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Fade of pulmonary function during residual neuromuscular blockade.

OBJECTIVES: A decrement in evoked muscle force with repetitive nerve stimulation (fade) suggests impaired neuromuscular transmission. We tested the hypothesis that fade of pulmonary function, ie, a decrease in values of FVC with the second spirometric maneuver compared to the first maneuver, occurs during impaired neuromuscular transmission. DESIGN: Prospective study. PARTICIPANTS: Six healthy male volunteers. INTERVENTIONS: A series of three consecutive spirometric maneuvers was performed every 5 min in six awake healthy volunteers before, during, and after partial paralysis evoked by rocuronium (0.01 mg/kg IV plus 2 to 8 microg/kg/min). MEASUREMENTS AND RESULTS: We measured FVC, FEV(1), forced inspiratory volume in 1 s (FIV(1)), peak expiratory flow (PEF), and peak inspiratory flow (PIF) by spirometry, and force of adductor pollicis muscle by mechanomyography (train-of-four [TOF] stimulation). A statistically significant fade (reduction of the second maneuver from the first maneuver) of FVC, FEV(1), FIV(1), PEF, and PIF was observed during neuromuscular blockade. With peak relaxation (TOF ratio, 0.5) fade amounted to medians of 10% (interquartile range [IQR], 9 to 23%), 7% (IQR, 2 to 16%), 31 (IQR, 19 to 47%), 9% (IQR, 3 to 24%), and 30% (IQR, 5 to 43%), respectively. A fade of >or= 10% was always associated with a clinically relevant (>or= 10%) FVC reduction from baseline (ie, FVC before rocuronium administration). However, FVC reduction from baseline was still present in 23% of measurements without a relevant FVC fade. CONCLUSIONS: A clinically relevant fall (fade) in FVC from the first to the second value during or after neuromuscular blockade suggests impaired pulmonary function and may be due to muscle paralysis. For this reason, the first (best) FVC value may overestimate pulmonary function and expose the patient to an unidentified risk.

Adult↗

Variability of pipecuronium neuromuscular blockade.

The dose-response relationship and the variability of the time variables in pipercuronium neuromuscular blockade were studied in 29 patients (ASA physical status 3) during halothane anaesthesia. The ED95 (twitch tension) was determined in 9 patients using the cumulative dose response technique. Another 20 patients received the resulting ED95 as a single bolus. The mean ED95 was 35 micrograms.kg-1 (95% confidence interval: 29-41 micrograms.kg-1). Following bolus injection of 1.ED95, an 80-100% twitch depression was achieved within 4.6 +/- 1.3 min (mean +/- s.d.). The duration from end of injection of pipecuronium to 25% twitch recovery, the time from 25% to 75% twitch recovery, and the time from 25% twitch recovery to the train-of-four ratio (TOF) returning to 0.7 was 35 +/- 14, 37 +/- 26, and 63 +/- 27 min, respectively. The time from end of injection to TOF = 0.7 varied within a 2-h range (54-160 min). Thus, the time variables in pipecuronium neuromuscular blockade were as poorly predictable as those reported in the literature on pancuronium, alcuronium and doxacurium.

Adult↗

The armlift test. An alternative to the headlift test for assessing recovery from neuromuscular blockade.

The armlift test was assessed as an alternative to the headlift test for recovery from neuromuscular blockade. Forty comparisons of inspiratory force, duration of arm-lift and duration of headlift were performed in 27 intubated patients after anaesthesia, which included the use of non-depolarising neuromuscular blockade. Patients' ability to keep one arm raised (with the elbow clear of the bed) correlated well with inspiratory force (r = 0.67). All patients capable of an armlift duration of 45 seconds or more were also found to have an inspiratory force of at least -2.5 kPa and were safely extubated. The headlift test was found to be less discerning (r = 0.34) and of 40 determinations of headlift and inspiratory force there were 18 false negatives and two false positives.

Adult↗

Prolonged (more than ten hours) neuromuscular blockade after cardiac surgery: report of two cases.

PURPOSE: We examine two cases of prolonged neuromuscular blockade (NMB) after cardiac surgery. To the best of our knowledge, these are the first reported cases of complete paralysis lasting more than ten hours after surgery. CLINICAL FEATURES: We attribute the extended durations of NMB (more than ten hours) to high doses of NMB drugs in combination with magnesium sulphate and moderate renal failure. Advanced age, hepatic disease, aminoglycoside exposure, hypocalcemia, and possible interaction between rocuronium and pancuronium may have played minor roles. CONCLUSION: We should avoid administering large doses of NMB agents, even in the context of planned postoperative ventilation. If NMB is not monitored intraoperatively in patients who are at risk of prolonged NMB, then train-of-four response should be measured in the intensive care unit. Adequate sedation should be provided until proper recovery of neuromuscular function is documented.

