Newer neuromuscular blocking agents: how do they compare with established agents?

Comparison of the Effects of Rocuronium Bromide and Cisatracurium Besylate on Intubating Conditions and Haemodynamic Response

Background General anaesthesia (GA) is predominantly important for conducting tracheal intubation; it should be quick and precise, having a prudent performance. It is preferable to use a neuromuscular blocking drug, which ideally should be highly potent, with a rapid onset and a short duration clinical effect in order to prevent the development of hypoxia during laryngoscopy and tracheal intubation and also avoid any changes in haemodynamics caused by the release of histamine, ganglion block, and anti-muscarinic actions. The non-depolarizing muscle relaxants rocuronium and cisatracurium don't have any noticeable independent side effects when used within the recommended dosage levels. Aim The aim was to compare the clinical efficacy of rocuronium bromide and cisatracurium besylate with respect to their property as muscle relaxants in producing favourable intubating conditions and to assess their haemodynamic stability. The objectives of the study were to evaluate the onset of action and any undesirable effects. Methods Between the ages of 20 to 60 years, 60 patients of either gender, divided randomly into groups of 30 each, of American Society of Anesthesiologists (ASA) physical status classification I and II, were put for elective surgical procedures to be done under general anaesthesia. Patients were given 0.6 mg kg-1 IV of rocuronium in Group R and 0.15 mg kg-1 IV of cisatracurium in Group C. After injecting the muscle relaxants, parameters were measured 60, 90, 120, 150, 180, 240, and 300 seconds later. Result Demographical variables like age, gender, and ASA physical status of the two groups were analogous. Group R had good to excellent/favourable intubating conditions by 90 seconds, and Group C by 240 seconds with comparable haemodynamic stability. The onset of action was significantly faster in Group R (92 ± 7.61 seconds) than in Group C (188 ± 40.88 seconds). Conclusion Rocuronium produced favourable intubating conditions having good haemodynamic stability and a statistically significant (p < 0.00001) faster onset of action in comparison to cisatracurium.

Management of Neuromuscular Blocking Agents in Critically Ill Patients with Lung Diseases

The use of neuromuscular blocking agents (NMBAs) is common in the intensive care unit (ICU). NMBAs have been used in critically ill patients with lung diseases to optimize mechanical ventilation, prevent spontaneous respiratory efforts, reduce the work of breathing and oxygen consumption, and avoid patient-ventilator asynchrony. In patients with acute respiratory distress syndrome (ARDS), NMBAs reduce the risk of barotrauma and improve oxygenation. Nevertheless, current guidelines and evidence are contrasting regarding the routine use of NMBAs. In status asthmaticus and acute exacerbation of chronic obstructive pulmonary disease, NMBAs are used in specific conditions to ameliorate patient-ventilator synchronism and oxygenation, although their routine use is controversial. Indeed, the use of NMBAs has decreased over the last decade due to potential adverse effects, such as immobilization, venous thrombosis, patient awareness during paralysis, development of critical illness myopathy, autonomic interactions, ICU-acquired weakness, and residual paralysis after cessation of NMBAs use. The aim of this review is to highlight current knowledge and synthesize the evidence for the effects of NMBAs for critically ill patients with lung diseases, focusing on patient-ventilator asynchrony, ARDS, status asthmaticus, and chronic obstructive pulmonary disease.

Analgesic and Anesthetic Efficacy of Rocuronium/Sugammadex in Otorhinolaryngologic Surgery: A Propensity Score-Matched Analysis

The use of rocuronium/sugammadex in otorhinolaryngologic surgery improves intubation conditions and surgical rating scales. This study primarily aimed to evaluate the effect of the combination of rocuronium and sugammadex on intraoperative anesthetic consumption. The secondary outcomes were the intraoperative and postoperative morphine milligram equivalent (MME) consumption, duration of intraoperative hypertension, extubation time, incidence of delayed extubation and postoperative nausea and vomiting, pain score, and length of stay. A total of 2848 patients underwent otorhinolaryngologic surgery at a tertiary medical center in southern Taiwan. After applying the exclusion criteria, 2648 of these cases were included, with 167 and 2481 in the rocuronium/sugammadex and cisatracurium/neostigmine groups, respectively. To reduce potential bias, 119 patients in each group were matched by propensity scores for sex, age, body weight, and type of surgery. We found that the rocuronium/sugammadex group was associated with significant preservation of the intraoperative sevoflurane and MME consumption, with reductions of 14.2% (p = 0.009) and 11.8% (p = 0.035), respectively. The use of the combination of rocuronium and sugammadex also significantly increased the dose of intraoperative labetalol (p = 0.002), although there was no significant difference in intraoperative hypertensive events between both groups. In conclusion, our results may encourage the use of the combination of rocuronium and sugammadex as part of volatile-sparing and opioid-sparing anesthesia in otorhinolaryngologic surgery.

Optimization of Intraoperative Neural Monitoring of the Recurrent Laryngeal Nerve in Thyroid Surgery

The application of intraoperative neural monitoring (IONM) has been widely accepted to improve surgical outcomes after thyroid surgery. The malfunction of an IONM system might interfere with surgical procedures. Thus, the development of anesthesia modalities aimed at ensuring functional neuromonitoring is essential. Two key issues should be taken into consideration for anesthetic management. Firstly, most patients undergo recurrent laryngeal nerve monitoring via surface electrodes embedded in an endotracheal tube. Thus, advanced video-assisted devices might optimize surface electrode positioning for improved neuromonitoring signaling accuracy. Secondly, neuromuscular blocking agents are routinely used during thyroid surgery. The ideal neuromuscular block should be deep enough for surgical relaxation at excision and recovered enough for an adequate signal f nerve stimulation. Proper neuromuscular block management could be achieved by titration doses of muscle relaxants and reversal agents.

