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PubMed1978

Diuretic-induced hypokalaemia, pancuronium neuromuscular blockade and its antagonism by neostigmine.

The effect of hypokalaemia on a neuromuscular blockade induced by pancuronium and its antagonism by neostigmine was studied in the cat anterior tibialis-peroneal nerve preparation using the constant infusion of pancuronium technique. Hypokalaemia was induced by chronic administration of chlorothiazide. The infusion rate of pancuronium required to maintain a 90% depression of twitch tension was reduced from 0.72 +/- 0.06 microgram kg-1 min-1 in the cats with a normal serum concentration of potassium (K+ = 4.4 +/- 0.2 mmol litre-1; n = 7) to 0.41 +/- 0.07 microgram kg-1 min-1 in the hypokalaemic cats (K+ = 2.3 +/- 0.1 mmol litre-1; n = 8). The dose of neostigmine necessary for 50% antagonism of the pancuronium-induced depression of twitch tension (ED50) was 10.0 microgram kg-1 in the cats with a normal potassium concentration and 18.5 microgram kg-1 in hypokalaemic cats. We conclude that hypokalaemia decreases the dose of pancuronium required for neuromuscular blockade and increased the dose of neotigmine required for antagonism of the block.

Animals↗

PubMed1991

Nitrous oxide potentiates succinylcholine neuromuscular blockade in humans.

Sixty ASA physical status I and II adults received 0.3 mg/kg succinylcholine to determine the effect of prolonged administration of thiopental and that of nitrous oxide on succinylcholine neuromuscular blockade. Succinylcholine was administered either 1 min (group 1) or 6 min (groups 2 and 3) after induction of anesthesia with thiopental. In group 2, anesthesia was maintained with thiopental and the patients' lungs were ventilated with oxygen. In group 3, anesthesia was maintained with only 70% nitrous oxide in oxygen. Train-of-four stimulation of the ulnar nerve was started 30 s before the administration of succinylcholine and repeated every 12 s. The force of contraction of the adductor pollicis muscle was measured. Maximum blockade (mean +/- SEM) did not vary significantly between group 1, where thiopental had been administered for 1 min, and group 2, where it had been administered for 6 min (group 1: 61% +/- 6%; group 2: 54% +/- 8%). However, the addition of nitrous oxide increased neuromuscular blockade (group 3: 80% +/- 6%; P less than 0.05 compared with group 2). The degree of twitch augmentation, i.e., greater than maximal response, and times to twitch augmentation and to maximum blockade did not vary significantly among the groups. It is concluded that nitrous oxide increases succinylcholine neuromuscular blockade and that this is manifest within 6 min. This effect is not due to the duration of the anesthetic because thiopental, administered over a similar time period, did not potentiate succinylcholine.

Drug Synergism↗

PubMed1996

Pharmacokinetics, effects on renal function, and potentiation of atracurium-induced neuromuscular blockade after administration of a high dose of gentamicin in isoflurane-anesthetized dogs.

OBJECTIVE: To determine pharmacokinetics, renal effects, and effect on atracurium-induced neuromuscular blockade of a high dose of gentamicin in isoflurane-anesthetized dogs. ANIMALS: 6 healthy, adult, mixed-breed dogs, anesthetized twice and receiving gentamicin (6 mg/kg of body weight, i.v.) or saline solution. PROCEDURE: Blood samples were collected before and at intervals after gentamicin administration. Pharmacokinetic values were evaluated by use of multivariant stepwise linear regression analysis. Gentamicin-induced renal changes were assessed by comparing pretreatment and 12- to 24-hour posttreatment values for serum urea nitrogen, serum creatinine, urine creatinine-to-gamma-glutamyl-transferase ratio, and urinalysis. Neuromuscular blockade, maintained by atracurium infusion, was assessed, using the train-of-four response. At stable 50% depression of first twitch (T1), gentamicin or saline solution was given. Before and at posttreatment intervals for 60 minutes, T1% and fourth twitch-to-T1 ratio were recorded. The infusion was discontinued and 50 to 75% T1 recovery time was recorded. At 75% T1, edrophonium (0.5 mg/kg) was administered i.v.. RESULTS: Mean values for volume of distribution and clearance were 0.263 L/kg and 2.0 ml/min/kg, respectively. Mean maximal serum concentration of gentamicin was 46.4 micrograms/ml. Pre and posttreatment values for serum urea nitrogen, serum creatinine, urine creatinine-to-gamma-glutamyltransferase ratio, and other urine analytes were not significantly different. Mean (+/- SD) values for T1% and fourth twitch-to-T1 ratio decreased significantly after gentamicin (depression was maximal at 5 minutes). Recovery time (50 to 75% T1) was not different between groups. Edrophonium restored twitch to baseline. CONCLUSIONS: Mean values for apparent volume of distribution and total body clearance of gentamicin were similar to values in unanesthetized dogs. Mean maximal serum concentration of gentamicin was greater than that in unanesthetized dogs. Renal function was unaffected. Gentamicin potentiated atracurium-induced neuromuscular blockade, but did not affect recovery time.

