The Effect of Phonomyography Prototype for Intraoperative Neuromuscular Monitoring: A Preliminary Study

Quantitative neuromuscular monitoring, as extolled by clinical guidelines, is advocated to circumvent the complications associated with neuromuscular blockers (NMBs), such as residual neuromuscular block (rNMB). Nonetheless, the worldwide utilization of such methods remains undesirable. Phonomyography (PMG) boasts the advantages of convenience, stability, and multi-muscle recording which may be a promising monitoring method. The purpose of this preliminary study is conducting a feasibility analysis and an effectiveness evaluation of a PMG prototype under general anesthesia. A prospective observational preliminary study was conducted. Twenty-five adults who had undergone none-cardiac elective surgery were enrolled. The PMG prototype and TOF-Watch SX simultaneously recorded the pharmacodynamic properties of single bolus rocuronium at the ipsilateral adductor pollicis for each patient. For the primary outcome, the time duration to 0.9 TOF ratio of the two devices reached no statistical significance (p > 0.05). For secondary outcomes, the multi-temporal neuromuscular-monitoring measurements between the two devices also reached no statistical significance (p > 0.05). What is more, both the Spearman's and Pearson's correlation tests revealed a strong correlation across all monitoring periods between the PMG prototype and TOF-Watch SX. Additionally, Bland-Altman plots demonstrated a good agreement between the two devices. Thus, the PMG prototype was a feasible, secure, and effective neuromuscular-monitoring technique during general anesthesia and was interchangeable with TOF-Watch SX.

Methods for Clinical Monitoring of Neuromuscular Transmission in Anesthesiology - A Review

The administration of general anesthesia is a crucial aspect of surgery. However, it can pose significant risks to patients, such as respiratory depression and prolonged neuromuscular blockade. To avoid such complications, it is essential to monitor neuromuscular transmission during anesthesia. While clinical tests have been used for decades to evaluate muscle function, they are now known to be unreliable, and relying on them increases the risk of postoperative complications. Thankfully, there are now six methods available for neuromuscular monitoring during anesthesia: mechanomyography, acceleromyography, electromyography, kinemyography, phonomyography, and compressomyography. Each of these methods differs in terms of their approach and methodology, and their importance in clinical practice varies accordingly. Mechanomyography involves measuring the mechanical response of a muscle to nerve stimulation, while acceleromyography measures the acceleration of muscle contraction. Electromyography records the electrical activity of muscles, while kinemyography tracks muscle movement. Phonomyography records the sound waves produced by contracting muscles, and compressomyography involves monitoring the pressure changes in a muscle during contraction. Overall, understanding the differences between these methods and their clinical significance is crucial for anesthesiologists. This review aims to provide an updated understanding of the current methods available for neuromuscular monitoring during anesthesia, so that anesthesiologists can make informed decisions about patient care and reduce the risk of postoperative complications.

Electrocardiogram Cream Reduces Skin-Electrode Impedance Upon Neuromuscular Monitoring Using TOF-Cuff®

Background Mechanistic insight into the high failure rate of TOF-Cuff® (RGB Medical Devices, Madrid, Spain) measurements on the lower leg is unclear. Aims We aimed to determine whether materials applied to pseudo-skin can reduce the impedance between a model arm and TOF-Cuff® electrodes and whether a material between TOF-Cuff® electrodes and the patient's skin surface decreases the skin-TOF-Cuff® electrode impedance within the appropriate range. Methods This was a combination of an in vitro study using non-living materials and a prospective observational clinical study. Eight patients aged > 70 years who had undergone elective surgery were eligible. One of the primary outcomes was whether water, electrocardiogram (ECG) cream, or ECG gel applied on the pseudo-skin could reduce the impedance between the model arm and the TOF-Cuff® electrodes in the in vitro study. Another was whether a material between the TOF-Cuff® electrodes and the patient's skin surface decreased the skin-TOF-Cuff® electrode impedance to an appropriate level of less than 5,000 Ω in the clinical study. Results The application of water, ECG cream, and ECG gel similarly reduced the impedance values within the electrical circuit in the in vitro study. ECG cream application between the patient's skin surface and the TOF-Cuff® electrodes decreased the skin-TOF-Cuff® electrode impedance (median (interquartile range (IQR)) Ω) from 8,600 (6,450 to 9,775) to 2,000 (1,600 to 2,600) (P = 0.012) in surgical patients. Conclusion ECG cream application between the patient's skin surface and the TOF-Cuff® electrodes decreased the skin-TOF-Cuff® electrode impedance appropriately, and thus, the application can facilitate precise TOF-Cuff® measurements in patients.

Rate of residual neuromuscular block using single-dose rocuronium in general anesthesia for ENT surgery: a retrospective cohort study

INTRODUCTION

NMB facilitates intubating conditions in general anesthesia. However, it is associated with significant residual postoperative paralysis and morbidity.

OBJECTIVE

To investigate the rate of underdiagnosed residual NMB based on two TOFR criteria (< 0.91 and < 1.00).

METHODS

We performed a retrospective study adhering to STROBE guidelines. We included patients undergoing ENT surgery using single-dose neuromuscular block for balanced general anesthesia from June to December 2018. We collected demographic and anthropometric data, ASA score, NMBA dose, TOFR recordings at 5, 30 and 60 min and end of the surgery, anesthesia and surgery time, and administration of reversal agent. Statistical analysis included descriptive and dispersion measures statistics, curve and cross tables for residual NMB on different TOFR criteria with sub-analysis for AR, RR, and OR in patients over 65 years old.

RESULTS

We included 57 patients, mean age 41; 43 females and 14 males. Mean anesthetic and surgical time were 139.4 and 116.1 min, respectively. All the patients received rocuronium under a mean ponderal single-dose of 0.48 mg/kg. Residual NMB rates were 29.9 and 49.1% for a TOFR < 0.91 and < 1.00, respectively. Older adults had an OR of 6.08 for residual NMB.

CONCLUSIONS

The rate of residual NMB was 29.9 to 49.1%, depending on the criteria used (TOFR < 0.91 and < 1.00, respectively). Patients above 65 years old had an increased risk of residual NMB (6.08 OR) and clinical symptoms related to residual NMB (11.75 OR). We recommend future research aiming to provide a specific surveillance protocol for patients above 65 years old, including shorter-action NMB, early reversal, and prolonged surveillance using the TOFR criteria of < 1.00 to identify patients at risk of residual NMB readily.