A tidal volume of 7 mL/kg PBW or higher may be safe for COVID-19 patients.

PURPOSE: The novel coronavirus disease (COVID-19) has revived the debate on the optimal tidal volume during acute respiratory distress syndrome (ARDS). Some experts recommend 6 mL/kg of predicted body weight (PBW) for all patients, while others suggest 7-9 mL/kg PBW for those with compliance >50 mL/cmH2O. We investigated whether a tidal volume ≥ 7 ml/kg PBW may be safe in COVID-19 patients, particularly those with compliance >50 mL/cmH2O. MATERIALS AND METHODS: This secondary analysis of a multicenter study compares the Intensive Care Unit (ICU) mortality among 600 patients ventilated with <7 or ≥ 7 mL/kg PBW. Compliance was categorized as <40, 40-50, or > 50 mL/cmH2O. RESULTS: 346 patients were ventilated with <7 (6.2 ± 0.5) mL/kg PBW and 254 with ≥7 (7.9 ± 0.9) mL/kg PBW. ICU mortality was 33 % and 29 % in the two groups (p = 0.272). At multivariable regression analysis, tidal volume ≥ 7 mL/kg PBW was associated with lower ICU mortality in the overall population (odds ratio: 0.62 [95 %-confidence interval: 0.40-0.95]) and in each compliance category. CONCLUSIONS: A tidal volume ≥ 7 (up to 9) mL/kg PBW was associated with lower ICU mortality in these COVID-19 patients, including those with compliance <40 mL/cmH2O. This finding should be interpreted cautiously due to the retrospective study design. TRIAL REGISTRATION: ClinicalTrails.govNCT04388670.

Impact of new lighting technology versus traditional fluorescent bulbs on sedation and delirium in the ICU.

BACKGROUND: Critically ill patients frequently encounter disruptions in their circadian rhythms in the intensive care unit (ICU) environment. New lighting systems have been developed to enhance daytime light levels and to promote circadian alignment. OBJECTIVES: To investigate the impact of implementing an innovative lighting technology that mimics natural light and reproduce the colour of the sky. DESIGN: Prospective, observational, non-randomized comparative trial. ICU patients were exposed to either a cutting-edge lighting system based on new technology (intervention group) or a conventional lighting system using fluorescent bulbs (control group). SETTING: An Italian intensive care unit with ten beds and five windowless rooms, thereby denying access to natural light. Three rooms had new lighting technology. MAIN OUTCOME MEASURES: The two groups were compared to assess the prevalence or absence of delirium and the need for sedatives during ICU stay. The secondary aim was to assess the presence of anxiety, depression, and post-traumatic stress disorder in patients at 3, 6, and 12 months after ICU discharge. RESULTS: 86 patients were included: 52 (60 %) in the intervention group and 34 (40 %) in the control group. Seventy-nine patients (82 %) were alive at ICU discharge. Fourteen patients (16 %) developed delirium (intervention group: n = 8 [15 %] vs. control group: n = 6 [18 %] in the control group, (P=0.781). The use of sedative drugs and neuromuscular blocking agents was similar in both the groups. No differences in the incidence of anxiety, depression, or post-traumatic stress disorders were observed among patients who underwent follow-up visits. CONCLUSIONS: Compared to traditional fluorescent tube lighting, the innovative lighting system did not provide any significant benefit in reducing the frequency of delirium or the necessity for sedative medications. IMPLICATIONS FOR CLINICAL PRACTICE: A single intervention, the use of lights that mimic sunny light and the sky, did not result in a statistically significant reduction in the incidence of delirium. Delirium has a multifactorial aetiology, necessitating interventions that are multifaceted and address different domains.

Mechanical ventilation settings during weaning from venovenous extracorporeal membrane oxygenation.

