Improve Gas Exchange Research Articles

Physiological evaluation of nano DAP on growth and yield of tomato

Tomato (Solanum lycopersicum), a solanaceous crop, is widely cultivated worldwide. This study evaluates the impact of Nano DAP (diammonium phosphate) on morpho-physiological traits, biochemical properties, yield, and quality parameters. Eight treatments comprising varying proportions of DAP and Nano DAP were evaluated for traits including plant height, leaf area, chlorophyll index, total dry matter production, gas exchange parameters, leaf soluble protein, total soluble solids (TSS), ascorbic acid, titratable acidity, firmness and fruit yield. The hybrid tomato variety 'Shivam' was cultivated in pot culture under a glasshouse at Tamil Nadu Agricultural University, Coimbatore, using a completely randomized design with five replications. Foliar sprays with different proportions of nano DAP and DAP were applied 30 and 45 days after transplanting. Among the treatments, 75% RDNP (recommended nitrogen and phosphorus dose) combined with two foliar sprays of nano DAP @ 0.7% (T5) significantly increased plant height (48.90 cm and 54.31 cm), chlorophyll index (40.05 and 42.15), dry matter production (55.45 g plant?¹), TSS (5.52 Brix), fruit production, and ascorbic acid content. This treatment also improved gas exchange parameters, fruit firmness, and overall `growth and productivity compared to other treatments. Conversely, the absolute control group demonstrated the lowest performance across all parameters. The study highlights that combining both conventional fertilizers with Nano DAP considerably improves tomato growth by enhancing nutrient absorption, particularly nitrogen and phosphorus, which are essential for cell division, photosynthesis, and energy transfer. Nano DAP, due to its small particle size and large surface area, effectively penetrates plant tissues, increasing nutrient availability, chlorophyll content, and plant height. These findings underscore the potential of Nano DAP to substantially enhance tomato yield and quality, thereby contributing to sustainable crop production.

Temperature governs the relative contributions of cuticle and stomata to leaf minimum conductance.

During periods of stomatal closure, such as drought, plant leaves continue to lose water at a rate determined by the minimum leaf conductance, gmin. Although gmin varies with temperature, less is known about what drives this variation, including how the pathways of water loss (cuticle or stomata) vary with temperature. We used gas exchange and bench drying methods to measure gmin and cuticular conductance, gcw, across a wide temperature range (20-50°C) in 11 broadleaf species. Vapour pressure deficit (VPD) covaried with temperature from 0.83 to 10.7 kPa. The dominant pathway of water loss for gmin shifted from stomatal transpiration towards cuticular transpiration as temperature increased. Leaf traits had variable, temperature-dependent relationships with gmin and gcw, with trait-conductance relationships being generally stronger at higher temperatures. Cuticular thickness varied inversely with high-temperature gcw. Simulation results showed that gcw may impact photosynthetic capacity estimates, particularly in species with low stomatal conductance. The pathways of water loss in leaves during times of stomatal closure depend strongly on temperature. This effect may have large implications for landscape-scale water balance modelling and improving gas exchange measurements. We propose variation in VPD as a potential contributing factor in gmin and gcw variation among studies.

Dodecafluoropentane improves neuro-behavioral outcomes and return of spontaneous circulation rate in a swine model of cardiac arrest

ABSTRACT Introduction Dodecafluoropentane emulsion (DDFPe) administration has previously demonstrated improved gas exchange in single-organ perfusion models. This could translate to prevention of brain injury in cardiac arrest. Methods We induced cardiac arrest in 12 pigs, performing CPR after 5-minute downtime. Pigs were randomly assigned to DDFPe (n = 7) or saline placebo (n = 5) groups. Neurologic injury biomarkers were measured at baseline, after return of spontaneous circulation (ROSC), and every 24 hours in survivors. Blinded Neurological Alertness Score, Neurological Dysfunction Score, and Overall Performance Score was performed in addition to histopathological scoring of parietal and hippocampal sections. Results One placebo and four DDFPe pigs survived the 96-hour observation period. The odds ratio for ROSC was 7.2 (p = 0.22). Survival odds ratio was 4.6 (p = 0.29). All surviving animals had impaired motor responses that recovered by 72 hours. DDFPe animals showed better neuro-behavioral scores than placebo. Conclusion The findings of this novel study provide a proof of concept and early signal toward efficacy of intravenous DDFPe in cardiac arrest. The trend toward improved ROSC and functional survival may reflect improved microcirculatory gas exchange in DDFPe animals. Improving gas exchange in brain microcirculation during resuscitation from cardiac arrest may provide a significant therapeutic benefit.

