End-inspiratory pause enhances ventilation efficiency without increasing autoPEEP in patients with COPD during controlled ventilation

INTRODUCTION: End-inspiratory pause (EIP) is traditionally discouraged in mechanically ventilated patients with chronic obstructive pulmonary disease (COPD) because it shortens expiratory time (TE) and may worsen hyperinflation. Previous data in hypoxemic patients suggest that, at equal total inspiratory time (TI), shorter insufflations followed by EIP can improve CO₂ elimination. Whether this strategy is effective and safe in obstructive lung disease remains unknown. OBJECTIVE: To evaluate whether a ventilation with high inspiratory flow and EIP reduces arterial carbon dioxide (PaCO₂) without increasing hyperinflation in mechanically ventilated patients with COPD undergoing controlled hypoventilation. METHODS: Prospective, single-center, randomized, cross-over physiological study including sedated, intubated adult patients with acute exacerbation of COPD, PaCO₂ ≥45 mmHg, and no spontaneous respiratory effort. Patients were randomized to two 30-minute ventilation strategies in volume-controlled mode: conventional ventilation without EIP (VentNO−PAUSE) and ventilation with EIP (VentPAUSE), in which inspiratory flow was increased and 40–50% of TI was replaced by an EIP. Total TI and TE were identical in both strategies. Arterial blood gases, respiratory mechanics, and hemodynamics were recorded. RESULTS: VentPAUSE significantly reduced PaCO₂ (58.5 ± 9.4 to 52.6 ± 10.4 mmHg; P < 0.001) and increased arterial pH (7.31 ± 0.09 to 7.34 ± 0.08; P < 0.001). Ventilatory ratio decreased (P < 0.001), indicating improved ventilatory efficiency. Oxygenation improved (PaO₂ and PaO₂/FiO₂; P < 0.05), while the alveolar–to–arterial oxygen difference was unchanged (p = 0.813). Total PEEP and auto-PEEP were not affected (P > 0.999). PaCO₂ reduction was greater in patients with higher respiratory system elastance. CONCLUSIONS: In sedated, mechanically ventilated patients with COPD, a strategy using high inspiratory flow with a short inspiratory pause reduces PaCO₂ and improves oxygenation without increasing auto-PEEP.