Anesthesia↗

PubMed1992

Pipecuronium-induced neuromuscular blockade during nitrous oxide-fentanyl, enflurane, isoflurane, and halothane anesthesia in surgical patients.

This study was designed to determine the capacity of several anesthetics to augment pipecuronium neuromuscular blockade. The potency of pipecuronium was determined with single-bolus administration of 20-50 micrograms/kg in 160 patients. Patients were anesthetized with N2O/O2 (60:40) supplemented with fentanyl (4-5 micrograms/kg), halothane (0.8%), isoflurane (1.2%), or enflurane (1.7%). Neuromuscular blockade was measured by an acceleration-responsive transducer (the Accelograph, Biometer International, Odense, Denmark). Responses were defined in terms of percent depression in first-twitch height and train-of-four response, and the dose-response curves were constructed after probit transformation of the responses. The dose-response curves were found to be parallel for both first twitch height and train-of-four responses. The dose-response lines for the enflurane and isoflurane groups were displaced significantly (P less than 0.01) to the left of the line for the fentanyl-N2O group. The calculated doses producing 50% depression of first twitch height were 21.9, 21.2, 18.9, and 17.8 micrograms/kg for the N2O-fentanyl, halothane, isoflurane, and enflurane groups, respectively. Corresponding calculated doses for 50% depression of train-of-four response were significantly smaller (15.5, 14.4, 13.7, 11.9 micrograms/kg, respectively). The enhancing effects of the volatile anesthetics were reflected by significant prolongation of the clinical duration of neuromuscular blockade by pipecuronium. It is concluded that the potency of pipecuronium is enhanced more by enflurane and isoflurane than halothane or fentanyl-N2O anesthesia.

Adult↗

PubMed1996

Technical and interpretive problems of peripheral nerve stimulation in monitoring neuromuscular blockade in the intensive care unit.

OBJECTIVE: To review the literature and provide an overview of the technical and interpretive problems associated with peripheral nerve stimulation in monitoring neuromuscular blockade in the intensive care unit. DATA SOURCES: A computerized search on MEDLINE from 1985 through 1994 was performed to identify English-language comparative studies, abstracts, and review articles pertaining to peripheral nerve stimulation, train-of-four monitoring, and neuromuscular blockade in the critical care setting. STUDY SELECTION AND DATA EXTRACTION: Relevant studies in humans were selected and information was extracted on the use of peripheral nerve monitoring in the critically ill. DATA SYNTHESIS: Use of peripheral nerve stimulation is complicated in the intensive care unit. Problems may occur with the patient, the device, as well as operator technique, all of which may lead to errors in interpretation of the depth of paralysis. The critically ill patient has changing comorbid disease states and total body water composition, which may impair the accuracy or reproducibility of measurements. Technical problems relate to the operation of the device, electrode placement, and suboptimal delivery of the desired current. Difficulties in performing peripheral nerve stimulation and interassessor variability contribute to errors of interpretation. CONCLUSIONS: These difficulties compromise the precision, accuracy, and reliability of the peripheral nerve stimulator as a tool for monitoring neuromuscular blockade in the critically ill. Peripheral nerve stimulation should be used in conjunction with clinical parameters to make decisions regarding dose adjustments. Doses should be reduced as much as possible to provide the minimum depth of paralysis that is clinically appropriate. Technical directions and training programs for peripheral nerve stimulation should be developed, and designated individuals should be trained in its application. Large, prospective, controlled studies are necessary to evaluate the incidence of prolonged paralysis or motor neuropathy with administration of neuromuscular blocking agents in patients whose dose is adjusted on the basis of peripheral nerve stimulation.

Critical Care↗

PubMed2003

[Neuromuscular blockade monitoring at the corrugator supercilii and ocular myasthenia gravis].