Advancing extracorporeal carbon dioxide removal technology: bridging basic science and clinical practice.

Recently, advancements in extracorporeal carbon dioxide removal (ECCO2R) technology have markedly enhanced its clinical applicability and efficacy for managing severe respiratory conditions. This review highlights critical innovations in ECCO2R, such as advanced catheter technologies, active mixing methods, and biochemical enhancements, which have substantially improved gas exchange efficiency and broadened the scope of ECCO2R applications. Integrating ECCO2R into acute and chronic respiratory care has led to a shift toward more mobile and less invasive modalities, promising for extending ECCO2R usage from intensive care units to home settings. By examining these technological advancements and their clinical impacts, this paper outlines the potential future directions of ECCO2R technology, emphasizing its role in transforming respiratory care practices and enhancing patient outcomes.

THE ROLE OF BRONCHOSCOPY IN INTENSIVE CARE MEDICINE, CASE REPORT

Purpose. Airway maintenance, adequate ventilation, and pulmonary gas exchange are crucial for critically ill patients. The challenges of performing in intensive care patients often differ significantly from routine surgical procedures in the operating room. The aim of our study was to assess the effectiveness of bronchoscopic aspiration in improving respiratory function in a patient on prolonged artificial ventilation. Material/Methods. A 69-year-old male was admitted to the ICU six days after an open cystoprostatectomy, presenting with respiratory failure. Initial treatment included blind airway suctioning, nebulization, chest physiotherapy, and empirical antibiotics. Due to persistent atelectasis and respiratory failure, bronchoscopic aspiration was performed. A total of nine bronchoscopies with bronchoalveolar lavage (BAL) were conducted for aspiration and microbiological testing, guiding adjustments in antibiotic therapy. After 61 days in the ICU, the patient was transferred to the Department of Urology and later discharged. Results. Bronchoscopic aspiration significantly improved the patient's condition, with noticeable improvements after the first bronchoalveolar lavage (BAL). Pulmonary imaging on X-ray and blood oxygenation showed clear progress, with better lung function and enhanced ventilation parameters. These changes allowed for a reduction in oxygen concentration and improved gas exchange. After 61 days in the ICU, the patient was successfully transferred to the Department of Urology and later discharged in stable condition. Conclusions. Bronchoscopic aspiration is a highly effective method for improving ventilation and oxygenation in patients on prolonged mechanical ventilation. It plays a crucial role in managing airway obstructions atelectasis, and enhancing microbiological diagnostics.

Effects of sildenafil on gas exchange, ventilatory, and sensory responses to exercise in subjects with mild-to-moderate COPD: A randomized cross-over trial

Excess exercise ventilation (high ventilation (V̇E)/carbon dioxide output (V̇CO2)) contributes significantly to dyspnea and exercise intolerance since the earlier stages of chronic obstructive pulmonary disease (COPD). A selective pulmonary vasodilator (inhaled nitric oxide) has shown to increase exercise tolerance secondary to lower V̇E/V̇CO2 and dyspnea in this patient population. We aimed to assess whether a clinically more practical option - oral sildenafil - would be associated with similar beneficial effects. In a randomized, placebo-controlled study, twenty-four patients with mild-to-moderate COPD completed, on different days, two incremental cardiopulmonary exercise tests (CPET) one hour after sildenafil or placebo. Eleven healthy participants performed a CPET in a non-interventional visit for comparative purposes with patients when receiving placebo. Patients (FEV1= 69.4 ± 13.5 % predicted) showed higher ventilatory demands (V̇E/V̇CO2), worse pulmonary gas exchange, and higher dyspnea during exercise compared to controls (FEV1= 98.3 ±11.6 % predicted). Contrary to our expectations, however, sildenafil (50 mg; N= 15) did not change exertional V̇E/V̇CO2, dead space/tidal volume ratio, operating lung volumes, dyspnea, or exercise tolerance compared to placebo (P>0.05). Due to the lack of significant beneficial effects, nine additional patients were trialed with a higher dose (100 mg). Similarly, active intervention was not associated with positive physiological or sensory effects. In conclusion, acute oral sildenafil (50 or 100 mg) failed to improve gas exchange efficiency or excess exercise ventilation in patients with predominantly moderate COPD. The current study does not endorse a therapeutic role for sildenafil to mitigate exertional dyspnea in this specific patient subpopulation.Clinical trial registry: https://ensaiosclinicos.gov.br/rg/RBR-4qhkf4Web of Science Researcher ID: O-7665–2019

