Pericardial Fenestration With Monitored Anesthesia Care Using Diluted Remifentanil: A Series of 10 Cases

Introduction Monitored anesthesia care (MAC) is an anesthesia management method in which anesthesiologists use the minimum necessary intravenous anesthetics to achieve sedation and pain relief while maintaining spontaneous breathing. The challenge for the anesthesiologist is to find the correct balance between inhibiting the patient's stress response to invasive treatment, maintaining intraoperative hemodynamic stability, and doing so as quickly as possible. We hypothesized that diluting remifentanil (D-remi) to 10 μg/mL and increasing the rate of administration would increase the responsiveness of the syringe pump and allow for better control of anesthetic depth. In this study, we aimed to evaluate the efficacy of MAC with D-remi in critically ill patients. Materials We investigated 10 cases in which anesthesia was managed by MAC with D-remi during emergency pericardial fenestration after cardiovascular surgery at our institution. Each parameter related to the patients' background and circulatory dynamics was extracted retrospectively from the electronic medical records and anesthesia records. The target depth of anesthesia was set at Richmond Agitation-Sedation Scale (RASS) -3 to -4 on MAC with spontaneous breathing. We increased the infusion rate of this analgesic during more invasive procedures. Results In all cases, the emergency pericardial fenestration could be performed with stable hemodynamics throughout the procedure. Spontaneous respiration never disappeared in any case. Although there were six cases in which airway maintenance by mandibular elevation was required due to glossoptosis, the minimum intraoperative SpO₂ was as high as 94% (92-100%), and none of the cases dropped below 92%. Conclusions The improved responsiveness of syringe pumps through the use of D-remi may be advantageous in situations where the infusion rate of anesthetic needs to be adjusted frequently and quickly. Since this is a small case study, we view our results cautiously and hope that further investigation of the usefulness of D-remi in MAC, including large-scale randomized studies, will be conducted in the future.