Onset Of Neuromuscular Block Research Articles

Administration of Magnesium Sulphate Prior to Vecuronium: Effects on the Speed of Onset and Duration of Neuromuscular Block

Background: We commonly encounter surgical patients who are on magnesium therapy in the operation theatre. It is important to know the interaction of magnesium on anaesthetic drugs including neuromuscular blocking agents. Our aim is to observe and compare the onset and duration of action of vecuronium following magnesium pre-treatment. Material and Method: 50 patients were randomly divided into 2 groups. Group 1 (n = 25) received placebo (normal saline) and group 2 (n=25) received 40 mg/kg magnesium sulphate added to 100 ml of normal saline infused over a period of 15 minutes prior to induction. Following the induction of anaesthesia muscle relaxation was achieved by 0.1 mg/kg vecuronium and time for onset, duration of neuromuscularblock and vecuronium dose requirement during surgery was assessed by monitoring the tactile response to Train of four stimulation. Results: Onset of time for intubation was significantly reduced to 120.19±6.53 seconds in the magnesium group compared to 259.150±26.131 seconds in thecontrol group(P< 0.001). It was observed that the average duration of neuromuscular blockage of vecuronium was almost doubled and statistically significant (P = 0.001) in the magnesium group(26.89±2.91) as compared to the control group (42.28±1.41).The total dose of vecuronium used or required was significantly less in the magnesium group when compared to the control group (p=0.008). Duration from last dose of vecuronium to reversal of anaesthesia was prolonged in the magnesium group (40.2±3.96) compared to the control group(29.8±6.03) which is statistically significant(p<0.001). Conclusion: Magnesium sulphate administered before vecuronium significantly accelerates the onset of neuromuscular block necessary for intubation of trachea and significantly increase the time course of neuromuscular blockade. Intraoperative consumption of vecuronium was less in the magnesium group.

Onset and duration of cis-atracurium neuromuscular block during fentanyl and lidocaine infusions in isoflurane-anaesthetised dogs

BackgroundThis retrospective study assessed the onset and duration of the neuromuscular block (NMB) induced by cis-atracurium 0.15 mg/kg intravenously with and without fentanyl or lidocaine infusions in 45 isoflurane-anaesthetised dogs.MethodsDogs...

The Effect of Magnesium Sulphate on Intubating Condition for Rapid-Sequence Induction; Comparative Study of Magnesium Sulphate versus Ketamine in Rapid Sequence Induction

AbstractBackground: Rapid sequence induction is the preferred method of endotracheal intubation in the emergency setting. The rapid sequence intubation technique involves the prompt sequential administration of a predetermined dose of hypnotic agent and muscle relaxant followed by tracheal intubation within 1min of giving the muscle relaxant.Aim of Study: Test the efficacy of magnesium sulphate (MgSo4) versus ketamine to assess intubating condition (primary outcome), rocuronium onset, rocuronium duration, train-of-four ratio upon intubation, and hemodynamic variables (secondary outcomes) for rapid sequence induction.Patients and Methods: We compared magnesium sulphate with control, ketamine with regard to intubation conditions during rapid-sequence induction.Design: This is a prospective, randomized, double-blinded study.Setting: The setting is at an operating room in Ain Shams University Hospital.Patients: 75 patients scheduled for general anesthesia were randomly allocated to the following 3 groups in equal numbers.Interventions: The control received rocuronium 0.6mg/kg; the ketamine group was given 0.5mg/kg ketamine 2 minutes before 0.6mg/kg rocuronium; and the magnesium group received 50mg/kg magnesium sulphate. Intubation was initiated 50 seconds after the rocuronium injection.Measurements: Intubating condition (primary outcome), rocuronium onset, rocuronium duration, train-of-four ratio upon intubation, and hemodynamic variables (secondary outcomes) were recorded.Results: The excellent intubating condition was more frequent in the magnesium group (p b.05). Onset of neuromus-cular block was shorter in the magnesium group than in the control, ketamine, (p b.05).Conclusions: Magnesium sulphate pre-treatment was most likely to provide excellent intubating condition for rapidsequence intubation compared with the control, ketamine. However, magnesium sulphate administration is associated with a burning or heat sensation.

The Role of Bolus Injection of Saline with Arm Elevation on Rocuronium onset Time: A Randomized Control Study.

