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1.
Procare ; 28(1-2): 12-16, 2023.
Artigo em Alemão | MEDLINE | ID: mdl-36846543

RESUMO

An effective (early) mobilization in COVID-19 intensive care patients with ECMO treatment is very important. Sedation, extracorporeal procedures with the danger of circuit malfunction, large lumen ECMO cannulas with a risk of dislocation and a very severe neuromuscular weakness are factors that could deem mobilization beyond stage 1 of the ICU mobility score (IMS) in some cases difficult or impossible; however, early mobilization is a key point of the ABCDEF bundle to counteract pulmonary complications, neuromuscular dysfunction and enable recovery. The case of a 53-year-old, previously healthy and active male patient with a severe and complicated course of COVID-19 and pronounced ICU-acquired weakness is described. While receiving ECMO the patient could be mobilized using a robotic system. Due to severe and rapidly progressing pulmonary fibrosis, additional low-dose methylprednisolone therapy (Meduri protocol) was implemented. Under this multimodal treatment the patient was successfully weaned from the ventilator and decannulated. Robotic assisted mobilization has the potential to be a novel and safe therapeutic option for a customized and highly effective mobilization in ECMO patients.

2.
Pharmaceutics ; 14(11)2022 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-36365205

RESUMO

In the present study, it was shown that a newly developed two-chamber setup (TCS) for containment investigations consisting of an emission and a detection chamber may serve to predict the dustiness of HPAPIs in a sealed system at different flow conditions. These flow conditions include the plain diffusive transport and the diffusive transport with the oppositely directed convective flow of airborne particles of the safe surrogate substance acetaminophen (ACAM). A linear correlation was found between an atomized amount of up to 400 mg of ACAM and the resulting dust emissions. The dust emission was reduced significantly by an oppositely directed convective flow. The results from the examinations, using either atomized ACAM or smoke for the determination of the evacuation time of the detection chamber, indicated that both methods are comparable. Furthermore, computational fluid dynamics (CFD) simulations were performed to determine the evacuation time. A time period of 9 min was sufficient for a reproducible evacuation and a reliable detection of most airborne ACAM particles within the detection chamber. CFD simulations were also carried out to simulate the air velocity resulting from various pressure differences and to visualize the flow of the airborne particles within the detection chamber.

3.
Physiol Meas ; 43(9)2022 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-36044904

RESUMO

Objective.The worldwide rising quantity of surgeries and the corresponding need of mechanical ventilation means a rising number of patients are at risk of suffering from post-operative pulmonary complications. To prevent this risk, individual mechanics of the lung should be considered when setting the parameters of mechanical ventilation. Intratidal compliance analysis based on transpulmonal pressure would provide an estimate for individual lung mechanics. The downside of such measure, however, is its invasiveness. Accurate measurement requires recording of the esophageal pressure as surrogate for the actual pleural pressure. Measuring pressure at the airway opening is considerably easier, but the resulting mechanics of the respiratory system may not represent the actual lung mechanics in a straightforward fashion.Approach.In order to evaluate if the mechanics of the lungs are represented by analysis of the mechanics of the respiratory system we determined intratidal dynamic compliance-volume profiles of both in 23 lung-healthy mechanically ventilated patients undergoing elective surgery. We also compared the accuracy of the compliance profiles resulting from analysis of the total breath with those resulting from the analysis of inspiration data only.Main results.When the whole breath was analyzed 54.3%, and with only inspiration data 69.6%, of compliance profiles of the respiratory system matched those of the lung. With both approaches profiles of the lung and the respiratory system matched or deviated by only one neighboring step (75% whole breath, 91.3% inspiration only), and never contradicted each other.Significance.Compliance profiles calculated from volume and pressure data of the respiratory system are an adequate surrogate for the compliance profiles of the lungs of lung-healthy patients. Therefore, invasive assessment of esophageal pressure for achievement of intrapleural pressure is unnecessary. The compliance profiles based on only inspiratory data appear more sensitive for indicating intratidal derecruitment than those based on data of the whole breath.


