Strictly Clinical
  • Evaluating a Quality Improvement Initiative to Increase Anesthesia Providers’ Use of and Understanding of Quantitative Neuromuscular Monitors

    Improved understanding of the monitoring and dosing practices of anesthesia providers regarding neuromuscular blockade is necessary. The use of subjective methods such as peripheral nerve stimulation and clinical assessment tests can increase the risk of residual neuromuscular blockade and adverse postoperative outcomes. Quantitative monitoring of neuromuscular blockade is an alternative tool to peripheral nerve stimulation to guide neuromuscular blockade; however, it is rarely used by providers. We developed an initiative to improve anesthesia providers’ knowledge of neuromuscular blockade pharmacology, physiology, monitoring, and management. After the initiative, an analysis assessed for practice change regarding the use of quantitative monitoring and dosing of neuromuscular blocking agents and neostigmine. The use of quantitative monitoring increased significantly from 14.0% in the preinitiative group to 48.0% after the initiative (P < .001). The least squares mean 95% effective dose (ED95) neuromuscular blocking agents dose was compared between pre-initiative and postinitiative groups, and case length was a significant predictor for patients receiving the highest neuromuscular blocking agents doses. Neostigmine doses were compared between preinitiative and postinitiative groups, and body mass index was a significant predictor of the least squares mean neostigmine dose (P = .002) and the likelihood of receiving a high neostigmine dose (odds ratio = 0.911, 95% CI = 0.870-0.955).

    Keywords: Neuromuscular, peripheral nerve stimulation, quantitative neuromuscular monitors.

    Neuromuscular blocking agents (NMBAs) are administered to facilitate endotracheal intubation and provide skeletal muscle relaxation improving operative conditions.1,2 Despite advancements in neuromuscular blockade (NMB) monitoring and the assessment of NMB recovery, clinical practices to assess NMBAs vary among providers3-6 because of the absence of an accepted, practicewide standard for monitoring and management of patients receiving NMBAs.2,3,7

    Residual NMB results from inadequate recovery from NMBAs and may manifest as generalized weakness, respiratory depression, airway obstruction, increased incidence of aspiration or pneumonia, dysphagia resulting in hypoxemia, and postoperative respiratory failure.8-16 Complications from residual NMB affects as many as 25% to 50% of patients in the postoperative period, with approximately 40% of postoperative patients demonstrating some degree of residual paralysis.3,5,17-19 Subjective clinical assessment methods used to confirm recovery from NMB (head-lift, grip strength, tongue depressor test) have low sensitivity, specificity, and predictive values for the detection of residual NMB.20 Use of peripheral nerve stimulators relies on the providers subjective visual or tactile assessment to evaluate level of recovery from NMB.21 Ineffective monitoring practices, along with dosing practices of nondepolarizing NMBAs and anticholinesterase reversal agents (primarily neostigmine), independently increase the risk of postoperative pulmonary complications.1,8,22,23

    Quantitative neuromuscular monitors (QNM) as an alternative practice of assessing NMB recovery provides an accurate train-of-four (TOF) count and has the potential to decrease the incidence of residual NMB in the postoperative period.24 In a survey of more than 3,000 randomly sampled anesthesia providers, 90% agree that QNMs should be routinely used in the intraoperative period.25 An initiative was implemented in a large, academic anesthesia department to increase the overall use of intraoperative QNMs and ideally improve provider dosing practices of nondepolarizing NMBAs and reversal agents (neostigmine).


    Institutional review board exemption for data collection was obtained before the start of this quantitative monitoring initiative, and approval for data publication was obtained from the institutional review board at the study site (Pro00084727).

    Quantitative Neuromuscular Monitoring Practice. The facility equipped all operating rooms (ORs) in the main operating suite with the Datex-Ohmeda Neuromuscular Transmission Monitoring modules (Datex-Ohmeda Inc). Both piezoelectric kinemyographic (Datex-Ohmeda MechanoSensors, Datex-Ohmeda Inc) and electromyographic (EMG; Datex-Ohmeda EMG ElectroSensor, Datex-Ohmeda Inc) sensors were available on request. The anesthesia information management system (AIMS) had the capability to record the quantitative monitoring output for both the TOF count and TOF ratio. Despite their availability, the use of QNMs was infrequent among anesthesia providers. All ORs were equipped with quantitative monitoring modules and EMG or kinemyographic cables. The monitoring modules in each OR were reconfigured to display the QNM output along with the American Society of Anesthesiologists (ASA) standard monitors on the default screen. Despite the availability of QNMs, most providers reported regular use of the peripheral nerve stimulator as their primary clinical assessment tool for NMB reversal.