A 67-year-old patient suffering from an ocular myasthenia gravis was scheduled for an elective ENT surgery. General anaesthesia was induced intravenously. Neuromuscular responses after train-of-four stimulation were normal at both the adductor pollicis (T(4)/T(1) = 1) and the corrugator supercilii (4 visual responses). Then cisatracurium (0,15 mg kg(-1)) was administered to allow tracheal intubation. The laryngoscopy attempted 45 s after cisatracurium injection (no response at the supercilii, T(1)/T(0) = 1 at the adductor pollicis) was unsuccessful because of closing and moving vocal cords. The second attempt was successful 4 min after cisatracurium injection (no response at the corrugator supercilii, T(1)/T(0) = 0.05 at the adductor pollicis). Residual neuromuscular blockade was antagonized at the end of surgery (1 h long) allowing an uneventful extubation. We concluded that monitoring neuromuscular blockade at the corrugator supercilii to assess the intubating conditions is not recommended in a case of ocular myasthenia gravis.

Aged↗

PubMed1994

Potentiation of neuromuscular blockade by calcium channel blockers.

A significant reduction was noticed in the amount of vecuronium needed to maintain steady neuromuscular blockade at 20% twitch height (T1) in patients given nicardipine intraoperatively. Bolus injection of either nicardipine or diltiazem during constant infusion of vecuronium produced transient depression of T1 and the train-of-four ratio (TOFR). Reversal of neuromuscular blockade with a choline esterase inhibitor (neo-stigmine) was not retarded by previous administration of Ca-channel blockers but concurrent administration of anticholine-esterase agent and Ca-channel blockers caused a delay in recovery from motor blockade. Monitoring of neuromuscular junction activity is strongly recommended whenever a large cumulative dose of Ca-channel blockers is used.

Adult↗

PubMed1999

The effects of antagonizing residual neuromuscular blockade by neostigmine and glycopyrrolate on nausea and vomiting after ambulatory surgery.

UNLABELLED: The effects of neostigmine on the incidence of postoperative nausea and vomiting (PONV) are controversial. In this study, we evaluated the effects of neostigmine and glycopyrrolate on the incidence of PONV and the need for antiemetics in patients undergoing ambulatory surgery. One hundred healthy patients undergoing outpatient surgical procedures were included in the study. A standardized anesthetic technique was used for all patients. Patients were randomized to receive either mivacurium (n = 50) or rocuronium (n = 50) to achieve muscle paralysis. Bolus doses of mivacurium 2-4 mg or rocuronium 5-10 mg were administered to maintain one or two twitches of the train-of-four stimulation of the ulnar nerve at the wrist. After surgery, residual neuromuscular blockade was reversed with neostigmine 2.5 mg i.v. and glycopyrrolate 0.5 mg i.v. only if clinically deemed necessary (i.e., fade on train-of-four stimulation, inadequate tidal volume, reduced hand grip, or inability to maintain head lift). The incidence of PONV and the need for antiemetics were recorded in the post-anesthesia care unit (PACU), in the phase II unit, and 24 h after surgery. We compared patients who received neostigmine (n = 40) for reversal of residual neuromuscular blockade with those who did not (n = 60). More patients receiving rocuronium required reversal drugs than those receiving mivacurium (68% vs 10%). There were no differences in the incidence of nausea (18% vs 15%), vomiting (8% vs 12%), and the need for antiemetics (13% in both the groups) in the PACU between patients who received neostigmine and those who did not. In addition, the duration of PACU stay and the time to home-readiness were also similar between the groups. We conclude that, compared with rocuronium, the use of mivacurium decreases the need for reversal drugs. In addition, reversal of residual neuromuscular blockade with neostigmine does not increase the incidence of PONV or the need for antiemetic medications in patients undergoing ambulatory surgery. IMPLICATIONS: In this study, we showed that the incidence of postoperative nausea and vomiting and the need for antiemetics do not increase with the use of neostigmine and glycopyrrolate for reversal of residual muscle paralysis.

Adult↗

PubMedDate not supplied

Comparative effects of (+)- and (-)-isomers of propranolol and INPEA on (+)-tubocurarine- and succinylcholine-induced neuromuscular blockade.

