Cellular and transcriptional dynamics of human neutrophils at steady state and upon stress.

Traditionally viewed as poorly plastic, neutrophils are now recognized as functionally diverse; however, the extent and determinants of neutrophil heterogeneity in humans remain unclear. We performed a comprehensive immunophenotypic and transcriptome analysis, at a bulk and single-cell level, of neutrophils from healthy donors and patients undergoing stress myelopoiesis upon exposure to growth factors, transplantation of hematopoietic stem cells (HSC-T), development of pancreatic cancer and viral infection. We uncover an extreme diversity of human neutrophils in vivo, reflecting the rates of cell mobilization, differentiation and exposure to environmental signals. Integrated control of developmental and inducible transcriptional programs linked flexible granulopoietic outputs with elicitation of stimulus-specific functional responses. In this context, we detected an acute interferon (IFN) response in the blood of patients receiving HSC-T that was mirrored by marked upregulation of IFN-stimulated genes in neutrophils but not in monocytes. Systematic characterization of human neutrophil plasticity may uncover clinically relevant biomarkers and support the development of diagnostic and therapeutic tools.

Circulating hematopoietic stem/progenitor cell subsets contribute to human hematopoietic homeostasis.

ABSTRACT: In physiological conditions, few circulating hematopoietic stem/progenitor cells (cHSPCs) are present in the peripheral blood, but their contribution to human hematopoiesis remain unsolved. By integrating advanced immunophenotyping, single-cell transcriptional and functional profiling, and integration site (IS) clonal tracking, we unveiled the biological properties and the transcriptional features of human cHSPC subpopulations in relationship to their bone marrow (BM) counterpart. We found that cHSPCs reduced in cell count over aging and are enriched for primitive, lymphoid, and erythroid subpopulations, showing preactivated transcriptional and functional state. Moreover, cHSPCs have low expression of multiple BM-retention molecules but maintain their homing potential after xenotransplantation. By generating a comprehensive human organ-resident HSPC data set based on single-cell RNA sequencing data, we detected organ-specific seeding properties of the distinct trafficking HSPC subpopulations. Notably, circulating multi-lymphoid progenitors are primed for seeding the thymus and actively contribute to T-cell production. Human clonal tracking data from patients receiving gene therapy (GT) also showed that cHSPCs connect distant BM niches and participate in steady-state hematopoietic production, with primitive cHSPCs having the highest recirculation capability to travel in and out of the BM. Finally, in case of hematopoietic impairment, cHSPCs composition reflects the BM-HSPC content and might represent a biomarker of the BM state for clinical and research purposes. Overall, our comprehensive work unveiled fundamental insights into the in vivo dynamics of human HSPC trafficking and its role in sustaining hematopoietic homeostasis. GT patients' clinical trials were registered at ClinicalTrials.gov (NCT01515462 and NCT03837483) and EudraCT (2009-017346-32 and 2018-003842-18).

Cerebral autoregulation in traumatic brain injury: ultra-low-frequency pressure reactivity index and intracranial pressure across age groups.

BACKGROUND: The ultra-low-frequency pressure reactivity index (UL-PRx) has been established as a surrogate method for bedside estimation of cerebral autoregulation (CA). Although this index has been shown to be a predictor of outcome in adult and pediatric patients with traumatic brain injury (TBI), a comprehensive evaluation of low sampling rate data collection (0.0033 Hz averaged over 5 min) on cerebrovascular reactivity has never been performed. OBJECTIVE: To evaluate the performance and predictive power of the UL-PRx for 12-month outcome measures, alongside all International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) models and in different age groups. To investigate the potential for optimal cerebral perfusion pressure (CPPopt). METHODS: Demographic data, IMPACT variables, in-hospital mortality, and Glasgow Outcome Scale Extended (GOSE) at 12 months were extracted. Filtering and processing of the time series and creation of the indices (cerebral intracranial pressure (ICP), cerebral perfusion pressure (CPP), UL-PRx, and deltaCPPopt (ΔCPPopt and CPPopt-CPP)) were performed using an in-house algorithm. Physiological parameters were assessed as follows: mean index value, % time above threshold, and mean hourly dose above threshold. RESULTS: A total of 263 TBI patients were included: pediatric (17.5% aged ≤ 16 y) and adult (60.5% aged > 16 and < 70 y and 22.0% ≥ 70 y, respectively) patients. In-hospital and 12-month mortality were 25.9% and 32.7%, respectively, and 60.0% of patients had an unfavorable outcome at 12 months (GOSE). On univariate analysis, ICP, CPP, UL-PRx, and ΔCPPopt were associated with 12-month outcomes. The cutoff of ~ 20-22 for mean ICP and of ~ 0.30 for mean UL-PRx were confirmed in all age groups, except in patients older than 70 years. Mean UL-PRx remained significantly associated with 12-month outcomes even after adjustment for IMPACT models. This association was confirmed in all age groups. UL-PRx resulted associate with CPPopt. CONCLUSIONS: The study highlights UL-PRx as a tool for assessing CA and valuable outcome predictor for TBI patients. The results emphasize the potential clinical utility of the UL-PRx and its adaptability across different age groups, even after adjustment for IMPACT models. Furthermore, the correlation between UL-PRx and CPPopt suggests the potential for more targeted treatment strategies. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT05043545, principal investigator Paolo Gritti, date of registration 2021.08.21.

