Identification and Development of BRD9 Chemical Probes.

The development of BRD9 inhibitors involves the design and synthesis of molecules that can specifically bind the BRD9 protein, interfering with the function of the chromatin-remodeling complex ncBAF, with the main advantage of modulating gene expression and controlling cellular processes. Here, we summarize the work conducted over the past 10 years to find new BRD9 binders, with an emphasis on their structure-activity relationships, efficacies, and selectivities in preliminary studies. BRD9 is expressed in a variety of cancer forms, hence, its inhibition holds particular significance in cancer research. However, it is crucial to note that the expanding research in the field, particularly in the development of new degraders, may uncover new therapeutic potentials.

Chemoproteomics Reveals USP5 (Ubiquitin Carboxyl-Terminal Hydrolase 5) as Promising Target of the Marine Polyketide Gracilioether A.

Mass spectrometry-based chemical proteomic approaches using limited proteolysis have become a powerful tool for the identification and analysis of the interactions between a small molecule (SM) and its protein target(s). Gracilioether A (GeA) is a polyketide isolated from a marine sponge, for which we aimed to trace the interactome using this strategy. DARTS (Drug Affinity Responsive Target Stability) and t-LiP-MS (targeted-Limited Proteolysis-Mass Spectrometry) represented the main techniques used in this study. DARTS was applied on HeLa cell lysate for the identification of the GeA target proteins, and t-LiP-MS was employed to investigate the protein's regions involved in the binding with GeA. The results were complemented through the use of binding studies using Surface Plasmon Resonance (SPR) and in silico molecular docking experiments. Ubiquitin carboxyl-terminal hydrolase 5 (USP5) was identified as a promising target of GeA, and the interaction profile of the USP5-GeA complex was explained. USP5 is an enzyme involved in the pathway of protein metabolism through the disassembly of the polyubiquitin chains on degraded proteins into ubiquitin monomers. This activity is connected to different cellular functions concerning the maintenance of chromatin structure and receptors and the degradation of abnormal proteins and cancerogenic progression. On this basis, this structural information opens the way to following studies focused on the definition of the biological potential of Gracilioether A and the rational development of novel USP5 inhibitors based on a new structural skeleton.

NMR Metabolomics and Chemometrics of Commercial Varieties of Phaseolus vulgaris L. Seeds from Italy and In Vitro Antioxidant and Antifungal Activity.

The metabolite fingerprinting of four Italian commercial bean seed cultivars, i.e., Phaseolus Cannellino (PCANN), Controne (PCON), Vellutina (PVEL), and Occhio Nero (PON), were investigated by Nuclear Magnetic Resonance (NMR) spectroscopy and multivariate data analysis. The hydroalcoholic and organic extract analysis disclosed more than 32 metabolites from various classes, i.e., carbohydrates, amino acids, organic acids, nucleosides, alkaloids, and fatty acids. PVEL, PCON, and PCANN varieties displayed similar chemical profiles, albeit with somewhat different quantitative results. The PON metabolite composition was slightly different from the others; it lacked GABA and pipecolic acid, featured a higher percentage of malic acid than the other samples, and showed quantitative variations of several metabolites. The lipophilic extracts from all four cultivars demonstrated the presence of omega-3 and omega-6 unsaturated fatty acids. After the determination of the total phenolic, flavonoids, and condensed tannins content, in vitro antioxidant activity was then assessed using the DPPH scavenging activity, the ABTS scavenging assay, and ferric-reducing antioxidant power (FRAP). Compared to non-dark seeds (PCON, PCANN), brown seeds (PVEL, PON) featured a higher antioxidant capacity. Lastly, only PON extract showed in vitro antifungal activity against the sclerotia growth of S. rolfsii, by inhibiting halo growth by 75%.

2-Substituted 1,5-benzothiazepine-based HDAC inhibitors exert anticancer activities on human solid and acute myeloid leukemia cell lines.

