A beat-by-beat cardiovascular index, CARDEAN, to titrate opioid administration in the setting of orthopaedic surgery: a prospective randomized trial

To determine whether a beat-by-beat cardiovascular index (CARDEAN: cardiovascular depth of analgesia, Alpha-2 Ltd, Lyon, France) reduces the incidence of tachycardia in ASA I-III patients undergoing orthopaedic surgery. A total of 76 patients were prospectively randomized into (1) a control group or (2) the CARDEAN group, in which the nurse anaesthetist was blinded to CARDEAN application. In addition to conventional signs, an external observer instructed the nurse anaesthetist to administer sufentanil 0.1 µg kg^-1 when the CARDEAN crossed a threshold (≥ 60). The primary outcome was the incidence of tachycardia (> 120% of reference heart rate, HR). Non-invasive blood pressure (BP), electrocardiogram (ECG), O₂ saturation-photoplethysmography and the bispectral index (40 < BIS < 60) were monitored. HR and an estimation of beat-by-beat BP changes acquired from photoplethysmography and ECG were combined in an algorithm that detected hypertension followed by tachycardia (index scaled 0-100). Sufentanil 0.1 µg kg^-1 was administered when tachycardia, hypertension or movement ("conventional signs") was observed. Data for 66 patients (27 with known hypertension) were analysed. In the CARDEAN group, (a) the dose of sufentanil was higher (control: 0.46 µg kg^-1 100 min^-1, CARDEAN: 0.57 µg kg^-1 100 min^-1, p = 0.016), (b) the incidence rates of tachycardia and untoward events were lower (respectively: - 44%; control: 2.52 events 100 min^-1 [1.98-3.22]; CARDEAN: 1.42 [1.03-1.96], p = 0.005, hazard ratio: 0.56; movement, muscular contraction, or coughing: control: 0.74 events 100 min^-1 [0.47-1.16]; CARDEAN: 0.31 [0.15-0.62], p = 0.038), and (c) extubation occurred more often in the operating room (control: 76.5%, CARDEAN: 97%, p = 0.016). CARDEAN-titrated opioid administration was associated with a higher dose of sufentanil, a reduction in tachycardia and earlier emergence in ASA I-III patients undergoing major orthopaedic surgery.