End-Tidal to Arterial Pco2 Ratio as Guide to Weaning from Venovenous Extracorporeal Membrane Oxygenation.

Rationale: Weaning from venovenous extracorporeal membrane oxygenation (VV-ECMO) is based on oxygenation and not on carbon dioxide elimination. Objectives: To predict readiness to wean from VV-ECMO. Methods: In this multicenter study of mechanically ventilated adults with severe acute respiratory distress syndrome receiving VV-ECMO, we investigated a variable based on CO2 elimination. The study included a prospective interventional study of a physiological cohort (n = 26) and a retrospective clinical cohort (n = 638). Measurements and Main Results: Weaning failure in the clinical and physiological cohorts were 37% and 42%, respectively. The main cause of failure in the physiological cohort was high inspiratory effort or respiratory rate. All patients exhaled similar amounts of CO2, but in patients who failed the weaning trial, [Formula: see text]e was higher to maintain the PaCO2 unchanged. The effort to eliminate one unit-volume of CO2, was double in patients who failed (68.9 [42.4-123] vs. 39 [20.1-57] cm H2O/[L/min]; P = 0.007), owing to the higher physiological Vd (68 [58.73] % vs. 54 [41.64] %; P = 0.012). End-tidal partial carbon dioxide pressure (PetCO2)/PaCO2 ratio was a clinical variable strongly associated with weaning outcome at baseline, with area under the receiver operating characteristic curve of 0.87 (95% confidence interval [CI], 0.71-1). Similarly, the PetCO2/PaCO2 ratio was associated with weaning outcome in the clinical cohort both before the weaning trial (odds ratio, 4.14; 95% CI, 1.32-12.2; P = 0.015) and at a sweep gas flow of zero (odds ratio, 13.1; 95% CI, 4-44.4; P < 0.001). Conclusions: The primary reason for weaning failure from VV-ECMO is high effort to eliminate CO2. A higher PetCO2/PaCO2 ratio was associated with greater likelihood of weaning from VV-ECMO.

The Oncogenic Theory of Preeclampsia: Is Amniotic Mesenchymal Stem Cells-Derived PLAC1 Involved?

The pathomechanisms of preeclampsia (PE), a complication of late pregnancy characterized by hypertension and proteinuria, and due to improper placentation, are not well known. Mesenchymal stem cells derived from the amniotic membrane (AMSCs) may play a role in PE pathogenesis as placental homeostasis regulators. PLACenta-specific protein 1 (PLAC1) is a transmembrane antigen involved in trophoblast proliferation that is found to be associated with cancer progression. We studied PLAC1 in human AMSCs obtained from control subjects (n = 4) and PE patients (n = 7), measuring the levels of mRNA expression (RT-PCR) and secreted protein (ELISA on conditioned medium). Lower levels of PLAC1 mRNA expression were observed in PE AMSCs as compared with Caco2 cells (positive controls), but not in non-PE AMSCs. PLAC1 antigen was detectable in conditioned medium obtained from PE AMSCs, whereas it was undetectable in that obtained from non-PE AMSCs. Our data suggest that abnormal shedding of PLAC1 from AMSC plasma membranes, likely by metalloproteinases, may contribute to trophoblast proliferation, supporting its role in the oncogenic theory of PE.

Dofetilide Dose Reductions and Discontinuation in Obese Compared with Nonobese Patients.