Herein, we report the development of a new series of histone deacetylase inhibitors (HDACi) containing a 2-substituted 1,5-benzothiazepine scaffold. First, a virtual combinatorial library (∼1.6 × 103 items) was built according to a convenient synthetic route, and then it was submitted to molecular docking experiments on seven HDACs isoforms belonging to classes I and II. Integrated computational filters were used to select the most promising ones that were synthesized through an optimized approach, also amenable to generating both racemic and enantioenriched benzothiazepine-based derivatives. The obtained compounds showed potent HDAC inhibitory activity, especially those containing the sulphone moiety, endowed with IC50 in the nanomolar range. In addition, in vitro outcomes of our synthesized compounds demonstrated a cytotoxic effect on U937 and HCT116 cell lines and an arrest in the G2/M phase (13 ≤ IC50 ≤ 18 µM). Finally, Western blot analyses outlined the modulation of the histone acetyl markers such as H3K9/14, acetyl-tubulin, and the apoptotic indicator p21 in both cancer cell lines, disclosing a good HDAC inhibitor activity exerted by the designed items. Given the key role of HDACs in many cellular pathways, which makes these enzymes appealing and "hot" drug targets, our findings highlighted the importance of these 2-substituted 1,5-benzothiazepine-based compounds (both in the reduced and oxidized version) for the development of novel epidrugs.

Exploring the chemical space of functionalized [1,2,4]triazolo[4,3-a]quinoxaline-based compounds targeting the bromodomain of BRD9.

Here we report a detailed structure-activity relationship (SAR) study related to [1,2,4]triazolo[4,3-a]quinoxaline-based compounds targeting the reader module of bromodomain containing-protein 9 (BRD9). 3D structure-based pharmacophore models, previously introduced by us, were here employed to evaluate a second generation of compounds, exploring different substitution patterns on the heterocyclic core. Starting from the promising data obtained from our previously identified [1,2,4]triazolo[4,3-a]quinoxaline-based compounds 1-4, the combination of in silico studies, chemical synthesis, biophysical and in vitro assays led to the identification of a new set of derivatives, selected for thoroughly exploring the chemical space of the bromodomain binding site. In more details, the investigation of different linkers at C-4 position highlighted the amine spacer as mandatory for the binding with the protein counterpart and the crucial role of the alkyl substituents at C-1 for increasing the selectivity toward BRD9. Additionally, the importance of a hydrogen bond donor group, critical to anchor the ZA region and required for the interaction with Ile53 residue, was inferred from the analysis of our collected results. Herein we also propose an optimization and an update of our previously reported "pharm-druglike2" 3D structure-based pharmacophore model, introducing it as "pharm-druglike2.1". Compounds 24-26, 32, 34 and 36 were identified as new valuable BRD9 binders featuring IC50 values in the low micromolar range. Among them, 24 and 36 displayed an excellent selectivity towards BRD9 and a good antiproliferative effect on a panel of leukemia models, especially toward CCRF-CEM cell line, with no cytotoxicity on healthy cells. Notably, the interaction of 24 and 36 with the bromodomain and PHD finger-containing protein 1 (BRPF1) also emerged, disclosing them as new and unexplored dual inhibitors for these two proteins highly involved in leukemia. These findings highlight the potential for the identification of new attractive dual epidrugs as well as a promising starting point for the development of chemical degraders endowed with anticancer activities.

Target identification by structure-based computational approaches: Recent advances and perspectives.

The use of computational techniques in the early stages of drug discovery has recently experienced a boost, especially in the target identification step. Finding the biological partner(s) for new or existing synthetic and/or natural compounds by "wet" approaches may be challenging; therefore, preliminary in silico screening is even more recommended. After a brief overview of some of the most known target identification techniques, recent advances in structure-based computational approaches for target identification are reported in this digest, focusing on Inverse Virtual Screening and its recent applications. Moreover, future perspectives concerning the use of such methodologies, coupled or not with other approaches, are analyzed.

Identification of 2,4,5-trisubstituted-2,4-dihydro-3H-1,2,4-triazol-3-one-based small molecules as selective BRD9 binders.