    A series of presentations were held for anesthesia providers to review the prevalence and clinical outcomes of residual NMB, physiology of NMB, pharmacology of NMBAs and neostigmine, and dosing concerns regarding nondepolarizing NMBAs and neostigmine. The limitations of subjective peripheral nerve stimulator monitoring modalities and benefits of quantitative monitoring were discussed. A follow-up to the presentation outlined proper use of the QNM including electrode application, the mechanism of the kinemyographic and EMG monitors, waveform and data interpretation, and monitor troubleshooting. In addition, a hands-on demonstration of the QNM was offered to anesthesia providers. A cognitive aid that provided written and pictorial instructions on electrode placement, instructions on how to start up the QNM, common troubleshooting problems and solutions, and a reversal dosing guide based on monitor output was created and distributed to all the ORs.

    Data Collection. Data were collected for 3 months before the quantitative monitoring initiative to assess the current state of practice of anesthesia providers regarding NMB monitoring. Postinitiative data were collected for a 3-month period from a random sample of intraoperative records in the electronic AIMS via a manual chart review. Inclusion criteria included any noncardiac, nonthoracic surgical procedure for adult patients (≥ 18 years) who required at least one dose of nondepolarizing NMBAs and were both intubated and extubated during the scheduled procedure. Patients undergoing ophthalmologic, endoscopic, and electrophysiologic procedures were excluded because of the lack of availability of quantitative monitoring in these locations. Cases were excluded if the patient received a reversal dose of sugammadex (because it was newly added to the formulary). Additional data collected from the patient carts included the following: surgical service, ASA physical status (1-4), height (centimeters), weight (kilograms), body mass index (BMI, kilograms per square meter), case length (minutes), nondepolarizing NMBA type (cisatracurium, rocuronium, vecuronium) and total dose of NMBA (milligrams), neostigmine total dose (milligrams), and type of NMB monitor used (QNM or peripheral nerve stimulator).

    Statistical Analysis. All statistical analyses were performed with SAS version 9.0 for Windows (SAS Institute Inc). A P value of less than .05 was considered statistically significant. An a priori sample size calculation was performed via a Fisher exact test and found that a sample of 34 was needed to detect a 50% increase in QNM use between the preinitiative and postinitiative groups with a power of 80.0%. Descriptive statistics were analyzed to report means, standard deviations (SDs), 95% CIs, and frequencies of the population. Ordinal and continuous variables were compared between preinitiative and postinitiative groups via independent t tests and c2 analysis. To compare the change in use of the QNMs, a c2 analysis was conducted. An analysis of covariance (ANCOVA) was conducted to compare the preinitiative and postinitiative groups on the least squares mean 95% effective dose (ED95) of nondepolarizing NMBAs and the least squares mean total dose of neostigmine, with both doses corrected for ideal body weight. An ordinal logistic regression was conducted to compare preinitiative and postinitiative groups on NMBA dosing quintiles. A binomial logistic regression was conducted to determine predictive odds of high neostigmine dosing (yes/no) between the preinitiative and postinitiative groups.

    The secondary outcomes analysis for the postinitiative group included an ANCOVA to analyze the effect of QNM use on the least squares mean ED95 dosing of nondepolarizing NMBAs and least squares mean total dose of neostigmine. An ordinal logistic regression was conducted to assess the effect of QNM use on the NMBA dosing quintile. A binomial logistic regression was conducted to determine predictive odds of high neostigmine dosage (yes/no) with QNM use. The covariate data controlled for in these models included ASA, BMI, age, and case length. The covariate data controlled for in the statistical model included ASA physical status (1-4), BMI (kg/m2), age (years), and case length (minutes).


