SOLVe: a closed-loop system focused on protective mechanical ventilation.

BACKGROUND: Mechanical ventilation is an essential component in the treatment of patients with acute respiratory distress syndrome. Prompt adaptation of the settings of a ventilator to the variable needs of patients is essential to ensure personalised and protective ventilation. Still, it is challenging and time-consuming for the therapist at the bedside. In addition, general implementation barriers hinder the timely incorporation of new evidence from clinical studies into routine clinical practice. RESULTS: We present a system combing clinical evidence and expert knowledge within a physiological closed-loop control structure for mechanical ventilation. The system includes multiple controllers to support adequate gas exchange while adhering to multiple evidence-based components of lung protective ventilation. We performed a pilot study on three animals with an induced ARDS. The system achieved a time-in-target of over 75 % for all targets and avoided any critical phases of low oxygen saturation, despite provoked disturbances such as disconnections from the ventilator and positional changes of the subject. CONCLUSIONS: The presented system can provide personalised and lung-protective ventilation and reduce clinician workload in clinical practice.

Magnetic Properties of Epitaxially Grown SrRuO3 Nanodots.

We present the fabrication and exploration of arrays of nanodots of SrRuO3 with dot sizes between 500 and 15 nm. Down to the smallest dot size explored, the samples were found to be magnetic with a maximum Curie temperature TC achieved by dots of 30 nm diameter. This peak in TC is associated with a dot-size-induced relief of the epitaxial strain, as evidenced by scanning transmission electron microscopy.

Long-Range Atomic Order on Double-Stepped Al2O3(0001) Surfaces.

The deterministic preparation of highly ordered single-crystalline surfaces is a key step for studying and utilizing the physical properties of various advanced materials. This paper presents the fast and straightforward preparation of vicinal Al2O3(0001) surfaces with micrometer-scale atomic order. Crisp electron-diffraction spots up to at least 20th order evidence atomic coherence on terraces with widths exceeding 1 µm. The unique combination of three properties of Al2O3(0001) underlie this remarkable coherence: its high-temperature stability; the differences in the ionic bonding systems of the surface as compared to the bulk; and the fact that the terraces are non-polar whereas the step edges have a polar character. The step edges are furthermore found to have alternating configurations, which drive a step-doubling transition. On double-stepped surfaces, the Al-rich ( 31 × 31 ) R ± 9 $(\sqrt {31}\times \sqrt {31})\textrm {R}\pm 9$ ° surface reconstruction attains a singular in-plane orientation. These results set a benchmark for high-quality surface preparation and thus expand the scope for both fundamental studies on and the technological utilization of exciting material systems.

Abdominal Wall Movements Predict Intra-Abdominal Pressure Changes in Rats: A Novel Non-Invasive Intra-Abdominal Pressure Detection Method.

(1) Background: As increases in intra-abdominal pressure (IAP) result in irreversible tissue damage, monitoring IAP in critically ill patients using the common urinary bladder catheter method is essential. However, this method can result in complications and is not suitable for very low birth weight neonates. The aim of this study was to establish a non-invasive and accurate method to detect IAP changes using an animal model. (2) Methods: IAP changes via intra-abdominal air application (up to 20 mmHg) were measured in 19 Wistar rats via an intra-abdominally placed intracranial pressure probe. Concurrently, abdominal surface tension was measured using a Graseby capsule (GC). (3) Results: A high correlation between abdominal wall distension and IAP (r = 0.9264, CI 0.9249-0.9279) was found for all subjects. (4) Conclusions: IAP changes in rats can be detected non-invasively using a GC. However, further studies are necessary to assess whether IAP changes can be measured using a GC in the neonatal population.

Randomised crossover trial comparing algorithms and averaging times for automatic oxygen control in preterm infants.

