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Ischemia with non-obstructive coronary arteries (INOCA) is an increasingly recognized entity. It encompasses different pathophysiological subtypes (i.e., endotypes), including coronary microvascular dysfunction (CMD), vasospastic angina (VSA) and mixed entities resulting from the variable combination of both. Diagnosing INOCA and precisely characterizing the endotype allows for accurate medical treatment and has proven prognostic implications. A breadth of diagnostic technique is available, ranging from non-invasive approaches to invasive coronary angiography adjuvated by functional assessment and provocative tests. This review summarizes the strength and limitations of these methodologies and provides the rationale for the routine referral for invasive angiography and functional assessment in this subset of patients.
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OBJECTIVE: Acute kidney injury (AKI) may complicate transcatheter aortic valve replacement (TAVR) and could be linked to atheroembolization associated with catheter manipulation in the supra-renal (SR) aorta. We sought to determine the impact of SR aortic atheroma burden (SR-AAB) and composition, as well as of the aortic valve calcium score (AV-CS), measured at pre-operative multislice computed tomography (PO-MSCT), on AKI-TAVR. METHODS: All TAVR-patients 3 January-2018 to December-2020 were included. A three-dimensional analysis of PO-MSCT was performed, calculating percentage SR-AAB (%SR-AAB) as [(absolute SR-AAB volume)*100/vessel volume]. Types of plaque were defined according to Hounsfield unit (HU) intensity ranges. Calcified plaque was subcategorized into 3 strata: low- (351-700 HU), mid- (701-1000 HU), and highcalcium (>1000 HU, termed 1 K-plaque). RESULTS: The study population included 222 patients [mean age 83.3 ± 5.7 years, 95 (42.8%) males], AKI-TAVR occurred in 67/222 (30.2%). Absolute SR-AAB (41.3 ± 16.4 cm3 vs. 32.5 ± 10.7 cm3,p < 0.001) and %SR-AAB (17.6 ± 5.1% vs. 13.9 ± 4.3%,p < 0.001) were significantly higher in patients developing AKI-TAVR. Patients who developed AKI-TAVR had higher midcalcium (6.9 ± 3.8% vs. 4.2 ± 3.5%,p < 0.001) and 1 K-plaque (5.4 ± 3.7% vs. 2.4 ± 2.4%,p < 0.001) with no difference in AV-CS (p = 0.691). Adjusted multivariable logistic regression analysis showed that %SR-AAB [OR (x%increase): 1.12, 95%CI: 1.04-1.22,p = 0.006] and %SR-calcified plaque [OR (x%increase): 5.60, 95%CI: 2.50-13.36,p < 0.001] were associated with AKI-TAVR. Finally, 3-knots spline analyses identified %SR-AAB >15.0% and %SR-calcified plaque >7.0% as optimal thresholds to predict an increased risk of AKI-TAVR. CONCLUSIONS: Suprarenal aortic atheroma, when highly calcified, is associated with AKI-TAVR. Perioperative-MSCT assessment of aortic atherosclerosis may help in identification of patients at high-risk for AKI-TAVR, who could benefit from higher peri-operative surveillance.