Acute Kidney Injury↗

Pharmacoeconomic impact of rational use guidelines on the provision of analgesia, sedation, and neuromuscular blockade in critical care.

OBJECTIVE: To determine the cost-effectiveness and safety of a set of rational use guidelines for analgesia, sedation, and neuromuscular blockade in critically ill ventilated patients when compared with similar factors in standard prescribing. DESIGN: Prospective cost-benefit analysis. SETTING: Medical and surgical intensive care units (ICU) of a 350-bed tertiary care university hospital. PATIENTS: Patients admitted to our ICUs who required mechanical ventilation and continuous analgesics, sedatives, and/or neuromuscular junction blockers (NMJBs). There were 72 patients in the baseline and 84 patients in the follow-up groups. INTERVENTIONS: Prospective tracking of eligible baseline patients was followed by the development and introduction of guidelines and an academic detailing process to promote the use of guidelines. Several months after the introduction of guidelines, a second group of eligible follow-up patients was tracked. The use and effectiveness of analgesics, sedatives, and NMJBs, as well as cost and outcomes, were followed in both groups. Data were subsequently reviewed and analyzed. MEASUREMENTS AND MAIN RESULTS: We recorded data by means of Paradox and Excel databases and included demographics, costs, outcomes (including adverse drug reactions, functional status, ventilator time in hours, lengths of stay), and mortality rates. Data were subsequently analyzed via the Winks statistical data analysis program. Both groups were similar with regard to demographics. There was a statistically significant increase in severity of illness in the follow-up group without a statistically significant increase in mortality. Direct drug costs, ventilator time, and lengths of stay were reduced in the follow-up group. In addition, the use of NMJBs was reduced from 30% in the baseline group to 5% in the follow-up group. CONCLUSIONS: Rational use guidelines resulted in safe, cost-effective improvements in the provision of continuous analgesia, sedation, and neuromuscular blockade to critically ill patients requiring ventilator management when compared with similar factors in baseline prescribing strategies.

APACHE↗

Time course of neuromuscular blockade with rocuronium in children with intracardiac shunts.

OBJECTIVE: To evaluate the time course of neuromuscular blockade after rocuronium in children with intracardiac shunts. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Consecutive children (n = 52) with intracardiac shunts scheduled for elective cardiac surgery. Participants were allocated to 2 groups according to the direction of the shunt. INTERVENTIONS: Rocuronium, 0.6 mg/kg, was administered for muscle relaxation. The ulnar nerve was stimulated at 20-second intervals with a supramaximal 2-Hz train-of-4 stimulation (TOF-Guard nerve stimulator; Biomet International, Odense, Denmark). The onset time to maximal twitch depression and the time to clinical recovery were compared between the 2 groups. MEASUREMENTS AND MAIN RESULTS: The time to maximal block was significantly faster in children with a right-to-left shunt: 56.8 +/- 5.3 seconds versus 77.1 +/- 6.6 seconds (p = 0.01). There was a tendency to shorter recovery in children with a right-to-left shunt: 42.3 +/- 6.1 minutes versus 55.4 +/- 4.9 minutes (p = NS). CONCLUSION: This study shows a more rapid onset of rocuronium in children with cyanotic congenital heart disease. In these patients, rocuronium is indicated, particularly for rapid airway control.

Androstanols↗

Use of 100-Hertz tetanus as an index of recovery from pancuronium-induced non-depolarizing neuromuscular blockade.

During recovery from non-depolarizing neuromuscular blockade the evoked response to train-of-four (TOF), 100-HZ tetanus (T100) and 50-HZ tetanus (T50) was measured in 10 patients. When the TOF fade ratio exceeded 0.70, tetanic tension to T50 was well sustained. However, even at TOF ratios as high as 0.88 a 2-second tetanic response to T100 showed marked fade. T100 stimulation appears to be too sensitive a test to residual curarization for routine clinical use. Fade on T100 may be quite apparent at a time when the use of additional neuromuscular antagonists are not indicated and may be counterproductive.

Electric Stimulation↗

Neuromuscular blockade in the management of cerebral palsy.

