Background: We sought to determine whether online use of a beat-by-beat cardiovascular index, CARDEAN (Alpha-2, Lyon, France), modifies the incidence of patient movement during colonoscopy under anesthesia.
Methods: Monitoring included an electrocardiogram, oscillometric and noninvasive beat-by-beat arterial blood pressure, O2 saturation, bispectral index (BIS), and CARDEAN. CARDEAN consists of beat-by-beat Finapres (Ohmeda, Madison, WI) combined with an algorithm that detects hypertension followed by tachycardia and produces an index scaled 0 to 100. The anesthesiologist was denied access to Finapres and CARDEAN. Propofol was adjusted to keep 40<BIS<60. Alfentanil 3.5 microg x kg(-1) was administered according to conventional signs (tachycardia, hypertension, and movement), unless the patient had signs of brady/apnea or Spo(2) <95%. One hundred fifty-nine patients presenting for colonoscopy under propofol anesthesia were prospectively randomized to (i) control: no other intervention, or (ii) CARDEAN: in addition to conventional signs, an observer instructed the anesthesiologist to administer alfentanil when CARDEAN was >60. The primary outcome was the number of observed movements.
Results: Data were analyzed in 146 patients (control: 75; CARDEAN: 71). The doses of propofol and alfentanil were similar in both groups. When BIS was <60, movements were less frequent in the CARDEAN group (3.3 movements/100 min [2.3-4.8]) than in the control group (6.7 [5.3-8.5]) (odds ratio: 0.5 [0.32; 0.76], P = 0.001). During the first 10 minutes of the procedure, the incidence of movements was 38% and 59% in the CARDEAN and control groups, respectively (P = 0.04).
Conclusion: With BIS <60, CARDEAN-guided opioid administration is associated with a reduction of 51% of clinically unpredictable movements in unparalyzed patients undergoing colonoscopy. More studies are required to refine the role of CARDEAN in surgical settings.