Automatic pressure support reduction based on a targeted respiratory frequency or MRV is disposable in the TAENA ventilator for an automatic reduction of pressure support during weaning of patients in the intensive care unit (ICU). We studied 23 patients (63.52 years) in the postoperative period (14 cardiac, two thoracic and seven abdominal surgeries) in a prospective, randomized protocol comparing automatic pressure support weaning with the traditional manual reduction of pressure support to 5–7 cmH2O in our ICU. After arriving in the ICU after cardiac, thoracic or abdominal surgery, the patients were randomly assigned to traditional weaning consisting of manual reduction of pressure support (the pressure support was decreased every 30 min, keeping the RR/TV(L) < 80 until 5–7 cmH2O pressure support ventilation) or to the automatic pressure support reduction (MRV) with a respiratory frequency target of 20/min (the TAENA ventilator automatically decreased the pressure support ventilation level by 1 cmH2O every four respiratory cycles if the patient's RR was less than 16/min). Twelve patients were assigned to manual weaning whereas 11 patients were assigned to the automatic pressure support reduction weaning. The weaning mean time for the manual group was 3.18 hours while the weaning mean time for the automatic pressure support reduction group was 2.24 hours. There was no reintubation in both groups.