Targeting bromodomain-containing protein 9 (BRD9) represents a promising strategy for the development of new agents endowed with anticancer properties. With this aim, a set of 2,4,5-trisubstituted-2,4-dihydro-3H-1,2,4-triazol-3-one-based compounds was investigated following a combined approach that relied on in silico studies, chemical synthesis, biophysical and biological evaluation of the most promising items. The protocol was initially based on molecular docking experiments, accounting a library of 1896 potentially synthesizable items tested in silico against the bromodomain of BRD9. A first set of 21 compounds (1-21) was selected and the binding on BDR9 was assessed through AlphaScreen assays. The obtained results disclosed compounds 17 and 20 able to bind BRD9 in the submicromolar range (IC50 = 0.35 ± 0.18 µM and IC50 = 0.14 ± 0.03 µM, respectively) showing a promising selectivity profile when tested against further nine bromodomains. Taking advantage of 3D structure-based pharmacophore models, additional 10 derivatives were selected in silico for the synthetic step and binding assessment, highlighting seven compounds (22, 23, 25, 26, 28, 29, 31) able to selectively bind BRD9 among different bromodomains. The ability of the identified BRD9 binders to cross artificial membranes in vitro was also assessed, revealing a very good passive permeability profile. Preliminary studies were carried out on a panel of healthy and cancer human cell lines to explore the biological behavior of the selected compounds, disclosing a moderate activity and significant selectivity profile towards leukaemia cells. These results highlighted the applicability of the reported multidisciplinary approach for accelerating the selection of promising items and for driving the chemical synthesis of novel selective BRD9 binders. Moreover, the low molecular weight of the reported 2,4,5-trisubstituted-2,4-dihydro-3H-1,2,4-triazol-3-one-based BRD9 binders suggests the possibility for further exploring the chemical space in order to obtain new analogues with improved potency.

Extensive Molecular Dynamics Simulations Disclosed the Stability of mPGES-1 Enzyme and the Structural Role of Glutathione (GSH) Cofactor.

A deep in silico investigation of various microsomal prostaglandin E2 synthase-1 (mPGES-1) protein systems is here reported using molecular dynamics (MD) simulations. Firstly, eight different proteins models (Models A-H) were built, starting from the active enzyme trimer system (Model A), namely that bound to three glutathione (GSH) cofactor molecules, and then gradually removing the GSHs (Models B-H), simulating each of them for 100 ns in explicit solvent. The analysis of the obtained data disclosed the structural role of GSH in the chemical architecture of mPGES-1 enzyme, thus suggesting the unlikely displacement of this cofactor, in accordance with experimentally determined protein structures co-complexed with small molecule inhibitors. Afterwards, Model A was submitted to microsecond-scale molecular dynamics simulation (total simulation time=10 µs), in order to shed light about the dynamical behaviour of this enzyme at atomic level and to obtain further structural features and protein function information. We confirmed the structural stability of the enzyme machinery, observing a conformational rigidity of the protein, with a backbone RMSD of ∼3 Šalong the simulation time, and highlighting the strong active contribution of GSH molecules due to their active role in packing the protein chains through a tight binding at monomer interfaces. Furthermore, the focused analysis on R73 residue disclosed its role in solvent exchange events, probably excluding its function as route for GSH to enter towards the endoplasmic reticulum membrane, in line with the recently reported function of cap domain residues F44-D66 as gatekeeper for GSH entrance into catalytic site.

Phytochemical Analysis of the Methanolic Extract and Essential Oil from Leaves of Industrial Hemp Futura 75 Cultivar: Isolation of a New Cannabinoid Derivative and Biological Profile Using Computational Approaches.

Cannabis sativa L. is a plant belonging to the Cannabaceae family, cultivated for its psychoactive cannabinoid (Δ9-THC) concentration or for its fiber and nutrient content in industrial use. Industrial hemp shows a low Δ9-THC level and is a valuable source of phytochemicals, mainly represented by cannabinoids, flavones, terpenes, and alkaloids, with health-promoting effects. In the present study, we investigated the phytochemical composition of leaves of the industrial hemp cultivar Futura 75, a monoecious cultivar commercially used for food preparations or cosmetic purposes. Leaves are generally discarded, and represent waste products. We analyzed the methanol extract of Futura 75 leaves by HPLC and NMR spectroscopy and the essential oil by GC-MS. In addition, in order to compare the chemical constituents, we prepared the water infusion. One new cannabinoid derivative (1) and seven known components, namely, cannabidiol (2), cannabidiolic acid (3), ß-cannabispirol (4), ß-cannabispirol (5), canniprene (6), cannabiripsol (7), and cannflavin B (8) were identified. The content of CBD was highest in all preparations. In addition, we present the outcomes of a computational study focused on elucidating the role of 2α-hydroxy-Δ3,7-cannabitriol (1), CBD (2), and CBDA (3) in inflammation and thrombogenesis.

