Significance of neuromuscular monitoring in laparoscopic Heller’s myotomy

To the Editor, Achalasia cardia is a rare esophageal motility disorder characterized by impaired lower esophageal sphincter relaxation and absence of peristalsis, attributed to selective degeneration of inhibitory neurons in the myenteric plexus.[1] It typically presents between 30 and 60 years with progressive dysphagia, regurgitation, chest discomfort, and weight loss. Laparoscopic Heller’s myotomy with fundoplication is considered a definitive treatment, especially in younger patients, and has largely replaced the thoracic approach due to faster recovery and lower morbidity.[2] We report the case of a 19-year-old male, weighing 50 kg, with achalasia cardia posted for laparoscopic Heller’s myotomy with fundoplication. Pre-anesthetic evaluation was unremarkable, with no known comorbidities. After adequate fasting and aspiration prophylaxis, rapid sequence induction was performed using fentanyl, propofol, and succinylcholine, followed by intubation and atracurium for maintenance. Standard American Society of Anesthesiologists (ASA) monitors were applied, and neuromuscular monitoring was done using train-of-four (TOF) at the adductor pollicis. About 6 min after the second atracurium dose, ventilator scalars (flow-time and pressure-time on Aisys CS2, GE Healthcare) showed regular deflections suggestive of spontaneous respiratory efforts despite a TOF count of 0/4 [Figure 1]. A similar pattern was noted on and off throughout the surgery, even at 32 min after the third dose, though the TOF continued to show complete neuromuscular blockade [TOF count of 0, Figure 2]. Possible reasons for the inadequate effect of atracurium, such as improper cold chain maintenance, degraded drug batch, or incorrect dilution, dosing, or administration technique, rapid metabolism, or altered pharmacokinetics in the patient, were considered but excluded.[3] The drug was freshly drawn from a verified batch stored at 2°C–8°C and dosed appropriately.Figure 1: Ventilator scalar showing spontaneous breathing at TOF count 0 after 32 min of relaxant administration. TOF = Train-of-fourFigure 2: Ventilator scalar showing spontaneous breathing at TOF count 0 after 5 min of relaxant administration. TOF = Train-of-fourAs the surgery involved dissection near the gastroesophageal junction and diaphragmatic hiatus, diaphragmatic stimulation due to mechanical irritation or electrocautery was considered the likely cause of the apparent ventilator waveforms. The diaphragm, being relatively resistant to non-depolarizing neuromuscular blockers and innervated by the phrenic nerve, can exhibit preserved or stimulated contractions even when peripheral muscle monitoring indicates complete paralysis.[4] Relying solely on ventilator scalars in this setting could have prompted unnecessary administration of muscle relaxants, which carries significant risks of prolonged neuromuscular blockade leading to delayed extubation, residual neuromuscular weakness, postoperative pulmonary complications like hypoventilation, atelectasis, aspiration and reintubation, increased intensive care unit (ICU) stays, and healthcare costs.[5] Guided by TOF monitoring, no additional relaxants were given; the surgery lasted approximately 2.5 h, and the patient was safely extubated when fully awake with a TOF ratio >0.9 and shifted to the postanesthesia care unit for further monitoring. This case highlights that diaphragmatic contractions from surgical stimulation may mimic spontaneous efforts during laparoscopic Heller’s myotomy. Quantitative neuromuscular monitoring is invaluable to avoid misinterpretation and unnecessary Neuromuscular blocking agents (NMBAs) administration, thereby enhancing perioperative safety. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.