The Safety Profile of General and Local Anaesthetic Agents: Data Collected during 20 Years of Spontaneous Reporting Activities in the Campania Region (Southern Italy)

Background: General and local anaesthetics are widely used during surgery. These drugs have peculiar safety profiles, being commonly associated with mild and reversible local adverse drug reactions (ADRs), but also with more severe and systemic ADRs, including respiratory and cardiovascular depression and anaphylaxis. Methods and Objectives: We carried out a descriptive analysis of Individual Case Safety Reports (ICSRs) sent to the Campania Regional Centre of Pharmacovigilance (Southern Italy) from 2001 to 2021 that reported general or local anaesthetics as suspected drugs, with the aim of describing their overall characteristics, focussing on the ADRs’ seriousness and distribution by System Organ Class (SOC) and Preferred Term (PT). Results: A total of 110 ICSRs documenting general or local anaesthetics were sent to the Italian pharmacovigilance database during 20 years of spontaneous reporting activities in the Campania region. ADRs mainly occurred in patients with a median age of 48 years and in a slightly higher percentage of men. ADRs were more commonly classified as not serious and had a favourable outcome. In terms of ADRs’ distribution by SOC and PT, both general and local anaesthetics were associated with general and cutaneous disorders, with common ADRs that included lack of efficacy, rash, and erythema. In addition, general anaesthetics were associated with the occurrence of respiratory ADRs, while local anaesthetics were associated with the occurrence of nervous ADRs. Conclusion: Even though a limited number of ICSRs documenting anaesthetics-induced ADRs were retrieved from the Italian spontaneous reporting database in the Campania region, we believe that the continuous monitoring of these drugs is highly recommended, especially among the frail population.

MRGPRX2 and Adverse Drug Reactions

Many adverse reactions to therapeutic drugs appear to be allergic in nature, and are thought to be triggered by patient-specific Immunoglobulin E (IgE) antibodies that recognize the drug molecules and form complexes with them that activate mast cells. However, in recent years another mechanism has been proposed, in which some drugs closely associated with allergic-type events can bypass the antibody-mediated pathway and trigger mast cell degranulation directly by activating a mast cell-specific receptor called Mas-related G protein-coupled receptor X2 (MRGPRX2). This would result in symptoms similar to IgE-mediated events, but would not require immune priming. This review will cover the frequency, severity, and dose-responsiveness of allergic-type events for several drugs shown to have MRGPRX2 agonist activity. Surprisingly, the analysis shows that mild-to-moderate events are far more common than currently appreciated. A comparison with plasma drug levels suggests that MRGPRX2 mediates many of these mild-to-moderate events. For some of these drugs, then, MRGPRX2 activation may be considered a regular and predictable feature after administration of high doses.

Comparison of neuromuscular blockade recovery co-administered with neostigmine and different doses of calcium gluconate: a randomized control trial

BACKGROUND

Calcium increases the probability of transmitter release at the neuromuscular junction. It is not known whether there is a dose-dependent relationship between the dosage of calcium gluconate and the probability of transmitter release for non-depolarizing neuromuscular blockade (NMB) recovery by acetylcholinesterase inhibitors (AchEIs). This study compared the neuromuscular recovery time and the incidence of postoperative residual curarization (PORC) according to the dosage of calcium gluconate co-administered with neostigmine in three patient groups.

METHODS

Patients were randomly allocated to a control group, a 5 mg/kg calcium gluconate group (calcium 5 group), or a 10 mg/kg calcium gluconate group (calcium 10 group). In patients with a TOF ratio (TOFr) between 0.2-0.7, 0.04 mg/kg of neostigmine was administered and both 0.2 mg of glycopyrrolate and 0.4 mg of atropine per 1 mg of neostigmine were administered. And additional 5 or 10 mg/kg of calcium gluconate were administrated to the calcium 5 and 10 groups. The primary endpoint was neuromuscular recovery time (the time between reversal and TOFr≥0.9). The secondary endpoints were the incidence of PORC at 5, 10, and 20 min after reversal administration and the train-of-four ratio (TOFr) at each time point.

RESULTS

The neuromuscular recovery time was 5.3 min in the control group, 3.9 min in the calcium 5 group, and 4.1 min in the calcium 10 group, respectively (P = 0.004). The incidence of PORC at 5 min after neostigmine administration was 12 in the control group, 4 in the calcium 5 group, and 4 in the calcium 10 group, respectively, with statistical significance (P = 0.014).

CONCLUSIONS

The co-administration of calcium gluconate with neostigmine safely promoted early NMB recovery, and the neuromuscular recovery time of the calcium 10 group tended to be more evenly distributed than that of the calcium 5 group.

TRIAL REGISTRATION

https://cris.nih.go.kr/cris/index.jsp(KCT0004182 ). Date of registration: August 122,019.

Minireview: Mas-related G protein-coupled receptor X2 activation by therapeutic drugs

Symptoms that resemble allergic reactions, such as pruritus, flushing, and hypotension, are common side effects of therapeutic drugs. In a true allergic reaction, Immunoglobulin E (IgE) antibodies recognize the drug and trigger mediator release from mast cells through cross-linking of IgE receptors. However, many drugs can bypass this pathway and can activate mast cells directly through MRGPRX2, a G protein-coupled receptor that responds to a wide range of small molecules, peptides, and proteins that have little in common except for a net positive charge. This review will provide an overview of MRGPRX2, including its expression pattern, studies of its pharmacology, and its orthologs. It also will review evidence for MRGPRX2 activation by many drugs closely associated with these reactions.

Comparison of the neuromuscular blocking effects of cisatracurium during isoflurane or propofol anesthesia in dogs

OBJECTIVE

To compare the neuromuscular blocking effects of cisatracurium during isoflurane versus propofol anesthesia in dogs.

STUDY DESIGN

Prospective, randomized study.

ANIMALS

A total of 20 healthy, client-owned dogs (16 females, four males) weighing 12.5-22 kg and aged 1-8 years.

