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Adaptive mechanical ventilation with automated minimization of mechanical power-a pilot randomized cross-over study.

ABSTRACT: BACKGROUND:Adaptive mechanical ventilation automatically adjusts respiratory rate (RR) and tidal volume (VT) to deliver the clinically desired minute ventilation, selecting RR and VT based on Otis' equation on least work of breathing. However, the resulting VT may be relatively high, especially in patients with more compliant lungs. Therefore, a new mode of adaptive ventilation (adaptive ventilation mode 2, AVM2) was developed which automatically minimizes inspiratory power with the aim of ensuring lung-protective combinations of VT and RR. The aim of this study was to investigate whether AVM2 reduces VT, mechanical power, and driving pressure (?Pstat) and provides similar gas exchange when compared to adaptive mechanical ventilation based on Otis' equation. METHODS:A prospective randomized cross-over study was performed in 20 critically ill patients on controlled mechanical ventilation, including 10 patients with acute respiratory distress syndrome (ARDS). Each patient underwent 1 h of mechanical ventilation with AVM2 and 1 h of adaptive mechanical ventilation according to Otis' equation (adaptive ventilation mode, AVM). At the end of each phase, we collected data on VT, mechanical power, ?P, PaO2/FiO2 ratio, PaCO2, pH, and hemodynamics. RESULTS:Comparing adaptive mechanical ventilation with AVM2 to the approach based on Otis' equation (AVM), we found a significant reduction in VT both in the whole study population (7.2?±?0.9 vs. 8.2?±?0.6?ml/kg, p?

SUBMITTER: Becher T

PROVIDER: S-EPMC6822420 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Adaptive mechanical ventilation with automated minimization of mechanical power-a pilot randomized cross-over study.

Becher Tobias T Adelmeier Anna A Frerichs Inéz I Weiler Norbert N Schädler Dirk D

Critical care (London, England) 20191030 1

<h4>Background</h4>Adaptive mechanical ventilation automatically adjusts respiratory rate (RR) and tidal volume (V<sub>T</sub>) to deliver the clinically desired minute ventilation, selecting RR and V<sub>T</sub> based on Otis' equation on least work of breathing. However, the resulting V<sub>T</sub> may be relatively high, especially in patients with more compliant lungs. Therefore, a new mode of adaptive ventilation (adaptive ventilation mode 2, AVM2) was developed which automatically minimize ...[more]

PMID: 31666136

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Project description:Timely regulation of oxygen (Fio2) is essential to prevent hyperoxemia or episodic hypoxemia. Exposure to excessive Fio2 is often noted early after onset of mechanical ventilation. In this pilot study, we examined the feasibility, safety, and efficacy of a clinical trial to prioritize Fio2 titration with electronic alerts to respiratory therapists.Study designOpen-labeled, randomized control pilot trial.SettingMedical ICU.SubjectsAdults requiring mechanical ventilation.InterventionsProtocolized oxygen titration was initiated one hour after initiation of mechanical ventilation. When Spo2 exceeded 92% while on Fio2 ≥ 0.5, an electronic alert to respiratory therapists was triggered at 30-minute intervals. In the control arm, respiratory therapists titrated Fio2 by standard physician's orders.Measurements and main resultsThe primary end point was to determine if early Fio2 titration based on automated alerts was feasible in terms of reducing hyperoxemia. Secondary analyses included the number and frequency of alerts, mechanical ventilation duration, and ICU length of stay. Among 135 randomized patients, 72 were assigned to the intervention arm and 63 to the control arm. A total 877 alerts were sent. Exposure to hyperoxemia was significantly reduced in the intervention group by a median of 7.5 hours (13.7 [interquartile range (IQR), 2.9-31.1] vs 21.2 [IQR, 10.9-64.4]; p < 0.0004). Maximal Fio2 titration during the first quartile resulted in significant reduction in mechanical ventilation duration and ICU stay. Minor hypoxemic events (Spo2 < 88%) represented 12% of alerts, 9% were transient and responded to a single Fio2 increase, whereas 3% of alerts were associated with recurrent transient hypoxemia.ConclusionsOur pilot study indicates that early Fio2 titration driven by automated alerts is feasible in the ICU, as reflected by a statistically significant reduction of hyperoxemia exposure, limited consequential hypoxemia, and reduced ICU resource utilization. The encouraging results of this pilot study need to be validated in a larger ICU cohort.

