Anesthesiology APPLIED Exam › Neuroanesthesia and neuromuscular

Residual neuromuscular blockade

Neuroanesthesia and neuromuscular·~5 min read· Physician-reviewed✓ Sourced · 5

Stem

A 66-year-old woman, 58 kg, has just had a three-hour laparoscopic sigmoid colectomy under sevoflurane with rocuronium redosed until 40 minutes before closure. Neostigmine and glycopyrrolate were given when four twitches were felt with no obvious fade, and she was extubated after a sustained head lift. Fifteen minutes into PACU she is anxious, says she cannot get a breath, has a weak cough, and her SpO2 is 89% on a face mask.

Question

What do you think is happening, and how will you manage it?

Ideal answer

HeadlineResidual neuromuscular blockade until proven otherwise, and an airway emergency. I sit her up, give 100% oxygen and call for help.

Support the airway; bag-mask if she tires, because weak pharyngeal muscles obstruct and she will fatigue; difficult-airway cart available.
Quantitative monitor on the adductor pollicis, to measure where she is rather than guess.¹
Sugammadex 2 mg/kg, about 120 mg, at two or more twitches; 4 mg/kg (about 230 mg) if deeper, on actual body weight.² More neostigmine will not help: it has a ceiling.
Train-of-four ratio recovered to at least 0.9, the threshold for safe pharyngeal function and airway protection.¹
Keep the differential open: opioid and residual volatile, atelectasis, hypoventilation after pneumoperitoneum, aspiration, pulmonary edema; a gas if slow to improve; reintubation if she cannot protect her airway or saturation despite reversal.

Breaking down the answer

Why she left weak — touch misses fade until the ratio is about 0.4; head lift is unreliable.¹ Residual blockade is reported in up to 64% at the end of surgery or in PACU; 80% with a ratio below 0.7 still lift their head.¹
The 0.9 threshold — the original definition was below 0.7, but pharyngeal dysfunction, aspiration risk and dyspnea persist below 0.9, so the guideline asks for 0.9 before extubation.¹
Adductor pollicis, not the eye — orbicularis oculi and corrugator recover earlier than the airway and overestimate recovery; the guideline recommends against eye muscles.¹
Sugammadex over neostigmine — preferred at deep, moderate and shallow rocuronium blockade; neostigmine is a reasonable alternative only at minimal depth, a ratio of 0.4 to under 0.9.¹ Repeated neostigmine adds muscarinic effects without more reversal.
Dose to depth — 4 mg/kg means one to two post-tetanic counts; underdosing to save money risks recurrence of blockade.²
When the monitor reads 1.0 — I move on to opioids, atelectasis, bronchospasm, aspiration, pulmonary edema, or upper-airway obstruction; that is adaptability under pressure.

Follow-up question

She recovers to a ratio of 0.95 after sugammadex 4 mg/kg. Forty minutes later her hemoglobin has fallen, she is tachycardic, and the surgeon wants her back in the OR for bleeding with a rapid sequence induction. How does the sugammadex change your plan?

Follow-up answer

HeadlineCirculating sugammadex will bind any rocuronium or vecuronium I give, so a standard dose is weak and unpredictable. I tell the team.

After up to 4 mg/kg of sugammadex, the label allows rocuronium 1.2 mg/kg after a 5-minute wait, while lower doses of rocuronium or vecuronium need a 4-hour wait; for faster or more reliable blockade, a nonsteroidal agent.² For this rapid sequence I use succinylcholine, or rocuronium 1.2 mg/kg since more than 5 minutes have passed, with a reduced hypnotic dose for her hypovolemia and blood ready. I monitor quantitatively from induction and confirm a ratio of at least 0.9 before extubating again.

Pitfalls that cost points

Extubating on head lift, grip, tidal volume or "four good twitches" by feel.
Anchoring on residual blockade and missing aspiration or opioid narcosis.

Rapid-fire

Q: At what train-of-four ratio can you no longer detect fade by feel? A: About 0.4; above that, fade is invisible to touch or eye.¹

Q: When does neostigmine reach its peak effect? A: Within about 10 minutes, so I wait at least that long before extubating a cisatracurium patient with only qualitative monitoring.¹

Q: What dose of sugammadex reverses rocuronium 1.2 mg/kg immediately? A: 16 mg/kg, about three minutes after the rocuronium.²

Q: What sugammadex effects do you counsel and watch for? A: Reduced hormonal contraceptive effect, so a backup non-hormonal method for 7 days; marked bradycardia within minutes, occasionally arrest, treated with an anticholinergic.²

Q: Stridor after extubation in PACU? A: Laryngeal edema in adults (subglottic in children): nebulized racemic epinephrine 0.5 mL of 2.25% in 3 mL saline (children 0.05 mL/kg, maximum 0.5 mL), dexamethasone; observe ≥4 hours for rebound.³^,4

Q: Pink frothy sputum minutes after laryngospasm? A: Negative-pressure pulmonary edema: relieve the obstruction, oxygen with CPAP or PEEP 5–10 cmH2O; diuretics are of uncertain value; most resolve in 12–24 hours.⁵

Numbers to know

Item	Value
Extubation threshold	TOF ratio ≥0.9 at adductor pollicis¹
Neostigmine depth window	TOF ratio 0.4 to <0.9¹
Sugammadex, T2 present	2 mg/kg actual body weight²
Sugammadex, 1–2 PTC	4 mg/kg²
Sugammadex, immediate	16 mg/kg²
Rocuronium 1.2 mg/kg after ≤4 mg/kg sugammadex	Wait 5 min²

Sources

1.New Practice Guidelines for Neuromuscular Blockade · APSF, 2023 · apsf.orgReproduces the recommendations of the 2023 ASA Practice Guidelines for Monitoring and Antagonism of Neuromuscular Blockade.
2.BRIDION (sugammadex) injection prescribing information · FDA / DailyMed · dailymed.nlm.nih.gov
3.Postextubation stridor · OpenAnesthesia, 2023 · openanesthesia.orgPediatric weight-based racemic epinephrine dose; observe at least 4 h for rebound.
4.Racemic epinephrine · WikEM · wikem.orgAdult post-extubation stridor: 0.5 mL of 2.25% in 3 mL normal saline by jet nebulizer, repeatable every 20 minutes; rebound edema typically 1-3 h after the dose.
5.Postobstructive (negative pressure) pulmonary edema · OpenAnesthesia, 2025 · openanesthesia.org

Facts on this page were checked against these sources on Oct 15, 2026. Guidelines change; confirm doses against current institutional protocols.