METHODS

Dogs undergoing elective surgery were randomized in equal numbers to an isoflurane (ISO) or propofol (PPF) group. Other drugs used during anesthesia were equal between groups. Single-twitch (ST) stimulation was used to monitor neuromuscular response. After recording the baseline ST (T0), cumulative doses of cisatracurium (0.05 mg kg^-1) were administered intravenously until ST/T0 ≤5%. Effective doses 50 (ED₅₀) and 95 (ED₉₅) of cisatracurium in each group were calculated from group dose-response curves. Recovery of ST (TR) was defined as spontaneous recovery of ST to 80-120% of T0 remaining stable for 2 minutes. The ST after each dose of cisatracurium, duration 25% (time after the last dose until 25% recovery of TR), recovery index (time to recovery from 25% to 75% of TR) and duration to TR (time after the last dose until recovery of TR) were recorded.

RESULTS

Incremental doses of cisatracurium, median (range), were 2 (1-3) in ISO and 4 (2-5) in PPF to achieve ≥95% depression of ST/T0 (p < 0.01). ED₅₀ and ED₉₅ were 20 μg kg^-1 and 117 μg kg^-1 in ISO and 128 μg kg^-1 and 167 μg kg^-1 in PPF, respectively. The duration 25%, recovery index and duration to TR, median (range), were longer in ISO [22.6 (10.3-24.3), 5.3 (3.0-7.8) and 36.1 (20.1-49.7) minutes, respectively] than in PPF [10.2 (6.8-16.5), 3.0 (2.0-3.8) and 17.7 (14.2-28.7) minutes, respectively] (p < 0.01).

CONCLUSIONS AND CLINICAL RELEVANCE

Cisatracurium-induced neuromuscular blockade was significantly enhanced and prolonged by isoflurane compared with propofol.

Manual vs pressure-controlled facemask ventilation during the induction of general anesthesia in children: A prospective randomized controlled study

BACKGROUND

Gastric insufflation frequently occurs during facemask ventilation in children. In the present study, we compared the incidence of gastric insufflation between pressure-controlled facemask ventilation and manual facemask ventilation during general anesthesia induction in children.

METHODS

Children in the pressure-controlled ventilation group (n = 76) received pressure-controlled facemask ventilation at an inspiratory pressure of 13 cm H₂ O. In the manual ventilation group (n = 75), facemask ventilation was manually performed by anesthesiologists, who tried to maintain an inspiratory pressure of 13 cm H₂ O. The adjustable pressure limiting valve was set at 13 cm H₂ O. The incidence of gastric insufflation during 90 seconds after the initiation of ventilation was assessed using epigastric auscultation and gastric ultrasonography.

RESULTS

The incidence of gastric insufflation was significantly higher in the manual  facemask ventilation group than in the pressure-controlled ventilation group (48% vs 12%, respectively; odds ratio 7.78, 95% confidence interval [CI] 3.38-17.9; P < 0.001). The mean peak airway pressure during ventilation was significantly higher in the manual ventilation group than in the pressure-controlled ventilation group (16.1 [3.0] cm H₂ O vs 13.0 [0.1] cm H₂ O; 95% CI of differences, 2.36-3.71 cm H₂ O; P < 0.001). The manual ventilation group exhibited a wide peak airway pressure  range (11-26 cm H₂ O) and a wide variation of tidal volume (0-7.0 mL/kg) compared with those of the pressure-controlled ventilation group (13-14 cm H₂ O and 0.6-16.0 mL/kg, respectively).

CONCLUSION

At an inspiratory pressure of 13 cm H₂ O, pressure-controlled ventilation may be more effective than manual ventilation in preventing gastric insufflation while providing stable ventilation in children.

The effect of tulobuterol patches on the respiratory system after endotracheal intubation

Background

Endotracheal intubation during anesthesia induction may increase airway resistance (R_aw) and decrease dynamic lung compliance (C_dyn). We hypothesized that prophylactic treatment with a transdermal β2-agonist tulobuterol patch (TP) would help to reduce the risk of bronchospasm after placement of the endotracheal tube.

Methods

Eighty-two American Society of Anesthesiologists (ASA) category I or II adult patients showing obstructive patterns were divided randomly into a control and a TP group (n = 41 each). The night before surgery, a 2-mg TP was applied to patients in the TP group. Standard monitors were recorded, and target controlled infusion (TCI) with propofol and remifentanil was used for anesthesia induction and maintenance. Simultaneously, end-tidal carbon dioxide, R_aw, and C_dyn were determined at 5, 10, and 15 min intervals after endotracheal intubation.

Results

There was no significant difference in demographic data between the two groups. The TP group was associated with a lower R_aw and a higher C_dyn, as compared to the control group. R_aw was significantly lower at 10 min (P < 0.05) and 15 min (P < 0.01), and C_dyn was significantly higher at 5 min (P < 0.05) and 15 min (P < 0.01) in the TP group. A trend towards a lower R_aw was observed showing a statistically significant difference 5 min after endotracheal intubation (P < 0.01) in each group.

Conclusions

Prophylactic treatment with TP showed a bronchodilatory effect through suppressing an increase in R_aw and a decrease in C_dyn after anesthesia induction without severe adverse effects.

A comparison of haemodynamic responses between clinical assessment-guided tracheal intubation and neuromuscular block monitoring-guided tracheal intubation: A prospective, randomised study

BACKGROUND AND AIMS

Haemodynamic responses to laryngoscopy and endotracheal intubation and their hazards are well documented. The purpose of the study was to compare the effects of laryngoscopy and intubation on cardiovascular responses when the appropriate moment for intubation was directed by either clinical judgment or train-of-four assessment.

METHODS

A total of 68 patients, posted for laparoscopic cholecystectomy, were randomised into two groups. In Group M patients, the trachea was intubated after train of four counts became zero in adductor pollicis muscle, whereas in Group C patients, the trachea was intubated after the clinical judgment of jaw muscle relaxation. Changes in heart rate (HR) and mean arterial pressure, intubating conditions and the time between the administration of a neuromuscular blocking agent and endotracheal intubation were recorded. Results were analysed by the Analysis of variance and chi-square tests.

RESULTS

HR and mean arterial pressure were significantly higher in Group C as compared to Group M after laryngoscopy and tracheal intubation (P < 0.05). The mean time required for intubation was significantly shorter in Group C compared to Group M (175 ± 7 s vs. 385 ± 101 s). Excellent and good intubation conditions were observed in all Group M patients, whereas 24 out of 34 patients (70%) in Group C showed excellent and good intubation conditions.