ABSTRACT: Dofetilide is an antiarrhythmic agent and primarily eliminated renally. Initial dosing is determined by creatinine clearance, calculated by total body weight in the Cockcroft-Gault equation. To date, there is no evidence comparing the dosing of dofetilide in obese versus nonobese patients. We conducted a retrospective review of 217 adults admitted for dofetilide loading to evaluate the tolerability of dofetilide in obese versus nonobese patients. The rate of dose adjustments, including dose reductions and discontinuations, was compared between obese versus nonobese patients in unadjusted and adjusted analyses. Electrocardiograms were collected throughout the loading period, and calculation of QT intervals was performed. Obese patients did not have a significantly higher frequency of dose adjustments compared with nonobese patients (51.5% vs. 44.8%, P = 0.33). Using total body weight to determine starting doses was associated with great odds of dose adjustments compared with ideal body weight (OR 3.69, P = 0.002) and adjusted body weight (OR 4.46, P = 0.02). Men required significantly fewer dose adjustments compared with women on multivariate analysis (OR 0.53, P = 0.03). Obesity is not associated with an increase in the rate of dose adjustments. Total body weight should be used with caution to calculate initial doses of dofetilide in women because it may lead to a higher rate of dose adjustments compared with ideal body weight. Additional studies are needed to confirm the optimal method for selecting starting doses of dofetilide in women, particularly those with a body mass index of ≥30.

Mobilizing Carbon Dioxide Stores. An Experimental Study.

Rationale: Understanding the physiology of CO2 stores mobilization is a prerequisite for intermittent extracorporeal CO2 removal (ECCO2R) in patients with chronic hypercapnia.Objectives: To describe the dynamics of CO2 stores.Methods: Fifteen pigs (61.7 ± 4.3 kg) were randomized to 48 hours of hyperventilation (group "Hyper," n = 4); 48 hours of hypoventilation (group "Hypo," n = 4); 24 hours of hypoventilation plus 24 hours of normoventilation (group "Hypo-Baseline," n = 4); or 24 hours of hypoventilation plus 24 hours of hypoventilation plus ECCO2R (group "Hypo-ECCO2R," n = 3). Forty-eight hours after randomization, the current [Formula: see text]e was reduced by 50% in every pig.Measurements and Main Results: We evaluated [Formula: see text]co2, [Formula: see text]o2, and metabolic [Formula: see text]co2 ([Formula: see text]o2 times the metabolic respiratory quotient). Changes in the CO2 stores were calculated as [Formula: see text]co2 - metabolic V̇co2. After 48 hours, the CO2 stores decreased by 0.77 ± 0.17 l kg-1 in group Hyper and increased by 0.32 ± 0.27 l kg-1 in group Hypo (P = 0.030). In group Hypo-Baseline, they increased by 0.08 ± 0.19 l kg-1, whereas in group Hypo-ECCO2R, they decreased by 0.32 ± 0.24 l kg-1 (P = 0.197). In the second 24-hour period, in groups Hypo-Baseline and Hypo-ECCO2R, the CO2 stores decreased by 0.15 ± 0.09 l kg-1 and 0.51 ± 0.06 l kg-1, respectively (P = 0.002). At the end of the experiment, the 50% reduction of [Formula: see text]e caused a PaCO2 rise of 9.3 ± 1.1, 32.0 ± 5.0, 16.9 ± 1.2, and 11.7 ± 2.0 mm Hg h-1 in groups Hyper, Hypo, Hypo-Baseline, and Hypo-ECCO2R, respectively (P < 0.001). The PaCO2 rise was inversely related to the previous CO2 stores mobilization (P < 0.001).Conclusions: CO2 from body stores can be mobilized over 48 hours without reaching a steady state. This provides a physiological rationale for intermittent ECCO2R in patients with chronic hypercapnia.

Characterization of compliance phenotypes in COVID-19 acute respiratory distress syndrome.