Project description:BackgroundMechanical power (MP) is the energy delivered to the respiratory system over time during mechanical ventilation. Our aim was to compare the currently available methods to calculate MP during volume- and pressure-controlled ventilation, comparing different equations with the geometric reference method, to understand whether the easier to use surrogate formulas were suitable for the everyday clinical practice. This would warrant a more widespread use of mechanical power to promote lung protection.MethodsForty respiratory failure patients, sedated and paralyzed for clinical reasons, were ventilated in volume-controlled ventilation, at two inspiratory flows (30 and 60 L/min), and pressure-controlled ventilation with a similar tidal volume. Mechanical power was computed both with the geometric method, as the area between the inspiratory limb of the airway pressure and the volume, and with two algebraic methods, a comprehensive and a surrogate formula.ResultsThe bias between the MP computed by the geometric method and by the comprehensive algebraic method during volume-controlled ventilation was respectively 0.053 (0.77, - 0.81) J/min and - 0.4 (0.70, - 1.50) J/min at low and high flows (r2 = 0.96 and 0.97, p < 0.01). The MP measured and computed by the two methods were highly correlated (r2 = 0.95 and 0.94, p < 0.01) with a bias of - 0.0074 (0.91, - 0.93) and - 1.0 (0.45, - 2.52) J/min at high-low flows. During pressure-controlled ventilation, the bias between the MP measured and the one calculated with the comprehensive and simplified methods was correlated (r2 = 0.81, 0.94, p < 0.01) with mean differences of - 0.001 (2.05, - 2.05) and - 0.81 (2.11, - 0.48) J/min.ConclusionsBoth for volume-controlled and pressure-controlled ventilation, the surrogate formulas approximate the reference method well enough to warrant their use in the everyday clinical practice. Given that these formulas require nothing more than the variables already displayed by the intensive care ventilator, a more widespread use of mechanical power should be encouraged to promote lung protection against ventilator-induced lung injury.

Project description:BACKGROUND:Volume-controlled ventilation has been suggested to optimize lung deposition during nebulization although promoting spontaneous ventilation is targeted to avoid ventilator-induced diaphragmatic dysfunction. Comparing topographic aerosol lung deposition during volume-controlled ventilation and spontaneous ventilation in pressure support has never been performed. The aim of this study was to compare lung deposition of a radiolabeled aerosol generated with a vibrating-mesh nebulizer during invasive mechanical ventilation, with two modes: pressure support ventilation and volume-controlled ventilation. METHODS:Seventeen postoperative neurosurgery patients without pulmonary disease were randomly ventilated in pressure support or volume-controlled ventilation. Diethylenetriaminepentaacetic acid labeled with technetium-99m (2 mCi/3 mL) was administrated using a vibrating-mesh nebulizer (Aerogen Solo(®), provided by Aerogen Ltd, Galway, Ireland) connected to the endotracheal tube. Pulmonary and extrapulmonary particles deposition was analyzed using planar scintigraphy. RESULTS:Lung deposition was 10.5 ± 3.0 and 15.1 ± 5.0 % of the nominal dose during pressure support and volume-controlled ventilation, respectively (p < 0.05). Higher endotracheal tube and tracheal deposition was observed during pressure support ventilation (27.4 ± 6.6 vs. 20.7 ± 6.0 %, p < 0.05). A similar penetration index was observed for the right (p = 0.210) and the left lung (p = 0.211) with both ventilation modes. A high intersubject variability of lung deposition was observed with both modes regarding lung doses, aerosol penetration and distribution between the right and the left lung. CONCLUSIONS:In the specific conditions of the study, volume-controlled ventilation was associated with higher lung deposition of nebulized particles as compared to pressure support ventilation. The clinical benefit of this effect warrants further studies. Clinical trial registration NCT01879488.

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Adaptive mechanical ventilation with automated minimization of mechanical power-a pilot randomized cross-over study.

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Adaptive mechanical ventilation with automated minimization of mechanical power-a pilot randomized cross-over study.

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