Critical Respiratory Events After Surgery: How Can You Stop Them?

From as far back as the 1970s or earlier, research has suggested that nearly half of patients arriving to the post-anesthesia care unit (PACU) have experienced residual paralysis, evidenced by sup-optimal train-of-four ratios (TOFR).¹

Those numbers have been confirmed in subsequent studies decades later, indicating that PACU residual paralysis below the gold standard of 0.9 TOFR continues to hover near the 40 percent mark.² Such ratios indicate inadequate recovery, can delay discharge by an average of 90 minutes,³ and have been linked to many factors:

• Administration of non-depolarizing muscle relaxants.⁴
• Usage of subjective monitoring or clinical tests to assess a block’s reversal before proceeding to tracheal extubation.
• Insufficient intraoperative monitoring.
• Long-duration procedures.⁵

The Risk of Critical Respiratory Events and Reintubation

Beyond existing signs of muscle weakness such as speech difficulties or distress, patients experiencing residual paralysis (or postoperative residual curarization, or PORC) are at risk for critical respiratory events, including postoperative hypoxemia and upper airway obstructions,⁶ at a rate of 1 to 3 percent.⁷

Given the implications of PORC (such as pneumonia and aspiration risk, as well as impaired lung function), critical respiratory events may call for tracheal reintubation,⁸ which happens in the recovery room anywhere from 17 to 45 percent of the time — despite adherence to clinical extubation guidelines. All told, more than half of all PACU reintubations are due to factors related to anesthesia.⁹

However, reintubation comes with consequences, both financially and clinically. For one, reintubation raises risk for cardiac and respiratory complications — along with extended length of stay (both in the PACU as well as the intensive care unit and the hospital itself), more time spent on ventilation, and a higher risk of death.¹⁰

Low Adoption Rates for Monitoring Despite Success

Despite these considerable risks, systematic neuromuscular monitoring is still not standard practice — even though it has been endorsed by a 2018 consensus statement in Anesthesia & Analgesia.¹¹

For example, European studies have indicated that less than half of clinicians have reported routine use of neuromuscular monitors, with some as low as 10 percent.¹² Perception likely feeds into those low adoption rates, with surveys suggesting that the large majority of respondents did not consider it necessary to monitor blocking agents with neuromuscular monitoring.

Quantifying residual paralysis with TOFR values also seems to be a rather unpopular concept: In one survey of European anesthetists, only 45 percent of respondents based their reversal decisions on objective TOFR numbers.¹³

Providing Objective Context for Subjective Surveillance

Despite these perceptions and low adoption rates, TOFR monitoring has shown to have a significant impact on residual paralysis, with previous research indicating that the use of it reduced paralysis from 62 percent to just 3 percent. ⁵

But there are ample reasons to engage in neuromuscular monitoring solutions beyond patient care, though that remains a substantial part of many care teams’ decisions to invest in such technologies. The prospect of providing objective context for what has been a historically subjective surveillance process provides more actionable, workable data that can be used both individually and more broadly for hospital efficiency, workflow, and performance improvement.

With proper monitoring, for example, clinicians can better identify the magnitude of neuromuscular blockades (NMBAs), manage antagonist dosage and administration times, and establish timeline parameters for reversal and extubation. In infusion cases, neuromuscular monitoring can also minimize undue accrual of infused agents.¹⁴

Looking at downstream impacts, those benefits may also bring potential reductions in length of stay, resourcing and allocation issues, and hospital costs as a result of faster patient throughput. Plus, improved monitoring enables more uniform global data collection on NMBA and antagonist doses, trends, and response rates to better manage clinic caseload and workflows.¹⁵

GE Healthcare’s NMT Solution

In comparison to conventional monitoring techniques that are largely subjective in nature, GE Healthcare’s neuromuscular transmission (NMT) monitoring solution module features evaluations through two modes, the MechanoSensor and the ElectroSensor:

• MechanoSensor: Converts physical motions from the patient’s thumb into quantifiable electrical signals.
• ElectroSensor: Outfitted on a patient’s foot or hand to measure the muscle’s electrical activity from recording electrodes that quantify nerve stimulation response.

Both options measure muscle response to stimulus through quantitative, automatic measurements, which can ascertain the degree of block and reversal so that extubation isn’t performed prematurely in cases of residual paralysis.¹⁶

Electromyography (EMG) in Comparison With Other Technologies

As an accurate and precise monitoring mechanism, the EMG solution is often compared with acceleromyography (AMG) and kinemyography (KMG). EMG is clearly the best of the three in terms of TOFR sensitivity. For example:

• A 30-participant study in Anesthesia and Intensive Care showed that a KMG value of 0.9 TOFR at the adductor pollicis muscle returned a value of 0.8 for the same assessment in a EMG.¹⁷
• A 14-participant study in the European Journal of Anesthesiology showed that EMG outperformed AMG in day-to-day use because it could better withstand outside influences, such as hand movements.¹⁸
• A 26-participant study in Anesthesia & Analgesia revealed that EMG showed more precision and better quantification of TOFR compared to AMG, with AMG overestimations as high as .15 or more.¹⁹

These analyses suggest that when it comes to objective, accurate TOFR estimation, EMG is often the only option for measuring paralysis during robotic surgery or whenever the hand is otherwise tucked. It requires less freedom of finger movements. Also, if the operative site is on the hand or if the patient has no limbs, it represents an additional indication for EMG.