The effects of the (+)- and (-)-isomers of propranolol and INPEA on the neuromuscular blocking action of (+)-tubocurarine and succinylcholine were studied in the tibialis anterior-peroneal nerve preparation of the rabbit and the isolated phrenic nerve-diaphragm preparation of the rat. (+)-Tubocurarine-induced neuromuscular blockade was intensified by (+)- and (-)-isomers of INPEA whereas it was unaffected by isomers of propranolol in both preparations. In the rabbit tibialis anterior-peroneal nerve preparation, only the (-)-isomers of propranolol and INPEA increased the duration of succinylcholine-induced neuromuscular blockade without affecting its magnitude. Higher doses of both (+)- and (-)-isomers of propranolol and INPEA potentiated succinylcholine-induced blockade in the rat phrenic nerve-diaphragm preparation. The results obtained indicate that only the increase in duration of succinylcholine-induced blockade with beta-adrenoceptor blockers can be related to beta-blocking property of these compounds.

Animals↗

PubMed2006

[Residual neuromuscular blockades. Clinical consequences, frequency and avoidance strategies].

Even after administration in routine clinical dosages, muscle relaxants can lead to long-lasting residual blockades which increase the risk of severe postoperative pulmonary complications. Even without the additional effects from analgetics, sedatives or anaesthetics, a partial neuromuscular blockade, which cannot reliably be avoided either by the anaesthetist alone or by the additional use of nerve stimulators (train-of-four [TOF] ratio 0.5-0.9), can cause reductions in the vital capacity and the hypoxic breathing response, as well as obstruction of the upper airway and disruption of pharangeal function. The extent of neuromuscular recovery after an operation depends on the muscle relaxant used, the duration of administration, the anaesthetic technique and possible accompanying illnesses of the patient. It must basically be assumed that residual neuromuscular blockades are more frequent after administration of slow acting muscle relaxants such as pancuronium, than after the use of medium or rapid acting substances. If the course of a neuromuscular blockade is continually monitored during the whole anaesthetic procedure using the TOF ratio and not only occasionally at the end, a TOF ratio of 1 measured with an acceleromyograph (e.g. TOF-watch) promises an adequate neuromuscular recovery from the effects of muscle relaxants.

Airway Obstruction↗

PubMed1960

Neuromuscular blockade by streptomycin and dihydrostreptomycin.

Both streptomycin and dihydrostreptomycin in large doses produced neuromuscular blockade in different types of skeletal nerve-muscle preparations. Streptomycin had a quicker, more marked and a longer-lasting action than dihydrostreptomycin. Neostigmine reversed a partial block of streptomycin, but a complete neuromuscular block remained unaffected. Calcium ions antagonized the neuromuscular block of streptomycin rapidly but incompletely.

Dihydrostreptomycin Sulfate↗

PubMed1998

[Prolonged neuromuscular blockade with mivacurium in a newborn].

Mivacurium is a short acting non-depolarising neuromuscular blocking agent. Short duration of action is due to a rapid hydrolysis by plasma cholinesterase (CHe). The duration of neuromuscular blockade can be prolonged by an abnormal variant of CHe. We report a case of a newborn with neuromuscular blockade for a duration of 8 hours following mivacurium 0.2 mg.kg-1. CHe activity values were not contributive for the diagnosis. The diagnosis was obtained with molecular study showing the new-born homozygocity. The whole family was heterozygous. This case emphasises the lack of precision of CHe activity measurement during the first 6 months of life.

Cholinesterases↗

PubMed1995

Prolonged neuromuscular blockade when mivacurium and pancuronium were administered in series.

Long acting non-depolarizing neuromuscular blockade is useful in many clinical circumstances, especially during surgical procedures. Reinstitution of the blockade for short periods to facilitate the completion of clinical tasks can be accomplished in different ways. We present a case wherein a short-acting non-depolarizing neuromuscular blocker used after a long-acting one resulted in an unusual prolongation of the neuromuscular blockade.

Adult↗

PubMed1999

Within-patient variability of myogenic motor-evoked potentials to multipulse transcranial electrical stimulation during two levels of partial neuromuscular blockade in aortic surgery.