Prone position applied to COVID-19 patients: Systematic review-meta-analysis.

Position change and interventions to increase lung capacity should be considered in mechanically ventilated patients. The most effective of these is the prone position. This systematic review and meta-analysis aimed to determine the effects of the prone position on respiratory parameters and outcomes and to guide nurses working in the intensive care unit. This systematic review-meta-analysis was conducted in accordance with the Preferred Reporting in Systematic Reviews and Meta-Analyses guideline. ScienceDirect, CINAHL, Academic Search Complete (EBSCOhost), MEDLINE, EMBASE, Web of Science, Cochrane and PubMed databases were searched between January 2022 and January 2023 to access studies related to prone position in COVID-19 patients. Twenty-three studies were included. This meta-analysis shows that a prone position is feasible and can achieve improvements in gas exchange. Prone position increases PaO2/FiO2 in the majority of patients followed with a diagnosis of COVID-19 and severe hypoxemic. The study has shown that the prone position is effective in improving patients' respiratory function and oxygenation. The results presented in this article support the notion that the prone position can be an effective strategy in the clinical management of COVID-19 patients.

Vertical farming goes dynamic: optimizing resource use efficiency, product quality, and energy costs

Vertical farming is considered to be a key enabler for transforming agrifood systems, especially in or nearby urbanized areas. Vertical farming systems (VFS) are advanced indoor cropping systems that allow for highly intensified and standardized plant production. The close control of environmental parameters makes crop production stable and repeatable, ensuring year-round uniform product quality and quantity irrespective of location. However, due to continuous changes in plant physiology and development, as well as frequent changes in electricity prices, the optimum conditions for crop production and its associated costs can change within days or even minutes. This makes it beneficial to dynamically adjust setpoints for light (intensity, spectrum, pattern, and daylength), CO2, temperature, humidity, air flow, and water and nutrient availability. In this review, we highlight the beneficial effects that dynamic growth conditions can have on key plant processes, including improvements in photosynthetic gas exchange, transpiration, organ growth, development, light interception, flowering, and product quality. Our novel findings based on modeling and experimentation demonstrate that a dynamic daily light intensity pattern that responds to frequent changes in electricity prices can save costs without reducing biomass. Further, we argue that a smart, dynamic VFS climate management requires feedback mechanisms: several mobile and immobile sensors could work in combination to continuously monitor the crop, generating data that feeds into crop growth models, which, in turn, generate climate setpoints. In addition, we posit that breeding for the VFS environment is at a very early stage and highlight traits for breeding for this specialized environment. We envision a continuous feedback loop between dynamic crop management, crop monitoring, and trait selection for genotypes that are specialized for these conditions.

Prone positioning for acute respiratory distress syndrome in adults : Update on the physiological effects, indications and implementation

The prone position is an immediately available and easily implemented procedure that was introduced more than 50 years ago as a method for improvement of gas exchange in patients with acute respiratory distress syndrome (ARDS). In the meantime, a survival advantage could also be shown in patients with severe ARDS, which led to the recommendation of the prone position for treatment of severe ARDS by expert consensus and specialist society guidelines. The continuing coronavirus disease 2019 (COVID-19) pandemic moved the prone position to the forefront of medicine, including the widespread implementation of the prone position for awake, spontaneously breathing nonintubated patients with acute hypoxemic respiratory insufficiency. The survival advantage is possible due to a reduction of the ventilator-associated lung damage. In this article, the physiological effects, data on clinical results, practical considerations and open questions with respect to the prone position are discussed.