BACKGROUND: The optimal timing of weaning from venovenous extracorporeal membrane oxygenation (VV ECMO) and its modalities have been rarely studied. METHODS: Retrospective, multicenter cohort study over 7 years in two tertiary ICUs, high-volume ECMO centers in France and Italy. Patients with ARDS on ECMO and successfully weaned from VV ECMO were classified based on their mechanical ventilation modality during the sweep gas-off trial (SGOT) with either controlled mechanical ventilation or spontaneous breathing (i.e. pressure support ventilation). The primary endpoint was the time to successful weaning from mechanical ventilation within 90 days post-ECMO weaning. RESULTS: 292 adult patients with severe ARDS were weaned from controlled ventilation, and 101 were on spontaneous breathing during SGOT. The 90-day probability of successful weaning from mechanical ventilation was not significantly different between the two groups (sHR [95% CI], 1.23 [0.84-1.82]). ECMO-related complications were not statistically different between patients receiving these two mechanical ventilation strategies. After adjusting for covariates, older age, higher pre-ECMO sequential organ failure assessment score, pneumothorax, ventilator-associated pneumonia, and renal replacement therapy, but not mechanical ventilation modalities during SGOT, were independently associated with a lower probability of successful weaning from mechanical ventilation after ECMO weaning. CONCLUSIONS: Time to successful weaning from mechanical ventilation within 90 days post-ECMO was not associated with the mechanical ventilation strategy used during SGOT. Further research is needed to assess the optimal ventilation strategy during weaning off VV ECMO and its impact on short- and long-term outcomes.

Retrospective ANalysis of multi-drug resistant Gram-nEgative bacteRia on veno-venous extracorporeal membrane oxygenation. The multicenter RANGER STUDY.

BACKGROUND: Veno-venous extracorporeal membrane oxygenation (V-V ECMO) is a rapidly expanding life-support technique worldwide. The most common indications are severe hypoxemia and/or hypercapnia, unresponsive to conventional treatments, primarily in cases of acute respiratory distress syndrome. Concerning potential contraindications, there is no mention of microbiological history, especially related to multi-drug resistant (MDR) bacteria isolated before V-V ECMO placement. Our study aims to investigate: (i) the prevalence and incidence of MDR Gram-negative (GN) bacteria in a cohort of V-V ECMOs; (ii) the risk of 1-year mortality, especially in the case of predetected MDR GN bacteria; and (iii) the impact of annual hospital V-V ECMO volume on the probability of acquiring MDR GN bacteria. METHODS: All consecutive adults admitted to the Intensive Care Units of 5 Italian university-affiliated hospitals and requiring V-V ECMO were screened. Exclusion criteria were age < 18 years, pregnancy, veno-arterial or mixed ECMO-configuration, incomplete records, survival < 24 h after V-V ECMO. A standard protocol of microbiological surveillance was applied and MDR profiles were identified using in vitro susceptibility tests. Cox-proportional hazards models were applied for investigating mortality. RESULTS: Two hundred and seventy-nine V-V ECMO patients (72% male) were enrolled. The overall MDR GN bacteria percentage was 50%: 21% (n.59) detected before and 29% (n.80) after V-V ECMO placement. The overall 1-year mortality was 42%, with a higher risk observed in predetected patients (aHR 2.14 [1.33-3.47], p value 0.002), while not in 'V-V ECMO-acquired MDR GN bacteria' group (aHR 1.51 [0.94-2.42], p value 0.090), as compared to 'non-MDR GN bacteria' group (reference). Same findings were found considering only infections. A larger annual hospital V-V ECMO volume was associated with a lower probability of acquiring MDR GN bacteria during V-V ECMO course (aOR 0.91 [0.86-0.97], p value 0.002). CONCLUSIONS: 21% of MDR GN bacteria were detected before; while 29% after V-V ECMO connection. A history of MDR GN bacteria, isolated before V-V ECMO, was an independent risk factor for mortality. The annual hospital V-V ECMO volume affected the probability of acquiring MDR GN bacteria. Trial Registration ClinicalTrial.gov Registration Number NCTNCT06199141, date 12.26.2023.

