A prospective comparison of IMV and T-piece weaning from mechanical ventilation.

Two hundred (200) consecutive medical and surgical patients requiring mechanical ventilation were entered into a prospective randomized trial of weaning by either intermittent mandatory ventilation (IMV) or T-piece. Patients in these groups were of similar age and sex and had the same total ventilation time (TVT). The study design provided equal time for each weaning mode after specific criteria for oxygenation and ventilation were satisfied (PaO 2 >55 mm Hg on FIo 2 2 VE, VT >5 ml/kg, FVC >10 ml/ kg, NIF ≤ – 20 cm H 2 O). Of the original 200 patients 165 were entered into the weaning phase; 35 patients were withdrawn prior to weaning due to the discretion of the attending physician or protocol error. Weaning time was not different between the IMV (5.3 ± 1.2 h, mean ± SEM) and T-piece groups (5.9 ± 1.4 h, p = NS). Of the 165 patients, 155 (93 percent) were weaned successfully by protocol, 79 in the IMV and 76 in the T-piece group. Of 155 patients, 136 (88 percent) were weaned on the first attempt by protocol. Of the 19 who were not weaned, 11 were weaned successfully on the second and five on the third trial; three patients required three-day weans. We conclude that clinically stable patients who require short-term mechanical ventilation and meet standard bedside weaning criteria can be weaned efficiently by protocol using either IMV or T-piece techniques. (Chest 1989; 96:348–52) IMV = intermittent mandatory ventilation; TVT = total ventilation time; MW = maximum voluntary ventilation; NIF = negative inspiratory force; AMV = assisted mandatory ventilation; WT = weaning time