Utility of non-invasive mechanical ventilation in critically ill patients with exacerbated COPD. Systematic review

Background: Non-invasive mechanical ventilation is a useful ventilatory support method for patients with acute respiratory failure or exacerbation of chronic obstructive pulmonary disease mediated by different mechanisms. It helps to reduce airflow resistance and facilitates lung expansion, reducing respiratory muscle fatigue. This allows the patient to breathe more efficiently. By providing positive pressure into the airways, it helps to open the collapsed alveoli and lower airways improving gas exchange. As a consequence oxygenation enhances. Additionally, by increasing air flow, it helps to eliminate carbon dioxide accumulated in the lungs. It reduces respiratory stress by relieving the feeling of shortness of breath as well as excessive respiratory work, reducing anxiety and stress associated with respiratory distress. Importantly, the decision to use non-invasive ventilation as an alternative to endotracheal intubation should be based on a careful evaluation of the patient and continuous monitoring of their response to the treatment. Not all patients are suitable candidates for non-invasive ventilation and in some cases endotracheal intubation may be necessary to ensure adequate ventilation. Material and methods: A systematic review was carried out. Results: 6 articles that met the criteria were reviewed, the number of patients included was 552. 23% (127 patients) were hospitalized in the general ward and 77% (425 patients) in the Intensive Care Unit, of the total patients. 83.51% received treatment with non-invasive ventilation, 11.77% oxygen therapy and 4.71% endotracheal intubation upon admission. 5.61% of the total patients required endotracheal intubation during the course of their hospitalization. Conclusion: In selected patients, Non-invasive ventilation reduces the rate of endotracheal intubation, infectious complications, hospital stay and relapsed. When appropriately used from its implementation until its withdrawal once the respiratory failure is solved, it has a beneficial impact on the patient as well as the economic burden by reducing healhcare cost.

Use of Nanobubbles to Improve Mass Transfer in Bioprocesses

Nanobubble technology has emerged as a transformative approach in bioprocessing, significantly enhancing mass-transfer efficiency for effective microbial activity. Characterized by their nanometric size and high internal pressure, nanobubbles possess distinct properties such as prolonged stability and minimal rise velocities, allowing them to remain suspended in liquid media for extended periods. These features are particularly beneficial in bioprocesses involving aerobic strains, where they help overcome common obstacles, such as increased culture viscosity and diffusion limitations, that traditionally impede efficient mass transfer. For instance, in an experimental setup, nanobubble aeration achieved 10% higher soluble chemical oxygen demand (sCOD) removal compared to traditional aeration methods. Additionally, nanobubble-aerated systems demonstrated a 55.03% increase in caproic acid concentration when supplemented with air nanobubble water, reaching up to 15.10 g/L. These results underscore the potential of nanobubble technology for optimizing bioprocess efficiency and sustainability. This review delineates the important role of the mass-transfer coefficient (kL) in evaluating these interactions and underscores the significance of nanobubbles in improving bioprocess efficiency. The integration of nanobubble technology in bioprocessing not only improves gas exchange and substrate utilization but also bolsters microbial growth and metabolic performance. The potential of nanobubble technology to improve the mass-transfer efficiency in biotechnological applications is supported by emerging research. However, to fully leverage these benefits, it is essential to conduct further empirical studies to specifically assess their impacts on bioprocess efficacy and scalability. Such research will provide the necessary data to validate the practical applications of nanobubbles and identify any limitations that need to be addressed in industrial settings.

Driving pressure decoded: Precision strategies in adult respiratory distress syndrome management

Mechanical ventilation (MV) is an important strategy for improving the survival of patients with respiratory failure. However, MV is associated with aggravation of lung injury, with ventilator-induced lung injury (VILI) becoming a major concern. Thus, ventilation protection strategies have been developed to minimize complications from MV, with the goal of relieving excessive breathing workload, improving gas exchange, and minimizing VILI. By opting for lower tidal volumes, clinicians seek to strike a balance between providing adequate ventilation to support gas exchange and preventing overdistension of the alveoli, which can contribute to lung injury. Additionally, other factors play a role in optimizing lung protection during MV, including adequate positive end-expiratory pressure levels, to maintain alveolar recruitment and prevent atelectasis as well as careful consideration of plateau pressures to avoid excessive stress on the lung parenchyma.