CONCLUSION

Haemodynamic responses to laryngoscopy and tracheal intubation can be significantly attenuated if tracheal intubation is performed following complete paralysis of laryngeal muscles, detected by neuromuscular monitoring of adductor pollicis muscle.

Effects of Combined Rocuronium and Cisatracurium in Laparoscopic Cholecystectomy

Background

Laparoscopic upper abdominal surgery can cause spontaneous respiration due to diaphragmatic stimulation and intra-abdominal CO₂ inflation. Therefore, sufficient muscle relaxation is necessary for a safe surgical environment.

Methods

We investigated if the combination of rocuronium and cisatracurium can counteract the delayed onset of cisatracurium’s action and delayed recovery of muscle relaxation and whether the dosage of rocuronium, which is metabolized hepatically, can be reduced. A total of 75 patients scheduled for laparoscopic cholecystectomy with an American Society of Anesthesiology physical status I-II, in the age range of 20–60 years, and with a 20–30 kg/m² body mass index were included in the study.

Results

The patients were divided into the following groups: combination group (Group RC, rocuronium 0.3 mg/kg and cisatracurium 0.05 mg/kg), rocuronium group (Group R, rocuronium 0.6 mg/kg), and cisatracurium group (Group C, cisatracurium 0.1 mg/kg), and the onset, 25% duration, recovery index, and addition/time ratio were measured. Patients in Group RC exhibited a significantly different addition/time ratio compared with patients in the other two groups (p = 0.003).

Conclusion

During laparoscopic cholecystectomy, the 95% effective dose of rocuronium in combination with cisatracurium is expected to provide a sufficient muscle relaxant effect.

Editor's Choice-The cardiovascular implications of sedatives in the cardiac intensive care unit

Patients admitted to the cardiac intensive care unit frequently develop multi-organ system dysfunction associated with their cardiac disease. In many cases, invasive mechanical ventilation is required, which often necessitates sedation for patient-ventilator synchrony, reduction of work of breathing, and patient comfort. In this paper, we describe the use of common sedatives available in the endotracheally intubated critically ill patient and emphasize the clinical and cardiovascular effects. We review γ-aminobutyric acid agonists such as etomidate, benzodiazepines, and propofol, the centrally acting α₂-agonist dexmedetomidine, and the N-methyl-D-aspartate receptor antagonist ketamine. Additionally, we outline the use of opioids and their role in potentiating other sedatives. We note that some sedatives are associated with increased delirium rates, and emphasize that judicious strategies minimizing sedative use are associated with decreases in morbidity and mortality. We also discuss standardized sedation assessment scales and highlight the importance of sedation weaning. Finally, we offer recommendations for sedation use during therapeutic hypothermia, and discuss the use of adjuvant neuromuscular blocking agents.

A New Structure-Activity Relationship (SAR) Model for Predicting Drug-Induced Liver Injury, Based on Statistical and Expert-Based Structural Alerts

The prompt identification of chemical molecules with potential effects on liver may help in drug discovery and in raising the levels of protection for human health. Besides in vitro approaches, computational methods in toxicology are drawing attention. We built a structure-activity relationship (SAR) model for evaluating hepatotoxicity. After compiling a data set of 950 compounds using data from the literature, we randomly split it into training (80%) and test sets (20%). We also compiled an external validation set (101 compounds) for evaluating the performance of the model. To extract structural alerts (SAs) related to hepatotoxicity and non-hepatotoxicity we used SARpy, a statistical application that automatically identifies and extracts chemical fragments related to a specific activity. We also applied the chemical grouping approach for manually identifying other SAs. We calculated accuracy, specificity, sensitivity and Matthews correlation coefficient (MCC) on the training, test and external validation sets. Considering the complexity of the endpoint, the model performed well. In the training, test and external validation sets the accuracy was respectively 81, 63, and 68%, specificity 89, 33, and 33%, sensitivity 93, 88, and 80% and MCC 0.63, 0.27, and 0.13. Since it is preferable to overestimate hepatotoxicity rather than not to recognize unsafe compounds, the model's architecture followed a conservative approach. As it was built using human data, it might be applied without any need for extrapolation from other species. This model will be freely available in the VEGA platform.

Interaction of rocuronium with human liver cytochromes P450

Rocuronium is a neuromuscular blocking agent acting as a competitive antagonist of acetylcholine. Results of an inhibition of eight individual liver microsomal cytochromes P450 (CYP) are presented. As the patients are routinely premedicated with diazepam, possible interaction of diazepam with rocuronium has been also studied. Results indicated that rocuronium interacts with human liver microsomal CYPs by binding to the substrate site. Next, concentration dependent inhibition of liver microsomal CYP3A4 down to 42% (at rocuronium concentration 189 μM) was found. This effect has been confirmed with two CYP3A4 substrates, testosterone (formation of 6β-hydroxytestosterone) and diazepam (temazepam formation). CYP2C9 and CYP2C19 activities were inhibited down to 75-80% (at the same rocuronium concentration). Activities of other microsomal CYPs have not been inhibited by rocuronium. To prove the possibility of rocuronium interaction with other drugs (diazepam), the effect of rocuronium on formation of main diazepam metabolites, temazepam (by CYP3A4) and desmethyldiazepam, (also known as nordiazepam; formed by CYP2C19) in primary culture of human hepatocytes has been examined. Rocuronium has caused inhibition of both reactions by 20 and 15%, respectively. The results open a possibility that interactions of rocuronium with drugs metabolized by CYP3A4 (and possibly also CYP2C19) may be observed.