Phenotyping COVID-19 respiratory failure in spontaneously breathing patients with AI on lung CT-scan.

BACKGROUND: Automated analysis of lung computed tomography (CT) scans may help characterize subphenotypes of acute respiratory illness. We integrated lung CT features measured via deep learning with clinical and laboratory data in spontaneously breathing subjects to enhance the identification of COVID-19 subphenotypes. METHODS: This is a multicenter observational cohort study in spontaneously breathing patients with COVID-19 respiratory failure exposed to early lung CT within 7 days of admission. We explored lung CT images using deep learning approaches to quantitative and qualitative analyses; latent class analysis (LCA) by using clinical, laboratory and lung CT variables; regional differences between subphenotypes following 3D spatial trajectories. RESULTS: Complete datasets were available in 559 patients. LCA identified two subphenotypes (subphenotype 1 and 2). As compared with subphenotype 2 (n = 403), subphenotype 1 patients (n = 156) were older, had higher inflammatory biomarkers, and were more hypoxemic. Lungs in subphenotype 1 had a higher density gravitational gradient with a greater proportion of consolidated lungs as compared with subphenotype 2. In contrast, subphenotype 2 had a higher density submantellar-hilar gradient with a greater proportion of ground glass opacities as compared with subphenotype 1. Subphenotype 1 showed higher prevalence of comorbidities associated with endothelial dysfunction and higher 90-day mortality than subphenotype 2, even after adjustment for clinically meaningful variables. CONCLUSIONS: Integrating lung-CT data in a LCA allowed us to identify two subphenotypes of COVID-19, with different clinical trajectories. These exploratory findings suggest a role of automated imaging characterization guided by machine learning in subphenotyping patients with respiratory failure. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04395482. Registration date: 19/05/2020.

Pressure Support Ventilation During Extracorporeal Membrane Oxygenation Support in Patients With Acute Respiratory Distress Syndrome.

In the initial phases of veno-venous extracorporeal membrane oxygenation (VV ECMO) support for severe acute respiratory distress syndrome (ARDS), ultraprotective controlled mechanical ventilation (CMV) is typically employed to limit the progression of lung injury. As patients recover, transitioning to assisted mechanical ventilation can be considered to reduce the need for prolonged sedation and paralysis. This study aimed to evaluate the feasibility of transitioning to pressure support ventilation (PSV) during VV ECMO and to explore variations in respiratory mechanics and oxygenation parameters following the transition to PSV. This retrospective monocentric study included 191 adult ARDS patients treated with VV ECMO between 2009 and 2022. Within this population, 131 (69%) patients were successfully switched to PSV during ECMO. Pressure support ventilation was associated with an increase in respiratory system compliance (p = 0.02) and a reduction in pulmonary shunt fraction (p < 0.001). Additionally, improvements in the cardiovascular Sequential Organ Failure Assessment score and a reduction in pulmonary arterial pressures (p < 0.05) were recorded. Ninety-four percent of patients who successfully transitioned to PSV were weaned from ECMO, and 118 (90%) were discharged alive from the intensive care unit (ICU). Of those who did not reach PSV, 74% died on ECMO, whereas the remaining patients were successfully weaned from extracorporeal support. In conclusion, PSV is feasible during VV ECMO and potentially correlates with improvements in respiratory function and hemodynamics.

Impact of a 'Catheter Bundle' on Infection Rates and Economic Costs in the Intensive Care Unit: A Retrospective Cohort Study.