Endophytic Fungi Inoculation Reduces Ramulosis Severity in Gossypium hirsutum Plants.

Biotic stress in cotton plants caused by the phytopathogenic fungus Colletotrichum gossypii var. cephalosporioides triggers symptoms of ramulosis, a disease characterized by necrotic spots on young leaves, followed by death of the affected branch's apical meristem, plant growth paralysis, and stimulation of lateral bud production. Severe cases of ramulosis can cause up to 85% yield losses in cotton plantations. Currently, this disease is controlled exclusively by using fungicides. However, few studies have focused on biological alternatives for mitigating the effects of contamination by C. gossypii var. cephalosporioides on cotton plants. Thus, the hypothesis raised is that endophytic fungi isolated from an Arecaceae species (Butia purpurascens), endemic to the Cerrado biome, have the potential to reduce physiological damage caused by ramulosis, decreasing its severity in these plants. This hypothesis was tested using plants grown from seeds contaminated with the pathogen and inoculated with strains of Gibberella moniliformis (BP10EF), Hamigera insecticola (BP33EF), Codinaeopsis sp. (BP328EF), G. moniliformis (BP335EF), and Aspergillus sp. (BP340EF). C. gossypii var. cephalosporioides is a leaf pathogen; thus, the evaluations were focused on leaf parameters: gas exchange, chlorophyll a fluorescence, and oxidative metabolism. The hypothesis that inoculation with endophytic strains can mitigate physiological and photochemical damage caused by ramulosis in cotton was confirmed, as the fungi improved plant growth and stomatal index and density, increased net photosynthetic rate (A) and carboxylation efficiency (A/Ci), and decreased photochemical stress (ABS/RC and DI0/RC) and oxidative stress by reducing enzyme activity (CAT, SOD, and APX) and the synthesis of malondialdehyde (MDA). Control plants developed leaves with a low adaxial stomatal index and density to reduce colonization of leaf tissues by C. gossypii var. cephalosporioides due to the absence of fungal antagonism. The Codinaeopsis sp. strain BP328EF can efficiently inhibit C. gossypii var. cephalosporioides in vitro (81.11% relative inhibition), improve gas exchange parameters, reduce photochemical stress of chlorophyll-a, and decrease lipid peroxidation in attacked leaves. Thus, BP328EF should be further evaluated for its potential effect as a biological alternative for enhancing the resistance of G. hirsutum plants and minimizing yield losses caused by C. gossypii var. cephalosporioides.

Effect of continuous positive airway pressure helmet on respiratory function following surgical procedures in brachycephalic dogs: A randomized controlled trial.

To evaluate the effect of continuous positive airway pressure (CPAP) on respiratory function in the early postoperative period of brachycephalic dogs. Prospective, randomized clinical trial. A total of 32 dogs. Dogs were assigned to recover with or without CPAP (control) and assessed at specific time points over 1 h. Treatment was discontinued for dogs with a CPAP tolerance score of 3 or more (from a range of 0-4). The primary outcome was pulse oximetry (SpO2). Secondary outcomes were arterial O2 pressure (PaO2)/FiO2 ratio (PaO2/FiO2), arterial CO2 pressure (PaCO2), and rectal temperature. For dogs that reached a CPAP tolerance score of 3 or more, only the data collected up to the time point before discontinuation were included in the analysis.The treatment effect (β) was analyzed using random effects models and the results were reported with 95% confidence intervals. Dogs were assigned randomly to each protocol. Baseline characteristics in both groups were comparable. Arterial blood gases were obtained in seven control group dogs and nine CPAP group dogs. Treatment did not affect SpO2 (β = -0.1, -2.1 to 2.0) but affected the PaO2/FiO2 ratio (β = 58.1, 2.6 to 113.6), with no effects on PaCO2 (β = -4.3, -10.5 to 1.9) or temperature (β = 0.4, -0.8 to 1.6). In postoperative brachycephalic dogs, CPAP had no effect on SpO2 but improved the PaO2/FiO2 ratio in brachycephalic dogs postoperatively. Continuous positive airway pressure offers a valuable solution to improve gas exchange efficiency, a prevalent concern in postoperative brachycephalic dogs, with the potential to enhance overall outcomes.

