Efficacy of target controlled infusion of remifentanil with spontaneous ventilation for procedural sedation and analgesia (Remi TCI PSA): A double center prospective observational study

Objective: Remifentanil, a rapid onset rapid offset synthetic opioid and potent analgesic, is often used for procedural conscious sedation in spontaneous ventilation, especially when delivered in target controlled infusion (TCI), which allows precise titration. We assessed efficacy, tolerance, and adverse events related with the use of remifentanil TCI during various procedures. Design: Prospective, observational. Setting: Two teaching hospitals. Patients: We enrolled 434 patients undergoing procedures suitable for conscious sedation. Interventions: The following procedures considered suitable were included: interventional radiology, gastrointestinal (GI) endoscopy, interventional cardiology, and peripheral dermatology. Sedation options were determined during the preoperative anesthesia assessment. Main outcome measures: Demographics were recorded as well as success rate, remifentanil dosage, pain scores, respiratory or cardiovascular events, and patient and operator satisfaction. Results: The procedure was successful in 429 patients (99 percent), canceled in four patients because of agitation, apnea, desaturation, and converted to general anesthesia in two for major pain. The maximal remifentanil target was around 2-3 ng/ml for most procedures, but it was 3-5 ng/ml for GI endoscopy and urology. A total of 172 patients (40 percent) had bradypnea < 8 min−¹, but only 26 (6 percent) had hypoxemia < 90 percent. Eighteen patients (4 percent) required mandibular luxation, and twelve needed face mask ventilation. There were no major cardiovascular adverse events. Conclusions: Remifentanil TCI is a suitable protocol for procedural sedation, but respiratory depression is a permanent concern. This risk requires equipped environment and competent medical personnel on hand to adjust the target before hypoxemia occurs. Respiratory rate monitoring, based on capnography or thoracic impedance is of a great help in anticipating this threat.