Background:The onset time of neuromuscular blockade is a crucial time associated with the risk of hypoxia and pulmonary aspiration. Various strategies have been undertaken to shorten this onset time. Therefore, we investigated the effects of bolus of 20 ml saline followed by limb elevation after administration of rocuronium in a dose of 0.6 mg/kg to study the onset time.Methodology:Thirty patients were randomly allocated to the bolus saline group or control group. General anesthesia was induced and maintained with fentanyl and propofol. Rocuronium 0.6 mg/kg intravenous (IV) was administered followed by 20 ml saline bolus and limb elevation in the study group compared to administration of 0.6 mg/kg in a running drip only in the control. Onset of neuromuscular block was assessed by acceleromyography at the adductor pollicis muscle with train-of-four stimulation.Results:The lag time was shorter in bolus group (34 s median) than in control group (45 s median), P < 0.017. The onset time was shorter in bolus group (55 s median) than in control group (110 s median), P < 0.001. The T1 recovery to 25% was longer in bolus group (42 min median) than in control group (39 min median) which was statistically not significant.Conclusion:Rocuronium 0.6 mg/kg IV followed by bolus 20 ml saline and concomitant limb elevation resulted in shorter lag time, faster onset of neuromuscular blockade, good intubating conditions without prolonging clinical duration of action when compared to the control.

Correction.

AnaesthesiaVolume 72, Issue 11 p. 1427-1427 CorrectionsFree Access Correction This article corrects the following: Comparison of reversal with neostigmine of low-dose rocuronium vs. reversal with sugammadex of high-dose rocuronium for a short procedure E. S. Choi, A. Y. Oh, B. W. Koo, J. W. Hwang, J. W. Han, K. S. Seo, S. H. Ahn, W. J. Jeong, Volume 72Issue 10Anaesthesia pages: 1185-1190 First Published online: May 11, 2017 First published: 19 October 2017 https://doi.org/10.1111/anae.14107AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL In the article by Choi et al. 1, there were 2 errors in the following sentence in the Summary section (indicated by underline): The onset of neuromuscular block was more rapid, and intubation conditions and ease of intra-operative laryngoscopy were more favourable, and the satisfaction score was lower in the moderate block group compared with the deep block group. The correct sentence should be: The onset of neuromuscular block was slower, and intubation conditions and ease of intra-operative laryngoscopy were less favourable, and the satisfaction score was lower in the moderate block group compared with the deep block group. Reference 1Choi ES, Oh AY, Koo BW, et al. Comparison of reversal with neostigmine of low-dose rocuronium vs. reversal with sugammadex of high-dose rocuronium for a short procedure. Anaesthesia 2017; 72: 1185– 90. Volume72, Issue11November 2017Pages 1427-1427 ReferencesRelatedInformation

Retraction Note to: Assessment of neuromuscular block at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles.

We studied neuromuscular block at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles in anesthetized patients. Fifty-four adult patients undergoing air–oxygen–sevoflurane–fentanyl and epidural anesthesia were randomly divided into orbicularis oris, corrugator supercilii, and adductor pollicis groups of 18 patients each. In the three groups, the degree of neuromuscular block caused by rocuronium 0.6 mg/kg was monitored at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles acceleromyographically. Onset of neuromuscular block did not significantly differ among the three groups [157 ± 60, 186 ± 73, and 148 ± 45 s; mean ± standard deviation (SD)]. Minimum value of 1st stimulation in train-of-four (T1)/control at the corrugator supercilii group was significantly higher than in the orbicularis oris and adductor pollicis groups (0.108 ± 0.066 vs. 0.021 ± 0.024 and 0.002 ± 0.007; P < 0.001). T1/control at the orbicularis oris group was significantly higher than at the adductor pollicis group 30 min after rocuronium (P < 0.05). T1/control at the corrugator supercilii group was significantly higher than at the orbicularis oris and adductor pollicis groups 10–30 and 10–40 min, respectively, after rocuronium (P < 0.05). Train-of-four ratios at the orbicularis oris and corrugator supercilii groups were significantly higher than at the adductor pollicis group 40–120 min after rocuronium (P < 0.05). The corrugator supercilii muscle is more resistant to rocuronium than the orbicularis oris and adductor pollicis muscles. Recovery of neuromuscular block at the orbicularis oris muscle is slower than that at the corrugator supercilii muscle but was faster than that at the adductor pollicis muscle.

