Why is this important?

First, because it identifies new novel risk factors for residual neuromuscular block (experienced surgeon, non-CRNA anesthesia provider...) and secondly, because the subtext reveals the lengths our specialty goes to avoid simply monitoring using qualitative NMB monitoring (TOFR)!

What did they find?

Rudolph et al. created a REsidual neuromuscular block Prediction Score (REPS) using Massachusetts General PACU data, applying covariate analysis to identify 10 risk factors, some more surprising than others:

1. Hepatic failure
2. Neurological disease
3. High-neostigmine dose > 60 mcg/kg
4. Metastatic solid tumour
5. Female sex
6. Less than 120 min between NMBD administration and extubation
7. Aminosteroid NMBD
8. BMI more than 35
9. Absence of nurse anaesthetist (CRNA)
10. Having an experienced surgeon

Be smart:

These risk factors might suggest patients who need more careful monitoring, but you will probably be better off just using qualitative monitoring routinely. The utility of REPS itself is only modest with NPV & PPVs of 85% each.

The other takeaway is that rNMB is still demonstratably common, occurring in 20% of this cohort!

summary

• Maíra I Rudolph, Pauline Y Ng, Hao Deng, Flora T Scheffenbichler, Stephanie D Grabitz, Jonathan P Wanderer, Timothy T Houle, and Matthias Eikermann.
• From the Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital (MIR, PYN, HD, FTS, SDG, TTH), Harvard Medical School, Boston, Massachusetts (MIR, PYN, HD, FTS, SDG, TTH, ME), Department of Adult Intensive Care, Queen Mary Hospital and The University of Hong Kong, Pok Fu Lam, Hong Kong (PYN), Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee (JPW), Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA (ME) and Universitätsklinikum Essen, Essen, Germany (ME).
• Eur J Anaesthesiol. 2018 Nov 1; 35 (11): 883-892.

BackgroundResidual neuromuscular block (rNMB) after surgery is not difficult to identify if proper neuromuscular monitoring is used, but many clinicians do not use quantitative neuromuscular monitoring.ObjectiveThe aim of this study was to develop a REsidual neuromuscular block Prediction Score (REPS) to predict postoperative rNMB and compare the predictive accuracy of the prediction score with train-of-four count (TOFC) measurement at the end of a surgical case.DesignRetrospective cohort study of data on file.Data SourceElectronic patient data and peri-operative data on vital signs, administered medications, and train-of-four ratio (TOFR) obtained in the postoperative recovery rooms [postanaesthesia care unit (PACU)] at Massachusetts General Hospital in Boston, Massachusetts, USA.PatientsQuantitative TOFR measurements obtained on admission to the PACU were available from 2144 adult noncardiac surgical patients.Main Outcome MeasurePresence of rNMB at PACU admission, defined as a TOFR of less than 0.9.ResultsIn the score development cohort (n=2144), rNMB occurred in 432 cases (20.2%). Ten independent predictors for residual paralysis were identified and used for the score development. The final model included: hepatic failure, neurological disease, high-neostigmine dose, metastatic tumour, female sex, short time between neuromuscular blocking agent administration and extubation, aminosteroidal neuromuscular blocking agent, BMI more than 35, absence of nurse anaesthetist and having an experienced surgeon. The model discrimination by C statistics was 0.63, 95% confidence interval (0.60 to 0.66), and risk categories derived from the REPS had a higher accuracy than the last documented intra-operative TOFC for predicting rNMB (net reclassification improvement score 0.26, standard error 0.03, P < 0.001).ConclusionThe REPS can be used to identify patients at greater risk of rNMB. This tool may inform anaesthetists better than an intra-operative TOFC and thus enable peri-operative anaesthetic practices to be tailored to the patient and minimise the undesirable effects of rNMB.Trial Registry NumberApproved by Partners Human Research Committee (protocol number 2016P000940) at MGH in Boston, Massachusetts, USA on 25 April 2016.

This article appears in the collection: Neuromuscular myths: the lies we tell ourselves.

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