New TRPM8 blockers exert anticancer activity over castration-resistant prostate cancer models.

TRPM8 has recently emerged as a druggable target in prostate cancer (PC) and TRPM8 modulators have been proposed as potential anticancer agents in this pathology. We have recently demonstrated their effectiveness in a castration-resistant prostate cancer (CRPC) model that is usually resistant to androgen deprivation therapy (ADT) and is considered the most aggressive form of PC. This is why the discovery of selective, effective, and potent TRPM8 modulators would improve the molecular arsenal in support of PC standard-of-care treatments. In the present paper we describe the design and the synthesis of a new series of TRPM8 antagonists, preliminarily characterized in vitro for their potency and selectivity by fluorimetric calcium assays. The preliminary screening allowed the identification of several potent (0.11 µM < IC50 < 0.49 µM) and selective compounds. The most potent derivatives were further characterized by patch-clamp electrophysiology assays, confirming their noteworthy activity. Moreover, the behavior of these compounds was investigated in 2D and 3D models of PC. These TRPM8 antagonists showed remarkable efficacy in inhibiting the growth induced by androgen in various PC cells as well as in CRPC models, confirming their potential as anticancer agents.

Structural Refinement of 2,4-Thiazolidinedione Derivatives as New Anticancer Agents Able to Modulate the BAG3 Protein.

The multidomain BAG3 protein is a member of the BAG (Bcl-2-associated athanogene) family of co-chaperones, involved in a wide range of protein-protein interactions crucial for many key cellular pathways, including autophagy, cytoskeletal dynamics, and apoptosis. Basal expression of BAG3 is elevated in several tumor cell lines, where it promotes cell survival signaling and apoptosis resistance through the interaction with many protein partners. In addition, its role as a key player of several hallmarks of cancer, such as metastasis, angiogenesis, autophagy activation, and apoptosis inhibition, has been established. Due to its involvement in malignant transformation, BAG3 has emerged as a potential and effective biological target to control multiple cancer-related signaling pathways. Recently, by using a multidisciplinary approach we reported the first synthetic BAG3 modulator interfering with its BAG domain (BD), based on a 2,4-thiazolidinedione scaffold and endowed with significant anti-proliferative activity. Here, a further in silico-driven selection of a 2,4-thiazolidinedione-based compound was performed. Thanks to a straightforward synthesis, relevant binding affinity for the BAG3BD domain, and attractive biological activities, this novel generation of compounds is of great interest for the development of further BAG3 binders, as well as for the elucidation of the biological roles of this protein in tumors. Specifically, we found compound 6 as a new BAG3 modulator with a relevant antiproliferative effect on two different cancer cell lines (IC50: A375 = 19.36 µM; HeLa = 18.67 µM).

Introducing structure-based three-dimensional pharmacophore models for accelerating the discovery of selective BRD9 binders.

A well-structured in silico workflow is here reported for disclosing structure-based pharmacophore models against bromodomain-containing protein 9 (BRD9), accelerating virtual screening campaigns and facilitating the identification of novel binders. Specifically, starting from 23 known ligands co-crystallized with BRD9, three-dimensional pharmacophore models, namely placed in a reference protein structure, were developed. Specifically, we here introduce a fragment-related pharmacophore model, useful for the identification of new promising small chemical probes targeting the protein region responsible of the acetyllysine recognition, and two further pharmacophore models useful for the selection of compounds featuring drug-like properties. A pharmacophore-driven virtual screening campaign was then performed to facilitate the selection of new selective BRD9 ligands, starting from a large library of commercially available molecules. The identification of a promising BRD9 binder (7) prompted us to re-iterate this computational workflow on a second focused in-house built library of synthesizable compounds and, eventually, three further novel BRD9 binders were disclosed (8-10). Moreover, all these compounds were tested among a panel comprising other nine bromodomains, showing a high selectivity for BRD9. Preclinical bioscreens for potential anticancer activity highlighted compound 7 as that showing the most promising biological effects, proving the reliability of this in silico pipeline and confirming the applicability of the here introduced structure-based three-dimensional (3D) pharmacophore models as straightforward tools for the selection of new BRD9 ligands.