Development of SPME method for concomitant sample preparation of rocuronium bromide and tranexamic acid in plasma

A high-throughput method using solid-phase microextraction coupled to liquid chromatography-tandem mass spectrometry (SPME-LC-MS/MS) for determination of tranexamic acid and rocuronium bromide in human plasma was developed and validated. Standard analytical approaches employ acidification of the sample due to the instability of rocuronium bromide in collected plasma samples. However, acidification affects the binding equilibrium of the drug and consequently no information on the free/bound concentration can be obtained. Contrary to these protocols, the proposed method requires minimum sample handling and no ion pairing and/or derivatization procedure. A weak cation exchange coating was chosen as the best extracting phase for selected drugs, guaranteed a good recovery, minimum carry-over, reusability and reproducibility. SPME procedure met all Food and Drug Administration acceptance criteria for bioanalytical assays at three concentration levels, for both selected drugs. Post-extraction addition experiments showed that matrix effect was less than ±3%. Here, a weak cation exchange thin-film solid-phase microextraction (WCX TF-SPME) approach is presented, offering effective cleanup procedure and full quantitation of the drugs in plasma, undoubtedly one the most challenging matrices with regards to its complexity. In addition, the 96-well plate format of WCX TF-SPME system provides considerable advantages, such as high throughput analysis for up to 96 samples in 35min (22s/sample), requirement of small amounts of plasma samples (0.8mL), and a simple sample preparation protocol, all of which shows a promise for possible on-site application in hospitals to monitor concentrations of the drugs in close to real time.

Influence of obstructive jaundice on pharmacodynamics of rocuronium

BACKGROUND

Anesthetics are variable in patients with obstructive jaundice. The minimum alveolar concentration awake of desflurane is reduced in patients with obstructive jaundice, while it has no effect on pharmacodynamics and pharmacokinetics of propofol. In this study, we investigated the influence of obstructive jaundice on the pharmacodynamics and blood concentration of rocuronium.

METHODS

Included in this study were 26 control patients and 27 patients with obstructive jaundice. Neuromuscular block of rocuronium was monitored by acceleromyography. Onset time, spontaneous recovery of the height of twitch first (T1) to 25% of the final T1 value (Duration 25%, Dur 25%), recovery index (RI), and spontaneous recovery of train-of-four (TOF) ratios to 70% were measured. The plasma rocuronium concentrations were determined by high performance liquid chromatography using berberine as an internal standard.

RESULTS

There was no significant difference in onset time between the two groups. The Dur 25%, the recovery index and the time of recovery of the TOF ratios to 70% were all prolonged in the obstructive jaundice group compared with the control group. The plasma concentration of rocuronium at 60, 90 and 120 min after bolus administration was significantly higher in the obstructive jaundice group.

CONCLUSIONS

The neuromuscular blockade by rocuronium is prolonged in obstructive jaundice patients, and therefore precautions should be taken in case of postoperative residual neuromuscular block. The possible reason is impedance of rocuronium excretion due to biliary obstruction and increased plasma unbound rocuronium because of free bilirubin competing with it for albumin binding.

Drug absorption, distribution, metabolism and excretion considerations in critically ill adults

INTRODUCTION

All critically ill patients require medication to treat organ dysfunction. However, the pharmacokinetics of drugs used to treat these patients is complex due to frequent alterations in drug absorption, distribution, metabolism, and excretion (ADME).

AREAS COVERED

This review examines pharmacokinetic aspects of drug administration for adult intensive care unit (ICU) patients. Specifically, the authors examine the ADME changes that occur and which should be considered by clinicians when delivering drug therapy to critically ill patients.

EXPERT OPINION

Dosage pharmacokinetics determined from single-dose or limited-duration administration studies in healthy volunteers may not apply to critically ill patients. Organ dysfunction among these patients may be due to pre-existing disease or the effects of a systemic or locoregional inflammatory response precipitated by their illness. Alterations in pharmacokinetics observed among the critically ill include altered bioavailability after enteral administration, increased volume of distribution and blood-brain barrier permeability and changes in P-glycoprotein and cytochrome P450 enzyme function. However, the effect of these changes on clinically important outcomes remains uncertain and poorly studied. Future investigations should examine not only pharmacokinetic changes among the critically ill, but also whether recognition of these changes and alterations in drug therapy directed as a consequence of their observation alters patient outcomes.

Anesthesiologist's satisfaction using between cisatracurium and rocuronium for the intubation in the anesthesia induced by remifentanil and propofol

BACKGROUND

Although cisatracurium has many advantages in anesthetic practices, the best choice of a nondepolarizing neuromuscular blocking agent that can replace succinylcholine is rocuronium. However, it is reported that remifentanil with propofol might provide reliable intubating condition, even without a neuromuscular blocking agent; therefore, it might improve the intubating condition with cisatracurium. This study examined intubating conditions after administering rocuronium or cisatracurium in a rapid sequence induction with remifentanil-propofol.

METHODS

Fifty two ASA physical status 1 or 2 adult patients scheduled for an elective surgery were enrolled in a randomized double-blinded trial. Anesthesia was induced in all patients with propofol 2.0 mg/kg and remifentanil 0.5 µg/kg, administered over 60 seconds. Rocuronium 0.9 mg/kg (3 × ED(95), R group, n = 23) or cisatracurium 0.15 mg/kg (3 × ED(95), C group, n = 29) was administered after the induction sequence. Laryngoscopy was attempted when the anesthesiologist thought it was 90 seconds after drug administration and appropriate time for intubation. The examiner, another anesthesiologist, recorded the exact time to intubation and suppression of maximal T1 on TOF. The intubating condition was assessed by the first anesthesiologist, as excellent, good, poor or not possible.

RESULTS

The best time to laryngoscopy was predicted by measuring TOF and was found to be significantly longer in the C group (197 ± 53 s) than in the R group (102 ± 49 s) (P value < 0.05). However, time to larygoscopy, intubating condition during the laryngoscopy, and hemodynamic changes after intubation was similar in both groups.

CONCLUSIONS

Despite fundamentally slower onset time, cisatracurium can provide quite good intubating conditions, which were comparable to those achieved with equipotent doses of rocuronium, which is more expensive in anesthesia inducted with remifentanil and propofol.

Effect of ulinastatin on the rocuronium-induced neuromuscular blockade

BACKGROUND

Ulinastatin 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.

METHODS

Forty 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.

RESULTS

In 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).