Assuntos
Pulmão , Respiração com Pressão Positiva , Humanos , Complacência Pulmonar , Respiração com Pressão Positiva/métodos , Respiração Artificial , Mecânica Respiratória , Tórax
5.
Respir Res ; 22(1): 292, 2021 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-34775965

RESUMO

BACKGROUND: Pursed-lips breathing (PLB) is a technique to attenuate small airway collapse by regulating the expiratory flow. During mandatory ventilation, flow-controlled expiration (FLEX), which mimics the expiratory flow course of PLB utilizing a digital system for measurement and control, was shown to exert lung protective effects. However, PLB requires a patient's participation and coordinated muscular effort and FLEX requires a complex technical setup. Here, we present an adjustable flow regulator to mimic PLB and FLEX, respectively, without the need of a patient's participation, or a complex technical device. METHODS: Our study consisted of two parts: First, in a lung model which was ventilated with standard settings (tidal volume 500 ml, respiratory rate 12 min-1, positive end-expiratory pressure (PEEP) 5 cmH2O), the possible reduction of the maximal expiratory flow by utilizing the flow regulator was assessed. Second, with spontaneously breathing healthy volunteers, the short-term effects of medium and strong expiratory flow reduction on airway pressure, the change of end-expiratory lung volume (EELV), and breathing discomfort was investigated. RESULTS: In the lung model experiments, expiratory flow could be reduced from - 899 ± 9 ml·s-1 down to - 328 ± 25 ml·s-1. Thereby, inspiratory variables and PEEP were unaffected. In the volunteers, the maximal expiratory flow of - 574 ± 131 ml·s-1 under baseline conditions was reduced to - 395 ± 71 ml·s-1 for medium flow regulation and to - 266 ± 58 ml·s-1 for strong flow regulation, respectively (p < 0.001). Accordingly, mean airway pressure increased from 0.6 ± 0.1 cmH2O to 2.9 ± 0.4 cmH2O with medium flow regulation and to 5.4 ± 2.4 cmH2O with strong flow regulation, respectively (p < 0.001). The EELV increased from baseline by 31 ± 458 ml for medium flow regulation and 320 ± 681 ml for strong flow regulation (p = 0.033). The participants rated breathing with the flow regulator as moderately uncomfortable, but none rated breathing with the flow regulator as intolerable. CONCLUSIONS: The flow regulator represents an adjustable device for application of a self-regulated expiratory resistive load, representing an alternative for PLB and FLEX. Future applications in spontaneously breathing patients and patients with mandatory ventilation alike may reveal potential benefits. TRIAL REGISTRATION: DRKS00015296, registered on 20th August, 2018; URL: https://www.drks.de/drks_web/setLocale_EN.do .


Assuntos
Medidas de Volume Pulmonar/métodos , Pulmão/fisiologia , Modelos Biológicos , Respiração com Pressão Positiva/métodos , Doença Pulmonar Obstrutiva Crônica/terapia , Volume de Ventilação Pulmonar/fisiologia , Adolescente , Adulto , Estudos Cross-Over , Expiração , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Adulto Jovem
6.
Metab Eng ; 66: 296-307, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33894339

RESUMO

Gas fermentation is a technology for producing platform chemicals as well as fuels and one of the most promising alternatives to petrochemicals. Medium-chained acids and alcohols such as hexanoate and hexanol are particularly interesting due to their versatile application. This study elucidated the pathway of chain elongation in native C6 compound-producing acetogens. Essential genes of Clostridium carboxidivorans for synthesis of medium-chained acids and alcohols were identified in order to demonstrate their catalytic activity in the acetogenic model organism Acetobacterium woodii. Two such gene clusters were identified, which are responsible for conversion of acetyl-CoA to butyryl-CoA by reverse ß-oxidation. Using RT-PCR it could be demonstrated that only genes of cluster 1 are expressed constitutively with simultaneous formation of C6 compounds. Based on genes from C. carboxidivorans, a modular hexanoyl-CoA synthesis (hcs) plasmid system was constructed and transferred into A. woodii. With the recombinant A. woodii strains AWO [pPta_hcs1], AWO [pPta_hcs2], AWO [pTet_hcs1], and AWO [pTet_hcs2] butyrate and hexanoate production under heterotrophic (1.22-4.15 mM hexanoate) and autotrophic conditions (0.48-1.56 mM hexanoate) with both hcs clusters could be detected. hcs Cluster 1 from C. carboxidivorans was transferred into the ABE-fermenting strain Clostridium saccharoperbutylacetonicum as well. For further analysis, genes were also cloned into the hcs plasmid system individually. The resulting recombinant C. saccharoperbutylacetonicum strains with just individual genes neither produced hexanoate nor hexanol, but the strains containing the entire gene cluster were capable of chain elongation. A production of 0.8 mM hexanoate and 5.2 mM hexanol in the fermentation with glucose could be observed.