    A total of 200 patients (100 before the initiative, 100 after the initiative) were included in the statistical analyses. The patient demographic characteristics for both initiative groups are displayed in Table 1. The QNM use increased significantly from 14.0% to 48.0% (n = 48) after the initiative (Figure).

    The influence of the quantitative monitoring initiative on the dosing of NMBAs and reversal agents is depicted in Table 2. The least squares mean total ED95 dose of NMBAs was compared between preinitiative and postinitiative groups. An exploratory analysis of odds ratios revealed that case length was a significant predictor for patients receiving the highest quintile doses of NMBAs (odds ratio = 0.99, 95% CI = 0.99-0.99). Neostigmine doses (µg/kg) were compared between pre-initiative and postinitiative groups. Type III sums of squares revealed BMI as a significant predictor of the least squares mean dose of neostigmine (P = .002). A significant predictor of receiving a high neostigmine dose was BMI (odds ratio = 0.91, 95% CI = 0.87-0.96).

    The quantitative monitoring initiative also included a secondary analysis, which examined the postinitiative group only to determine if QNM use affected dosing practices. The demographic data of the postinitiative sample are shown in Table 3. The effect of quantitative monitoring on dosing of NMBAs and neostigmine is displayed in Table 4. Case length was a significant predictor of least squares mean total ED95 dose (P < .001). An exploratory analysis of odds ratios revealed that case length was a positive, significant variable for predicting the likelihood of receiving the highest quintile doses of NMBAs (odds ratio = 0.98, 95% CI = 0.98-0.99).

    The neostigmine dose (µg/kg) was compared between patients who had the QNM and those who did not in the postinitiative group. The analysis revealed that BMI was a positive, significant predictor of least squares mean neostigmine dose (P = .04). The percentage of patients receiving high doses of neostigmine was not affected by use of the QNM (27.1% with QNM, 26.9% without QNM, P = .08). A significant predictor of receiving a high neostigmine dose was increased BMI (odds ratio = 0.93, 95% CI = 0.88-0.99).


    This quantitative monitoring initiative was successful in increasing the use of the QNM; however, it did not affect provider’s overall dosing practices of NMBAs and neostigmine. The core of evidence-based practice is the integration of high-quality research into clinical practice as a means to decrease variances in healthcare delivery and improve patient outcomes, with an added benefit of providing savings to healthcare costs.26,27 Assimilating research findings into routine clinical practice is a slow process that sometimes results in the failure to sustain practice change in the long term.27,28

    In a similar undertaking to implement quantitative monitoring into an academic anesthesiology department, Todd et al5 used a formal educational program that included dissemination of literature, morbidity and mortality conferences, postanesthesia care unit monitoring of TOF ratios, and weekly meetings reporting these findings. As a result, they were able to increase their use of intraoperative QNMs over a 16-month period. Their noted increase in QNM use with little change in dosing practices of nondepolarizing NMBAs and neostigmine was similar to our findings.5 Although the increase in the use of QNMs represents a positive shift in practice culture, the need to increase the understanding of the management and dosing practices of NMBAs and reversal agents is equally important. It is essential to use the output of QNMs to safely titrate medication doses and ensure adequate recovery before extubation because high doses of NMBAs and neostigmine carry substantial postoperative respiratory risks.1,8,23 Major progress would include the use of not only the QNMs but also quantitative monitoring data to guide dosing practice, particularly in vulnerable patient populations.

    Several patient populations, such as the obese population and the elderly population, are at high risk of postoperative residual NMB, and the use of QNM would be beneficial to their perioperative course.29-34 Obese patients have increased oxygen consumption and airway resistance, and decreased respiratory compliance and functional residual capacity compared with healthy-weight patients,29 increasing their risk of postoperative respiratory complications.30 The higher risk of upper airway collapsibility makes obese patients prone to experience more severe symptoms of residual NMB, even at shallow degrees of blockade.10 Additionally, the duration of action of NMBAs, such as rocuronium, has been found to be double in obese patients who received doses based on actual body weight compared with those who receive doses based on ideal body weight.31 Our finding suggests that anesthesia providers are aware of the pharmacology of dosing NMBAs in the overweight and obese population. We found that BMI negatively correlated to the least squares mean ED95 dose of nondepolarizing NMBAs when controlled for covariates. However, we found that BMI was positively correlated to the least squares mean dose of neostigmine; therefore, overweight and obese patients may be receiving inappropriate doses of neostigmine. Neostigmine, particularly in high doses (> 5 mg or > 60 µg/kg), has been shown to increase atelectasis and upper airway collapsibility8,22; thus, it is vital to calculate dose based on ideal body weight.