CONCLUSIONS

Ulinastatin significantly delays the onset of neuromuscular block and accelerates the recovery from the block caused by rocuronium.

Continuous-infusion neuromuscular blocking agents in critically ill neonates and children

Neuromuscular blocking agents (NMBAs) are often administered as a prolonged (> 24 hrs) continuous infusion in infants and children in the intensive care unit for a variety of reasons including facilitation of oxygenation and ventilation. No guidelines on the use of NMBAs in pediatric patients are available yet in the United States; however, pediatric guidelines are available in the United Kingdom. Based on a 2007 U.S. survey, the most commonly used nondepolarizing NMBAs for sustained neuromuscular blockade in critically ill children are pancuronium and vecuronium. Recent national drug shortages involving NMBAs have been reported for atracurium, cisatracurium, pancuronium, rocuronium, and vecuronium. Therefore, to explore alternative options for neuromuscular blockade, we conducted a literature search to identify articles evaluating prolonged use (> 24 hrs) of NMBAs administered by continuous infusion. The search was limited to English-language articles in the MEDLINE (1950-August 2010), EMBASE (1988-August 2010), International Pharmaceutical Abstracts (1970-August 2010), and Cochrane Library (1996-August 2010) databases. Relevant abstracts, reference citations, and manufacturers' product information were also reviewed. A total of 13 reports representing 208 children were included in the analysis. Many of the reports described wide interpatient variability in dosing for the specific NMBAs evaluated. Selection of the most appropriate NMBA should be based on the patient's clinical status, potential adverse effects, and pharmacoeconomics. All patients receiving sustained neuromuscular blockade should be monitored routinely to ensure that dosing is appropriate in order to obtain the desired level of blockade. The goal is to use the lowest dose possible in an effort to limit adverse effects or prolonged blockade.

Reversal of profound vecuronium-induced neuromuscular block under sevoflurane anesthesia: sugammadex versus neostigmine

Background

Acetylcholinesterase inhibitors cannot rapidly reverse profound neuromuscular block. Sugammadex, a selective relaxant binding agent, reverses the effects of rocuronium and vecuronium by encapsulation. This study assessed the efficacy of sugammadex compared with neostigmine in reversal of profound vecuronium-induced neuromuscular block under sevoflurane anesthesia.

Methods

Patients aged ≥18 years, American Society of Anesthesiologists class 1-4, scheduled to undergo surgery under general anesthesia were enrolled in this phase III, multicenter, randomized, safety-assessor blinded study. Sevoflurane anesthetized patients received vecuronium 0.1 mg/kg for intubation, with maintenance doses of 0.015 mg/kg as required. Patients were randomized to receive sugammadex 4 mg/kg or neostigmine 70 μg/kg with glycopyrrolate 14 μg/kg at 1-2 post-tetanic counts. The primary efficacy variable was time from start of study drug administration to recovery of the train-of-four ratio to 0.9. Safety assessments included physical examination, laboratory data, vital signs, and adverse events.

Results

Eighty three patients were included in the intent-to-treat population (sugammadex, n = 47; neostigmine, n = 36). Geometric mean time to recovery of the train-of-four ratio to 0.9 was 15-fold faster with sugammadex (4.5 minutes) compared with neostigmine (66.2 minutes; p < 0.0001) (median, 3.3 minutes with sugammadex versus 49.9 minutes with neostigmine). No serious drug-related adverse events occurred in either group.

Conclusions

Recovery from profound vecuronium-induced block is significantly faster with sugammadex, compared with neostigmine. Neostigmine did not rapidly reverse profound neuromuscular block (Trial registration number: NCT00473694).

The effect of priming with rocuronium on onset time and intubation conditions during endotracheal intubation with low-dose rocuronium

BACKGROUND

A priming dose of rocuronium can shorten the onset time of neuromuscular blockade. The purpose of this study was to evaluate the effect of priming with rocuronium on the onset time and intubation conditions during tracheal intubation with low-dose rocuronium (0.35 mg/kg) and to compare results with those for rocuronium 0.45 mg/kg.

METHODS

One hundred twenty four patients were randomly allocated to three groups. Following induction of anesthesia, groups I and III received normal saline while group II received a priming dose of rocuronium (0.05 mg/kg). Three minutes after priming, groups I, II and III received, respectively, 0.45 mg/kg, 0.3 mg/kg and 0.35 mg/kg rocuronium. Intubation was performed 2 minutes after the administration of an intubating dose and intubation conditions were evaluated. Neuromuscular blockade was assessed by accelerography.

RESULTS

The proportion of cases having optimal intubation conditions in group I was higher than in groups II and III. There was no significant difference in the onset times among groups. Neuromuscular blockade at 60, 90 and 120 seconds after an intubating dose was similar among all groups except at 60 sec. Maximal blockade for group I was deep compared to groups II and III.

CONCLUSIONS

Rocuronium 0.35 mg/kg does not provide satisfactory intubation conditions. There are no effects on onset time and intubation conditions due to priming during tracheal intubation with rocuronium 0.35 mg/kg.

Incidence and duration of residual paralysis at the end of surgery after multiple administrations of cisatracurium and rocuronium

In a randomised, controlled, double-blind, multicentre trial in 338 patients, we assessed the incidence of residual paralysis following administration of cisatracurium or rocuronium. The incidence at the end of surgery was significantly lower in patients treated with rocuronium (62 of 142 patients, 44%) than in those given cisatracurium (99 of 175 patients, 57%) (p < 0.05). In contrast, with rocuronium the mean (SD) time between skin closure and extubation was 28 (28) min vs 18 (19) min for cisatracurium, and the duration 0.9 (time from administration of last top-up dose to recovery of the train-of-four ratio to 0.9) was significantly longer and more variable for rocuronium than for cisatracurium. Thus, after repeated administration, the duration and variability of duration of action are greater with rocuronium compared with cisatracurium. These pharmacodynamic differences do not necessarily translate into a higher incidence of residual paralysis, because clinicians compensate for the longer duration of action and variability of rocuronium by terminating administration of the neuromuscular blocking earlier.