Assuntos
Álcoois , Clostridium , Acetobacterium , Clostridium/genética
7.
Medicine (Baltimore) ; 100(6): e23570, 2021 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-33578509

RESUMO

ABSTRACT: The Gas Man simulation software provides an opportunity to teach, understand and examine the pharmacokinetics of volatile anesthetics. The primary aim of this study was to investigate the accuracy of a cardiac output and alveolar ventilation matched Gas Man model and to compare its predictive performance with the standard pharmacokinetic model using patient data.Therefore, patient data from volatile anesthesia were successively compared to simulated administration of desflurane and sevoflurane for the standard and a parameter-matched simulation model with modified alveolar ventilation and cardiac output. We calculated the root-mean-square deviation (RMSD) between measured and calculated induction, maintenance and elimination and the expiratory decrement times during emergence and recovery for the standard and the parameter-matched model.During induction, RMSDs for the standard Gas Man simulation model were higher than for the parameter-matched Gas Man simulation model [induction (desflurane), standard: 1.8 (0.4) % Atm, parameter-matched: 0.9 (0.5) % Atm., P = .001; induction (sevoflurane), standard: 1.2 (0.9) % Atm, parameter-matched: 0.4 (0.4) % Atm, P = .029]. During elimination, RMSDs for the standard Gas Man simulation model were higher than for the parameter-matched Gas Man simulation model [elimination (desflurane), standard: 0.7 (0.6) % Atm, parameter-matched: 0.2 (0.2) % Atm, P = .001; elimination (sevoflurane), standard: 0.7 (0.5) % Atm, parameter-matched: 0.2 (0.2) % Atm, P = .008]. The RMSDs during the maintenance of anesthesia and the expiratory decrement times during emergence and recovery showed no significant differences between the patient and simulated data for both simulation models.Gas Man simulation software predicts expiratory concentrations of desflurane and sevoflurane in humans with good accuracy, especially when compared to models for intravenous anesthetics. Enhancing the standard model by ventilation and hemodynamic input variables increases the predictive performance of the simulation model. In most patients and clinical scenarios, the predictive performance of the standard Gas Man simulation model will be high enough to estimate pharmacokinetics of desflurane and sevoflurane with appropriate accuracy.


Assuntos
Débito Cardíaco/efeitos dos fármacos , Desflurano/farmacocinética , Expiração/fisiologia , Ventilação Pulmonar/fisiologia , Sevoflurano/farmacocinética , Adulto , Idoso , Algoritmos , Anestésicos Inalatórios/administração & dosagem , Anestésicos Inalatórios/farmacocinética , Débito Cardíaco/fisiologia , Ensaios Clínicos como Assunto , Simulação por Computador/estatística & dados numéricos , Desflurano/administração & dosagem , Quimioterapia Combinada , Feminino , Humanos , Pulmão/metabolismo , Pulmão/fisiologia , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Alvéolos Pulmonares/efeitos dos fármacos , Alvéolos Pulmonares/metabolismo , Alvéolos Pulmonares/fisiologia , Sevoflurano/administração & dosagem
8.
J Clin Monit Comput ; 35(2): 343-354, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32067148

RESUMO

Anesthesia care providers and anesthesia decision support tools use mathematical pharmacokinetic models to control delivery and especially removal of anesthetics from the patient's body. However, these models are not able to reflect alterations in pharmacokinetics of volatile anesthetics caused by obesity. The primary aim of this study was to refine those models for obese patients. To investigate the effects of obesity on the elimination of desflurane, isoflurane and sevoflurane for various anesthesia durations, the Gas Man® computer simulation software was used. Four different models simulating patients with weights of 70 kg, 100 kg, 125 kg and 150 kg were constructed by increasing fat weight to the standard 70 kg model. For each modelled patient condition, the vaporizer was set to reach quickly and then maintain an alveolar concentration of 1.0 minimum alveolar concentration (MAC). Subsequently, the circuit was switched to an open (non-rebreathing) circuit model, the inspiratory anesthetic concentration was set to 0 and the time to the anesthetic decrements by 67% (awakening times), 90% (recovery times) and 95% (resolution times) in the vessel-rich tissue compartment including highly perfused tissue of the central nervous system were determined. Awakening times did not differ greatly between the simulation models. After volatile anesthesia with sevoflurane and isoflurane, awakening times were lower in the more obese simulation models. With increasing obesity, recovery and resolution times were higher. The additional adipose tissue in obese simulation models did not prolong awakening times and thus may act more like a sink for volatile anesthetics. The results of these simulations should be validated by comparing the elimination of volatile anesthetics in obese patients with data from our simulation models.