BACKGROUND: Coronavirus disease 2019-associated acute respiratory distress syndrome (COVID-19 ARDS) seems to differ from the "classic ARDS", showing initial significant hypoxemia in the face of relatively preserved compliance and evolving later in a scenario of poorly compliant lungs. We tested the hypothesis that in patients with COVID-19 ARDS, the initial value of static compliance of respiratory system (Crs) (1) depends on the previous duration of the disease (i.e., the fewer days of illness, the higher the Crs and vice versa) and (2) identifies different lung patterns of time evolution and response to prone positioning. METHODS: This was a single-center prospective observational study. We enrolled consecutive mechanically ventilated patients with a diagnosis of COVID-19 who met ARDS criteria, admitted to intensive care unit (ICU). Patients were divided in four groups based on quartiles of initial Crs. Relationship between Crs and the previous duration of the disease was evaluated. Respiratory parameters collected once a day and during prone positioning were compared between groups. RESULTS: We evaluated 110 mechanically ventilated patients with a diagnosis of COVID-19 who met ARDS criteria admitted to our ICUs. Patients were divided in groups based on quartiles of initial Crs. The median initial Crs was 41 (32-47) ml/cmH2O. No association was found between the previous duration of the disease and the initial Crs. The Crs did not change significantly over time within each quartile. Positive end-expiratory pressure (PEEP) and driving pressure were respectively lower and greater in patients with lower Crs. Prone positioning significantly improved PaO2/FiO2 in the 4 groups, however it increased the Crs significantly only in patients in lower quartile of Crs. CONCLUSIONS: In our cohort, the initial Crs is not dependent on the previous duration of COVID-19 disease. Prone positioning improves oxygenation irrespective to initial Crs, but it ameliorates respiratory mechanics only in patients with lower Crs.

Second stimulation in the same ovarian cycle: an option to fully-personalize the treatment in poor prognosis patients undergoing PGT-A.

PURPOSE: Our primary objective was to assess whether immediately undergoing a second stimulation in the same ovarian cycle (DuoStim) for advanced-maternal-age and/or poor-ovarian-reserve (AMA/POR) patients obtaining ≤ 3 blastocysts for preimplantation-genetic-testing-for-aneuploidies (PGT-A) is more efficient than the conventional-approach. METHODS: All AMA/POR patients obtaining ≤ 3 blastocysts after conventional-stimulation between 2017 and 2019 were proposed DuoStim, and 143 couples accepted (DuoStim-group) and were matched for the main confounders to 143 couples who did not accept (conventional-group). GnRH-antagonist protocol with recombinant-gonadotrophins and agonist trigger, intra-cytoplasmatic-sperm-injection (ICSI) with ejaculated sperm, PGT-A and vitrified-warmed euploid single-blastocyst-transfer(s) were performed. The primary outcome was the cumulative-live-birth-delivery-rate per intention-to-treat (CLBdR per ITT) within 1 year. If not delivering, the conventional-group had 1 year to undergo another conventional-stimulation. A cost-effectiveness analysis was also conducted. RESULTS: The CLBdR was 10.5% in the conventional-group after the first attempt. Only 12 of the 128 non-pregnant patients returned (165 ± 95 days later; drop-out = 116/128,90.6%), and 3 delivered. Thus, the 1-year CLBdR was 12.6% (N = 18/143). In the DuoStim-group, the CLBdR was 24.5% (N = 35/143; p = 0.01), 2 women delivered twice and 13 patients have other euploid blastocysts after a LB (0 and 2 in the conventional-group). DuoStim resulted in an incremental-cost-effectiveness-ratio of 23,303€. DuoStim was costlier and more effective in 98.7% of the 1000 pseudo-replicates generated through bootstrapping, and the cost-effectiveness acceptability curves unveiled that DuoStim would be more cost-effective than the conventional-approach at a willingness-to-pay threshold of 23,100€. CONCLUSIONS: During PGT-A treatments in AMA/POR women, DuoStim can be suggested in progress to rescue poor blastocyst yields after conventional-stimulation. It might indeed prevent drop-out or further aging between attempts.

Open versus arthroscopic ankle arthrodesis in high-risk patients: a comparative study.

PURPOSE: Arthroscopic ankle arthrodesis is known to offer high fusion rates, improvements in pain and functional outcomes, low risks of complications, and reinterventions. The aim of this study is to compare open vs. arthroscopic ankle arthrodesis in patients at high risk of complications. METHODS: A single-centre retrospective comparative analysis of ankle fusions was conducted. Patient records were screened for demographics, type of arthrodesis, follow-up length, pre-operative diagnosis, risk factors for non-union, operative time, radiographic union, time to union, complications, and reinterventions. The American Orthopedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot Scale, the Italian version of the Foot Function Index (FFI), and a visual analog scale (VAS) for pain scores collected pre-operatively and in the last follow-up were used to assess clinical outcomes. RESULTS: There were 23 open and 21 arthroscopic ankle fusions. Union rate was higher (90.5% vs. 65.2%, p < 0.05) and complication rate was lower (14.3% vs. 47.8%, p < 0.05) in the arthroscopic group. In addition, patients who underwent arthroscopic arthrodesis reported better pain control, with higher improvements in VAS for pain scores. There was no significant difference in length of operative time, time to fusion, AOFAS, and FFI scores improvements between the two groups. CONCLUSIONS: Arthroscopic ankle arthrodesis resulted in higher union rates, fewer complications, and lower reoperation rates in patients at high risk of complications.

