Causes of Difficult Weaning: Which Mechanisms Are Associated with Long-Term Ventilator Dependence?

Each year, over 400,000 patients in the United States receive mechanical ventilation as a result of acute or acute-on-chronic respiratory failure (1,2). About a quarter of acutely ventilated patients repeatedly fail attempts at weaning and may require prolonged mechanical ventilation (PMV) (Fig. 1) (3,4). The proportion of patients experiencing PMV ranges between 0% and 20% (5-13). Out of patients who survive PMV, 9-66% become dependent on long-term mechanical ventilation (LTMV) (4,9,14-21). Two factors account for these wide variations in the outcome. The first factor is differences in patient population. The second one is the nosology of what constitutes PMV and what constitutes LTMV is unsatisfactory.