INTRODUCTION: Catheter-related infections (CBRSIs) are a widespread problem that increase morbidity and mortality in intensive care unit (ICU) patients and management costs. OBJECTIVE: The main aim of this study was to assess the prevalence of CBRSIs in an intensive care unit following international literature guidelines for managing vascular lines in critically ill patients. These guidelines include changing vascular lines every 7 days, using needle-free devices and port protectors, standardising closed infusion lines, employing chlorhexidine-impregnated dressings, and utilising sutureless devices for catheter securement. MATERIALS AND METHODS: This single-centre retrospective observational study was conducted in a general Italian ICU. This study included all eligible patients aged > 1 year who were admitted between January 2018 and December 2022. RESULTS: During the study period, 1240 patients were enrolled, of whom 9 were diagnosed with a CRBSI. The infection rate per 1000 catheters/day was as follows: femorally inserted central catheter, 1.04; centrally inserted central catheter, 0.77; pulmonary arterial catheter 0.71, arterial catheter, 0.1; and peripherally inserted central catheter and continuous veno-venous haemodialysis dialysis catheters equal to 0. No difference in CRBSI was observed between the years included in the study (p = 0.874). The multivariate analysis showed an association between the diagnosis of CBRSI and Nursing Activities Score (per single point increase ß = 0.04-95%CI: -0.01-0.09, p = 0.048), reason for ICU admission-trauma (ß = 0.77-95%CI: -0.03-1.49, p = 0.039), and use of therapeutic hypothermia (ß = 2.06, 95%CI: 0.51-3.20, p < 0.001). Implementing the study protocol revealed a cost of EUR 130.00/patient, equivalent to a daily cost of EUR 15.20 per patient. CONCLUSIONS: This study highlights the importance of implementing a catheter care bundle to minimise the risk of CRBSI and the associated costs in the ICU setting. A policy change for infusion set replacement every 7 days has helped to maintain the CRBSI rate below the recommended rate, resulting in significant cost reduction and reduced production of ICU waste.

Derivation and external validation of predictive models for invasive mechanical ventilation in intensive care unit patients with COVID-19.

BACKGROUND: This study aimed to develop prognostic models for predicting the need for invasive mechanical ventilation (IMV) in intensive care unit (ICU) patients with COVID-19 and compare their performance with the Respiratory rate-OXygenation (ROX) index. METHODS: A retrospective cohort study was conducted using data collected between March 2020 and August 2021 at three hospitals in Rio de Janeiro, Brazil. ICU patients aged 18 years and older with a diagnosis of COVID-19 were screened. The exclusion criteria were patients who received IMV within the first 24 h of ICU admission, pregnancy, clinical decision for minimal end-of-life care and missing primary outcome data. Clinical and laboratory variables were collected. Multiple logistic regression analysis was performed to select predictor variables. Models were based on the lowest Akaike Information Criteria (AIC) and lowest AIC with significant p values. Assessment of predictive performance was done for discrimination and calibration. Areas under the curves (AUC)s were compared using DeLong's algorithm. Models were validated externally using an international database. RESULTS: Of 656 patients screened, 346 patients were included; 155 required IMV (44.8%), 191 did not (55.2%), and 207 patients were male (59.8%). According to the lowest AIC, arterial hypertension, diabetes mellitus, obesity, Sequential Organ Failure Assessment (SOFA) score, heart rate, respiratory rate, peripheral oxygen saturation (SpO2), temperature, respiratory effort signals, and leukocytes were identified as predictors of IMV at hospital admission. According to AIC with significant p values, SOFA score, SpO2, and respiratory effort signals were the best predictors of IMV; odds ratios (95% confidence interval): 1.46 (1.07-2.05), 0.81 (0.72-0.90), 9.13 (3.29-28.67), respectively. The ROX index at admission was lower in the IMV group than in the non-IMV group (7.3 [5.2-9.8] versus 9.6 [6.8-12.9], p < 0.001, respectively). In the external validation population, the area under the curve (AUC) of the ROX index was 0.683 (accuracy 63%), the AIC model showed an AUC of 0.703 (accuracy 69%), and the lowest AIC model with significant p values had an AUC of 0.725 (accuracy 79%). CONCLUSIONS: In the development population of ICU patients with COVID-19, SOFA score, SpO2, and respiratory effort signals predicted the need for IMV better than the ROX index. In the external validation population, although the AUCs did not differ significantly, the accuracy was higher when using SOFA score, SpO2, and respiratory effort signals compared to the ROX index. This suggests that these variables may be more useful in predicting the need for IMV in ICU patients with COVID-19. GOV IDENTIFIER: NCT05663528.