The effect of magnesium sulphate on intubating condition for rapid-sequence intubation: a randomized controlled trial

Study objectivesWe compared magnesium sulphate with control, ketamine, rocuronium prime, and large-dose rocuronium (0.9 mg/kg) with regard to intubation conditions during rapid-sequence induction. DesignThis is a prospective, randomized, double-blinded study. SettingThe setting is at an operating room in a university-affiliated hospital. PatientsOne hundred ten patients scheduled for general anesthesia were randomly allocated to the following 5 groups in equal numbers. InterventionsThe control and rocuronium 0.9 groups received rocuronium 0.6 and 0.9 mg/kg, respectively; the ketamine group was given 0.5 mg/kg ketamine 2 minutes before 0.6 mg/kg rocuronium; the rocuronium prime group received 0.06 mg/kg rocuronium 3 minutes before 0.54 mg/kg rocuronium; and the magnesium group received 50 mg/kg magnesium sulphate. Intubation was initiated 50 seconds after the rocuronium injection. MeasurementsIntubating condition (primary outcome), rocuronium onset, rocuronium duration, train-of-four ratio upon intubation, and hemodynamic variables (secondary outcomes) were recorded. Main resultsThe excellent intubating condition was more frequent in the magnesium group (P < .05). Onset of neuromuscular block was shorter in the magnesium group than in the control, ketamine, and rocuronium prime groups (P < .05). No difference in onset time was found between the magnesium and rocuronium 0.9 groups. Block duration was longest in the rocuronium 0.9 group. The train-of-four ratio on intubation was lowest in the rocuronium prime group. The only adverse event was a burning or heat sensation reported by 5 patients in the magnesium group. ConclusionsMagnesium sulphate pretreatment was most likely to provide excellent intubating condition for rapid-sequence intubation compared with the control, ketamine pretreatment, rocuronium prime, and large-dose rocuronium. However, magnesium sulphate administration is associated with a burning or heat sensation.

Response of bispectral index to neuromuscular block in awake volunteers

The bispectral index (BIS) monitor is a quantitative electroencephalographic (EEG) device that is widely used to assess the hypnotic component of anaesthesia, especially when neuromuscular blocking drugs are used. It has been shown that the BIS is sensitive to changes in electromyogram (EMG) activity in anaesthetized patients. A single study using an earlier version of the BIS showed that decreased EMG activity caused the BIS to decrease even in awake subjects, to levels that suggested deep sedation and anaesthesia. We administered suxamethonium and rocuronium to 10 volunteers who were fully awake, to determine whether the BIS decreased in response to neuromuscular block alone. An isolated forearm technique was used for communication during the experiment. Two versions of the BIS monitor were used, both of which are in current use. Sugammadex was used to antagonise the neuromuscular block attributable to rocuronium. The BIS decreased after the onset of neuromuscular block in both monitors, to values as low as 44 and 47, and did not return to pre-test levels until after the return of movement. The BIS showed a two-stage decrease, with an immediate reduction to values around 80, and then several minutes later, a sharp decrease to lower values. In some subjects, there were periods where the BIS was <60 for several minutes. The response was similar for both suxamethonium and rocuronium. Neither monitor was consistently superior in reporting the true state of awareness. These results suggest that the BIS monitor requires muscle activity, in addition to an awake EEG, in order to generate values indicating that the subject is awake. Consequently, BIS may be an unreliable indicator of awareness in patients who have received neuromuscular blocking drugs. ACTRN12613000587707.

Use of ProSeal(®) LMA and thoracic epidural in myasthenia patients for trans-sternal thymectomy: A case series.

Myasthenia gravis is an autoimmune disease, resulting from the production of antibodies against the acetylcholine receptors of the neuromuscular endplate. Muscular weakness and fatigability are the hallmarks of myasthenia gravis. Myasthenic patients are sensitive to non-depolarising relaxants and post-operative ventilatory support may be required in high-risk patients. This can be attributed partly to endotracheal intubation and use of intermediate or long-acting muscle relaxants in such cases. The rate of post-operative ventilation after a trans-sternal thymectomy has been reported to be more than 50% in myasthenia gravis patients.[1] Two techniques have been recommended for general anaesthesia in the myasthenic patient. Due to the unpredictable response to succinylcholine and the marked sensitivity to non-depolarising muscle relaxants, some anaesthesiologists avoid muscle relaxants and depend on deep inhalational anaesthesia for tracheal intubation and maintenance of anaesthesia.[2,3] However, others utilise a balanced technique which includes the use of muscle relaxants, without the need for deep inhalational anaesthesia with its concomitant respiratory and cardiovascular side effects, provided neuromuscular transmission is monitored. In this paper, we would like to describe a new and successful technique of using ProSeal® laryngeal mask airway (LMA) with thoracic epidural for three cases who underwent trans-sternal thymectomy. We avoided muscle relaxant during the entire course of surgery and none of our cases required post-operative ventilation.