Assuntos
Anestésicos Inalatórios , Anestésicos , Isoflurano , Éteres Metílicos , Anestesia por Inalação , Simulação por Computador , Desflurano , Humanos , Masculino , Obesidade
9.
Paediatr Anaesth ; 30(8): 905-911, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32445609

RESUMO

BACKGROUND: The lungs of pediatric patients are subjected to tidal derecruitment during mechanical ventilation and in contrast to adult patients this unfavorable condition cannot be resolved with small c increases. This raises the question if higher end-expiratory pressure increases or recruitment maneuvers may resolve tidal derecruitment in pediatric patients. AIMS: We hypothesized that higher PEEP resolves tidal derecruitment in pediatric patients and that recruitment maneuvers between the pressure changes support the improvement of respiratory system mechanics. METHODS: The effects of end-expiratory pressure changes from 3 to 7 cmH2 O and vice versa without and with intermediate recruitment maneuvers on respiratory system mechanics and regional ventilation were investigated in 57 mechanically ventilated pediatric patients. The intratidal respiratory system compliance was determined from volume and pressure data before and after PEEP changes and categorized to indicate tidal derecruitment. RESULTS: Tidal derecruitment occurred comparably frequently at PEEP 3 cmH2 O without (13 out of 14 cases) and with recruitment maneuver (14 out of 14 cases) and at PEEP 7 cmH2 O without (13 out of 14 cases) and with recruitment maneuver (13 out of 15 cases). CONCLUSIONS: We conclude that contrary to our hypothesis, PEEP up to 7 cmH2 O is not sufficient to resolve tidal derecruitment and that recruitment maneuvers may be dispensable in mechanically ventilated pediatric patients.


Assuntos
Respiração com Pressão Positiva , Mecânica Respiratória , Adulto , Criança , Estudos Cross-Over , Humanos , Pulmão , Complacência Pulmonar , Volume de Ventilação Pulmonar
10.
BMC Anesthesiol ; 20(1): 42, 2020 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-32079526

RESUMO

BACKGROUND: The application of positive end-expiratory pressure (PEEP) may reduce dynamic strain during mechanical ventilation. Although numerous approaches for PEEP titration have been proposed, there is no accepted strategy for titrating optimal PEEP. By analyzing intratidal compliance profiles, PEEP may be individually titrated for patients. METHODS: After obtaining informed consent, 60 consecutive patients undergoing general anesthesia were randomly allocated to mechanical ventilation with PEEP 5 cmH2O (control group) or PEEP individually titrated, guided by an analysis of the intratidal compliance profile (intervention group). The primary endpoint was the frequency of each nonlinear intratidal compliance (CRS) profile of the respiratory system (horizontal, increasing, decreasing, and mixed). The secondary endpoints measured were respiratory mechanics, hemodynamic variables, and regional ventilation, which was assessed via electrical impedance tomography. RESULTS: The frequencies of the CRS profiles were comparable between the groups. Besides PEEP [control: 5.0 (0.0), intervention: 5.8 (1.1) cmH2O, p < 0.001], the respiratory and hemodynamic variables were comparable between the two groups. The compliance profile analysis showed no significant differences between the two groups. The loss of ventral and dorsal regional ventilation was higher in the control [ventral: 41.0 (16.3)%; dorsal: 25.9 (13.8)%] than in the intervention group [ventral: 29.3 (17.6)%; dorsal: 16.4 (12.7)%; p (ventral) = 0.039, p (dorsal) = 0.028]. CONCLUSIONS: Unfavorable compliance profiles indicating tidal derecruitment were found less often than in earlier studies. Individualized PEEP titration resulted in slightly higher PEEP. A slight global increase in aeration associated with this was indicated by regional gain and loss analysis. Differences in dorsal to ventral ventilation distribution were not found. TRIAL REGISTRATION: This clinical trial was registered at the German Register for Clinical Trials (DRKS00008924) on August 10, 2015.