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Injúria Renal Aguda , Estenose da Valva Aórtica , Placa Aterosclerótica , Substituição da Valva Aórtica Transcateter , Masculino , Humanos , Idoso , Idoso de 80 Anos ou mais , Feminino , Substituição da Valva Aórtica Transcateter/efeitos adversos , Substituição da Valva Aórtica Transcateter/métodos , Placa Aterosclerótica/complicações , Cálcio , Estenose da Valva Aórtica/diagnóstico por imagem , Estenose da Valva Aórtica/cirurgia , Estenose da Valva Aórtica/complicações , Fatores de Risco , Resultado do Tratamento , Estudos Retrospectivos , Injúria Renal Aguda/diagnóstico , Injúria Renal Aguda/epidemiologia , Injúria Renal Aguda/etiologia , Valva Aórtica/cirurgia , Tomografia Computadorizada Multidetectores , Aorta/cirurgiaRESUMO
PURPOSE: The Italian Registry of Contrast Material use in Cardiac Computed Tomography (iRCM-CCT) is a multicenter, multivendor, observational study on the use of contrast media (CM) in patients undergoing cardiac computed tomography (CCT). The aim of iRCM-CCT is to assess image quality and safety profile of intravenous CM compounds. MATERIALS AND METHODS: iRCM-CCT enrolled 1842 consecutive patients undergoing CCT (≥50 per site) at 20 cluster sites with the indication of suspected coronary artery disease. Demographic characteristics, CCT, and CM protocols, clinical indications, safety markers, radiation dose reports, qualitative (ie, poor vascular enhancement) and quantitative (ie, HU attenuation values) image parameters were recorded. A centralized coordinating center collected and assessed all image parameters. RESULTS: The cohort included 891 men and 951 women (age: 63±14 y, body mass index: 26±4 kg/m2) studied with ≥64 detector rows computed tomography scanners and different iodinated intravenous CM protocols and compounds (iodixanol, iopamidol, iohexol, iobitridol, iopromide, and iomeprol). The following vascular attenuation was reported: 504±147 HU in the aorta, 451±146 HU in the right coronary artery, 474±146 HU in the left main, 451±146 HU in the left anterior descending artery, and 441±149 HU in the circumflex artery. In 4% of cases the image quality was not satisfactory due to poor enhancement. The following adverse reactions to CM were recorded: 6 (0.3%) extravasations and 17 (0.9%) reactions (11 mild, 4 moderate, 2 severe). CONCLUSIONS: In a multicenter registry on CM use during CCT the prevalence of CM-related adverse reactions was very low. The appropriate use of CM is a major determinant of image quality.
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Meios de Contraste , Doença da Artéria Coronariana , Masculino , Humanos , Feminino , Pessoa de Meia-Idade , Idoso , Tomografia Computadorizada por Raios X/métodos , Angiografia Coronária/métodos , Sistema de RegistrosRESUMO
BACKGROUND: The prospective, multicentre EURECA registry assessed the use of imaging and adoption of the European Society of Cardiology (ESC) Guidelines (GL) in patients with chronic coronary syndromes (CCS). METHODS: Between May 2019 and March 2020, 5156 patients were recruited in 73 centres from 24 ESC member countries. The adoption of GL recommendations was evaluated according to clinical presentation and pre-test probability (PTP) of obstructive coronary artery disease (CAD). RESULTS: The mean age of the population was 64 ± 11 years, 60% of patients were males, 42% had PTP >15%, 27% had previous CAD, and ejection fraction was <50% in 5%. Exercise ECG was performed in 32% of patients, stress imaging as the first choice in 40%, and computed tomography coronary angiography (CTCA) in 22%. Invasive coronary angiography (ICA) was the first or downstream test in 17% and 11%, respectively. Obstructive CAD was documented in 24% of patients, inducible ischaemia in 19%, and 13% of patients underwent revascularization. In 44% of patients, the overall diagnostic process did not adopt the GL. In these patients, referral to stress imaging (21% vs. 58%; P < 0.001) or CTCA (17% vs. 30%; P < 0.001) was less frequent, while exercise ECG (43% vs. 22%; P < 0.001) and ICA (48% vs. 15%; P < 0.001) were more frequently performed. The adoption of GL was associated with fewer ICA, higher proportion of diagnosis of obstructive CAD (60% vs. 39%, P < 0.001) and revascularization (54% vs. 37%, P < 0.001), higher quality of life, fewer additional testing, and longer times to late revascularization. CONCLUSIONS: In patients with CCS, current clinical practice does not adopt GL recommendations on the use of diagnostic tests in a significant proportion of patients. When the diagnostic approach adopts GL recommendations, invasive procedures are less frequently used and the diagnostic yield and therapeutic utility are superior.