Comparision of the neuromuscular effects of vecuronium in young and middle-age female patient during general anesthesia

Objective To observe and compare the neuromuscular effects of vecuronium in young and middle-age female patient during general anesthesia.Methods A total of 40 ASA Ⅰ-Ⅱ female patients scheduled for breast mass excision were randomly assigned to two groups:young-age group 18-44 years old and middle-age group 45years old-59 years old,with 20 patients each.Vecuronium of 2 ED95 (0.1 mg/kg) was injected during anesthesia induction,using TOF-Watch acceleration monitoring instrument for muscle relaxation.Thumb adductorius contractile response was monitored with train of four(TOF) stimulation.The time of neuromuscular block onset,duration of blockade maintenance,duration of in vivo action,recovery index and the time of TOF ration of recovery to 25％ were recorded.Results The muscle relaxant onset time,duration of action in vivo and TOF recovery to 25％ of the time in youth group were significantly shorter than that in the middle-aged group [(156±33),(186±44) s,(67±29),(77±20),(48± 14),(60±16) min] (P＜0.05).There were on significant difference in duration of blockade maintenance [(37± 10),(43± 11) min] (P＞0.05)and neuromuscular block recover index [(21±17),(22±13) min](P＞0.05)between two groups.Conclusions Compared to patients with middle-aged women,young female patient showed more sensitive to vecuronium with faster neuromuscular block onset,shorter duration of clinical action,but had no effect on the recovery process of muscle relaxants. Key words: Vecuronium; Age; Neuromuscular block ; Female

Evaluation of changes in tidal volume during mask ventilation following administration of neuromuscular blocking drugs.

The practice of checking the ability to mask ventilate before administering neuromuscular blocking drugs remains controversial. We prospectively evaluated the changes in the expired tidal volume during pressure-controlled ventilation (two-handed mask ventilation technique) as a surrogate marker to assess the ease of mask ventilation following administration of rocuronium. After informed consent, 125 patients were anaesthetised using a standard induction technique consisting of fentanyl, propofol and rocuronium, with anaesthesia then maintained with isoflurane in oxygen. The mean (SD) expired tidal volume before administration of rocuronium increased by 61 (13) ml at 2 min following onset of neuromuscular block (p < 0.001). This supports the concept that neuromuscular blockade induced by rocuronium facilitates mask ventilation.

Pre-treatment with Magnesium sulphate before non depolarizing muscle relaxants: Effect on speed on onset, induction and recovery

Background: Magnesium sulphate is used during anaesthesia for its antihypertensive/ antiarrhythmic properties and attenuating the response to endotrachial intubation and as an anticonvulsant for women with eclampsia. At the motor nerve terminal, MgSO 4 inhibits acetylcholine release. Thus, it enhances the effect of neuromuscular blocking agents. Aims & Objectives: To determine the effect of magnesium sulphate pre-treatment on the onset, duration and recovery of nondepolarizing muscle relaxant and to quantify the haemodynamic effects of administration of MgSO4 on the arterial blood pressure. Materials and Methods: One year old prospective, randomized, double blinded, controlled clinical study was conducted on randomly selected 45 patients of either sex, aged between 18-55 years, of grade I or II of American Society of Anaesthesiologists, undergoing elective surgery at a Medical College of eastern Uttar Pradesh. Patients were divided into three groups according to the doses of MgSO4 used for pre-treatment. Statistical evaluation was done by using student’s ‘t’ test for paired data. Results: The Mean Arterial Blood Pressure response to laryngoscopy, tracheal intubation, was almost abolished in Group A (p<0.05) followed by Group B (p<0.05) and maximum pressure response occurred in Group C where MgSO4 was not used (p<0.05). The speed of onset of neuromuscular block was accelerated by pre-treatment with MgSO4 before non-depolarizing muscle relaxants. The mean onset time was 144.3 ± 12.08 seconds (p<0.001) in Group A, 192.66 ± 19.81 second (p<0.001) in Group B and 286.33 ± 34.20 seconds in Group C. The clinical duration was prolonged in MgSO4 group as compared with control group. Mean value was 52.4 ± 8.97 minutes (p<0.001), 44.86 ± 6.59 minutes (p<0.01), and 34.2±8.05 minutes respectively in Group A, B and C. Pre-treatment with MgSO4 before non-depolarizing muscle relaxant, accelerated speed of onset of neuromuscular block, necessary for intubation of trachea. MgSO4, in the presence of non-depolarizing muscle relaxant, intensified and prolonged the neuromuscular blockade and recovery.