UNLABELLED: Intraoperative recording of myogenic motor responses evoked by transcranial electrical stimulation (tcMEPs) is a method of assessing the integrity of the motor pathways during aortic surgery. To identify conditions for optimal spinal cord monitoring, we investigated the effects of manipulating the level of neuromuscular blockade (T1 response of the train-of-four (TOF) stimulation 5%-15% versus T1 response 45%-55% of baseline), as well as the number of transcranial pulses (two versus six stimuli) on the within-patient variability and amplitude of tcMEPs. Ten patients (30-76 yr) scheduled to undergo surgery on the thoracic and thoracoabdominal aorta were studied. After achieving a stable anesthetic state and before surgery, 10 tcMEPs were recorded from the right extensor digitorum communis muscle and the right tibialis anterior muscle in response to two-pulse and six-pulse transcranial electrical stimulation with an interstimulus interval of 2 ms during two levels of neuromuscular blockade. The right thenar eminence was used for recording the level of relaxation. The tcMEP amplitude using the six-pulse paradigm was larger (P < 0.01; leg and arm) compared with the amplitude evoked by two-pulse stimulation during both levels of relaxation. The within-patient variability, expressed as median coefficient of variation, was less when six-pulse stimulation was used. At a T1 response of 45%-55% of baseline, larger, less variable tcMEPs were recorded than at a T1 response of 5%-15%. Our results suggest that the best quality of tcMEP signals (tibialis anterior muscle) is obtained when the six-pulse paradigm is used with a stable level of muscle relaxation (the first twitch of the TOF-thenar eminence-at 45%-55% of baseline). IMPLICATIONS: This study shows that six-pulse (rather than two-pulse) transcranial electrical stimulation during a stable anesthetic state and a stable neuromuscular blockade aimed at 45%-55% (rather than 5%-15%) of baseline provides reliable and recordable muscle responses sufficiently robust for spinal cord monitoring in aortic surgery.

Anesthesia, General↗

PubMed2005

Cisatracurium-induced neuromuscular blockade is affected by chronic phenytoin or carbamazepine treatment in neurosurgical patients.

The effect of chronic anticonvulsant therapy (CAT) on the maintenance and recovery profiles of cisatracurium-induced neuromuscular blockade has not been adequately studied. In this study, we compared the pharmacokinetics and pharmacodynamics of cisatracurium after a prolonged infusion in patients with or without CAT. Thirty patients undergoing intracranial surgery were enrolled in the study: 15 patients under CAT (carbamazepine and phenytoin, Group A) and 15 controls receiving no anticonvulsant therapy (Group C). Anesthesia was standardized and both groups received a bolus of cisatracurium followed by an infusion to maintain a 95% twitch depression. A steady-state was obtained and the infusion was kept constant for 2 additional hours. Neuromuscular blockade was then allowed to spontaneously recover. Blood samples were taken for measurement of cisatracurium plasma concentration during the steady-state period (Cp(ss)95) and at various times during recovery. Demographic and intraoperative data were similar. CAT resulted in faster 25% and 75% recovery of the first twitch. The rate of infusion of cisatracurium needed to maintain a 95% twitch depression at steady-state was 44% faster in Group A (P < 0.001). The clearance of cisatracurium was significantly faster in Group A when compared with Group C (7.12 +/- 1.87 versus 5.72 +/- 0.70 L . kg(-1) . min(-1), P = 0.01). The Cp(ss)95 was also significantly larger in Group A (191 +/- 45 versus 159 +/- 36 ng/mL, P = 0.04). In addition, patients receiving CAT had a 20% increase in the clearance of cisatracurium that, in turn, resulted in a faster recovery of neuromuscular blockade after an infusion of the drug. Also, patients under CAT had a 20% increase in their Cp(ss)95, indicating an increased resistance to the effect of cisatracurium.

Adolescent↗

PubMed1990

Comparison of double-burst and train-of-four stimulation to assess neuromuscular blockade in children.

Double-burst stimulation (DBS), a new technique to evaluate neuromuscular function, consists of two 50-Hz trains of 60-ms duration and 750 ms apart. DBS was compared with train-of-four (TOF) stimulation in 21 children aged 3-10 yr, during halothane anesthesia. On one arm the ulnar nerve was stimulated supramaximally with TOF stimulation every 12 s and the force of the evoked contraction of the adductor pollicis measured with an FTO3 force transducer and recorded on paper. Atracurium (0.4-0.5 mg.kg-1) was administered. During recovery from neuromuscular blockade, TOF stimulation was interrupted periodically and DBS substituted. The same stimulation patterns were applied to the ulnar nerve of the other arm simultaneously, and the clinical anesthesiologist was asked to estimate the degree of fade with both. There was good correlation between the measured TOF ratio (ratio of fourth to first response) and DBS ratio (ratio of second to first response). The TOF and DBS ratios above which fade could no longer be appreciated manually were (mean +/- SEM) 0.44 +/- 0.03 and 0.67 +/- 0.04 (P = 0.0002). Corresponding ranges were 0.3-0.8 for TOF and 0.4-0.9 for DBS, but DBS fade was always apparent if TOF fade could be detected. Therefore, in children, DBS is more sensitive than is TOF stimulation for the clinical assessment of recovery from neuromuscular blockade.