Neuromuscular blocking agents-45% alcohol, 4% to 6% aqueous phenol, local anesthetics, and botulinum A toxin-have been used for many years in the evaluation and management of spasticity and movement disorders in children with cerebral palsy. Recent reports suggest that longer-acting neuromuscular blocking agents may impact positively on the natural history of dynamic deformity and improve health-related quality of life. This review includes the mechanism of action, techniques, indications, complications, and clinical outcomes associated with these agents.

Cerebral Palsy↗

[The effects of nicardipine and verapamil on the recovery time of vecuronium-induced neuromuscular blockade].

The present study investigated the effects of intravenous therapeutic dose of either nicardipine or verapamil on the recovery from transient neuromuscular blockade produced by vecuronium in 21 adult patients scheduled for elective surgery. Neuromuscular function was evaluated by single twitch height (T1), an amplitude of activity of the ulnar nerve being evoked by an electrical stimulation (0.2 msec, 0.1 Hz) under N2O/O2 and halothane anesthesia. The patients given vecuronium were randomly assigned to one of 3 groups: a control group who received no Ca entry blocker, nicardipine group and verapamil group. Nicardipine (30 mcg.kg-1) or verapamil (50 mcg.kg-1) was injected when T1 reached to 10% of the control twitch height. The recovery time of vecuronium (the time between 25% and 75% recovery) was not different significantly among the control (9.4 +/- 3.7 min), nicardipine (8.5 +/- 3.1 min) and verapamil (9.8 +/- 4.3 min) groups. We conclude that a therapeutic dose of either nicardipine or verapamil could be safely given intravenously to the patients under vecuronium-induced neuromuscular blockade.

Adult↗

Clinical, electrical and mechanical correlations during recovery from neuromuscular blockade with vecuronium.

In order to determine correlations between electromyographic (EMG), mecanomyographic (MMG) and clinical criteria of adequate recovery from neuromuscular blockade with vecuronium, seven young healthy conscious volunteers were given subparalysing doses of vecuronium. During recovery from neuromuscular blockade, vital capacity, negative inspiratory pressure, peak expiratory flow rate and five-second head lift were assessed. Neuromuscular monitoring included the evoked EMG response of the adductor digiti minimi and the simultaneous evoked MMG response of the adductor pollicis on the same side. We found that all subjects maintained head lift for five seconds at EMG T4T1 of 0.70, and they achieved normal respiratory tests at EMG T4/T1 of 0.90. The MMG T4/T1 needed for the subjects to perform normal respiratory tests was found to be 0.50, at which time six of the seven subjects were able to perform adequately the head lift test.

Adult↗

Effect of nutritional status on vecuronium induced neuromuscular blockade.

Based on simple clinical and biochemical parameters of nutritional status, seventy adult patients scheduled for elective surgery under general anaesthesia were categorized as having normal nutrition, mild, moderate or severe malnutrition or obesity. Under anaesthesia, evoked responses on train-of-four nerve stimulation were recorded every 15 seconds on a mechanomyograph. Vecuronium 0.1 mg.kg-1 was used to achieve neuromuscular blockade. Compared with patients having normal nutrition, the time to onset of action was significantly prolonged in the moderate and severely malnourished groups; the time to no response on train-of-four stimulation was delayed only in severely malnourished groups (P < 0.001). The duration of action of the initial dose was shorter in the moderate and severely malnourished groups. The obese group had an earlier onset of action and a longer duration of action compared with patients of normal nutrition (P < 0.001). No significant difference in recovery time to a train-of-four ratio of 0.70 was observed between the malnourished and patients with normal nutrition. Malnutrition has a marked effect on vecuronium-induced neuromuscular blockade.

Adolescent↗

Neuromuscular blockade significantly decreases systemic oxygen consumption during hypothermic cardiopulmonary bypass.

The design limits of cardiopulmonary bypass (CPB) equipment and the performance characteristics of membrane oxygenators may place the patient with a very large body surface area at risk for incurring an oxygen debt during CPB. The influence of resting muscle tone on systemic oxygen consumption (VO2) during hypothermic (25 to 28 degrees C) nonpulsatile CPB was calculated using the Fick equation prior to, and following, neuromuscular blockade (pancuronium, 0.15 mg/kg, n = 10; or succinylcholine, 1.5 mg/kg, n = 7). During hypothermic CPB, initial VO2 was 70 +/- 30 mL/min/m2, which was significantly reduced (by 30%) to 49 +/- 13 mL/min/m2 after onset of neuromuscular blockade, with a concomitant increase in mixed venous O2 saturation from 73% +/- 18% to 83% +/- 14%. Choice of muscle relaxant did not influence the change in VO2. With succinylcholine there was a return of VO2 to control values with recovery of neuromuscular function. This study demonstrates that in the unconscious and unmoving patient during hypothermic CPB, administration of muscle relaxants to achieve complete neuromuscular blockade can significantly reduce systemic oxygen consumption.