    Elderly patients are another high-risk population at increased risk of residual NMB because of decreased cardiac output, decreased muscle mass, increased body water, and alterations in hepatic and renal systems.32 Postoperative respiratory complications are more prevalent in patients greater than 65 years of age, regardless of presence of residual NMB, secondary to preexisting comorbidities and decreased muscle tone.8 A prospective study by Murphy et al33 reviewed the incidence of residual NMB and found that it occurred in 58% of elderly patients (70-90 years), compared with 30% of younger patients (18-50 years). Elderly patients were also prone to an increased incidence of airway obstruction, peripheral oxygen desaturation, and symptoms of muscle weakness.33 This population may experience delayed recovery from nondepolarizing NMBAs, with recovery from a single intubating dose requiring more than 2 hours in some cases.34 Our findings emphasize the need for providers to use the objective data associated with the use of QNMs and dosing practices for those of advanced age when administering NMBAs and reversal agents (ie, neostigmine).

    Providers were unaware of the limitations of clinical assessment tests and peripheral nerve stimulators as indicators for recovery from NMB. We attempted to address these issues with our quantitative monitoring initiative by providing instruction on the placement of monitoring electrodes, and on output interpretation, and by troubleshooting suggestions while simultaneously increasing exposure to the QNM. Consistent education on these topics, along with the presence of cognitive aids in the OR, led to early increased use of the QNM. Clearly, additional education is needed to assess outcomes associated with residual NMB. Finally, a substantial barrier to implementing improved NMB monitoring and dosing practices of NMBAs and neostigmine includes the adoption of a new NMB management system. Before our initiative, many providers did not see residual NMB as a perioperative issue and believed their practice was sufficient in preventing its occurrence. It is essential to make the case for providers on the use of the quantitative monitoring to guide intraoperative dosing practices regarding NMB and reversals by linking quantitative monitoring output to postoperative outcomes.

    There were limitations to our study that may have affected the results. Extraction of data from the AIMS electronically was not feasible. The manual extraction of data limited the number of subjects that could be included, which affected the number of confounding variables that could be controlled for in the statistical models.


    Our initiative was successful in significantly increasing the use of QNMs, indicating a shift in anesthesia provider attitude to incorporating an evidence-based practice approach to the management of NMB. Vital improvements are still needed to create a meaningful link between quantitative monitoring data and dosing practices for nondepolarizing NMBAs and reversal agents. Future studies analyzing postoperative outcomes of patients receiving high doses of NMBAs and/or neostigmine in conjunction with quantitative monitoring would be beneficial in determining the safety of these doses in quantitatively monitored patients. The creation of a culture of improved management for assessing NMB requires a well-developed, highly integrated system that includes standards and that provides regular and meaningful feedback to providers regarding patient outcomes related to NMB.


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    Meredith B. Bedsworth, DNP, CRNA, is a graduate from the Duke University School of Nursing in Durham, North Carolina. Email:

    Erica M. Harris, MSN, CRNA, is in the Duke University Hospital Department of Anesthesiology, Durham, North Carolina.

    Charles A. Vacchiano, PhD, CRNA, FAAN, is a professor at the Duke University School of Nursing. Email:

    Julie A. Thompson, PhD, is a professor at the Duke University School of Nursing.

    Stuart A. Grant, MB ChB, FRCA, is in the Department of Anesthesiology, Duke University Hospital, Durham, North Carolina.

    Victoria M. Goode, PhD, CRNA, is an instructor at the Duke University School of Nursing.


    The authors have declared no financial relationships with any commercial entity related to the content of this article. The authors did not discuss off label use within the article.

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