“I don’t need no stinkin’ quantitative neuromuscular blockade monitor”…you probably do
Myron Yaster MD, Lynne Maxwell MD, and Debra Faulk MD
The use of quantitative neuromuscular blockade monitoring and sugammadex in routine anesthesia practice is a recurrent topic in our literature. In today’s PAAD we’ll review an editorial and a pro-con debate that was published in the July issue of Anesthesia and Analgesia on this topic. “These articles provide an interesting and educational debate, clearly designed to expose the reasons behind clinicians’ decisions to use quantitative neuromuscular monitors (Pro section) or to avoid their use (Con). The discussion is germane, well balanced, and covers most issues that anesthesiologists consider when making clinical decisions”.1
Fülesdi B, Brull SJ. Quantitative Neuromuscular Monitoring: "Love All, Trust a Few, Do Wrong to None". Anesth Analg. 2022 Jul 1;135(1):35-38. PMID: 35709442 1
Blobner M, Hollmann MW, Luedi MM, Johnson KB. Pro-Con Debate: Do We Need Quantitative Neuromuscular Monitoring in the Era of Sugammadex? Anesth Analg. 2022 Jul 1;135(1):39-48. PMID: 35709443 2
Lynne and I began our anesthesiology residencies before pulse oximetry, capnography, end-tidal vapor analysis, and automated non-invasive blood pressure monitoring were available. When each of these devices entered into practice there were many deniers who didn’t believe they were necessary. Indeed, even pulse oximetry had to be “proven” to be a necessary, and ultimately mandatory, monitor.3 Why?
“New medical technologies require on average 10 to 15 years for widespread adoption once practice guidelines are established. Many new medical devices do not have the staying power to last that long. As described by the Rogers Innovation Adoption Curve, new technologies are quickly embraced by innovators and early adopters. Clinicians who are motivated by new ideas are willing to try new technology and require minimal evidence before using it. They represent only 16% of clinician users. The early majority (34%), however, require more evidence. Late majority (34%) and laggards (16%) not only require more evidence but personal experience that confirms new devices (eg, EMG-based quantitative neuromuscular monitoring) meet expectations. A marker of successful adoption is crossing the “chasm” from early adopters to early majority. Once across, new technologies enjoy more widespread adoption. Newer quantitative neuromuscular monitors to guide administration and reversal of non-depolarizing neuromuscular blockade may be on the cusp of crossing the chasm”,2 as demonstrated by the publication recently reviewed in the PAAD which described a successful departmental implementation strategy for quantitative neuromuscular blockade monitoring.4
To be honest, I (MY) was initially skeptical of the need for quantitative monitoring in pediatric practice, until data presented in abstract form by one of us (DF) at SPA and IARS meetings (and recently submitted for journal peer review) convinced me otherwise. Residual neuromuscular blockade in the PACU, when using clinical judgement and qualitative assessment, particularly when neostigmine is used for reversal, is much more common than we think. Indeed, Deb and her colleagues found that almost 30% of pediatric patients reversed with neostigmine/glycopyrrolate had TOF ratios of <0.9 despite 4/4 twitches on qualitative monitoring in the PACU. “Where there’s smoke there’s fire”. I think we are crossing the chasm.
This pro/con debate is terrific, and I think it does justice to both sides. We are not doing justice to all of the points raised in this paper and would encourage you to read it in its entirety. A glossary of abbreviations: TOF = Train-of-four, NMM = neuromuscular monitoring, NMB-neuromuscular blockade, EMG=electromyography
Key elements in the CON side2. “Experienced clinicians maintain that with sugammadex, reversal of NMB is fast and effective. If patients exhibit adequate strength, the consequences of imperceptible residual blockade are of little clinical consequence during the recovery period.
1. Peripheral nerve stimulator, a TOF count of 4/4 with sustained 5-s tetanus at eye or wrist muscles provides an adequate assessment of NMB reversal
2. Quantitative NMM is not needed when sugammadex is available
3. The incidence of clinically meaningful residual neuromuscular blockade leading to a postoperative adverse pulmonary event is very low
4. Quantitative NMM is expensive. The devices are more expensive. There is a recurring cost for an electrode-sensor array with each use.