Finally, EMG has been recognized as the currently available gold standard due to its higher accuracy, lower sensitivity to changes in muscle contractility, independency of the hand position, the free mobility of the thumb, and any preload.¹¹

References:

1. Residual Curarization in the Recovery Room. Anesthesiology. http://anesthesiology.pubs.asahq.org/article.aspx?articleid=1959020. Accessed Apr. 17, 2019.
2. Neuromuscular monitoring and postoperative residual curarisation: a meta-analysis. British Journal of Anaesthesia. https://www.ncbi.nlm.nih.gov/pubmed/17307778. Accessed Apr. 17, 2019.
3. Postoperative residual curarization from intermediate-acting neuromuscular blocking agents delays recovery room discharge. British Journal of Anaesthesia. https://www.ncbi.nlm.nih.gov/pubmed/20576632. Accessed Apr. 17, 2019.
4. Residual Neuromuscular Blockade in Critical Care. Critical Care Nurse. http://ccn.aacnjournals.org/content/32/3/e1.full?sid=4dff22dc-6854-4d89-90a0-306622a486a3. Accessed Apr. 17, 2019.
5. Postoperative residual neuromuscular block: a survey of management. British Journal of Anaesthesia. https://www.sciencedirect.com/science/article/pii/S0007091217349966. Accessed Apr. 17, 2019.
6. Postoperative residual neuromuscular blockade. Anesthesia & Pain Medicine. http://www.anesth-pain-med.org/journal/view.html?volume=10&number=1&spage=1. Accessed Apr. 17, 2019.
7. Residual neuromuscular block: lessons unlearned. Part I: definitions, incidence, and adverse physiologic effects of residual neuromuscular block. Anesthesia & Analgesia. https://www.ncbi.nlm.nih.gov/pubmed/20442260. Accessed Apr. 17, 2019.
8. Monitoring of Neuromuscular Blockade: What Would You Expect If You Were the Patient? Anesthesia Patient Safety Foundation. https://www.apsf.org/article/monitoring-of-neuromuscular-blockade-what-would-you-expect-if-you-were-the-patient/. Accessed Apr. 17, 2019.
9. Reintubation in the postanesthesia care unit: An analysis from a database of 21,349 cases at Chiang Mai University Hospital, Thailand. European Journal of Anaesthesiology. https://journals.lww.com/ejanaesthesiology/Fulltext/2008/05001/Reintubation_in_the_postanesthesia_care_unit__An.25.aspx. Accessed Apr. 17, 2019.
10. Risk factors for reintubation in the post-anaesthetic care unit: a case–control study. British Journal of Anaesthesia. https://www.sciencedirect.com/science/article/pii/S0007091217349966https://academic.oup.com/bja/article/109/4/636/237310. Accessed Apr. 17, 2019.
11. Consensus Statement on Perioperative Use of Neuromuscular Monitoring. Anesthesia & Analgesia. https://journals.lww.com/anesthesia-analgesia/FullText/2018/07000/Consensus_Statement_on_Perioperative_Use_of.17.aspx. Accessed Apr. 17, 2019.
12. A Survey of Current Management of Neuromuscular Block in the United States and Europe. Anesthesia and Analgesia. https://www.researchgate.net/publication/267633610_A_Survey_of_Current_Management_of_Neuromuscular_Block_in_the_United_States_and_Europe_Anesthesia_and_Analgesia_2010_111_110-9. Accessed Apr. 17, 2019.
13. Neuromuscular monitoring and postoperative residual curarisation: a meta-analysis. British Journal of Anaesthesia. https://www.ncbi.nlm.nih.gov/pubmed/17307778. Accessed Apr. 17, 2019.
14. Factors that affect the onset of action of non-depolarizing neuromuscular blocking agents. Korean Journal of Anesthesiology. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5645582/. Accessed Apr. 17, 2019.
15. Neuromuscular Transmission. GE Healthcare. https://www.gehealthcare.co.uk/-/media/94bd15d7a0c544b0b3cf93939cbacde9.pdf?la=en-gb&hash=D22F512C0C0E69030E5E3342FDAEB6B603167185. Accessed Apr. 17, 2019.
16. Neuromuscular Transmission. GE Healthcare. https://www.gehealthcare.co.uk/-/media/94bd15d7a0c544b0b3cf93939cbacde9.pdf?la=en-gb&hash=D22F512C0C0E69030E5E3342FDAEB6B603167185. Accessed Apr. 17, 2019.
17. Comparison of electromyography and kinemyography during recovery from non-depolarising neuromuscular blockade. Anaesthesia & Intensive Care. https://www.ncbi.nlm.nih.gov/pubmed/24794479. Accessed Apr. 17, 2019.
18. Clinical validation of electromyography and acceleromyography as sensors for muscle relaxation. European Journal of Anaesthesiology. https://www.researchgate.net/publication/6560607_Clinical_validation_of_electromyography_and_acceleromyography_as_sensors_for_muscle_relaxation. Accessed Apr. 17, 2019.
19. An Ipsilateral Comparison of Acceleromyography and Electromyography During Recovery from Nondepolarizing Neuromuscular Block Under General Anesthesia in Humans. Anesthesia & Analgesia. https://insights.ovid.com/pubmed?pmid=23821356. Accessed Apr. 17, 2019.