Signs of Hemolysis Predict Mortality and Ventilator Associated Pneumonia in Severe Acute Respiratory Distress Syndrome Patients Undergoing Veno-Venous Extracorporeal Membrane Oxygenation.

Cell-free hemoglobin (CFH) is used to detect hemolysis and was recently suggested to trigger acute lung injury. However, its role has not been elucidated in severe acute respiratory distress syndrome (ARDS) patients undergoing extracorporeal membrane oxygenation (ECMO). We investigated the association of carboxyhemoglobin (COHb) and haptoglobin-two indirect markers of hemolysis-with mortality in critically ill patients undergoing veno-venous ECMO (VV-ECMO) with adjusted and longitudinal models (primary aim). Secondary aims included assessment of association between COHb and haptoglobin with the development of ventilator-associated pneumonia (VAP) and with hemodynamics. We retrospectively collected physiological, laboratory biomarkers, and outcome data in 147 patients undergoing VV-ECMO for severe ARDS. Forty-seven patients (32%) died in the intensive care unit (ICU). Average levels of COHb and haptoglobin were higher and lower, respectively, in patients who died. Higher haptoglobin was associated with lower pulmonary (PVR) and systemic vascular resistance, whereas higher COHb was associated with higher PVR. Carboxyhemoglobin was an independent predictor of VAP. Both haptoglobin and COHb independently predicted ICU mortality. In summary, indirect signs of hemolysis including COHb and haptoglobin are associated with modulation of vascular tone, VAP, and ICU mortality in respiratory ECMO. These findings suggest that CFH may be a mechanism of injury in this patient population.

Perfusion deficits may underlie lung and kidney injury in severe COVID-19 disease: insights from a multicenter international cohort study.

BACKGROUND: Lung perfusion defects, mainly due to endothelial and coagulation activation, are a key contributor to COVID-19 respiratory failure. COVID-19 patients may also develop acute kidney injury (AKI) because of renal perfusion deficit. We aimed to explore AKI-associated factors and the independent prediction of standardized minute ventilation (MV)-a proxy of alveolar dead space-on AKI onset and persistence in COVID-19 mechanically ventilated patients. METHODS: This is a multicenter observational cohort study. We enrolled 157 COVID-19 patients requiring mechanical ventilation and intensive care unit (ICU) admission. We collected clinical information, ventilation, and laboratory data. AKI was defined by the 2012 KDIGO guidelines and classified as transient or persistent according to serum creatinine criteria persistence within 48 h. Ordered univariate and multivariate logistic regression analyses were employed to identify variables associated with AKI onset and persistence. RESULTS: Among 157 COVID-19 patients on mechanical ventilation, 47% developed AKI: 10% had transient AKI, and 37% had persistent AKI. The degree of hypoxia was not associated with differences in AKI severity. Across increasing severity of AKI groups, despite similar levels of paCO2, we observed an increased MV and standardized MV, a robust proxy of alveolar dead space. After adjusting for other clinical and laboratory covariates, standardized MV remained an independent predictor of AKI development and persistence. D-dimer levels were higher in patients with persistent AKI. CONCLUSIONS: In critically ill COVID-19 patients with respiratory failure, increased wasted ventilation is independently associated with a greater risk of persistent AKI. These hypothesis-generating findings may suggest that perfusion derangements may link the pathophysiology of both wasted ventilation and acute kidney injury in our population.

Prone-position decreases airway closure in a patient with ARDS undergoing venovenous extracorporeal membrane oxygenation.