The dose effect of ephedrine on the onset time and intubating conditions after cisatracurium administration.

BackgroundThe aim of this randomized, double-blind, placebo-controlled study was to evaluate dose effects of ephedrine pretreatment on the onset time and intubating conditions after cisatracurium administration.MethodsA total of 140 adult patients were randomized into 4 groups to receive either 30 µg/kg ephedrine (Group 30, n = 35), 70 µg/kg ephedrine (Group 70, n = 35), 110 µg/kg ephedrine (Group 110, n = 35), 3 ml normal saline (Group C, n = 35) as pretreatment given 30 s before anesthetic induction. Neuromuscular block was achieved with 0.15 mg/kg cisatracurium, evaluated accelomyographically with train-of-four stimulation. An anesthesiologist blinded to patient grouping assessed the intubating conditions 1.5 min after cisatracurium administration.ResultsAn onset time of 70 s was obtained in the ephedrine groups (Group 30: 155.4 ± 44.7 s, Group 70: 152.6 ± 40.3 s, Group 110: 151.2 ± 51.6 s) compared to Group C (224.6 ± 56.9 s) after 0.15 mg/kg of cisatracurium (P < 0.001). Ephedrine doses of either 70 or 110 µg/kg for pretreatment significantly improved intubating conditions (P < 0.05). Systolic and diastolic blood pressure and heart rate at 1 min after tracheal intubation were significantly increased than other times in all groups (P < 0.001), with no differences among the groups. However, 5 patients in Group 110 experienced marked hypertension (systolic/diastolic blood pressure: > 200/100 mmHg) 1 min after tracheal intubation with no patients in other groups.ConclusionsWe conclude that pre-treatment with ephedrine 70 µg/kg improved intubating conditions 1.5 min after cisatracurium administration and facilitated the onset of neuromuscular block (70 s) without adverse hemodynamic effects.

Effect of ulinastatin on the rocuronium-induced neuromuscular blockade.

BackgroundUlinastatin is a glycoprotein derived from human urine and a serine protease inhibitor found in human urine and blood. Ulinastatin increases both liver blood flow and urine output. Rocuronium is eliminated mainly through the liver and partly through the kidney, hepatic elimination of rocuronium might be enhanced by ulinastatin. We examined the effect of ulinastatin on the neuromuscular block caused by rocuronium.MethodsForty four adult patients were randomly divided into two groups of 22 patients each, i.e. the study group and the control group. In the study group, a bolus dose of ulinastatin 5,000 U/kg was administered 2 min before the injection of rocuronium 0.6 mg/kg. In the control group, normal saline was administered instead of ulinastatin. For the monitoring of both onset and recovery from neuromuscular blockade, train-of-four (TOF) and post-tetanic count were used with TOF-Watch Sx. All patients underwent general anesthesia with total intravenous anesthesia (TIVA) of remifentanil and propofol, using the effect site target infusion system.ResultsIn the study group, the onset of neuromuscular block was significantly slower than in the control group (P < 0.05). The recovery time from the rocuronium injection to the return of PTC was also significantly shorter in the study group than in the control group (P < 0.05). Similarly, times to the return of T1, T2, T3, and T4 (i.e. the first, second, third, and fourth response of TOF) were significantly shorter in the study group than in the control group (P < 0.05).ConclusionsUlinastatin significantly delays the onset of neuromuscular block and accelerates the recovery from the block caused by rocuronium.

