Analgesia Nociception Index-Guided Remifentanil versus Standard Care during Propofol Anesthesia: A Randomized Controlled Trial

Abstract

The clinical benefits to be expected from intraoperative nociception monitors are currently under investigation. Among these devices, the Analgesia Nociception-Index (ANI) has shown promising results under sevoflurane anesthesia. Our study investigated ANI-guided remifentanil administration under propofol anesthesia. We hypothesized that ANI guidance would result in reduced remifentanil consumption compared with standard management. This prospective, randomized, controlled, single-blinded, bi-centric study included women undergoing elective gynecologic surgery under target-controlled infusion of propofol and remifentanil. Patients were randomly assigned to an ANI or Standard group. In the ANI group, remifentanil target concentration was adjusted by 0.5 ng mL-1 steps every 5 min according to the ANI value. In the Standard group, remifentanil was managed according to standard practice. Our primary objective was to compare remifentanil consumption between the groups. Our secondary objectives were to compare the quality of anesthesia, postoperative analgesia and the incidence of chronic pain. Eighty patients were included. Remifentanil consumption was lower in the ANI group: 4.4 (3.3; 5.7) vs. 5.8 (4.9; 7.1) µg kg-1 h-1 (difference = -1.4 (95% CI, -2.6 to -0.2), p = 0.0026). Propofol consumption was not different between the groups. Postoperative pain scores were low in both groups. There was no difference in morphine consumption 24 h after surgery. The proportion of patients reporting pain 3 months after surgery was 18.8% in the ANI group and 30.8% in the Standard group (difference = -12.0 (95% CI, -32.2 to 9.2)). ANI guidance resulted in lower remifentanil consumption compared with standard practice under propofol anesthesia. There was no difference in short- or long-term postoperative analgesia.

Keywords: ANI; analgesia nociception index; intravenous anesthesia; monitoring; nociception; remifentanil.

Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1

CONSORT flow diagram.

Figure 2

Individual evolution of remifentanil effect-site target concentration in the ANI (38 lines; left) and Standard group (40 lines; right). Each line represents a patient. Red lines represent the means.

Figure 3

Individual evolution of heart rate (A) and systolic blood pressure (B) in the ANI group (38 lines; left) and Standard group (40 lines; right). Each line represents a patient. Red lines represent the means.

Figure 4

Postoperative pain with (A) acute pain during the first 24 h, by visual analog scale (VAS) in the ANI and Standard groups. Mean is represented by circle and median by the horizontal line inside the box; and (B) chronic pain at the surgical site 3 months after the procedure (phone survey). Light gray indicates number of patients who reported persistent pain; dark gray indicates number of patients who reported no persistent pain; white indicates number of patients who did not answer our phone calls.