Neuromuskuläre Blockade

Currently, the main aims of using neuromuscular blocking agents during general anaesthesia are the improvement of surgical and intubation conditions. Neuromuscular blocking agents themselves are neither analgesic nor anaesthetic. All agents interact with the acetylcholinergic receptor at the neuromuscular junction and induce a blockade either through a continuous activation imitating the effect of acetylcholine or through a competitive antagonism against acetylcholine. Succinylcholine is the only depolarizing muscle relaxant that is in clinical use. Non-depolarizing neuromuscular blockers may be grouped by their chemical structure into benzylisoquinolines or aminosteroids, and cover the complete range from short and intermediate, to long acting agents. Possible adverse drug reactions to the single agents are also related to their mechanism of action. Moreover, pharmacokinetic properties and effects such as histamine liberation could play an important role when choosing a myorelaxant. The depth of a neuromuscular block and recovery from paralysis can be monitored using qualitative and quantitative techniques. Therefore, the monitoring of neuromuscular recovery plays an important role in the prevention of postoperative complications due to residual paralysis. In case of residual paralysis, cholinesterase inhibitors are suitable for reversal.

Cisatracurium: myographical and electrophysiological studies in the isolated rat muscle

Myographical and electrophysiological studies of cisatracurium were performed, in vitro, in the isolated sciatic nerve-extensor digitorum longus muscle preparation of the rat. Indirect twitches were generated at 0.1 Hz and tetanic contractions at 50 Hz. endplate potentials (epps) were generated in trains of 50 Hz. The electrophysiological variables used in the analysis of the epps were: amplitude of the first epp in the train, average amplitude of the 30 degrees to the 59 degrees epp in the train (epps-plateau), tetanic rundown (percent loss in amplitude of epps-plateau relative to the first epp in the train), quantal size and quantal content. The myographical results showed that the inhibitory concentration 50% (IC(50)) of cisatracurium for the blockade of twitches (0.48 microm) is 12 times its IC(50) for the induction of tetanic fade (0.04 microm). The electrophysiological results showed a concentration dependent decrease in the amplitudes of first epps in the trains and of epps-plateau in the two used concentrations (0.13 microm and 0.38 microm). The tetanic rundown was intensified only in the presence of the higher (0.38 microm) concentration of cisatracurium. In cisatracurium 0.13 microm (a concentration which affects only tetanic contractions, inducing their fade, while leaving the twitch unaffected) there was a decrease in the quantal content of the first epp and of epps-plateau in the train. In cisatracurium (0.38 microm), a concentration, which affects the twitch, there was a decrease of the quantal size and of quantal content of epps-plateau, but not of the quantal content of the first epp in the train. The results indicate that the fade of the tetanic contraction induced by cisatracurium at the concentration of 0.13 microm is entirely because of a pre-synaptic blocking effect while the decrease in the twitch induced by cisatracurium at the concentration of 0.38 microm is due to a post-synaptic blocking effect.

Cough suppressant and pharmacologic protussive therapy: ACCP evidence-based clinical practice guidelines

BACKGROUND

Cough-suppressant therapy, previously termed nonspecific antitussive therapy, incorporates the use of pharmacologic agents with mucolytic effects and/or inhibitory effects on the cough reflex itself. The intent of this type of therapy is to reduce the frequency and/or intensity of coughing on a short-term basis.

METHODS

Data for this review were obtained from several National Library of Medicine (PubMed) searches (from 1960 to 2004), which were performed between May and September 2004, of the literature published in the English language, limited to human studies, using combinations of the search terms "cough," "double-blind placebo-controlled," "antitussive," "mucolytic," "cough clearance," "common cold," "protussive," "guaifenesin," "glycerol," and "zinc."

RESULTS

Mucolytic agents are not consistently effective in ameliorating cough in patients with bronchitis, although they may be of benefit to this population in other ways. Peripheral and central antitussive agents can be useful in patients with chronic bronchitis, but can have little efficacy in patients with cough due to upper respiratory infection. Some protussive agents are effective in increasing cough clearance, but their long-term effectiveness has not been established. DNase is not effective as a protussive agent in patients with cystic fibrosis. Inhaled mannitol is acutely effective in this patient population, but its therapeutic potential must be investigated further.

CONCLUSIONS

These findings suggest that suppressant therapy is most effective when used for the short-term reduction of coughing. Relatively few drugs are effective as cough suppressants.

Neuromuskuläre Restblockaden

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.

Strategies and algorithms for management of the difficult airway

Management of the difficult airway is the most important patient safety issue in the practice of anaesthesia. Many national societies have developed algorithms and guidelines for management of the difficult airway. The key issues of this chapter are definition of terms, the advantages and disadvantages of the use of guidelines, and a comparison of different algorithms and guidelines for management of the most important clinical airway scenarios. Although there is no strong evidence of benefit for any specific strategy or algorithm for management of the difficult airway, there is strong agreement that a pre-planned strategy may lead to improved outcome.

Prolonged paralysis related to mivacurium: A case study

Pseudocholinesterase deficiency is usually identified when an anesthetized patient has prolonged paralysis after receiving neuromuscular blocking agents dependent on pseudocholinesterase enzymes for hydrolysis. This rare complication, most frequently associated with succinylcholine, can occur with the use of mivacurium, one of the newer nondepolarizing muscle relaxants also hydrolyzed by pseudocholinesterase. Prolonged paralysis has occurred 3 times in the past 2 years at this pediatric hospital after administration of mivacurium. The following case study describes causality and interventions for a patient with prolonged paralysis after receiving mivacurium.

Low doses of rocuronium during remifentanil-propofol-based anesthesia in children: comparison of intubating conditions

BACKGROUND

In this prospective double-blind study, intubation conditions were compared at 90 s following two different low doses of rocuronium during remifentanil and propofol anesthesia in children undergoing ambulatory procedures.

