[Anesthetic conserving device (AnaConDa) used after cardiac surgery: experience in a postoperative recovery unit]

To assess the safety and efficacy of using the Anesthetic Conserving Device (AnaConDa) when maintaining sedation after cardiac surgery.

Descriptive study of 46 consecutive patients in the postoperative recovery unit after cardiac surgery between January and April 2009. The patients were under sevoflurane sedation administered with the AnaConDa placed in the inhalation tube. No exclusion criteria were established before enrollment. The sevoflurane dose was set using the manufacturer's normogram and was later adjusted to give an end-tidal concentration of sevoflurane between 0.5% and 0.7% on the basis of data from a gas analyzer. Remifentanil was administered to all patients; a fast-track extubation protocol was used. The only criterion for excluding a patient's data from analysis was prolonged sedation (> 5 hours).

The mean (SD) time patients were under sedation with the AnaConDa in place was 2588 (12.32) minutes. The end-tidal concentration of sevoflurane never exceeded 1%. Scores on the Richmond agitation-sedation scale were -5 at 60 minutes in all cases; there was some score variability at 120 minutes. Deeper sedation was desired for the first 60 minutes to avoid awakening related to rewarming. The mean time until awakening was 6.17 minutes (range, 1-30 minutes). The mean time until extubation was 43 (6.69) minutes. The most common adverse effect was arterial hypotension (12 cases). Hypotension was related to bleeding in 3 patients and to low cardiac output in 4 patients.

Administering sevoflurane through the AnaConDa can be a safe, valid, and reliable method for sedating patients after cardiac surgery. With this device, it is possible to monitor the concentration administered.