Endoscopes used in positive and critically ill patients are SARS-CoV-2 negative at virological assessment.

The risk of SARS-CoV-2 transmission in endoscopy is not only between patients and endoscopy staff but is also through inadequately reprocessed endoscopes. There are no studies that could confirm the efficacy of current ways of endoscope reprocessing on the elimination of SARS-CoV-2. The aim of this pilot study was to evaluate the efficacy of high disinfection of endoscopes with peracetic acid on eliminating SARS-CoV-2, but surprisingly we found that the virus cannot be detected on any part of endoscopes used in critically ill patients due to SARS-CoV-2 and this was the same for all types of endoscopies and procedures. If confirmed in larger studies, these findings will probably open a new scenario in the overall understanding of the real impact of the virus.

Determination of copper by AAS in tear fluid of patients with keratoconus.

Keratoconus (KC) is the most common degenerative corneal disease and no single biomarker for KC has been discovered. Its causes have not yet been clarified and this work aims to be a contribution to the deepening of the knowledge of this disease and a preliminary data to the evaluation of the possibility of the use of copper (Cu) concentration in the tear fluid as a specific marker. A tear fluid sampling and Cu determination by spectrometric atomic absorption method was optimized to determine Cu levels in the tear fluid of patients with KC compared to that of healthy patients. Results demonstrate that in the KC subjects (n = 6) the concentration of Cu ions was 325.5 ± 110.7 ng/ml, while in the control group was 141.3 ± 71.1 ng/ml. A significant increase in Cu ion levels in the tear fluid was observed in the KC group compared to the control group (p value < 0.001).

Coagulopathy and COVID-19.

SARS-CoV-2 infection is associated with frequent thrombotic events, at the micro and macro-vascular level, due to the perpetuation of a state of hypercoagulability. The so-called 'COVID-19 associated coagulopathy' (CAC) represents a key aspect in the genesis of organ damage from SARS-CoV-2. The main coagulative alterations described in the literature are represented by high levels of D-dimer and fibrinogen. Although CAC has some common features with disseminated intravascular coagulation and sepsis-induced coagulopathy, there are important differences between these clinical pictures and the phenotype of CAC is unique. The pathogenesis of CAC is complex and is affected by the strong interconnection between the inflammatory system and coagulation, in the phenomenon of immunothrombosis and thrombo-inflammation. Several mechanisms come into play, such as inflammatory cytokines, neutrophils, the complement system as well as an alteration of the fibrinolytic system. Finally, an altered platelet function and especially endothelial dysfunction also play a central role in the pathophysiology of CAC. Heparin has several potential effects in CAC, in fact in addition to the anticoagulant effect, it could have a direct antiviral effect and anti-inflammatory properties. The high incidence of thrombo-embolic phenomena despite the use of antithrombotic prophylaxis have led some experts to recommend the use of anticoagulant doses of heparin, but at present the optimal anticoagulant regimen remains to be determined.

Does Iso-mechanical Power Lead to Iso-lung Damage?: An Experimental Study in a Porcine Model.

BACKGROUND: Excessive tidal volume, respiratory rate, and positive end-expiratory pressure (PEEP) are all potential causes of ventilator-induced lung injury, and all contribute to a single variable: the mechanical power. The authors aimed to determine whether high tidal volume or high respiratory rate or high PEEP at iso-mechanical power produce similar or different ventilator-induced lung injury. METHODS: Three ventilatory strategies-high tidal volume (twice baseline functional residual capacity), high respiratory rate (40 bpm), and high PEEP (25 cm H2O)-were each applied at two levels of mechanical power (15 and 30 J/min) for 48 h in six groups of seven healthy female piglets (weight: 24.2 ± 2.0 kg, mean ± SD). RESULTS: At iso-mechanical power, the high tidal volume groups immediately and sharply increased plateau, driving pressure, stress, and strain, which all further deteriorated with time. In high respiratory rate groups, they changed minimally at the beginning, but steadily increased during the 48 h. In contrast, after a sudden huge increase, they decreased with time in the high PEEP groups. End-experiment specific lung elastance was 6.5 ± 1.7 cm H2O in high tidal volume groups, 10.1 ± 3.9 cm H2O in high respiratory rate groups, and 4.5 ± 0.9 cm H2O in high PEEP groups. Functional residual capacity decreased and extravascular lung water increased similarly in these three categories. Lung weight, wet-to-dry ratio, and histologic scores were similar, regardless of ventilatory strategies and power levels. However, the alveolar edema score was higher in the low power groups. High PEEP had the greatest impact on hemodynamics, leading to increased need for fluids. Adverse events (early mortality and pneumothorax) also occurred more frequently in the high PEEP groups. CONCLUSIONS: Different ventilatory strategies, delivered at iso-power, led to similar anatomical lung injury. The different systemic consequences of high PEEP underline that ventilator-induced lung injury must be evaluated in the context of the whole body.