METHODS

Forty-four children (ASA I-II, aged 3-12 years) undergoing day case ENT surgery were premedicated with midazolam 0.5 mg x kg(-1). Following atropine 10 microg x kg(-1), remifentanil infusion 0.5 microg x kg(-1) x min(-1) was started. After 60 s, anesthesia was induced with propofol 2.5 mg x kg(-1). Immediately after a bolus dose of propofol, the children received rocuronium doses of 0.15 mg x kg(-1) (group I, n = 22) or 0.3 mg x kg(-1) (group II, n = 22) in a randomized manner, after which an infusion of propofol 6 mg x kg(-1) h(-1) was added to the infusion of remifentanil 0.5 microg x kg(-1) min(-1) for maintenance of anesthesia. Intubating conditions were evaluated 90 s after rocuronium administration applying the Copenhagen Scoring System which included components of laryngoscopy, vocal cord movement and reaction to intubation. Hemodynamic values were recorded at predetermined time intervals.

RESULTS

Excellent, good and poor intubation conditions were 18.2, 40.9 and 40.9% in group I and 40.9, 54.5 and 4.5% in group II. Clinically acceptable intubating conditions (excellent and good) were significantly higher in group II (95.5%) than in group I (59.1%) (P = 0.004). Mean values of heart rate and blood pressure did not differ significantly between groups. No children required any intervention for hemodynamic instability and/or muscle rigidity.

CONCLUSIONS

The results suggest that 0.3 mg x kg(-1) of rocuronium may be a better low dose than 0.15 mg x kg(-1) of rocuronium for clinically acceptable intubating conditions in pediatric ambulatory surgery during remifentanil-propofol-based anesthesia at the doses used in the study.

Comparison of the neuromuscular blocking effect of cisatracurium and atracurium on the larynx and the adductor pollicis

BACKGROUND

Cisatracurium unlike atracurium is devoid of histamine-induced cardiovascular effects and this alone would be the greatest advantage in replacing atracurium for the facilitation of tracheal intubation. On the other hand, 2 ED(95) doses of cisatracurium (100 micro g/kg) do not yield satisfactory intubating conditions such as those seen with equipotent doses of atracurium and therefore the recommended intubating dose of cisatracurium is 3 ED(95). To understand this discrepancy better, we evaluated the potency and onset of atracurium and cisatracurium directly at the larynx adductors in humans.

METHODS

The study was conducted in 54 patients (ASA class I or II) undergoing peripheral surgery requiring general anesthesia. Cisatracurium 25-150 micro g/kg or atracurium 120-500 micro g/kg intravenous (i.v.) boluses doses were administered during anesthesia with propofol, nitrous oxide, oxygen and fentanyl. Neuromuscular block was measured by electromyography (single twitch stimulation every 10 s) at the larynx and the adductor pollicis. The dose-response effect measured at both muscles included maximum neuromuscular blockade achieved (Emax), the time to maximum depression of twitch height (onset) and time to spontaneous recovery of the twitch height to 25%, 75% and 90% (T25, T75, T90) of control value.

RESULT

The onset at the larynx was of 196 +/- 28 s after the 100 micro g/kg cisatracurium dose compared with 140 +/- 14 s after the 500 micro g/kg atracurium dose (P < 0.05). Emax at the larynx was 92 +/- 1% and 98 +/- 1% after 100 micro g/kg cisatracurium and 500 micro g/kg atracurium, respectively (P < 0.05). The time to onset of maximum suppression Emax = 100 +/- 0% after a 150 micro g/kg cisatracurium dose was 148 +/- 29 s. At the larynx, the ED(50) was 25 micro g/kg for cisatracurium and 180 micro g/kg for atracurium and the ED(95) was 87 micro g/kg for cisatracurium compared with 400 micro g/kg for atracurium.

CONCLUSION

The slow onset time at the laryngeal muscles after cisatracurium can be explained by the higher potency as compared with atracurium.

Neuromuscular blocking activity and therapeutic potential of mixed-tetrahydroisoquinolinium halofumarates and halosuccinates in rhesus monkeys

Structure-activity relationships in rhesus monkeys for a novel mixed-onium class of ultra-short-acting nondepolarizing tetrahydroisoquinolinium neuromuscular blockers (NMBs) are described. Bis-onium chlorofumarate 20a with (1R,2S)-benzyltetrahydroisoquinolinium groups was a potent lead compound (ED(95) = 0.079 mg/kg) with an ultra-short duration of NMB effect (7.1 min) and a selectivity index (SI: defined as a ratio of the cardiovascular threshold dose to the ED(95)) similar to that of mivacurium (3). The mean threshold dose for cardiovascular effects with 20a was ca. 20 times its ED(95) value (SI = 20). A novel mixed-onium analogue of 20a was prepared by replacing the benzyltetrahydroisoquinolinium group distal to the fumarate chlorine atom with a (1S,2R)-phenyltetrahydroisoquinolinium moiety. The resulting mixed-onium chlorofumarate 24a displayed good NMB potency (ED(95) = 0.063 mg/kg), ultra-short duration of action (5.6 min) and an improved selectivity index (SI = 57). Several other mixed-onium derivatives containing octanedioate (25a; ED(95) = 0.103 mg/kg), difluorosuccinate (27c; ED(95) = 0.056 mg/kg), and fluorofumarate (28a; ED(95) = 0.137 mg/kg) linkers were also potent, ultra-short-acting NMBs with good to excellent selectivity index values (SI = 37-96). Octanedioate 25a was longer acting at higher doses compared to difluorosuccinate 27c and chlorofumarate 24a. Durations of NMB effect following a 0.4 mg/kg bolus dose (100% block) of 25a, 27c, and 24a were 16.9, 13.0, and 10.0 min, respectively. Recovery time for mixed-onium chlorofumarate 24a following a 1 h continuous infusion at 10-20 microg/kg/min (95-100% block) was ca. 5 min which is similar to that observed following a 0.2 mg/kg bolus dose of this compound and indicates a lack of cummulative effects. Preliminary studies with chlorofumarate 24a in whole human blood revealed that mixed-onium thiazolidine 29 was the major metabolite and that plasma cholinesterases do not play the primary role in duration of NMB effect. The NMB properties of 24a in rhesus monkeys led to its clinical evaluation as a possible alternative to succinylcholine.