OBJECTIVE: Automatic control (SPOC) of the fraction of inspired oxygen (FiO2), based on continuous analysis of pulse oximeter saturation (SpO2), improves the proportion of time preterm infants spend within a specified SpO2-target range (Target%). We evaluated if a revised SPOC algorithm (SPOCnew, including an upper limit for FiO2) compared to both routine manual control (RMC) and the previously tested algorithm (SPOCold, unrestricted maximum FiO2) increases Target%, and evaluated the effect of the pulse oximeter's averaging time on controlling the SpO2 signal during SPOC periods. DESIGN: Unblinded, randomised controlled crossover study comparing 2 SPOC algorithms and 2 SpO2 averaging times in random order: 12 hours SPOCnew and 12 hours SPOCold (averaging time 2 s or 8 s for 6 hours each) were compared with 6-hour RMC. A generated list of random numbers was used for allocation sequence. SETTING: University-affiliated tertiary neonatal intensive care unit, Germany PATIENTS: Twenty-four infants on non-invasive respiratory support with FiO2 >0.21 were analysed (median gestational age at birth, birth weight and age at randomisation were 25.3 weeks, 585 g and 30 days). MAIN OUTCOME MEASURE: Target%. RESULTS: Mean (SD) [95% CI] Target% was 56% (9) [52, 59] for RMC versus 69% (9) [65, 72] for SPOCold_2s, 70% (7) [67, 73] for SPOCnew_2s, 71% (8) [68, 74] for SPOCold_8s and 72% (8) [69, 75] for SPOCnew_8s. CONCLUSIONS: Irrespective of SpO2-averaging time, Target% was higher with both SPOC algorithms compared to RMC. Despite limiting the maximum FiO2, SPOCnew remained significantly better at maintaining SpO2 within target range compared to RMC. TRIAL REGISTRATION: NCT03785899.

Induction of severe hypoxemia and low lung recruitability for the evaluation of therapeutic ventilation strategies: a translational model of combined surfactant-depletion and ventilator-induced lung injury.

BACKGROUND: Models of hypoxemic lung injury caused by lavage-induced pulmonary surfactant depletion are prone to prompt recovery of blood oxygenation following recruitment maneuvers and have limited translational validity. We hypothesized that addition of injurious ventilation following surfactant-depletion creates a model of the acute respiratory distress syndrome (ARDS) with persistently low recruitability and higher levels of titrated "best" positive end-expiratory pressure (PEEP) during protective ventilation. METHODS: Two types of porcine lung injury were induced by lung lavage and 3 h of either protective or injurious ventilation, followed by 3 h of protective ventilation (N = 6 per group). Recruitment maneuvers (RM) and decremental PEEP trials comparing oxygenation versus dynamic compliance were performed after lavage and at 3 h intervals of ventilation. Pulmonary gas exchange function, respiratory mechanics, and ventilator-derived parameters were assessed after each RM to map the course of injury severity and recruitability. RESULTS: Lung lavage impaired respiratory system compliance (Crs) and produced arterial oxygen tensions (PaO2) of 84±13 and 80±15 (FIO2 = 1.0) with prompt increase after RM to 270-395 mmHg in both groups. After subsequent 3 h of either protective or injurious ventilation, PaO2/FIO2 was 104±26 vs. 154±123 and increased to 369±132 vs. 167±87 mmHg in response to RM, respectively. After additional 3 h of protective ventilation, PaO2/FIO2 was 120±15 vs. 128±37 and increased to 470±68 vs. 185±129 mmHg in response to RM, respectively. Subsequently, decremental PEEP titration revealed that Crs peaked at 36 ± 10 vs. 25 ± 5 ml/cm H2O with PEEP of 12 vs. 16 cmH2O, and PaO2/FIO2 peaked at 563 ± 83 vs. 334 ± 148 mm Hg with PEEP of 16 vs. 22 cmH2O in the protective vs. injurious ventilation groups, respectively. The large disparity of recruitability between groups was not reflected in the Crs nor the magnitude of mechanical power present after injurious ventilation, once protective ventilation was resumed. CONCLUSION: Addition of transitory injurious ventilation after lung lavage causes prolonged acute lung injury with diffuse alveolar damage and low recruitability yielding high titrated PEEP levels. Mimicking lung mechanical and functional characteristics of ARDS, this porcine model rectifies the constraints of single-hit lavage models and may enhance the translation of experimental research on mechanical ventilation strategies.

Effects of a new device for automated closed loop control of inspired oxygen concentration on fluctuations of arterial and different regional organ tissue oxygen saturations in preterm infants.