p140Cap Regulates GABAergic Synaptogenesis and Development of Hippocampal Inhibitory Circuits.

The neuronal scaffold protein p140Cap was investigated during hippocampal network formation. p140Cap is present in presynaptic GABAergic terminals and its genetic depletion results in a marked alteration of inhibitory synaptic activity. p140Cap-/- cultured neurons display higher frequency of miniature inhibitory postsynaptic currents (mIPSCs) with no changes of their mean amplitude. Consistent with a potential presynaptic alteration of basal GABA release, p140Cap-/- neurons exhibit a larger synaptic vesicle readily releasable pool, without any variation of single GABAA receptor unitary currents and number of postsynaptic channels. Furthermore, p140Cap-/- neurons show a premature and enhanced network synchronization and appear more susceptible to 4-aminopyridine-induced seizures in vitro and to kainate-induced seizures in vivo. The hippocampus of p140Cap-/- mice showed a significant increase in the number of both inhibitory synapses and of parvalbumin- and somatostatin-expressing interneurons. Specific deletion of p140Cap in forebrain interneurons resulted in increased susceptibility to in vitro epileptic events and increased inhibitory synaptogenesis, comparable to those observed in p140Cap-/- mice. Altogether, our data demonstrate that p140Cap finely tunes inhibitory synaptogenesis and GABAergic neurotransmission, thus regulating the establishment and maintenance of the proper hippocampal excitatory/inhibitory balance.

Inpatient Care during the COVID-19 Pandemic: A Survey of Italian Physicians.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is a potentially fatal disease that is of great global public health concern. OBJECTIVE: We explored the clinical management of inpatients with COVID-19 in Italy. METHODS: A self-administered survey was sent by email to Italian physicians caring for adult patients with COVID-19. A panel of experts was selected according to their clinical curricula and their responses were analyzed. RESULTS: A total of 1,215 physicians completed the survey questionnaire (17.4% response rate). Of these, 188 (15.5%) were COVID-19 experts. Chest computed tomography was the most used method to detect and monitor COVID-19 pneumonia. Most of the experts managed acute respiratory failure with CPAP (56.4%), high flow nasal cannula (18.6%), and non-invasive mechanical ventilation (8%), while an intensivist referral for early intubation was requested in 17% of the cases. Hydroxychloroquine was prescribed as an antiviral in 90% of cases, both as monotherapy (11.7%), and combined with protease inhibitors (43.6%) or azithromycin (36.2%). The experts unanimously prescribed low-molecular-weight heparin to patients with severe COVID-19 pneumonia, and half of them (51.6%) used a dose higher than standard. The respiratory burden in patients who survived the acute phase was estimated as relevant in 28.2% of the cases, modest in 39.4%, and negligible in 9%. CONCLUSIONS: In our survey some major topics, such as the role of non-invasive respiratory support and drug treatments, show disagreement between experts, likely reflecting the absence of high-quality evidence studies. Considering the significant respiratory sequelae reported following COVID-19, proper respiratory and physical therapy programs should be promptly made available.

Prone Positioning in Acute Respiratory Distress Syndrome.

Prone positioning is nowadays considered as one of the most effective strategies for patients with severe acute respiratory distress syndrome (ARDS). The evolution of the pathophysiological understanding surrounding the prone position closely follows the history of ARDS. At the beginning, the focus of the prone position was the improvement in oxygenation attributed to a perfusion redistribution. However, the mechanisms behind the prone position are more complex. Indeed, the positive effects on oxygenation and CO2 clearance of the prone position are to be ascribed to a more homogeneous inflation-ventilation, to the lung/thoracic shape mismatch, and to the change of chest wall elastance. In the past 20 years, five major trials have tried, starting from different theories, hypotheses, and designs, to demonstrate the effectiveness of the prone position, which finally found its definitive place among the different ARDS supportive therapies.