PURPOSE: Airway closure is a interruption of communication between larger and smaller airways. The presence of airway closure during mechanical ventilation may lead to the overestimation of driving pressure (DP), introducing errors in the assessment of respiratory mechanics and in positive end-expiratory pressure (PEEP) setting on the ventilator. Patients with severe acute respiratory distress syndrome (ARDS) may exhibit the airway closure phenomenon, which can be easily diagnosed with a low-flow inflation. Prone positioning is a therapeutic manoeuver proven to reduce mortality in ARDS patients, and has been widely implemented also in patients requiring veno-venous extracorporeal membrane oxygenation (V-V ECMO). To date, the impact of prone positioning on changes in airway closure has not been described. METHODS: We present an image analysis of the pressure waveform during volume-controlled ventilation and low-flow inflations before and after prone positioning in an ARDS patient on VV ECMO. RESULTS: A high airway opening pressure level (23 cmH2O) was detected in the supine position during tidal ventilation. Airway closure was confirmed by using a low-flow inflation. Prone positioning significantly attenuated airway closure, with the airway opening pressure decreasing to 13 cmH2O. After re-supination, airway closure was lower as compared with supine position at baseline (17 cmH2O). CONCLUSION: Prone positioning reduced airway closure in an ARDS patient on VV ECMO support.

Modelling lung diffusion-perfusion limitation in mechanically ventilated SARS-CoV-2 patients.

This is the first study to describe the daytime evolution of respiratory parameters in mechanically ventilated COVID-19 patients. The data base refers to patients hospitalised in the intensive care unit (ICU) at Arequipa Hospital (Peru, 2335 m) in 2021. In both survivors (S) and non-survivors (NS) patients, a remarkable decrease in respiratory compliance was observed, revealing a proportional decrease in inflatable alveolar units. The S and NS patients were all hyperventilated and their SatO2 was maintained at >90%. However, while S remained normocapnic, NS developed progressive hypercapnia. We compared the efficiency of O2 uptake and CO2 removal in the air blood barrier relying on a model allowing to partition between diffusion and perfusion limitations to gas exchange. The decrease in O2 uptake was interpreted as diffusion limitation, while the impairment in CO2 removal was modelled by progressive perfusion limitation. The latter correlated with the increase in positive end-expiratory pressure (PEEP) and plateau pressure (Pplat), leading to capillary compression, increased blood velocity, and considerable shortening of the air-blood contact time.

Feasibility of Delivering a 5-Day Normobaric Hypoxia Breathing in Healthy Volunteers in a Hospital Setting.

BACKGROUND: Beneficial effects of breathing at FIO2 < 0.21 on disease outcomes have been reported in previous preclinical and clinical studies. However, the safety and intra-hospital feasibility of breathing hypoxic gas for 5 d have not been established. In this study, we examined the physiologic effects of breathing a gas mixture with FIO2 as low as 0.11 in 5 healthy volunteers. METHODS: All 5 subjects completed the study, spending 5 consecutive days in a hypoxic tent, where the ambient oxygen level was lowered in a stepwise manner over 5 d, from FIO2 of 0.16 on the first day to FIO2 of 0.11 on the fifth day of the study. All the subjects returned to an environment at room air on the sixth day. The subjects' SpO2 , heart rate, and breathing frequency were continuously recorded, along with daily blood sampling, neurologic evaluations, transthoracic echocardiography, and mental status assessments. RESULTS: Breathing hypoxia concentration dependently caused profound physiologic changes, including decreased SpO2 and increased heart rate. At FIO2 of 0.14, the mean SpO2 was 92%; at FIO2 of 0.13, the mean SpO2 was 93%; at FIO2 of 0.12, the mean SpO2 was 88%; at FIO2 of 0.11, the mean SpO2 was 85%; and, finally, at an FIO2 of 0.21, the mean SpO2 was 98%. These changes were accompanied by increased erythropoietin levels and reticulocyte counts in blood. All 5 subjects concluded the study with no adverse events. No subjects exhibited signs of mental status changes or pulmonary hypertension. CONCLUSIONS: Results of the current physiologic study suggests that, within a hospital setting, delivering FIO2 as low as 0.11 is feasible and safe in healthy subjects, and provides the foundation for future studies in which therapeutic effects of hypoxia breathing are tested.