RETRACTED ARTICLE: Assessment of neuromuscular block at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles

We studied neuromuscular block at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles in anesthetized patients. Fifty-four adult patients undergoing air-oxygen-sevoflurane-fentanyl and epidural anesthesia were randomly divided into orbicularis oris, corrugator supercilii, and adductor pollicis groups of 18 patients each. In the three groups, the degree of neuromuscular block caused by rocuronium 0.6 mg/kg was monitored at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles acceleromyographically. Onset of neuromuscular block did not significantly differ among the three groups [157 ± 60, 186 ± 73, and 148 ± 45 s; mean ± standard deviation (SD)]. Minimum value of 1st stimulation in train-of-four (T1)/control at the corrugator supercilii group was significantly higher than in the orbicularis oris and adductor pollicis groups (0.108 ± 0.066 vs. 0.021 ± 0.024 and 0.002 ± 0.007; P < 0.001). T1/control at the orbicularis oris group was significantly higher than at the adductor pollicis group 30 min after rocuronium (P < 0.05). T1/control at the corrugator supercilii group was significantly higher than at the orbicularis oris and adductor pollicis groups 10-30 and 10-40 min, respectively, after rocuronium (P < 0.05). Train-of-four ratios at the orbicularis oris and corrugator supercilii groups were significantly higher than at the adductor pollicis group 40-120 min after rocuronium (P < 0.05). The corrugator supercilii muscle is more resistant to rocuronium than the orbicularis oris and adductor pollicis muscles. Recovery of neuromuscular block at the orbicularis oris muscle is slower than that at the corrugator supercilii muscle but was faster than that at the adductor pollicis muscle.

RETRACTED ARTICLE: Monitoring of vecuronium-induced neuromuscular block at the sternocleidomastoid muscle in anesthetized patients

To assess the degree of neuromuscular block acceleromyographically at the sternocleidomastoid muscle. Eighteen adult patients scheduled for air-oxygen-sevoflurane-fentanyl and epidural anesthesia were studied. In the patients, the right accessory nerve and the sternocleidomastoid muscle were stimulated and the contraction of the sternocleidomastoid muscle was evaluated acceleromyographically. Simultaneously, the response of the adductor pollicis muscle was measured electromyographically. Supramaximal stimulating current, degree of maximum neuromuscular block after vecuronium 0.1mg/kg, and onset of or recovery from vecuronium-induced neuromuscular block were compared between the two muscles. The supramaximal stimulating current at the sternocleidomastoid muscle was significantly higher than that at the adductor pollicis muscle (54.8±7.1 vs. 33.7±10.3mA, mean±SD, P<0.001). The onset of neuromuscular block at the sternocleidomastoid muscle did not significantly differ from that at the adductor pollicis muscle (214±117 vs. 161±87s, P=0.131). The degree of maximum neuromuscular block at the sternocleidomastoid muscle was significantly less than that at the adductor pollicis muscle (93.6±3.1 vs. 99.2±2.5%, P<0.001). During recovery from neuromuscular block, T1/control and train-of-four ratio measured at the sternocleidomastoid muscle were significantly higher than those at the adductor pollicis muscle 10-30 and 40-120min after vecuronium, respectively (P<0.05). The sternocleidomastoid muscle is more resistant to vecuronium than the adductor pollicis muscle. Recovery from neuromuscular block is faster at the sternocleidomastoid muscle than at the adductor pollicis muscle.

Median effective dose of cisatracurium priming accelerating onset of neuromuscular block in patients of different genders

