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  • 1
    In: Frontiers in Pharmacology, Frontiers Media SA, Vol. 9 ( 2018-3-5)
    Type of Medium: Online Resource
    ISSN: 1663-9812
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2018
    detail.hit.zdb_id: 2587355-6
    SSG: 15,3
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  • 2
    In: Frontiers in Physiology, Frontiers Media SA, Vol. 14 ( 2023-5-15)
    Abstract: Lung recruitment maneuvers following one-lung ventilation (OLV) increase the risk for the development of acute lung injury. The application of continuous negative extrathoracic pressure (CNEP) is gaining interest both in intubated and non-intubated patients. However, there is still a lack of knowledge on the ability of CNEP support to recruit whole lung atelectasis following OLV. We investigated the effects of CNEP following OLV on lung expansion, gas exchange, and hemodynamics. Ten pigs were anesthetized and mechanically ventilated with pressure-regulated volume control mode (PRVC; FiO 2 : 0.5, Fr: 30–35/min, VT: 7 mL/kg, PEEP: 5 cmH 2 O) for 1 hour, then baseline (BL) data for gas exchange (arterial partial pressure of oxygen, PaO 2 ; and carbon dioxide, PaCO 2 ), ventilation and hemodynamical parameters and lung aeration by electrical impedance tomography were recorded. Subsequently, an endobronchial blocker was inserted, and OLV was applied with a reduced VT of 5 mL/kg. Following a new set of measurements after 1 h of OLV, two-lung ventilation was re-established, combining PRVC (VT: 7 mL/kg) and CNEP (−15 cmH 2 O) without any hyperinflation maneuver and data collection was then repeated at 5 min and 1 h. Compared to OLV, significant increases in PaO 2 (154.1 ± 13.3 vs. 173.8 ± 22.1) and decreases in PaCO 2 (52.6 ± 11.7 vs. 40.3 ± 4.5 mmHg, p & lt; 0.05 for both) were observed 5 minutes following initiation of CNEP, and these benefits in gas exchange remained after an hour of CNEP. Gradual improvements in lung aeration in the non-collapsed lung were also detected by electrical impedance tomography ( p & lt; 0.05) after 5 and 60 min of CNEP. Hemodynamics and ventilation parameters remained stable under CNEP. Application of CNEP in the presence of whole lung atelectasis proved to be efficient in improving gas exchange via recruiting the lung without excessive airway pressures. These benefits of combined CNEP and positive pressure ventilation may have particular value in relieving atelectasis in the postoperative period of surgical procedures requiring OLV.
    Type of Medium: Online Resource
    ISSN: 1664-042X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
    detail.hit.zdb_id: 2564217-0
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  • 3
    In: Frontiers in Physiology, Frontiers Media SA, Vol. 9 ( 2018-12-12)
    Type of Medium: Online Resource
    ISSN: 1664-042X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2018
    detail.hit.zdb_id: 2564217-0
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  • 4
    In: Frontiers in Physiology, Frontiers Media SA, Vol. 13 ( 2022-4-11)
    Abstract: Background: Although spontaneous breathing is known to exhibit substantial physiological fluctuation that contributes to alveolar recruitment, changes in the variability of the respiratory pattern following inhalation of carbon dioxide (CO 2 ) and volatile anesthetics have not been characterized. Therefore, we aimed at comparing the indices of breathing variability under wakefulness, sleep, hypercapnia and sedative and anesthetic concentrations of sevoflurane. Methods: Spontaneous breathing pattern was recorded on two consecutive days in six rabbits using open whole-body plethysmography under wakefulness and spontaneous sleep and following inhalation of 5% CO 2 , 2% sevoflurane (0.5 MAC) and 4% (1 MAC) sevoflurane. Tidal volume (V T ), respiratory rate (RR), minute ventilation (MV), inspiratory time (T I ) and mean inspiratory flow (V T /T I ) were calculated from the pressure fluctuations in the plethysmograph. Means and coefficients of variation were calculated for each measured variable. Autoregressive model fitting was applied to estimate the relative contributions of random, correlated, and oscillatory behavior to the total variance. Results: Physiological sleep decreased MV by lowering RR without affecting V T . Hypercapnia increased MV by elevating V T . Sedative and anesthetic concentrations of sevoflurane increased V T but decreased MV due to a decrease in RR. Compared to the awake stage, CO 2 had no effect on V T /T I while sevoflurane depressed significantly the mean inspiratory flow. Compared to wakefulness, the variability in V T , RR, MV, T I and V T /T I were not affected by sleep but were all significantly decreased by CO 2 and sevoflurane. The variance of T I originating from correlated behavior was significantly decreased by both concentrations of sevoflurane compared to the awake and asleep conditions. Conclusions: The variability of spontaneous breathing during physiological sleep and sevoflurane-induced anesthesia differed fundamentally, with the volatile agent diminishing markedly the fluctuations in respiratory volume, inspiratory airflow and breathing frequency. These findings may suggest the increased risk of lung derecruitment during procedures under sevoflurane in which spontaneous breathing is maintained.