SCARLET (Supplemental Citicoline Administration to Reduce Lung injury Efficacy Trial): study protocol for a single-site, double-blinded, placebo-controlled, and randomized Phase 1/2 trial of i.v. citicoline (CDP-choline) in hospitalized SARS CoV-2-infected patients with hypoxemic acute respiratory failure

BackgroundThe SARS CoV-2 pandemic has resulted in more than 1.1 million deaths in the USA alone. Therapeutic options for critically ill patients with COVID-19 are limited. Prior studies showed that post-infection treatment of influenza A virus-infected mice with the liponucleotide CDP-choline, which is an essential precursor for de novo phosphatidylcholine synthesis, improved gas exchange and reduced pulmonary inflammation without altering viral replication. In unpublished studies, we found that treatment of SARS CoV-2-infected K18-hACE2-transgenic mice with CDP-choline prevented development of hypoxemia. We hypothesize that administration of citicoline (the pharmaceutical form of CDP-choline) will be safe in hospitalized SARS CoV-2-infected patients with hypoxemic acute respiratory failure (HARF) and that we will obtain preliminary evidence of clinical benefit to support a larger Phase 3 trial using one or more citicoline doses.MethodsWe will conduct a single-site, double-blinded, placebo-controlled, and randomized Phase 1/2 dose-ranging and safety study of Somazina® citicoline solution for injection in consented adults of any sex, gender, age, or ethnicity hospitalized for SARS CoV-2-associated HARF. The trial is named “SCARLET” (Supplemental Citicoline Administration to Reduce Lung injury Efficacy Trial). We hypothesize that SCARLET will show that i.v. citicoline is safe at one or more of three doses (0.5, 2.5, or 5 mg/kg, every 12 h for 5 days) in hospitalized SARS CoV-2-infected patients with HARF (20 per dose) and provide preliminary evidence that i.v. citicoline improves pulmonary outcomes in this population. The primary efficacy outcome will be the SpO2:FiO2 ratio on study day 3. Exploratory outcomes include Sequential Organ Failure Assessment (SOFA) scores, dead space ventilation index, and lung compliance. Citicoline effects on a panel of COVID-relevant lung and blood biomarkers will also be determined.DiscussionCiticoline has many characteristics that would be advantageous to any candidate COVID-19 therapeutic, including safety, low-cost, favorable chemical characteristics, and potentially pathogen-agnostic efficacy. Successful demonstration that citicoline is beneficial in severely ill patients with SARS CoV-2-induced HARF could transform management of severely ill COVID patients.Trial registrationThe trial was registered at www.clinicaltrials.gov on 5/31/2023 (NCT05881135).Trial statusCurrently enrolling.

Serotonin improves plant growth, foliar functions and antioxidant defence system in Ethiopian mustard (Brassica carinata A. Br.)

Every year, high salinity reduces agricultural crop yields by a substantial amount due to osmotic and ionic impacts that prevent plants from absorbing the required water and promote the hyperaccumulation of ions, which enter the transpiration stream and injure plant cells. Thus, in general, the effects of salinity stress on plant physio-chemicals functions are well known, but little has been explored on how serotonin combats abiotic stress in Ethiopian mustard (Brassica carinata). In this study, the effect of serotonin (SR; 200 µmol L−1) on Ethiopian mustard under salt stress (SS; 0, 50, 100 and 150 mM) was examined. Results exhibited that all SS levels tested in this trial were able to offer a significant reduction of plant growth parameters, chlorophyll contents, gas exchange, water use efficiency, fv/fm and nitrate reductase activity (NR) and increased the antioxidants and proline contents. However, the foliar application of SR significantly ameliorated the influence of all SS levels by improving gas exchange parameters, chlorophyll contents, PSll photochemical efficiency, antioxidant activities, proline, NR, water use efficiency and growth parameters. Based on these results, it is recommended that SR application is useful to uplift the growth, yield and physio-chemical mechanisms of Ethiopian mustard. Furthermore, the SR application can be carried out on various traditional crops under different climate conditions for sustainable agriculture production.