Dynamic inflation prevents and standardized lung recruitment reverts volume loss associated with percutaneous tracheostomy during volume control ventilation: results from a Neuro-ICU population.

To determine how percutaneous tracheostomy (PT) impacts on respiratory system compliance (Crs) and end-expiratory lung volume (EELV) during volume control ventilation and to test whether a recruitment maneuver (RM) at the end of PT may reverse lung derecruitment. This is a single center, prospective, applied physiology study. 25 patients with acute brain injury who underwent PT were studied. Patients were ventilated in volume control ventilation. Electrical impedance tomography (EIT) monitoring and respiratory mechanics measurements were performed in three steps: (a) baseline, (b) after PT, and (c) after a standardized RM (10 sighs of 30 cmH2O lasting 3 s each within 1 min). End-expiratory lung impedance (EELI) was used as a surrogate of EELV. PT determined a significant EELI loss (mean reduction of 432 arbitrary units p = 0.049) leading to a reduction in Crs (55 ± 13 vs. 62 ± 13 mL/cmH2O; p < 0.001) as compared to baseline. RM was able to revert EELI loss and restore Crs (68 ± 15 vs. 55 ± 13 mL/cmH2O; p < 0.001). In a subgroup of patients (N = 8, 31%), we observed a gradual but progressive increase in EELI. In this subgroup, patients did not experience a decrease of Crs after PT as compared to patients without dynamic inflation. Dynamic inflation did not cause hemodynamic impairment nor raising of intracranial pressure. We propose a novel and explorative hyperinflation risk index (HRI) formula. Volume control ventilation did not prevent the PT-induced lung derecruitment. RM could restore the baseline lung volume and mechanics. Dynamic inflation is common during PT, it can be monitored real-time by EIT and anticipated by HRI. The presence of dynamic inflation during PT may prevent lung derecruitment.

Algor-ethics: charting the ethical path for AI in critical care.

The integration of Clinical Decision Support Systems (CDSS) based on artificial intelligence (AI) in healthcare is groundbreaking evolution with enormous potential, but its development and ethical implementation, presents unique challenges, particularly in critical care, where physicians often deal with life-threating conditions requiring rapid actions and patients unable to participate in the decisional process. Moreover, development of AI-based CDSS is complex and should address different sources of bias, including data acquisition, health disparities, domain shifts during clinical use, and cognitive biases in decision-making. In this scenario algor-ethics is mandatory and emphasizes the integration of 'Human-in-the-Loop' and 'Algorithmic Stewardship' principles, and the benefits of advanced data engineering. The establishment of Clinical AI Departments (CAID) is necessary to lead AI innovation in healthcare, ensuring ethical integrity and human-centered development in this rapidly evolving field.

The "ZEEP-PEEP test" to evaluate the response to positive end-expiratory pressure delivered by helmet: A prospective physiologic study.