    Type of Medium: Online Resource
    ISSN: 1664-042X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2564217-0
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  • 5
    In: Frontiers in Pediatrics, Frontiers Media SA, Vol. 10 ( 2022-9-9)
    Abstract: Flow-controlled ventilation (FCV) is characterized by a constant flow to generate active inspiration and expiration. While the benefit of FCV on gas exchange has been demonstrated in preclinical and clinical studies with adults, the value of this modality for a pediatric population remains unknown. Thus, we aimed at observing the effects of FCV as compared to pressure-regulated volume control (PRVC) ventilation on lung mechanics, gas exchange and lung aeration before and after surfactant depletion in a pediatric model. Ten anesthetized piglets (10.4 ± 0.2 kg) were randomly assigned to start 1-h ventilation with FCV or PRVC before switching the ventilation modes for another hour. This sequence was repeated after inducing lung injury by bronchoalveolar lavage and injurious ventilation. The primary outcome was respiratory tissue elastance. Secondary outcomes included oxygenation index (PaO 2 /FiO 2 ), PaCO 2 , intrapulmonary shunt (Qs/Qt), airway resistance, respiratory tissue damping, end-expiratory lung volume, lung clearance index and lung aeration by chest electrical impedance tomography. Measurements were performed at the end of each protocol stage. Ventilation modality had no effect on any respiratory mechanical parameter. Adequate gas exchange was provided by FCV, similar to PRVC, with sufficient CO 2 elimination both in healthy and surfactant-depleted lungs (39.46 ± 7.2 mmHg and 46.2 ± 11.4 mmHg for FCV; 36.0 ± 4.1 and 39.5 ± 4.9 mmHg, for PRVC, respectively). Somewhat lower PaO 2 /FiO 2 and higher Qs/Qt were observed in healthy and surfactant depleted lungs during FCV compared to PRVC ( p & lt; 0.05, for all). Compared to PRVC, lung aeration was significantly elevated, particularly in the ventral dependent zones during FCV ( p & lt; 0.05), but this difference was not evidenced in injured lungs. Somewhat lower oxygenation and higher shunt ratio was observed during FCV, nevertheless lung aeration improved and adequate gas exchange was ensured. Therefore, in the absence of major differences in respiratory mechanics and lung volumes, FCV may be considered as an alternative in ventilation therapy of pediatric patients with healthy and injured lungs.
    Type of Medium: Online Resource
    ISSN: 2296-2360
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2711999-3
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  • 6
    Online Resource
    Online Resource
    Frontiers Media SA ; 2021
    In:  Frontiers in Physiology Vol. 11 ( 2021-1-13)
    In: Frontiers in Physiology, Frontiers Media SA, Vol. 11 ( 2021-1-13)
    Abstract: The advantages of physiologically variable ventilation (PVV) based on a spontaneous breathing pattern have been demonstrated in several respiratory conditions. However, its potential benefits in chronic obstructive pulmonary disease (COPD) have not yet been characterized. We used an experimental model of COPD to compare respiratory function outcomes after 6 h of PVV versus conventional pressure-controlled ventilation (PCV). Materials and Methods Rabbits received nebulized elastase and lipopolysaccharide throughout 4 weeks. After 30 days, animals were anesthetized, tracheotomized, and randomized to receive 6 h of physiologically variable ( n = 8) or conventional PCV ( n = 7). Blood gases, respiratory mechanics, and chest fluoroscopy were assessed hourly. Results After 6 h of ventilation, animals receiving variable ventilation demonstrated significantly higher oxygenation index (PaO 2 /FiO 2 441 ± 37 (mean ± standard deviation) versus 354 ± 61 mmHg, p & lt; 0.001) and lower respiratory elastance (359 ± 36 versus 463 ± 81 cmH 2 O/L, p & lt; 0.01) than animals receiving PCV. Animals ventilated with the variable mode also presented less lung derecruitment (decrease in lung aerated area, –3.4 ± 9.9 versus –17.9 ± 6.7%, p & lt; 0.01) and intrapulmonary shunt fraction (9.6 ± 4.1 versus 17.0 ± 5.8%, p & lt; 0.01). Conclusion PVV applied to a model of COPD improved oxygenation, respiratory mechanics, lung aeration, and intrapulmonary shunt fraction compared to conventional ventilation. A reduction in alveolar derecruitment and lung tissue stress leading to better aeration and gas exchange may explain the benefits of PVV.
    Type of Medium: Online Resource
    ISSN: 1664-042X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
    detail.hit.zdb_id: 2564217-0
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  • 7
    Online Resource
    Online Resource
    Frontiers Media SA ; 2019
    In:  Frontiers in Physiology Vol. 10 ( 2019-6-26)
    In: Frontiers in Physiology, Frontiers Media SA, Vol. 10 ( 2019-6-26)
    Type of Medium: Online Resource
    ISSN: 1664-042X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2019
    detail.hit.zdb_id: 2564217-0
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