Up for Debate: What’s The Ideal Time to Reverse Neuromuscular Blockade?

SAN FRANCISCO—The timing of neuromuscular blockade (NMB) reversal, specifically as it relates to transporting patients from the OR to the ICU who are not expected to be extubated in the OR, was the focus of a debate session held at the 2023 annual meeting of the American Society of Anesthesiologists.

Reverse Before Transport

Arguing the position that NMB should always be reversed before transporting the patient was Marvin G. Chang, MD, PhD, an anesthesiologist/intensivist at Massachusetts General Hospital and an assistant professor of anesthesiology at Harvard Medical School, in Boston.

“As we all know, critical care transport is really high risk and many complications can occur, including accidental dislodgment of peripheral IVs, invasive lines, surgical drains and—the most feared—dislodgment of tracheal tubes and tracheostomies,” Chang said. “Other complications include interruption of medication administration, hemodynamic instability, ventilator disconnects and malfunction, as well as cardiac and respiratory arrest.”

Chang stressed the importance of the use of neuromuscular blockers during surgical procedures. “In fact our surgeons require them in order to do their jobs effectively and efficiently,” he said.

However, he noted, the drugs used to facilitate NMB are quite dangerous, thus it’s of critical importance to determine the ideal time to reverse the block. “Neuromuscular blockers are probably the most dangerous drugs that us as healthcare providers can deliver to patients.”

Although inadequate sedation can cause awareness in patients and lead to post-traumatic stress disorder (PTSD), studies have shown that residual NMB (RNMB) can be responsible for multiple complications in the ICU.

“Postoperative RNMB is associated with postoperative respiratory complications,” Chang said, citing a study by Raval et al (J Clin Anesth 2020;66:109962). “RNMB can be found in as much as 91% of patients, and the study also found higher rates of acute respiratory events in patients with RNMB.”

A second study, which Chang referenced, found that approximately 21% of patients had RNMB when presenting to the PACU, which was associated with an almost threefold higher odds of ICU admission (Anesth Analg 2019;128[6]:1129-1136).

“So, the question is, how good are we at monitoring NMB in the ICU?” Chang asked.

The answer, it seems, is not great.

In a survey study of intensivists, 84% of respondents admitted to using peripheral neurostimulation for monitoring. Of those who did monitor, 49% admitted that they do so routinely, 40% frequently and 10% said occasionally (Crit Care Med 2006;34[2]:374-380).

One potential risk of reversing NMB before transport to the ICU involved unintentional extubations.

However, Chang noted, studies show that self-extubations during transport in the operating realm are extremely uncommon.

Although unintentional extubations are more common in the ICU setting, patients are oftentimes very lightly sedated in the ICU compared with during transport from the OR to the ICU when they are more deeply sedated. A systematic review, conducted by Lee et al, found the pooled prevalence of unintentional extubations in the ICU—both accidental and self-extubations—was about 7% with an incidence of 1.06 events per 100 ventilator days (Intensive Crit Care Nurs 2022;70:103219). A study by Christie et al found that only 5% of unplanned extubations in the ICU were during transport, with only one being a self-extubation and four accidental extubations, which have likely occurred whether or not a neuromuscular blocker was used (J Clin Anesth 1996;8[4]:289-293).

Chang stated that RNMB is associated with worse outcomes, and it’s been demonstrated that there is poor compliance with ensuring the absence of RNMB in the ICU setting.

“Serious considerations should be made to ensure NMB is reversed before transition of care from the OR to the ICU to prevent iatrogenic complications, and improve and progress clinical care,” he concluded. “Knowing what we know about NMB and how dangerous it can be, in general the benefits outweigh the risks in terms of reversing NMB.”

Reverse After the Handoff

Arguing the other perspective, favoring for waiting NMB reversal until a handoff to the ICU has been completed, was Milad Sharifpour, MD, an associate professor of anesthesiology and critical care medicine at Cedars-Sinai, in Los Angeles.

“I agree wholeheartedly with what Chang said,” Sharifpour stated. “You do have to reverse NMB.But there are absolutely no data that tell you when is the best time to do so.”

To illustrate the challenges posed by this question, Sharifpour presented the challenges associated with moving patients at his hospital, where the OR is located in one tower of the facility and the ICU receiving the patients is multiple city blocks away.

“If you have to walk half a mile to get from the OR to the ICU, do you really want to reverse the patient’s NMB before you hit the road?” he asked.

Furthermore, if a patient has already had their NMB reversed, deeper sedation will be needed in order to ensure you are not risking awareness and PTSD.

“It is not humane to transport a paralyzed patient because of the increased risk for PTSD,” Sharifpour said. However, the use of deeper sedation can cause undesirable issues, such as increased hypotension.

Among patients in cardiac ORs and those with pulmonary hypotension, “the right ventricle is tenuous to begin with: One untimely cough or bucking against the ventilator increases the intrathoracic pressure and all of a sudden you get an acute right ventricular failure that you have to deal with in the middle of a lengthy transport,” according to Sharifpour.

Much of controlling the transport and handoff processes, he said, involves mitigating risk. And this, in his opinion, is best done by keeping the process as controlled as possible before reversing the patient’s NMB.

Other situations where it makes the most sense to wait to reverse the NMB include the treatment of patients for whom there are no immediate plans to extubate, such as those with severe neurologic injury, high-grade subarachnoid hemorrhage with vasospasm or those who may have to be sent back to the OR for repeat procedures.

“If you have no plans to extubate, then why reverse?” Sharifpour asked.

Sharifpour admitted that the primary issue with his position is the lack of direct data to back up the claims, meaning that clinicians often need to resort to trusting their own experience.

“This is a completely data-free zone,” he said. “There is no one-size-fits-all approach. Patients come out of the operating room in different stages of resuscitation or dynamic instability. Patients might not be warmed yet; they might just not be ready for extubation. We always wait until the patient is resuscitated, has been warmed and is ready to be extubated, and the labs have become acceptable—then we reverse the NMB.”

By Ethan Covey

---

Chang and Sharifpour reported no relevant financial disclosures.