The Efficacy of Noninvasive Ventilation in Patients Affected by Rett Syndrome With Hypoventilation

BackgroundRett syndrome is a progressive neurological disorder associated to several comorbidities that contribute significantly to impair lung function. Respiratory morbidity represents a major cause of death in this population. Little is known about the benefit of noninvasive ventilation. MethodsWe retrospectively enrolled patients with Rett syndrome who underwent a pneumological evaluation combined with a cardiorespiratory polygraphy and/or a pulse oximetry and capnography from 2012 to 2022. ResultsMedical records of 11 patients with Rett syndrome, mean age 13 ± 6 years, were evaluated. Most patients presented with both epilepsy and scoliosis. Five patients showed a pathologic sleep study and/or impaired night gas exchange: mean obstructive apnea-hypopnea index was 4 ± 3 events/hour; mean and minimal SpO2 were, respectively, 93% ± 2% and 83% ± 6%, while mean and maximal transcutaneous carbon dioxide monitoring (PtcCO2) were, respectively, 51 ± 5 mm Hg and 55 ± 8 mm Hg; and mean oxygen desaturation index was 13 ± 11 events/hour. These patients started noninvasive ventilation with clinical benefit and improved gas exchange mostly in terms of PtcCO2 (mean PtcCO2 51 ± 5 mm Hg before and 46 ± 6 mm Hg after noninvasive ventilation). ConclusionsNoninvasive ventilation is a suitable option for patients with Rett syndrome.

Diaphragm Force and Mitochondrial Function Following Enhanced Nitric Oxide Availability During Mechanical Ventilation

During mechanical ventilation (MV), force developed by the diaphragm decreases over time much faster than locomotor muscles, known as ventilator-induced diaphragm dysfunction (VIDD). VIDD is accompanied by an increase in intramyofiber protein S-nitrosylation, a modification of cysteines by nitric oxide (NO). During the treatment of acute respiratory distress syndrome (ARDS), inhaled NO is commonly used to improve gas exchange, but little is known about the effects of increased NO availability to the diaphragm during MV and the intracellular mechanisms to protect against excessive S-nitrosylation. We hypothesize that the enzyme S-nitrosoglutathione reductase (GSNOR) protects against excessive protein S-nitrosylation in diaphragm myofibers in conditions where NO availability is enhanced during MV, thereby preserving contractile function. We tested this hypothesis by enhancing NO availability and blocking GSNOR activity in mice during MV. Mice were treated with GSNOR inhibitor (SPL-334; GSNORi) or both GSNORi and NO donor isosorbide dinitrate (GSNORi-ISDN) together, and mechanically ventilated for 2h. E x vivo diaphragm force and mitochondrial respiration were measured. Male (C57BL/6J) 3-4 month old mice (n=27) were anesthetized and subjected to MV for 0 (non-MV), 2, 4, or 6h (150 breaths/min, 10 cmH2O PIP, 3.5 cmH2O PEEP. 8 mL/kg VT). Alternatively, mice were treated with PBS/10% DMSO (DMSO, n=6) or 25 μg SPL-334 in PBS/DMSO (GSNORi, n=6) or 25 μg SPL-334 + 1.7 mg ISDN in PBS/DMSO (GSNORi-ISDN; n=6), and then subjected to MV for 2 h. After MV, mice were euthanized, and diaphragm strips were used for force, and permeabilized fiber bundles for mitochondrial oxidative phosphorylation and H2O2 generation measurements. Peak tetanic force was decreased by MV ~23% at 4 h and ~40% at 6 h (P=0.0183 and P=0.0062, respectively, one-way ANOVA, Tukey post-test) vs 0 h. However, peak force was not different between DMSO, GSNORi and GSNORi-ISDN at 2 h MV. Coupled-phosphorylating mitochondrial respiration (Kruskal-Wallis H=2.2, p=0.35) was not different but H2O2 flux was highest in GSNORi-ISDN vs DMSO and GSNORi (Kruskal-Wallis H=6.6, p=0.03). GSNORi and ISDN treatment during MV did not produce any changes to VIDD and to mitochondrial respiration, but increased ROS production. If exogenous NO is not provided, inhibiting GSNOR in vivo alone does not affect diaphragm function ex vivo during short MV. Support: TRDRP (T32IR5221 and T29KT0397CA, to L.N.) and SDSU 2023 SEED Grant (to L.N.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Effect of Recruitment Maneuver on Static Lung Compliance in Patients Undergoing General Anesthesia for Laparoscopic Cholecystectomy: A Single-Centre Prospective Clinical Intervention Study.