OBJECTIVE: To assess the efficacy of a newly developed system for closed loop control of the fraction of inspired oxygen (FiO2) on variation of arterial (SpO2) and on regional tissue oxygen saturation (StO2) in preterm infants with fluctuations in SpO2. DESIGN: Randomised crossover trial comparing automated (auto) to manual FiO2 adjustment (manual) during two consecutive 24 hours periods using a Sophie infant ventilator (SPO2C). SETTING: Tertiary university medical centre. PATIENTS: Twelve very low birthweight infant (VLBWI) (gestational age (median; IQR): (25; 23-26 weeks); birth weight (mean±SD): (667±134 g); postnatal age (mean±SD): (31.5±14 days)). MAIN OUTCOME MEASURE: Time within SpO2 target range. RESULTS: There was an increase in time within the intended SpO2 target range (88%-96%) during auto as compared with manual mode (77.8%±7.1% vs 68.5%±7.7% (mean±SD), p<0.001) and a decrease in time below the SpO2 target during the auto period (18.1%±6.4% vs 25.6%±7.6%; p<0.01). There was a dramatic reduction in events with an SpO2 <88% with >180 s duration: (2 (0-10) vs 10 (0-37) events, p<0.001) and the need for manual adjustments. The time the infants spent above the intended arterial oxygen range (4.1%±3.8% vs 5.9%±3.6%), median FiO2, mean SpO2 over time and StO2 in the brain, liver and kidney did not differ significantly between the two periods. CONCLUSIONS: Closed-loop FiO2 using SPO2C significantly increased time of arterial SpO2 within the intended range in VLBWI and decreased the need for manual adjustments when compared with the routine adjustment by staff members. StO2 was not significantly affected by the mode of oxygen control.

Thyroid metastases of renal cell carcinoma: clinical course in 45 patients undergoing surgery. Assessment of factors affecting patients' survival.

BACKGROUND: Metastases of renal cell carcinoma (RCC) to the thyroid gland are uncommon. There is no clear consensus regarding the role of surgery in metastatic disease to the thyroid since most clinical studies include small numbers of patients. Also, risk factors associated with disease progression following thyroidectomy are not yet defined. We examined the determinants of the outcome in patients undergoing surgery for thyroid metastases of RCC. METHODS: The medical records of 45 patients undergoing resection of thyroid metastases of RCC at 15 institutions in Germany and Austria were reviewed retrospectively. The outcome parameters assessed were overall survival and tumor-related survival. Factors associated with disease progression following thyroid surgery have been calculated. RESULTS: The overall 5-year survival rate following thyroid metastasectomy was 51%. Nineteen patients died during the study: 14 of disseminated disease and 5 of non-tumor-related causes. In the multivariate analysis, the prognosis was significantly worse in patients older than > or = 70 years and in patients who had undergone nephrectomy for metastases in the contralateral kidney during the course of the disease. Nine patients developed a thyroid recurrence following surgery. No local disease relapse occurred if resection margins were documented to be free of the tumor. Of the 45 patients with thyroid metastases, 14 (31%) developed pancreatic metastases during the course of disease. Ten of these patients also underwent pancreatic surgery with a 5-year survival rate of 43% in this subgroup. CONCLUSIONS: The overall survival of patients undergoing thyroidectomy for metastases of RCC is affected rather by general health status than by tumor-related factors. There is a significant coincidence of thyroid and pancreatic metastases of RCC.

Analyzing and Modelling the Corrosion Behavior of Ni/Al2O3, Ni/SiC, Ni/ZrO2 and Ni/Graphene Nanocomposite Coatings.

A study has been presented on the effects of intrinsic mechanical parameters, such as surface stress, surface elastic modulus, surface porosity, permeability and grain size on the corrosion failure of nanocomposite coatings. A set of mechano-electrochemical equations was developed by combining the popular Butler-Volmer and Duhem expressions to analyze the direct influence of mechanical parameters on the electrochemical reactions in nanocomposite coatings. Nanocomposite coatings of Ni with Al2O3, SiC, ZrO2 and Graphene nanoparticles were studied as examples. The predictions showed that the corrosion rate of the nanocoatings increased with increasing grain size due to increase in surface stress, surface porosity and permeability of nanocoatings. A detailed experimental study was performed in which the nanocomposite coatings were subjected to an accelerated corrosion testing. The experimental results helped to develop and validate the equations by qualitative comparison between the experimental and predicted results showing good agreement between the two.

Kinetic optimum of volmer-weber growth.

We find that the molecular beam epitaxy of Fe3Si on GaAs(001) observed by real-time x-ray diffraction begins by the abrupt formation of 3 monolayer (ML) high islands and approaches two-dimensional layer-by-layer growth at a thickness of 7 ML. A surface energy increase is confirmed by ab initio calculations and allows us to identify the growth as a strain-free Volmer-Weber transient. Kinetic Monte Carlo simulations incorporating this energy increase correctly reproduce the characteristic x-ray intensity oscillations found in the experiment. Simulations indicate an optimum growth rate for Volmer-Weber growth in between two limits, the appearance of trenches at slow growth and surface roughening at fast growth.