Assuntos
Pulmão/fisiologia , Respiração com Pressão Positiva/métodos , Mecânica Respiratória/fisiologia , Impedância Elétrica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Volume de Ventilação Pulmonar/fisiologia
11.
BMC Anesthesiol ; 20(1): 24, 2020 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-31992213

RESUMO

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 crossover 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. TRIAL REGISTRATION: German Clinical Trials Register: DRKS00014925. Registered 12 July 2018.


Assuntos
Pulmão/fisiopatologia , Obesidade/fisiopatologia , Respiração Artificial/métodos , Mecânica Respiratória/fisiologia , Adulto , Estudos Cross-Over , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
12.
Respir Physiol Neurobiol ; 271: 103303, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31546026

RESUMO

Flow Controlled Expiration (FLEX) has been demonstrated to be lungprotective in models of ARDS during controlled mechanical ventilation. However, modern ventilation strategies in critical care include spontaneous breathing. Therefore, we investigated breathing discomfort and potential performance constraints of FLEX in 24 healthy test persons under increased ventilation demand. The subjects generated 20, 50 or 100 W pedal power on a bicycle ergometer while breathing with and without FLEX and rated breathing discomfort on a scale ranging from 0 (comfortable) to 10 (not tolerable). Then the subjects were asked to indicate the power they could maintain for 30 min with and without FLEX. With FLEX, tidal volume was higher and respiratory rate lower than without. Breathing discomfort was slightly increased by FLEX (on average from 2.2 to 3.2, p = 0.002). The estimated maintainable power was similar with and without FLEX (p = 0.986). We conclude that FLEX does not intolerably increase breathing discomfort and does not impair physical performance.


Assuntos
Ciclismo/fisiologia , Teste de Esforço/métodos , Exercício Físico/fisiologia , Expiração/fisiologia , Fluxo Expiratório Forçado/fisiologia , Volume de Ventilação Pulmonar/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
13.
Crit Care Med ; 48(3): e241-e248, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31856000

RESUMO

OBJECTIVES: Lung-protective ventilation for acute respiratory distress syndrome aims for providing sufficient oxygenation and carbon dioxide clearance, while limiting the harmful effects of mechanical ventilation. "Flow-controlled ventilation", providing a constant expiratory flow, has been suggested as a new lung-protective ventilation strategy. The aim of this study was to test whether flow-controlled ventilation attenuates lung injury in an animal model of acute respiratory distress syndrome. DESIGN: Preclinical, randomized controlled animal study. SETTING: Animal research facility. SUBJECTS: Nineteen German landrace hybrid pigs. INTERVENTION: Flow-controlled ventilation (intervention group) or volume-controlled ventilation (control group) with identical tidal volume (7 mL/kg) and positive end-expiratory pressure (9 cm H2O) after inducing acute respiratory distress syndrome with oleic acid. MEASUREMENTS AND MAIN RESULTS: PaO2 and PaCO2, minute volume, tracheal pressure, lung aeration measured via CT, alveolar wall thickness, cell infiltration, and surfactant protein A concentration in bronchoalveolar lavage fluid. Five pigs were excluded leaving n equals to 7 for each group. Compared with control, flow-controlled ventilation elevated PaO2 (154 ± 21 vs 105 ± 9 torr; 20.5 ± 2.8 vs 14.0 ± 1.2 kPa; p = 0.035) and achieved comparable PaCO2 (57 ± 3 vs 54 ± 1 torr; 7.6 ± 0.4 vs 7.1 ± 0.1 kPa; p = 0.37) with a lower minute volume (6.4 ± 0.5 vs 8.7 ± 0.4 L/min; p < 0.001). Inspiratory plateau pressure was comparable in both groups (31 ± 2 vs 34 ± 2 cm H2O; p = 0.16). Flow-controlled ventilation increased normally aerated (24% ± 4% vs 10% ± 2%; p = 0.004) and decreased nonaerated lung volume (23% ± 6% vs 38% ± 5%; p = 0.033) in the dependent lung region. Alveolar walls were thinner (5.5 ± 0.1 vs 7.8 ± 0.2 µm; p < 0.0001), cell infiltration was lower (20 ± 2 vs 32 ± 2 n/field; p < 0.0001), and normalized surfactant protein A concentration was higher with flow-controlled ventilation (1.1 ± 0.04 vs 1.0 ± 0.03; p = 0.039). CONCLUSIONS: Flow-controlled ventilation enhances lung aeration in the dependent lung region and consequently improves gas exchange and attenuates lung injury. Control of the expiratory flow may provide a novel option for lung-protective ventilation.