Biological Profile of Two Gentiana lutea L. Metabolites Using Computational Approaches and In Vitro Tests.

Natural products have been the main source of bioactive molecules for centuries. We tested the biological profile of two metabolites extracted from Gentiana lutea L. by means of computational techniques and in vitro assays. The two molecules (loganic acid and gentiopicroside) were tested in silico using an innovative technique, named Inverse Virtual Screening (IVS), to highlight putative partners among a panel of proteins involved in inflammation and cancer events. A positive binding with cyclooxygenase-2 (COX-2), alpha-1-antichymotrypsin, and alpha-1-acid glycoprotein emerged from the computational experiments and the outcomes from the promising interaction with COX-2 were confirmed by Western blot, highlighting the reliability of IVS in the field of the natural products.

Inverse Virtual Screening for the rapid re-evaluation of the presumed biological safe profile of natural products. The case of steviol from Stevia rebaudiana glycosides on farnesoid X receptor (FXR).

Nonnutritive sweeteners (NNSs) are widely employed as dietary substitutes for classical sugars thanks to their safety profile and low toxicity. In this study, a re-evaluation of the biological effects of steviol (1), the main metabolite from Stevia rebaudiana glycosides, was performed using the Inverse Virtual Screening (IVS) target fishing computational approach. Starting from well-known pharmacological properties of Stevia rebaudiana glycosides, this computational tool was employed for predicting the putative interacting targets of 1 and, afterwards, of its five synthetic ester derivatives 2-6, accounting a large panel of proteins involved in cancer and inflammation events. Applying this methodology, the farnesoid X receptor (FXR) was identified as the putative target partner of 1-6. The predicted ligand-protein interactions were corroborated by transactivation assays, specifically disclosing the agonistic activity of 1 and the antagonistic activities of 2-6 on FXR. The reported results highlight the feasibility of IVS as a fast and potent tool for predicting the interacting targets of query compounds, addressing the re-evaluation of their bioactivity. In light of the obtained results, the presumably safe profile of known compounds, such as the case of steviol (1), is critically discussed.

Isolation, Synthesis And Structure Determination Of Cannabidiol Derivatives And Their Cytotoxic Activities.

In a continuing effort to explore the structural diversity and pharmacological activities of natural products based scaffolds, herein, we report the isolation, synthesis, and structure determination of cannabidiol and its derivatives along with their cytotoxic activities. Treatment of cannabidiol (1) with acid catalyst POCl3 afforded a new derivative 6 along with six known molecules 2 - 5, 7 and, 8. The structure of 6 was elucidated by extensive spectroscopic analyses and DFT calculations of the NMR and ECD data. All the compounds (2 - 8) were evaluated for their cytotoxic potential against a panel of eight cancer cell lines. Compounds 4, 5, 7, and 8 showed pronounced in vitro cytotoxic activity with IC50 values ranging from 5.6 to 60 µM. Out of the active molecules, compounds 4, and 7 were found to be comparable to that of the parent molecule 1 on the inhibition of almost all the tested cancer cell lines.

Esophageal balloon calibration during Sigh: A physiologic, randomized, cross-over study.