5. The use of quantitative NMM disrupt workflow. They require placement of the electrode-sensor array at the wrist, connection to a cable, and visualization of an additional monitor”2
Key elements in the PRO side2. Myron’s mentor, the late Dick Traystman always used to say: “You can believe what you want but show me the data!” And the data is very clear, qualitative monitoring and clinical signs of reversal on NMB are inadequate and no better than flipping a coin. The risks of residual blockade are “still widely ignored by many anesthesiologists and poses an unnecessary threat to patients.”
1. TOF count, by itself, is not an adequate measure of NMB reversal. A TOF ratio is required and no patient should be extubated without first verifying that the TOF ratio is >0.9 at the adductor pollicis
2. Neither qualitative NMM nor clinical tests accurately detect residual NMB
3. Sugammadex does not guarantee complete NMB recovery. Without quantitative NMM, uncertainty remains
4. Reversal drugs should be given only if necessary. Using quantitative NMM can exclude residual NMB and can avoid unnecessary administration of a reversal agent. It can be used to titrate the amount of sugammadex
5. Although rare, there is an association between residual NMB and the risk of postoperative pulmonary complications, coma, and mortality. Residual NMB increases the incidence of critical respiratory events in the PACU
6. The application of the quantitative NMM is a one-time event before anesthesia induction and, therefore, not disruptive at all. Calibration of the NMM before administration of the NMB agents is automated. These 20 s can be used to optimize conditions for laryngoscopy. In contrast to the tactile NMM, no additional measure needs to be taken subsequently until extubation.
7. EMG quantitative NMMs do not require unimpeded thumb movement and can be used with the arms tucked”2
One final thought. When using NMM it is key to apply the probes to the adductor pollicis at the wrist. Do not use eye muscles. Eye muscles recover faster leading to assessments of adequate reversal when residual NMB persists and may be due to direct stimulation of muscle, not nerve.
My position (DF) is, of course, firmly on the “PRO” side of this debate. While I accept that peripheral nerve stimulators are likely adequate to guide the administration of antagonists (sugammadex or neostigmine), the fact remains that we cannot know that the antagonism of that blockade has been successful and adequate without objective monitoring. This is clearly emphasized in these 2 articles. The “con” side of the argument asserts that there are no clinically significant consequences of a little bit of weakness in our patients, so qualitative assessments are sufficient for standard practice. The potential clinical consequences of TOFr < 0.9 though have been reported in numerous adult studies. But what does this mean for children? The “chasm” we face in pediatric anesthesia may be even greater than that in adult anesthesia practice where inappropriate monitoring locations (eye muscles) are used routinely, and the lack of current evidence of “significant” clinical complications is difficult to overcome with the challenges involved in pediatric studies. The argument that “we don’t see problems with pediatric patients” actually takes me back to my medical school days, before the advent of EMRs and the banning of abbreviations in the medical record. Common shorthand in the written (yes, pen and paper!) daily progress was a physical exam that said “WNL”, or “within normal limits”. The joke was when this was written without truly examining the patient – WNL became “we never looked”. Which WNL does your patient fall into when thinking about the potential or real consequences of residual neuromuscular blockade? As pointed out by Blobner and colleagues, there are many gaps to fill to help us cross the “chasm”, and WE ARE LOOKING!
1. Fülesdi B, Brull SJ: Quantitative Neuromuscular Monitoring: "Love All, Trust a Few, Do Wrong to None". Anesth Analg 2022; 135: 35-38
2. Blobner M, Hollmann MW, Luedi MM, Johnson KB: Pro-Con Debate: Do We Need Quantitative Neuromuscular Monitoring in the Era of Sugammadex? Anesth Analg 2022; 135: 39-48
3. Cote CJ, Goldstein EA, Cote MA, Hoaglin DC, Ryan JF: A single-blind study of pulse oximetry in children. Anesthesiology 1988; 68: 184-188
4. Weigel WA, Williams BL, Hanson NA, Blackmore CC, Johnson RL, Nissen GM, James AB, Strodtbeck WM: Quantitative Neuromuscular Monitoring in Clinical Practice: A Professional Practice Change Initiative. Anesthesiology 2022; 136: 901-915