Introduction: The improvement in oxygenation after helmet application in hypoxemic patients may be explained by the alveolar recruitment obtained with positive end expiratory pressure (PEEP) or by the administration of a more accurate inspiratory fraction of oxygen (FiO2). We have designed the "ZEEP-PEEP test", capable to distinguish between the FiO2-related or PEEP-related oxygenation improvement. Our primary aim was to describe the use of this test during helmet CPAP to assess the oxygenation improvement attributable to PEEP application. Material and methods: We performed a prospective physiological study including adult critically ill patients. Respiratory and hemodynamic parameters were recorded before helmet application (PRE step), after helmet application without PEEP (ZEEP step) and after the application of the PEEP valve (PEEP step), while maintaining a constant FiO2. We defined as "PEEP responders" patients showing a PaO2/FiO2 ratio improvement ≥10% after PEEP application. Results: 93 patients were enrolled. Compared to the PRE step, PaO2/FiO2 ratio was significantly improved during helmet CPAP both at ZEEP and PEEP step (189 ± 55, 219 ± 74 and 241 ± 82 mmHg, respectively, p < 0.01). Both PEEP responders (41%) and non-responders showed a significant improvement of PaO2/FiO2 ratio after the application of helmet at ZEEP, PEEP responders also showed a significant improvement of oxygenation after PEEP application (208 ± 70 vs 267 ± 85, p < 0.01). Conclusions: Helmet CPAP improved oxygenation. This improvement was not only due to the PEEP effect, but also to the increase of the effective inspired FiO2. Performing the ZEEP-PEEP test may help to identify patients who benefit from PEEP.

Pulmonary shunt in critical care: a practical approach with clinical scenarios.

BACKGROUND: Pulmonary shunt refers to the passage of venous blood into the arterial blood system bypassing the alveoli-blood gas exchange. Pulmonary shunt is defined by a drop in the physiologic coupling of lung ventilation and lung perfusion. This may consequently lead to respiratory failure. MAIN BODY: The pulmonary shunt assessment is often neglected. From a mathematical point of view, pulmonary shunt can be assessed by estimating the degree of mixing between oxygenated and deoxygenated blood. To compute the shunt, three key components are analyzed: the oxygen (O2) content in the central venous blood before gas exchange, the calculated O2 content in the pulmonary capillaries after gas exchange, and the O2 content in the arterial system, after the mixing of shunted and non-shunted blood. Computing the pulmonary shunt becomes of further importance in patients on extracorporeal membrane oxygenation (ECMO), as arterial oxygen levels may not directly reflect the gas exchange of the native lung. CONCLUSION: In this review, the shunt analysis and its practical clinical applications in different scenarios are discussed by using an online shunt simulator.

Role of hemolysis on pulmonary arterial compliance and right ventricular systolic function after cardiopulmonary bypass.

BACKGROUND: Cardiopulmonary bypass (CPB) is associated with intravascular hemolysis which depletes endogenous nitric oxide (NO). The impact of hemolysis on pulmonary arterial compliance (PAC) and right ventricular systolic function has not been explored yet. We hypothesized that decreased NO availability is associated with worse PAC and right ventricular systolic function after CPB. METHODS: This is a secondary analysis of an observational cohort study in patients undergoing cardiac surgery with CPB at Massachusetts General Hospital, USA (2014-2015). We assessed PAC (stroke volume/pulmonary artery pulse pressure ratio), and right ventricular function index (RVFI) (systolic pulmonary arterial pressure/cardiac output), as well as NO consumption at 15 min, 4 h and 12 h after CPB. Patients were stratified by CPB duration. Further, we assessed the association between changes in NO consumption with PAC and RVFI between 15min and 4 h after CPB. RESULTS: PAC was lowest at 15min after CPB and improved over time (n = 50). RVFI was highest -worse right ventricular function- at CPB end and gradually decreased. Changes in hemolysis, PAC and RVFI differed over time by CPB duration. PAC inversely correlated with total pulmonary resistance (TPR). TPR and PAC positively and negatively correlated with RVFI, respectively. NO consumption between 15min and 4 h after CPB correlated with changes in PAC (-0.28 ml/mmHg, 95%CI -0.49 to -0.01, p = 0.012) and RVFI (0.14 mmHg*L-1*min, 95%CI 0.10 to 0.18, p < 0.001) after multivariable adjustments. CONCLUSION: PAC and RVFI are worse at CPB end and improve over time. Depletion of endogenous NO may contribute to explain changes in PAC and RVFI after CPB.