Anesthesia, Intravenous↗

[Potentiation by nitrous oxide of vecuronium neuromuscular blockade measured by EMG].

This study was designed to evaluate the potentiation by nitrous oxide of the neuromuscular blockade by vecuronium measured by the evoked electromyogram (EMG). Vecuronium, 0.0225, 0.03 or 0.04 mg.kg-1 was given during thiamylalfentanyl anesthesia with and without nitrous oxide, and EMG of the hypothenar muscle was measured. ED50 and ED95 were 0.0271 and 0.0480 mg.kg-1 in the group receiving nitrous oxide, and 0.0304 and 0.0555 mg.kg-1 in the group not receiving nitrous oxide. Dose-response curve (DRC) constructed from log-probit transformation for the group not receiving nitrous oxide was shifted to the right by 12.4%. By multiple regression analysis it was also revealed that the magnitude of the blockade was influenced by dose, nitrous oxide, sex and body mass index (BMI). DRCs for the female patients were shifted to the left, and the those differences caused by sex were shown to increase during anesthesia without nitrous oxide. It is concluded that the potentiation by nitrous oxide of vecuronium neuromuscular blockade obtained by EMG is less than that reported measuring by mechanomyogram, and also the magnitude of the blockade is influenced by sex and BMI, but the difference caused by sex is decreased by administration of nitrous oxide.

Adolescent↗

Feedback control of neuromuscular blockade. A simple system for infusion of atracurium.

A simple system for closed-loop control of neuromuscular blockade is described. It comprises a Datex Relaxograph, a small relay and a syringe pump. The equipment is commercially available and requires no complex custom-built electronics. Atracurium was infused in a semicontinuous manner to 11 patients who underwent general anaesthesia for a variety of surgical procedures. Neuromuscular blockade oscillated within a narrow range around the preset level. The mean rate of infusion of atracurium was 0.5 mg/kg/hour (SD 0.13). The mean recovery time was 25.5 minutes (SD 7.95).

Adult↗

The corrugator supercilii, not the orbicularis oculi, reflects rocuronium neuromuscular blockade at the laryngeal adductor muscles.

BACKGROUND: Some studies suggest that the orbicularis oculi is resistant to neuromuscular blocking drugs and behaves like laryngeal muscles. Others report little or no difference between the orbicularis oculi and the adductor pollicis. These discrepancies could be related to the exact site of recording. The purpose of this study was to compare two monitoring sites around the eye with the adductor pollicis and the laryngeal adductor muscles. METHODS: After institutional approval and informed consent, the evoked response to train-of-four stimulation was measured in 12 patients by acceleromyography at the thumb (adductor pollicis), the eyelid (orbicularis oculi), and the superciliary arch (corrugator supercilii) after 0.5 mg/kg rocuronium during propofol-fentanyl-nitrous oxide anesthesia. In 12 other patients, laryngeal adductor neuromuscular blockade was assessed via the cuff of the tracheal tube and compared with the adductor pollicis and the corrugator supercilii after 0.6 mg/kg rocuronium. RESULTS: After 0.5 mg/kg, maximum blockade (%T1, mean +/- SD) was less at the corrugator supercilii (80+/-20%) than at the adductor pollicis (100+/-1%) and the orbicularis oculi (93+/-8%) (P < 0.01). Clinical duration (25%T1) was shorter at the corrugator supercilii (12+/-7 min) than at the adductor pollicis (25+/-4 min) and orbicularis oculi (24+/-10 min) (P < 0.01). After 0.6 mg/kg, maximum blockade was similar at the corrugator supercilii (88+/-8%) and the laryngeal adductor muscles (89+/-11%). Clinical duration at the corrugator supercilii and the laryngeal adductors was 17+/-7 and 17+/-10 min, respectively. CONCLUSIONS: Muscles around the eye vary in their response to rocuronium. The response of the superciliary arch (corrugator supercilii) reflects blockade of laryngeal adductor muscles. However, the eyelid (orbicularis oculi) and thumb (adductor pollicis) have similar sensitivities.

