Effect of protracted dexamethasone exposure and its withdrawal on rocuronium-induced neuromuscular blockade and sugammadex reversal: an ex vivo rat study

Optimization of Application-Driven Development of In Vitro Neuromuscular Junction Models

Neuromuscular junctions (NMJs) are specialized synapses responsible for signal transduction between motor neurons (MNs) and skeletal muscle tissue. Malfunction at this site can result from developmental disorders, toxic environmental exposures, and neurodegenerative diseases leading to severe neurological dysfunction. Exploring these conditions in human or animal subjects is restricted by ethical concerns and confounding environmental factors. Therefore, in vitro NMJ models provide exciting opportunities for advancements in tissue engineering. In the last two decades, multiple NMJ prototypes and platforms have been reported, and each model system design is strongly tied to a specific application: exploring developmental physiology, disease modeling, or high-throughput screening. Directing the differentiation of stem cells into mature MNs and/or skeletal muscle for NMJ modeling has provided critical cues to recapitulate early-stage development. Patient-derived inducible pluripotent stem cells provide a personalized approach to investigating NMJ disease, especially when disease etiology cannot be resolved down to a specific gene mutation. Having reproducible NMJ culture replicates is useful for high-throughput screening to evaluate drug toxicity and determine the impact of environmental threat exposures. Cutting-edge bioengineering techniques have propelled this field forward with innovative microfabrication and design approaches allowing both two-dimensional and three-dimensional NMJ culture models. Many of these NMJ systems require further validation for broader application by regulatory agencies, pharmaceutical companies, and the general research community. In this summary, we present a comprehensive review on the current state-of-art research in NMJ models and discuss their ability to provide valuable insight into cell and tissue interactions. Impact statement In vitro neuromuscular junction (NMJ) models reveal the specialized mechanisms of communication between neurons and muscle tissue. This site can be disrupted by developmental disorders, toxic environmental exposures, or neurodegenerative diseases, which often lead to fatal outcomes and is therefore of critical importance to the medical community. Many bioengineering approaches for in vitro NMJ modeling have been designed to mimic development and disease; other approaches include in vitro NMJ models for high-throughput toxicology screening, providing a platform to limit or replace animal testing. This review describes various NMJ applications and the bioengineering advancements allowing for human NMJ characteristics to be more accurately recapitulated. While the extensive range of NMJ device structures has hindered standardization attempts, there is still a need to harmonize these devices for broader application and to continue advancing the field of NMJ modeling.

Reducing the dose of neuromuscular blocking agents with adjuncts: a systematic review and meta-analysis

BACKGROUND

Acute global shortages of neuromuscular blocking agents (NMBA) threaten to impact adversely on perioperative and critical care. The use of pharmacological adjuncts may reduce NMBA dose. However, the magnitude of any putative effects remains unclear.

METHODS

We conducted a systematic review and meta-analysis of RCTs. We searched Medline, Embase, Web of Science, and Cochrane Database (1970-2020) for RCTs comparing use of pharmacological adjuncts for NMBAs. We excluded RCTs not reporting perioperative NMBA dose. The primary outcome was total NMBA dose used to achieve a clinically acceptable depth of neuromuscular block. We assessed the quality of evidence using the GRADE (Grades of Recommendation, Assessment, Development, and Evaluation) criteria. Data are presented as the standardised mean difference (SMD); I² indicates percentage of variance attributable to heterogeneity.

RESULTS

From 3082 records, the full texts of 159 trials were retrieved. Thirty-one perioperative RCTs met the inclusion criteria for meta-analysis (n=1962). No studies were conducted in critically ill patients. Reduction in NMBA dose was associated with use of magnesium (SMD: -1.10 [-1.44 to -0.76], P<0.001; I²=85%; GRADE=moderate), dexmedetomidine (SMD: -0.89 [-1.55 to -0.22]; P=0.009; I²=87%; GRADE=low), and clonidine (SMD: -0.67 [-1.13 to -0.22]; P=0.004; I²=0%; GRADE=low) but not lidocaine (SMD: -0.46 [-1.01 to -0.09]; P=0.10; I²=68%; GRADE=moderate). Meta-analyses for nicardipine, diltiazem, and dexamethasone were not possible owing to the low numbers of studies. We estimated that 30-50 mg kg^-1 magnesium preoperatively (8-15 mg kg h^-1 intraoperatively) reduces rocuronium dose by 25.5% (inter-quartile range, 14.7-31).

CONCLUSIONS

Magnesium, dexmedetomidine, and clonidine may confer a clinically relevant sparing effect on the required dose of neuromuscular block ing drugs in the perioperative setting.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO: CRD42020183969.