Adding Low-Dose Propofol to Limit Anxiety during Target-Controlled Infusion of Remifentanil for Gastrointestinal Endoscopy: Respiratory Issues and Safety Recommendations

Abstract

Backgroundand Objectives: Remifentanil-based sedation is one of many protocols proposed for endoscopy procedures in spontaneous ventilation, alone or in combination with propofol. However, the effect of these small doses of propofol on the efficacy and safety of remifentanil target-controlled infusion (TCI) deserves to be examined in this context. The objective of this study was to assess the adverse respiratory and cardiovascular effects of small boluses of propofol combined with remifentanil, in comparison with remifentanil alone, and balanced with the quality of sedation and recovery. Materials andMethods: This was an observational bicenter study, representing a subgroup of a larger study describing remifentanil-based procedural sedation. In center 1, patients scheduled for gastrointestinal (GI) endoscopy had remifentanil TCI alone. In center 2, patients had a 10 mg propofol bolus before TCI and other boluses were allowed during the procedure. Remifentanil TCI was started at a target of 2 ng/mL then adapted by 0.5 ng/mL steps according to patient response to endoscopy stimulations. Results: Center 1 included 29 patients, while center 2 included 60 patients. No difference was found in the patients’ characteristics, incidence of success, average remifentanil consumption, or cardiovascular variables. Light sedation was achieved when propofol was added. The incidence of respiratory events, such as bradypnea, desaturation < 90%, and apnea requiring rescue maneuvers, were significantly higher with propofol. Conclusions: Adding propofol boluses to a remifentanil TCI for GI endoscopy ensures light sedation that may be necessary for anxiolysis but increases respiratory events, even after administration of small-dose boluses. Its safety is acceptable if the procedure is performed in an equipped environment with sedation providers trained to manage respiratory events and drugs titrated to minimal doses.

Keywords: drug interactions; gastrointestinal endoscopy; procedural sedation; propofol; remifentanil; spontaneous ventilation; target-controlled infusion.

Figure 1

Minimal respiratory rate as a function of total dose of propofol received (1 point/patient). Higher propofol doses were significantly correlated with lower minimal respiratory rates (r = −0.25).

Figure 2

Example of predicted propofol concentration after an initial bolus of 20 mg, followed by a second bolus of 10 mg. Simulation performed with the Stanpump R shareware program (https://stanpumpr.io/ accessed on 12 December 2021).