Use of a fully closed-loop ventilation mode in long-term ventilated ICU patients: a prospective study

Introduction

IntelliVent-ASV^® is a closed-loop ventilation mode that automatically adjusts ventilation and oxygenation settings in passive and active breathing patients. The minute volume is adjusted according to end-tidal CO₂ (ETCO₂) information in passive breathing patients (and respiratory rate in active breathing patients), and oxygenation is adjusted according to SpO₂ information. This study reports the ventilation and oxygenation delivered by IntelliVent-ASV^® in long-term ventilated ICU patients.

Methods

This prospective, observational study included 100 patients invasively ventilated using IntelliVent-ASV^® from admission to weaning or death. The rate and reason for stopping automation were recorded. Settings automatically selected, delivered ventilation, respiratory mechanics and arterial blood gas results were collected once a day. Patients were categorized in different lung conditions: normal lung, ALI/ARDS, COPD. Analysis of variance compared the ventilation-days for each type of lung condition for active and passive breathing patients.

Results

Patients (age 73 (64 to 79) years; SAPS II 56 (48 to 69)) were ventilated using IntelliVent-ASV^® to weaning or death (31%) for a median duration of 3.0 (2.0 to 7.0) days without any safety issue. The ventilation controller was deactivated in two patients because of high PaCO₂-ETCO₂ gradient. Oxygenation controller was deactivated in seven patients for 1 day because of a poor SpO₂ signal. In passive and active ventilation-days, minute volume, VT/PBW, respiratory rate, FiO₂, and PEEP were statistically different based on lung condition. In passive ALI/ARDS ventilation-days, VT/PBW was significantly lower (7.5 (6.9 to 7.9) ml/kg) than passive normal lung (8.1 (7.3 to 8.9) ml/kg; P < 0.05) and passive COPD patients (9.9 (8.3 to 11.1) ml/kg; P < 0.05). In passive ALI/ARDS ventilation-days, FiO₂ and PEEP were statistically higher than passive normal lung (35 (33 to 47)% vs. 30 (30 to 31)% and 11 (8 to 13) cmH₂O vs. 5 (5 to 6) cmH₂O, respectively; P < 0.05). In active normal lung ventilation-days, VT/PBW was not different (8.4 (7.8 to 9.1) ml/kg) than in active ALI/ARDS (8.1 (7.5 to 9.3) ml/kg), and in active COPD (9.3 (8.6 to 11.6) ml/kg). In active ALI/ARDS and COPD ventilation-days, PEEP was significantly higher than active normal lung (8 (5 to 10) cmH₂O, 7 (5 to 10) cmH₂O, and 5 (5 to 5) cm H₂O, respectively; P < 0.05).

Conclusion

IntelliVent-ASV^® can be used safely in long-term ventilated ICU patients and selects automatically different ventilation and oxygenation settings according to the lung condition, especially for passive breathing patients.