Anesthesia, Inhalation↗

PubMed2004

Simultaneous determination of neuromuscular blockade at the adducting and abducting laryngeal muscles using phonomyography.

UNLABELLED: Phonomyography (PMG) is a new method for measuring neuromuscular blockade (NMB) at the larynx. In this study, we used PMG to compare NMB at the posterior cricoarytenoid (PCA) and the lateral cricoarytenoid muscle (LCA) in humans. Twelve patients were included in this study. Endotracheal intubation was performed without aid of neuromuscular blocking drugs. One small condenser microphone was inserted beside the vocal cords into the muscular process at the base of the arytenoid cartilage to record acoustic responses of the LCA (vocal cord adduction), and a second microphone was placed behind the larynx to measure NMB of the PCA (vocal cord abduction). Stimulation of the recurrent laryngeal nerve was performed using superficial electrodes placed at the neck (midline between jugular notch and cricoid cartilage) using train-of-four (TOF) stimulation every 12 s. After supramaximal stimulation, mivacurium 0.1 mg/kg was injected and onset, peak effect, and offset of NMB measured and compared using t-test (P < 0.05). The data are presented as mean (SD). Peak effect, onset time, and early recovery to 25% of control twitch height were not significantly different between PCA and LCA at 86% (13) versus 78% (16), 2.3 min (0.45) versus 2.3 min (1.0), and 9.55 min (3.05) versus 8.5 min (4.7), respectively. However, recovery to 75%, 90% of control twitch height, and recovery to a TOF ratio of 0.8 were significantly longer at the PCA than at the LCA at 14 min (4) versus 11 min (5), 17 min (5) versus 11.8 min (5.6), and 17.5 min (5.6) versus 12.3 min (5.5), respectively. The authors conclude that recovery of NMB at the PCA takes longer than at the LCA in humans after mivacurium. IMPLICATIONS: After neuromuscular blockade in humans, the recovery of the ability to open the vocal cords takes longer than the ability to close the vocal cords.

Adult↗

PubMed2003

Magnesium potentiates neuromuscular blockade with cisatracurium during cardiac surgery.

PURPOSE: Magnesium potentiates the effect of nondepolarizing neuromuscular blocking agents. It is used in cardiac anesthesia to prevent hypertension and arrhythmias. This study was performed to measure the interaction between magnesium and cisatracurium in cardiac surgery. METHODS: Twenty patients scheduled for elective cardiac surgery were randomly assigned to receive magnesium sulfate (70 mg x kg(-1) at induction followed by 30 mg x kg(-1) x hr(-1)) or placebo. The ulnar nerve was stimulated and the electromyographic response of the adductor pollicis was measured. Cisatracurium 0.1 mg x kg(-1) was given at induction, followed by 0.05 mg x kg(-1) when the first twitch in the train-of-four reached 25%. RESULTS: Ionized magnesium was 1.32 +/- 0.24 mmol x L(-1) in the treatment group vs 0.47 +/- 0.4 mmol x L(-1) in the control group. Duration of action of the intubating dose was longer in the magnesium group (74 +/- 20 min) than in the placebo group (42 +/- 6 min, P = 0.0001). Duration of the first maintenance dose was 69 +/- 16 min in the magnesium group vs 35 +/- 7 min in the placebo group (P = 0.0001). Total dose of cisatracurium administered throughout surgery was 0.19 +/- 0.07 mg x kg(-1) in the magnesium group compared with 0.29 +/- 0.01 mg x kg(-1) in the placebo group (P = 0.017). Hemodynamic variables and temperature were similar in both groups. CONCLUSION: In patients undergoing cardiac surgery, administration of magnesium sulfate, resulting in ionized levels of 1.3 mmol x L(-1), results in a 30-35 min prolongation of the neuromuscular blockade induced with intubating and maintenance doses of cisatracurium and does not alter hemodynamic stability.

Aged↗