blockers and had undergone elective surgery were randomly allocated to receive neostigmine 50 microgram kg-1 given concurrently with either atropine 20 microgram kg-1 (10 patients) or glycopyrrolate 10 microgram kg-1 (10 patients). Before administration, five baseline measurements of s.Gaw were obtained and measurements were then made at intervals of 1 min for the next 10 min. At 3 min there was a significant difference in s.Gaw between the two groups, higher values being found in the atropine group. At 10 min, no significant difference was seen between the groups, although both showed a significant decrease in s.Gaw compared with baseline values (P less than 0.05).

Atropine↗