Residual Neuromuscular Blockade and PACU Admission

Overview

Residual neuromuscular blockade (RNMB) remains an underrecognized postoperative safety concern associated with pulmonary complications, prolonged post-anesthesia care unit stay, and reduced patient satisfaction. Because conventional clinical tests are insufficiently sensitive and specific, current guidelines recommend quantitative neuromuscular monitoring to confirm adequate recovery, defined as a train-of-four ratio of ≥0.9. This prospective observational study included adult patients aged 18-90 years with ASA physical status I-III who underwent elective surgery under general anesthesia with neuromuscular blocking agents. Demographic, clinical, anesthetic, surgical, and reversal-related variables were recorded. Postoperative neuromuscular recovery was quantitatively assessed at the adductor pollicis muscle using TOFscan® acceleromyography at the 10th postoperative minute. Patients were subsequently followed in either the PACU or surgical ward according to clinical indications, and postoperative adverse events were documented. The study aimed to evaluate the incidence and potential determinants of RNMB in accordance with contemporary neuromuscular monitoring guidelines.

Residual neuromuscular blockade (RNMB) remains an important patient safety concern throughout the postoperative period and continues to be underrecognized by healthcare professionals. Current evidence suggests that RNMB is associated with an increased risk of postoperative pulmonary complications, prolonged length of stay in the post-anesthesia care unit (PACU), and reduced patient satisfaction. Clinical assessment methods may include, but are not limited to, a 5-second head lift, sustained hand grip, eye opening, tongue protrusion, and the presence of spontaneous ventilation. Although these tests are commonly used by anesthesiologists, they lack sufficient sensitivity and specificity for the detection of RNMB. The 2023 American Society of Anesthesiologists Practice Guidelines for Monitoring and Antagonism of Neuromuscular Blockade provide recommendations regarding the use of quantitative neuromuscular monitoring in conjunction with pharmacological reversal to improve the recognition of RNMB and reduce its incidence. These guidelines recommend quantitative monitoring because it enables more reliable confirmation of a train-of-four ratio (TOFR) of ≥0.9 compared with qualitative assessment methods. The use of quantitative neuromuscular monitoring to assess the depth of neuromuscular blockade may substantially reduce the risk of RNMB in patients undergoing general anesthesia. Several studies have also investigated whether combining pharmacological reversal of neuromuscular blockade with quantitative monitoring may further improve postoperative patient safety. Patients scheduled for postoperative admission to the PACU commonly have significant comorbidities and higher American Society of Anesthesiologists physical status classifications. Therefore, postoperative RNMB may be particularly critical in this high-risk patient population. The present study was designed to evaluate postoperative neuromuscular recovery in accordance with current evidence-based guidelines. Patients aged 18-90 years, classified as American Society of Anesthesiologists (ASA) physical status I-III, who underwent elective surgery under general anesthesia and received a neuromuscular blocking agent were eligible for inclusion in the study. Patients younger than 18 years or older than 90 years, those requiring postoperative invasive mechanical ventilation and transfer to the intensive care unit while intubated, patients undergoing emergency surgery, and those with a pre-existing neuromuscular disorder were excluded. Preoperative demographic and clinical data, including age, sex, body weight, height, body mass index, comorbidities, smoking status, and preoperative serum creatinine levels, were recorded using the patients' study identification numbers. The type and duration of surgery were also documented for each patient. The type and dose of the neuromuscular blocking agent administered during general anesthesia were recorded. At the end of surgery, whether pharmacological reversal of neuromuscular blockade was performed was documented, together with the type and dose of the reversal agent used. The interval between the last dose of the neuromuscular blocking agent and administration of the reversal agent, as well as the time from reversal to recovery, was recorded. Once the patients fulfilled the Aldrete recovery criteria, they were transferred to the postoperative recovery unit. Routinely monitored physiological parameters, including blood pressure, peripheral oxygen saturation, heart rate, and body temperature, were recorded. In accordance with the recommendations of the 2023 American Society of Anesthesiologists Practice Guidelines for Monitoring and Antagonism of Neuromuscular Blockade, postoperative residual neuromuscular blockade was assessed at the adductor pollicis muscle using TOFscan® acceleromyography (Dräger® Technologies, Mississauga, ON, Canada). TOFscan® is a quantitative neuromuscular monitor that uses three-dimensional acceleromyography. The stimulating electrodes were placed on the skin over the ulnar nerve at the wrist, 3 cm apart, and the electrical stimulus intensity was set at 30 mA to provide an appropriate balance between adequate monitoring and patient comfort. Neuromuscular function was assessed at the 10th postoperative minute in both the recovery unit and the post-anesthesia care unit. The decision regarding postoperative follow-up in the PACU or the surgical ward was made by the attending physicians according to the patients' clinical condition. Postoperative adverse events, including nausea and vomiting, dyspnea, and deterioration in vital signs, were recorded throughout the perioperative and postoperative periods.