ELEVATED STATIC COMPLIANCE OF THE TOTAL RESPIRATORY SYSTEM - EARLY PREDICTOR OF WEANING UNSUCCESS IN SEVERE COPD PATIENTS MECHANICALLY VENTILATED

Objective: To assess in a group of COPD patients mechanically ventilat ed for an episode of acute respiratory failure the respiratory mechani cs with a simple and non invasive method at the bedside in order to ev aluate if these parameters may be predictive of weaning failure or suc cess. Design: A prospective study. Setting: Intensive care and interme diate intensive care units. Patients: 23 COPD patients ventilated for acute respiratory failure and studied within 24 hours from intubation. Methods: Using end-expiratory and end-inspiratory airway occlusion te chnique, we measured PEEPi, static compliance of the respiratory syste m (Crs, st) maximum respiratory resistance (Rrsmax) and minimum respir atory resistance (Rrsmin). Measurements and results: The weaned group (A) and the not weaned group (B) were not different regarding to stati c PEEPi (group A 8.5 +/- 4.0 vs group B 8.9 +/- 2.6 cmH(2)O), to Rrsma x (22.4 +/- 5.3 versus 22.2 +/- 9.0 cmH(2)O/I/s) and to Rrsmin (17.6 /- 5.5 versus 17.9 +/- 8.0 cmH(2)O/l/s), while a significant differenc e (p<0.001) has been found in Cst, rs (62.7 +/- 17.5 versus 111.6 +/- 18.0 ml/cm H2O). The threshold value of 88.5 ml/cmH(2)O was identified by discriminant analysis and provided the best separation between the two groups, with a sensitivity of 0.85 and a specificity of 0.87. Con clusion: Cst, rs measured non invasively in the first 24 h from intuba tion, provided a good separation between the patients who were success fully weaned and those who failed.