PURPOSE: Optimal esophageal balloon filling volume (Vbest) depends on the intrathoracic pressure. During Sigh breath delivered by the ventilator machine, esophageal balloon is surrounded by elevated intrathoracic pressure that might require higher filling volume for accurate measure of tidal changes in esophageal pressure (Pes). The primary aim of our investigation was to evaluate and compare Vbest during volume controlled and pressure support breaths vs. Sigh breath. MATERIALS AND METHODS: Twenty adult patients requiring invasive volume-controlled ventilation (VCV) for hypoxemic acute respiratory failure were enrolled. After the insertion of a naso-gastric catheter equipped with 10 ml esophageal balloon, each patient underwent three 30-min trials as follows: VCV, pressure support ventilation (PSV), and PSV + Sigh. Sigh was added to PSV as 35 cmH2O pressure-controlled breath over 4 s, once per minute. PSV and PSV + Sigh were randomly applied and, at the end of each step, esophageal balloon calibration was performed. RESULTS: Vbest was higher for Sigh breath (4.5 [3.0-6.8] ml) compared to VCV (1.5 [1.0-2.9] ml, P = 0.0004) and PSV tidal breath (1.0 [0.5-2.4] ml, P < 0.0001). CONCLUSIONS: During Sigh breath, applying a calibrated approach for Pes assessment, a higher Vbest was required compared to VCV and PSV tidal breath.

Discovery of a Secalonic Acid Derivative from Aspergillus aculeatus, an Endophyte of Rosa damascena Mill., Triggers Apoptosis in MDA-MB-231 Triple Negative Breast Cancer Cells.

A new secalonic acid derivative, F-7 (1), was isolated from the endophytic Aspergillus aculeatus MBT 102, associated with Rosa damascena. The planar structure of 1 was established on the basis of 1D and 2D NMR and ESI-TOF-MS spectra. The relative configuration of 1 was determined applying a combined quantum mechanical/NMR approach and, afterward, the comparison of calculated and experimental electronic circular dichroism spectra determined the assignment of its absolute configuration. The compound possesses strong cytotoxic activity against triple negative breast cancer (TNBC) cells. It was found to induce apoptosis, as evidenced by scanning electron microscopy and phase contrast microscopy. Furthermore, flow cytometry analyses demonstrated that 1 induced mitochondrial damage and reactive oxygen species mediated apoptosis, arresting the G1 phase of the cells in a dose-dependent manner. Also, the compound causes significant microtubule disruption in TNBC cells. Subsequently, 1 restricted the cell migration leading to the concomitant increase in expression of cleaved caspase and PARP.

Discovery of noscapine derivatives as potential ß-tubulin inhibitors.

Twenty novel 1,2,3-triazole noscapine derivatives were synthesized starting from noscapine by consecutive N-demethylation, reduction of lactone ring, N-propargylation and Huisgen 1,3-dipolar cycloaddition reaction. In order to select the most promising molecules to subject to further biophysical and biological evaluation, a molecular docking analysis round was performed using noscapine as reference compound. The molecules featuring docking predicted binding affinity better than that of noscapine were then subjected to MTT assay against MCF7 cell line. The obtained results disclosed that all the selected triazole derivatives exhibited a remarkably lower cell viability compared to noscapine in the range of 20 µM in 48 h. In an attempt to correlate the biological activity with the ability to bind tubulin, the surface plasmon resonance (SPR) assay was employed. Compounds 8a, 8h, 9c, 9f and 9j were able to bind tubulin with affinity constant values in the nanomolar range and higher if compared to noscapine. Integrating computational predictions and experimental evaluation, two promising compounds (8h and 9c) were identified, whose relevant cytotoxicity was supposed to be correlated with tubulin binding affinity. These findings shed lights onto structural modifications of noscapine toward the identification of more potent cytotoxic agents targeting tubulin.

Esophageal Pressure Versus Gas Exchange to Set PEEP During Intraoperative Ventilation.