Assuntos
Respiração Artificial , Síndrome do Desconforto Respiratório , Lesão Pulmonar Induzida por Ventilação Mecânica , Animais , Modelos Animais de Doenças , Distribuição Aleatória , Respiração Artificial/métodos , Síndrome do Desconforto Respiratório/terapia , Suínos , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle
14.
Acta Anaesthesiol Scand ; 64(4): 481-488, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31828755

RESUMO

BACKGROUND: Flow-controlled ventilation (FCV) is a new ventilation mode that provides constant inspiratory and expiratory flow. FCV was shown to improve gas exchange and lung recruitment in porcine models of healthy and injured ventilated lungs. The primary aim of our study was to verify the influences of FCV on gas exchange, respiratory mechanics and haemodynamic variables in mechanically ventilated lung-healthy patients. METHODS: After obtaining ethical approval and informed consent, we measured arterial blood gases, respiratory and haemodynamic variables during volume-controlled ventilation (VCV) and FCV in 20 consecutive patients before they underwent abdominal surgery. After baseline (BL) ventilation, patients were randomly assigned to either BL-VCV-FCV or BL-FCV-VCV. Thereby, BL ventilation settings were kept, except for the ventilation mode-related differences (FCV is supposed to be used with an I:E ratio of 1:1). RESULTS: Compared to BL and VCV, PaO2 was higher [PaO2 : FCV: 38.2 (7.1), BL ventilation: 35.0 (5.8), VCV: 35.2 (7.0) kPa, P < .001] and PaCO2 lower [PaCO2 : FCV: 4.8 (0.5), BL ventilation: 5.1 (0.5), VCV: 5.1 (0.5) kPa, P < .001] during FCV. With comparable plateau pressure [BL: 14.9 (1.9), VCV: 15.3 (1.6), FCV: 15.2 (1.5) cm H2 O), P = .185], tracheal mean pressure was higher during FCV [BL: 10.2 (1.1), VCV: 10.4 (0.7), FCV: 11.5 (1.0) cm H2 O, P < .001]. Haemodynamic variables did not differ between ventilation phases. CONCLUSION: Flow-controlled ventilation improves oxygenation and carbon dioxide elimination within a short time, compared to VCV with identical tidal volume, inspiratory plateau pressure and end-expiratory pressure.


Assuntos
Pulmão/fisiologia , Troca Gasosa Pulmonar/fisiologia , Respiração Artificial/métodos , Idoso , Estudos Cross-Over , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Volume de Ventilação Pulmonar
15.
Eur J Anaesthesiol ; 36(12): 963-971, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31644514

RESUMO

BACKGROUND: Good visibility is essential for successful laryngeal surgery. A Tritube with outer diameter 4.4 mm, combined with flow-controlled ventilation (FCV), enables ventilation by active expiration with a sealed trachea and may improve laryngeal visibility. OBJECTIVES: We hypothesised that a Tritube with FCV would provide better laryngeal visibility and surgical conditions for laryngeal surgery than a conventional microlaryngeal tube (MLT) with volume-controlled ventilation (VCV). DESIGN: Randomised, controlled trial. SETTING: University Medical Centre. PATIENTS: A total of 55 consecutive patients (>18 years) undergoing elective laryngeal surgery were assessed for participation, providing 40 evaluable data sets with 20 per group. INTERVENTIONS: Random allocation to intubation with Tritube and ventilation with FCV (Tritube-FCV group) or intubation with MLT 6.0 and ventilation with VCV (MLT-VCV) as control. Tidal volumes of 7 ml kg predicted body weight, and positive end-expiratory pressure of 7 cmH2O were standardised between groups. MAIN OUTCOME MEASURES: Primary endpoint was the tube-related concealment of laryngeal structures, measured on videolaryngoscopic photographs by appropriate software. Secondary endpoints were surgical conditions (categorical four-point rating scale), respiratory variables and change of end-expiratory lung volume from atmospheric airway pressure to ventilation with positive end-expiratory pressure. Data are presented as median [IQR]. RESULTS: There was less concealment of laryngeal structures with the Tritube than with the MLT; 7 [6 to 9] vs. 22 [18 to 27] %, (P < 0.001). Surgical conditions were rated comparably (P = 0.06). A subgroup of residents in training perceived surgical conditions to be better with the Tritube compared with the MLT (P = 0.006). Respiratory system compliance with the Tritube was higher at 61 [52 to 71] vs. 46 [41 to 51] ml cmH2O (P < 0.001), plateau pressure was lower at 14 [13 to 15] vs. 17 [16 to 18] cmH2O (P < 0.001), and change of end-expiratory lung volume was higher at 681 [463 to 849] vs. 414 [194 to 604] ml, (P = 0.023) for Tritube-FCV compared with MLT-VCV. CONCLUSION: During laryngeal surgery a Tritube improves visibility of the surgical site but not surgical conditions when compared with a MLT 6.0. FCV improves lung aeration and respiratory system compliance compared with VCV. TRIAL REGISTRY NUMBER: DRKS00013097.