Adolescent↗

Mivacurium chloride (BW B1090U)-induced neuromuscular blockade during nitrous oxide-isoflurane and nitrous oxide-narcotic anesthesia in adult surgical patients.

The neuromuscular and cardiovascular effects of mivacurium were studied in 90 adult patients during nitrous oxide-oxygen-isoflurane (n = 45, ISO group) and nitrous oxide-oxygen-narcotic (n = 45, BAL group) anesthesia. Neuromuscular blockade was measured using electromyographic activity of the adductor pollicis muscle after supramaximal stimulation of the ulnar nerve at 2 Hz for 2 seconds at 10-second intervals. To estimate dose-response relations, three subgroups of nine patients in the ISO group received mivacurium doses of 0.025, 0.03, and 0.04 mg/kg, respectively. Similarly, three subgroups of nine patients in the BAL group received mivacurium doses of 0.03, 0.04, and 0.05 mg/kg, respectively. The ED50 and ED95 of mivacurium in each group were estimated from linear regression plots of log dose vs probit of maximum percentage depression of neuromuscular function. The estimated ED50 values for the ISO and BAL groups were 0.029 and 0.041 mg/kg, respectively. The estimated ED95 values for the ISO and BAL groups were 0.045 and 0.058 mg/kg, respectively. Recovery indexes were measured in 26 patients who received ED95 or greater doses of mivacurium in either the ISO or BAL groups. The recovery index was shorter in the BAL group (5.5 +/- 1.6 minutes [n = 10]), than in the ISO group (7.4 +/- 3.0 minutes [n = 16]). The addition of isoflurane (0.5-0.75% end-tidal concentration) to nitrous oxide-narcotic anesthesia augments the degree of neuromuscular blockade from a given dose of mivacurium and also prolongs the recovery index.

Adult↗

The effects of hypercarbia and hypocarbia on pancuronium and vecuronium neuromuscular blockades in anesthetized humans.

To determine the effects of hypercarbia and hypocarbia on a pancuronium or vecuronium neuromuscular blockade, 54 patients were anesthetized with halothane and 60% nitrous oxide in oxygen. In 30 patients, end-tidal PCO2 was maintained at either 25 mmHg (3.5 kPa, N = 10), 41 mmHg (5.5 kPa, N = 10), or 56 mmHg (7.5 kPa, N = 10). Five patients in each group then were given pancuronium or vecuronium 0.022 mg/kg iv. Neither maximal depressions of twitch tension nor recovery indexes (time for spontaneous recovery of twitch tension from 25 to 75% of control) were altered by hypercarbia or hypocarbia. The remaining 24 patients were divided into three equal groups. Either pancuronium (N = 8) or vecuronium (N = 8) was administered iv as continuous infusion at a rate sufficient to produce a 50% depression of twitch tension. In the remaining eight patients, no muscle relaxant was given. After twitch tension was stable, half of the patients in each group had hypercarbia induced, which depressed twitch tension in all three groups. The patients who received vecuronium had a significantly larger decrease in twitch tension than those who received pancuronium or no muscle relaxant. Conversely, in the remaining patients, hypocarbia produced a significant increase in twitch tension. There was no difference in the magnitude of the increases in twitch tension among the three groups. The authors conclude that pre-muscle relaxant administration-induced hypercarbia or hypocarbia has no effect on a subsequent neuromuscular blockade from pancuronium or vecuronium.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Spectral analysis and acoustic transmission of mitral and aortic valve closure sounds in dogs. Part 2. Effects of neuromuscular blockade, sternotomy and pacemaker control, and a two-week recovery period.

The paper describes the effects of neuromuscular blockade, sternotomy and atrio-ventricular pacing, and a two-week recovery period on the spectra and acoustic transmission of mitral M1 and aortic A2 sound components in dogs. Results indicate that neuromuscular blockade does not affect the attenuation properties of the heart/thorax acoustic system even if it modifies the intensity of M1 and the phase of the transfer function. The immediate effect of sternotomy and cardiac pacing is an important increase in the attenuation of the heart/thorax acoustic system. This increased attenuation is different for both sounds (20 dB for M1 and 11 dB for A2) and disappears after a two-week recovery period. However, the resulting controlled dog model shows slightly different acoustic characteristics than those of the normal animal model.

Animals↗