Flow-controlled ventilation (FCV) improves regional ventilation in obese patients – a randomized controlled crossover trial
Background In obese patients, high closing capacity and low functional residual capacity increase the risk for expiratory alveolar collapse. Constant expiratory flow, as provided by the new flow-controlled ventilation (FCV) mode, was shown to improve lung recruitment. We hypothesized that lung aeration and respiratory mechanics improve in obese patients during FCV. Methods We compared FCV and volume-controlled (VCV) ventilation in 23 obese patients in a randomized cross-over setting. Starting with baseline measurements, ventilation settings were kept identical except for the ventilation mode related differences (VCV: inspiration to expiration ratio 1:2 with passive expiration, FCV: inspiration to expiration ratio 1:1 with active, linearized expiration). Primary endpoint of the study was the change of end-expiratory lung volume compared to baseline ventilation. Secondary endpoints were the change of mean lung volume, respiratory mechanics and hemodynamic variables. Results The loss of end-expiratory lung volume and mean lung volume compared to baseline was lower during FCV compared to VCV (end-expiratory lung volume: FCV, -126 ± 207 ml; VCV, -316 ± 254 ml; p < 0.001, mean lung volume: FCV, -108.2 ± 198.6 ml; VCV, -315.8 ± 252.1 ml; p < 0.001) and at comparable plateau pressure (baseline, 19.6 ± 3.7; VCV, 20.2 ± 3.4; FCV, 20.2 ± 3.8 cmH2O; p = 0.441), mean tracheal pressure was higher (baseline, 13.1 ± 1.1; VCV, 12.9 ±1.2; FCV, 14.8 ± 2.2 cmH2O; p < 0.001). All other respiratory and hemodynamic variables were comparable between the ventilation modes. Conclusions This study demonstrates that, compared to VCV, FCV improves regional ventilation distribution of the lung at comparable PEEP, tidal volume, PPlat and ventilation frequency. The increase in end-expiratory lung volume during FCV was probably caused by the increased mean tracheal pressure which can be attributed to the linearized expiratory pressure decline.
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Flow-controlled ventilation (FCV) improves regional ventilation in obese patients – a randomized controlled crossover trial
Posted 17 Jan, 2020
On 28 Jan, 2020
On 16 Jan, 2020
On 15 Jan, 2020
On 14 Jan, 2020
On 14 Jan, 2020
On 01 Jan, 2020
On 22 Dec, 2019
On 21 Dec, 2019
On 21 Dec, 2019
On 15 Dec, 2019
Received 30 Nov, 2019
On 23 Nov, 2019
Received 22 Nov, 2019
On 21 Nov, 2019
Invitations sent on 21 Nov, 2019
On 21 Nov, 2019
On 20 Nov, 2019
On 20 Nov, 2019
On 22 Oct, 2019
Received 20 Oct, 2019
On 25 Aug, 2019
Received 19 Aug, 2019
On 02 Aug, 2019
Invitations sent on 12 Jul, 2019
On 11 Jul, 2019
On 11 Jul, 2019
On 10 Jul, 2019
On 02 Jul, 2019
Background In obese patients, high closing capacity and low functional residual capacity increase the risk for expiratory alveolar collapse. Constant expiratory flow, as provided by the new flow-controlled ventilation (FCV) mode, was shown to improve lung recruitment. We hypothesized that lung aeration and respiratory mechanics improve in obese patients during FCV. Methods We compared FCV and volume-controlled (VCV) ventilation in 23 obese patients in a randomized cross-over setting. Starting with baseline measurements, ventilation settings were kept identical except for the ventilation mode related differences (VCV: inspiration to expiration ratio 1:2 with passive expiration, FCV: inspiration to expiration ratio 1:1 with active, linearized expiration). Primary endpoint of the study was the change of end-expiratory lung volume compared to baseline ventilation. Secondary endpoints were the change of mean lung volume, respiratory mechanics and hemodynamic variables. Results The loss of end-expiratory lung volume and mean lung volume compared to baseline was lower during FCV compared to VCV (end-expiratory lung volume: FCV, -126 ± 207 ml; VCV, -316 ± 254 ml; p < 0.001, mean lung volume: FCV, -108.2 ± 198.6 ml; VCV, -315.8 ± 252.1 ml; p < 0.001) and at comparable plateau pressure (baseline, 19.6 ± 3.7; VCV, 20.2 ± 3.4; FCV, 20.2 ± 3.8 cmH2O; p = 0.441), mean tracheal pressure was higher (baseline, 13.1 ± 1.1; VCV, 12.9 ±1.2; FCV, 14.8 ± 2.2 cmH2O; p < 0.001). All other respiratory and hemodynamic variables were comparable between the ventilation modes. Conclusions This study demonstrates that, compared to VCV, FCV improves regional ventilation distribution of the lung at comparable PEEP, tidal volume, PPlat and ventilation frequency. The increase in end-expiratory lung volume during FCV was probably caused by the increased mean tracheal pressure which can be attributed to the linearized expiratory pressure decline.
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Figure 4
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Figure 6