Background and Objectives: The aim of this study was to examine whether the use of an alveolar recruitment maneuver (RM) leads to a significant increase in static lung compliance (Cstat) and an improvement in gas exchange in patients undergoing laparoscopic cholecystectomy. Material and Methods: A clinical prospective intervention study was conducted. Patients were divided into two groups according to their body mass index (BMI): normal-weight (group I) and pre-obese and obese grade I (group II). Lung mechanics were monitored (Cstat, dynamic compliance-Cdin, peak pressure-Ppeak, plateau pressure-Pplat, driving pressure-DP) alongside gas exchange, and hemodynamic changes (heart rate-HR, mean arterial pressure-MAP) at six time points: T1 (induction of anesthesia), T2 (formation of pneumoperitoneum), T3 (RM with a PEEP of 5 cm H2O), T4 (RM with a PEEP of 7 cm H2O), T5 (desufflation), and T6 (RM at the end). The RM was performed by increasing the peak pressure by +5 cm of H2O at an equal inspiration-to-expiration ratio (I/E = 1:1) and applying a PEEP of 5 and 7 cm of H2O. Results: Out of 96 patients, 33 belonged to group I and 63 to group II. An increase in Cstat values occurred after all three RMs. At each time point, the Cstat value was measured higher in group I than in group II. A higher increase in Cstat was observed in group II after the second and third RM. Cstat values were higher at the end of the surgical procedure compared to values after the induction of anesthesia. The RM led to a significant increase in PaO2 in both groups without changes in HR or MAP. Conclusions: During laparoscopic cholecystectomy, the application of RM leads to a significant increase in Cstat and an improvement in gas exchange. The prevention of atelectasis during anesthesia should be initiated immediately after the induction of anesthesia, using protective mechanical ventilation and RM.

Disrupted BMP-9 Signaling Impairs Pulmonary Vascular Integrity in Hepatopulmonary Syndrome.

Rationale: Hepatopulmonary syndrome (HPS) is a severe complication of liver diseases characterized by abnormal dilation of pulmonary vessels, resulting in impaired oxygenation. Recent research highlights the pivotal role of liver-produced BMP-9 (bone morphogenetic protein-9) in maintaining pulmonary vascular integrity. Objectives: This study aimed to investigate the involvement of BMP-9 in human and experimental HPS. Methods: Circulating BMP-9 levels were measured in 63 healthy control subjects and 203 patients with cirrhosis with or without HPS. Two animal models of portal hypertension were employed: common bile duct ligation with cirrhosis and long-term partial portal vein ligation without cirrhosis. Additionally, the therapeutic effect of low-dose BMP activator FK506 was investigated, and the pulmonary vascular phenotype of BMP-9-knockout rats was analyzed. Measurements and Main Results: Patients with HPS related to compensated cirrhosis exhibited lower levels of circulating BMP-9 compared with patients without HPS. Patients with severe cirrhosis exhibited consistently low levels of BMP-9. HPS characteristics were observed in animal models, including intrapulmonary vascular dilations and an increase in the alveolar-arterial gradient. HPS development in both rat models correlated with reduced intrahepatic BMP-9 expression, decreased circulating BMP-9 level and activity, and impaired pulmonary BMP-9 endothelial pathway. Daily treatment with FK506 for 2 weeks restored the BMP pathway in the lungs, alleviating intrapulmonary vascular dilations and improving gas exchange impairment. Furthermore, BMP-9-knockout rats displayed a pulmonary HPS phenotype, supporting its role in disease progression. Conclusions: The study findings suggest that portal hypertension-induced loss of BMP-9 signaling contributes to HPS development.