Assuntos
Procedimentos Cirúrgicos Eletivos/instrumentação , Glote/diagnóstico por imagem , Doenças da Laringe/cirurgia , Máscaras Laríngeas , Respiração com Pressão Positiva/instrumentação , Idoso , Anestesia Geral , Anestesia Intravenosa , Feminino , Glote/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Volume de Ventilação Pulmonar , Resultado do Tratamento
16.
Proc Natl Acad Sci U S A ; 116(34): 16697-16702, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31391310

RESUMO

A detailed experimental investigation of Fe1+y Te (y = 0.11, 0.12) using pulsed magnetic fields up to 60 T confirms remarkable magnetic shape-memory (MSM) effects. These effects result from magnetoelastic transformation processes in the low-temperature antiferromagnetic state of these materials. The observation of modulated and finely twinned microstructure at the nanoscale through scanning tunneling microscopy establishes a behavior similar to that of thermoelastic martensite. We identified the observed, elegant hierarchical twinning pattern of monoclinic crystallographic domains as an ideal realization of crossing twin bands. The antiferromagnetism of the monoclinic ground state allows for a magnetic-field-induced reorientation of these twin variants by the motion of one type of twin boundaries. At sufficiently high magnetic fields, we observed a second isothermal transformation process with large hysteresis for different directions of applied field. This gives rise to a second MSM effect caused by a phase transition back to the field-polarized tetragonal lattice state.

17.
Sci Adv ; 5(8): eaaw9867, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31453332

RESUMO

The band inversion in topological phase matters bring exotic physical properties such as the topologically protected surface states (TSS). They strongly influence the surface electronic structures of the materials and could serve as a good platform to gain insight into the surface reactions. Here we synthesized high-quality bulk single crystals of Co3Sn2S2 that naturally hosts the band structure of a topological semimetal. This guarantees the existence of robust TSS from the Co atoms. Co3Sn2S2 crystals expose their Kagome lattice that constructed by Co atoms and have high electrical conductivity. They serves as catalytic centers for oxygen evolution process (OER), making bonding and electron transfer more efficient due to the partially filled orbital. The bulk single crystal exhibits outstanding OER catalytic performance, although the surface area is much smaller than that of Co-based nanostructured catalysts. Our findings emphasize the importance of tailoring TSS for the rational design of high-activity electrocatalysts.

18.
Angew Chem Int Ed Engl ; 58(37): 13107-13112, 2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31342613

RESUMO

Conductivity, carrier mobility, and a suitable Gibbs free energy are important criteria that determine the performance of catalysts for a hydrogen evolution reaction (HER). However, it is a challenge to combine these factors into a single compound. Herein, we discover a superior electrocatalyst for a HER in the recently identified Dirac nodal arc semimetal PtSn4 . The determined turnover frequency (TOF) for each active site of PtSn4 is 1.54 H2 s-1 at 100 mV. This sets a benchmark for HER catalysis on Pt-based noble metals and earth-abundant metal catalysts. We make use of the robust surface states of PtSn4 as their electrons can be transferred to the adsorbed hydrogen atoms in the catalytic process more efficiently. In addition, PtSn4 displays excellent chemical and electrochemical stabilities after long-term exposure in air and long-time HER stability tests.