Objective To investigate the median effective dose (ED50) of cisatracurium priming accelerating the onset of neuromuscular block in patients of different genders. Methods Ninety ASA Ⅰ or Ⅱ patients aged 18-55 yr undergoing elective abdominal operation under general anesthesia were divided into 2 groups ( n = 45 each): male group (group M) and female group (group F). Neuromuscular block was monitored with accelerograph F (TOF-Watch SX). A single twitch stimulation of ulnar nerve was used to monitor neuromuscular function.Anesthesia was induced with midazolam 0.04 mg/kg and fentanyl 1 μg/kg. Accelerograph F was opened after the patients lost consciousness. The priming dose of cisatracurium was injected intravenously, then fentanyl 5 μg/kg and propofol 2 mg/kg were injected intravenously 3 min later and the left dose of cisatracurium for intubation was injected intravenously 4 min later. Tracheal intubation was performed when the ratio of the single twitch stimulation value to control value (T/Tc). decreased to 10%. Anesthesia was maintained with iv infusion of propofol and remifentanil and inhalation of isoflurane. The priming dose of cisatracurium was determined by up-and-down sequential trial. The initial priming dose was set at 5 μg/kg. The ratio of two successive doses was 1.2. T/Tc, time to 90% block, onset time, maximal neuromuscular block and clinical duration were recorded 4 min after the administration of the priming dose. The ED50 and 95% confidence interval (CI) of cisatracurium priming required to accelerate the onset were caculated. Results Time to 90% block was significantly longer-in group M than in group F (P ＜0.05). No significant difference was found in the other parameters among the groups. The ED50 and 95% CI of cisatracurium priming required to accelerate the onset were 21.36 μg/kg (95% CI 20.52-22.23 μg/kg)in group M and 14.53 μg/kg (95% CI 13.77-15.33 μg/kg) in group F. The ED50 was significantly higher in group M than in group F ( P ＜ 0.05). Conclusion The ED50 of cisatracurium priming accelerating thd onset is 21.36 and 14.53 μg/kg in male and female respectively and it is significantly higher in male than in female. Key words: Atracurium; Sex factrs; Dose-response relationship,drug

Acceleromyographic monitoring of neuromuscular block over the orbicularis oris muscle in anesthetized patients receiving vecuronium

Study Objective To evaluate the level of neuromuscular block acceleromyographically over the orbicularis oris muscle. Design Prospective, randomized, controlled study. Setting Operating room of a university-affiliated hospital. Patients 36 adult, ASA physical status I and II women scheduled for mastectomy with air-oxygen-isoflurane-fentanyl anesthesia. Interventions Patients were randomized to two groups. In the orbicularis oris group (n=18), the facial nerve was stimulated and movement of the orbicularis oris muscle was measured acceleromyographically. In the control group (n=18), adduction of the thumb was quantified mechanically. Measurements Onset and recovery of neuromuscular block caused by vecuronium 0.1 mg/kg were compared between the groups. Main Results Time to onset of neuromuscular block in the orbicularis oris group was significantly shorter than in the control group (176 ± 52 vs. 220 ± 34 sec, mean ± SD; P = 0.004). Times to return of the first, second, third, or fourth (T1, T2, T3, or T4) response of train-of four (TOF), and recovery of T1/control were comparable between the groups. Train-of-four ratio (T4/T1) in the orbicularis oris group was significantly higher than in the control group 50 to 120 minutes after vecuronium administration ( P < 0.05). Conclusion Depth of neuromuscular block can be assessed acceleromyographically over the orbicularis oris muscle. Onset of neuromuscular block is quicker and recovery of TOF ratio is faster over the orbicularis oris muscle than at the thumb in patients receiving vecuronium.

Urinary trypsin inhibitor: miraculous medicine in many surgical situations?

Urinary trypsin inhibitor: miraculous medicine in many surgical situations?

The optimal dose of rocuronium for rapid sequence induction

To the Editor, In their study using lidocaine, low-dose rocuronium, remifentanil, and propofol for tracheal intubation, SiddikSayyid et al. found tracheal intubation conditions 90 sec after rocuronium 0.3 mg kg to be comparable to those achieved 60 sec following succinylcholine 1.5 mg kg. The onset of neuromuscular block is a function of the dose given. Using electromyography, the onset of rocuronium 0.6 mg kg at the laryngeal adductors was found to be 106 sec in one study and 124 sec in another. The onset of lower doses is further delayed and can be too slow for rapid sequence induction purposes. Higher doses (1 mg kg) are recommended when rapid tracheal intubation is indicated. Low doses will also result in a less intense block at the laryngeal adductors, which are known to be more resistant than skeletal muscles to the action of rocuronium. Using a 0.25 mg kg dose, Meistelman et al. found the maximum block attained at the vocal cords to be only 37 ± 8%. Thus, low doses may only result in a delayed and partial laryngeal block. The authors’ favourable results are due to their strict adherence to the described induction technique. As pointed out in the accompanying editorial, minor deviations from that technique may lead to different results, including failure to achieve tracheal intubation due to poor relaxation and inadequate intubation conditions. This may increase the risk of aspiration during the rapid sequence induction which the technique was originally instituted to guard against. The authors are to be commended for describing a technique that can be advantageous for brief surgical procedures that require muscle relaxation. A Cochrane database review, however, showed that the optimal dose of rocuronium for rapid sequence induction probably should be higher than 1 mg kg.