BACKGROUND: Pneumoperitoneum and Trendelenburg position affect respiratory system mechanics and oxygenation during elective pelvic robotic surgery. The primary aim of this randomized pilot study was to compare the effects of a conventional low tidal volume ventilation with PEEP guided by gas exchange (VGas-guided) versus low tidal volume ventilation tailoring PEEP according to esophageal pressure (VPes-guided) on oxygenation and respiratory mechanics during elective pelvic robotic surgery. METHODS: This study was conducted in a single-center tertiary hospital between September 2017 and January 2019. Forty-nine adult patients scheduled for elective pelvic robotic surgery were screened; 28 subjects completed the full analysis. Exclusion criteria were American Society of Anesthesiologists physical status ≥ 3, contraindications to nasogastric catheter placement, and pregnancy. After dedicated naso/orogastric catheter insertion, subjects were randomly assigned to VGas-guided ([Formula: see text] and PEEP set to achieve [Formula: see text] > 94%) or VPes-guided (PEEP tailored to equalize end-expiratory transpulmonary pressure). Oxygenation ([Formula: see text]/[Formula: see text]) was evaluated (1) at randomization, after pneumoperitoneum and Trendelenburg application; (2) at 60 min; (3) at 120 min following randomization; and (4) at end of surgery. Respiratory mechanics were assessed during the duration of the study. RESULTS: Compared to VGas-guided, oxygenation was higher with VPes-guided at 60 min (388 ± 90 vs 308 ± 95 mm Hg, P = .02), at 120 min after randomization (400 ± 90 vs 308 ± 81 mm Hg, P = .008), and at the end of surgery (402 ± 95 vs 312 ± 95 mm Hg, P = .009). Respiratory system elastance was lower with VPes-guided compared to VGas-guided at 20 min (24.2 ± 7.3 vs 33.4 ± 10.7 cm H2O/L, P = .001) and 60 min (24.1 ± 5.4 vs 31.9 ± 8.5 cm H2O/L, P = .006) from randomization. CONCLUSIONS: Oxygenation and respiratory system mechanics were improved when applying a ventilatory strategy tailoring PEEP to equalize expiratory transpulmonary pressure in subjects undergoing pelvic robotic surgery compared to a VGas-guided approach. (ClinicalTrials.gov registration NCT03153592).

Mechanical Ventilation Guided by Uncalibrated Esophageal Pressure May Be Potentially Harmful.

BACKGROUND: Esophageal balloon calibration was proposed in acute respiratory failure patients to improve esophageal pressure assessment. In a clinical setting characterized by a high variability of abdominal load and intrathoracic pressure (i.e., pelvic robotic surgery), the authors hypothesized that esophageal balloon calibration could improve esophageal pressure measurements. Accordingly, the authors assessed the impact of esophageal balloon calibration compared to conventional uncalibrated approach during pelvic robotic surgery. METHODS: In 30 adult patients, scheduled for elective pelvic robotic surgery, calibrated end-expiratory and end-inspiratory esophageal pressure, and the associated respiratory variations were obtained at baseline, after pneumoperitoneum-Trendelenburg application, and with positive end-expiratory pressure (PEEP) administration and compared to uncalibrated values measured at 4-ml filling volume, as per manufacturer recommendation. Data are expressed as median and [25th, 75th percentile]. RESULTS: Ninety calibrations were successfully performed. Chest wall elastance worsened with pneumoperitoneum-Trendelenburg and PEEP (19.0 [15.5, 24.6] and 16.7 [11.4, 21.7] cm H2O/l) compared to baseline (8.8 [6.3, 9.8] cm H2O/l; P < 0.0001 for both comparisons). End-expiratory and end-inspiratory calibrated esophageal pressure progressively increased from baseline (3.7 [2.2, 6.0] and 7.7 [5.9, 10.2] cm H2O) to pneumoperitoneum-Trendelenburg (6.2 [3.8, 10.2] and 16.1 [13.1, 20.6] cm H2O; P = 0.014 and P < 0.001) and PEEP (8.8 [7.7, 15.6] and 18.9 [16.3, 22.0] cm H2O; P < 0.0001 vs. baseline for both comparison; P < 0.001 and P = 0.002 vs. pneumoperitoneum-Trendelenburg) and, at each study step, they were persistently lower than uncalibrated esophageal pressure (P < 0.0001 for all comparisons). Overall, difference among uncalibrated and calibrated esophageal pressure was 5.1 [3.8, 8.4] cm H2O at end-expiration and 3.8 [3.0, 6.3] cm H2O at end-inspiration. Uncalibrated esophageal pressure swing was always lower than calibrated one (P < 0.0001 for all comparisons) with a difference of -1.0 [-1.8, -0.4] cm H2O. CONCLUSIONS: In a clinical setting with variable chest wall mechanics, uncalibrated measurements substantially overestimated absolute values and underestimated respiratory variations of esophageal pressure. Calibration could substantially improve mechanical ventilation guided by esophageal pressure.