19.
Eur J Anaesthesiol ; 36(5): 327-334, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30730422

RESUMO

BACKGROUND: Flow-controlled ventilation (FCV) is a new mechanical ventilation mode that maintains constant flow during inspiration and expiration with standard tidal volumes via cuffed narrow-bore endotracheal tubes. Originating in manually operated 'expiratory ventilation assistance', FCV extends this technique by automatic control of airway flow, monitoring of intratracheal pressure and control of peak inspiratory pressure and end-expiratory pressure. FCV has not yet been described in a clinical study. OBJECTIVE: The aim of this study was to provide an initial assessment of FCV in mechanically ventilated patients undergoing ear, nose and throat surgery and evaluate its potential for future use. DESIGN: An observational study. SETTING: Two German academic medical centres from 24 November 2017 to 09 January 2018. PATIENTS: Consecutive patients (≥ 18 years) scheduled for elective ear, nose and throat surgery. Exclusion criteria were planned laser surgery, intended fibreoptic awake intubation, emergency procedures, increased risk of aspiration, American Society of Anesthesiologists (ASA) physical status more than III and chronic obstructive pulmonary disease classified as GOLD stage more than II. INTERVENTION: Peri-operative use of FCV provided by a new type of ventilator (Evone) via a narrow-bore endotracheal tube (Tritube). MAIN OUTCOME MEASURES: Minute volume, respiratory rate, intratidal tracheal pressure amplitude (Δp) and end-tidal CO2 (PetCO2) were recorded every 5 min. All adverse events were noted. Data are presented as median [IQR]. RESULTS: Sixteen patients provided 15 evaluable data sets. A minute volume of 5.0 [4.4 to 6.4] l min and a respiratory rate of 9 [8 to 11] min generated a PetCO2 of 4.9 [4.8 to 5.0] kPa. Δp was 10 [9 to 12] cmH2O. Five adverse events were recorded: a tube obstruction due to airway secretions and four tube dislocations (two attributed to coughing, two not study-related). CONCLUSION: FCV achieves adequate PetCO2 levels with minute volume and Δp in the normal range. Tritube's high flow resistance may increase the likelihood of tube dislocations if the patient coughs. Although further evaluation is necessary, FCV provides a new option for short-term mechanical ventilation. The successful operation of FCV with narrow-bore tubes contributes to the armamentarium for airway management. TRIAL REGISTRATION: DRKS00013312.


Assuntos
Intubação Intratraqueal/métodos , Procedimentos Cirúrgicos Otorrinolaringológicos/efeitos adversos , Respiração Artificial/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Intubação Intratraqueal/efeitos adversos , Intubação Intratraqueal/instrumentação , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Respiração Artificial/efeitos adversos , Respiração Artificial/instrumentação , Volume de Ventilação Pulmonar , Ventiladores Mecânicos , Adulto Jovem
20.
J Anesth ; 33(1): 33-39, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30421240

RESUMO

PURPOSE: Facemask ventilation during the induction of general anesthesia in paediatric patients remains a challenge as it may result in hypoxic conditions and gastric insufflation with subsequent regurgitation and aspiration. So far, it is unclear if pressure-controlled or manual facemask ventilation is preferable in children. We hypothesized that pressure-controlled ventilation in apnoeic children results in lower peak airway pressure and flow rates compared to manual ventilation at comparable respiratory rates and tidal volumes. METHODS: Sixty-two lung-healthy children undergoing scheduled ear-nose-throat surgery were included in the study. After the induction of anesthesia, the patient's lungs were consecutively ventilated via a facemask in either manual or pressure-controlled mode, in randomized order. The primary outcome measure was peak airway pressure. Secondary outcome measures included positive end-expiratory pressure, airway compliance, tidal volume and airway flow. RESULTS: Data of 52 patients could be analyzed. Pressure-controlled ventilation resulted in a lower mean and peak inspiratory pressure (both p < 0.001), airway pressure amplitude (p = 0.01) and inspiratory peak flow rate (p = 0.005) compared to manual ventilation. The ratio of inspiration to expiration time was lower in pressure-controlled ventilation compared to manual ventilation (p < 0.001). CONCLUSION: Pressure-controlled facemask ventilation during induction of anesthesia in pediatric patients results in lower airway pressure, and lower flow rates compared to manual ventilation, at comparable tidal and minute volumes.


Assuntos
Anestesia Geral/métodos , Máscaras Laríngeas , Respiração com Pressão Positiva/métodos , Respiração Artificial/métodos , Apneia/terapia , Criança , Pré-Escolar , Estudos Cross-Over , Feminino , Humanos , Lactente , Insuflação , Masculino , Volume de Ventilação Pulmonar
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