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Doença da Artéria Coronariana , Qualidade de Vida , Masculino , Humanos , Pessoa de Meia-Idade , Idoso , Feminino , Angiografia Coronária/métodos , Estudos Prospectivos , Doença da Artéria Coronariana/diagnóstico por imagem , Doença da Artéria Coronariana/terapia , Tomografia Computadorizada por Raios X/métodos , Angiografia por Tomografia Computadorizada , Valor Preditivo dos TestesRESUMO
Despite updated guidelines and technological developments that allow for an accurate diagnosis, many asymptomatic individuals have a high risk of developing CAD or cardiac events. The CAC score can estimate a correct risk level for these subjects, which is clinically significant for adequate management of risk factors and obtaining personalized preventive therapy. This systematic review aims to assess the prognostic value of CAC score in asymptomatic individuals. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, a systematic literature search was performed to identify original articles since 2010 that evaluated the prognostic value of CAC score in asymptomatic individuals. The quality of the included studies was assessed by the QUIPS tool. A total of 45 articles were selected. Many of these (25 studies) evaluated the prognostic value of CAC score in asymptomatic subjects. In comparison, others (20 studies) evaluated the association of CAC score with other clinical parameters and imaging modalities or the comparison with computed tomography coronary angiography (CTCA). Our findings showed that the CAC score provides valuable prognostic information for predicting CAD risk in asymptomatic individuals.
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INTRODUCTION: Albeit described since 1763, cardiac contusions is still an under-recognised clinical condition in the acute care setting. This evidence-based review aims to provide an overview of the topic by focusing on etiopathogenesis, classification and clinical presentation of patients with cardiac contusions, as well as on the diagnostic work-up and therapy options available for this subset population in the acute care setting. METHODS: A targeted research strategy was performed using PubMed, MEDLINE, Embase and Cochrane Central databases up to June 2022. The literature search was conducted using the following keywords (in Title and/or Abstract): ("cardiac" OR "heart" OR "myocardial") AND ("contusion"). All available high-quality resources written in English and containing information on epidemiology, etiopathogenesis, clinical findings, diagnosis and management of cardiac contusions were included in our research. RESULTS: Biochemical samples of cardiac troponins together with a 12lead ECG appear to be sufficient screening tools in hemodynamically stable subjects, while cardiac ultrasound provides a further diagnostic clue for patients with hemodynamic instability or those more likely to have a significant cardiac contusion. CONCLUSIONS: The management of patients with suspected cardiac contusion remains a challenge in clinical practice. For this kind of patients a comprehensive diagnostic approach and a prompt emergency response are required, taking into consideration the degree of severity and clinical impairment of associated traumatic injuries.
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Contusões , Traumatismos Cardíacos , Contusões Miocárdicas , Ferimentos não Penetrantes , Humanos , Ferimentos não Penetrantes/complicações , Contusões Miocárdicas/complicações , Contusões/diagnóstico , Contusões/terapia , Contusões/etiologia , Traumatismos Cardíacos/diagnóstico , Traumatismos Cardíacos/terapia , Traumatismos Cardíacos/complicações , TroponinaRESUMO
In the past 20âyears, cardiac computed tomography (CCT) has become a pivotal technique for the noninvasive diagnostic workup of coronary and cardiac diseases. Continuous technical and methodological improvements, combined with fast growing scientific evidence, have progressively expanded the clinical role of CCT. Randomized clinical trials documented the value of CCT in increasing the cost-effectiveness of the management of patients with acute chest pain presenting in the emergency department, also during the pandemic. Beyond the evaluation of stents and surgical graft patency, the anatomical and functional coronary imaging have the potential to guide treatment decision-making and planning for complex left main and three-vessel coronary disease. Furthermore, there has been an increasing demand to use CCT for preinterventional planning in minimally invasive procedures, such as transcatheter valve implantation and mitral valve repair. Yet, the use of CCT as a roadmap for tailored electrophysiological procedures has gained increasing importance to assure maximum success. In the meantime, innovations and advanced postprocessing tools have generated new potential applications of CCT from the simple coronary anatomy to the complete assessment of structural, functional and pathophysiological biomarkers of cardiac disease. In this complex and revolutionary scenario, it is urgently needed to provide an updated guide for the appropriate use of CCT in different clinical settings. This manuscript, endorsed by the Italian Society of Cardiology (SIC) and the Italian Society of Medical and Interventional Radiology (SIRM), represents the second of two consensus documents collecting the expert opinion of cardiologists and radiologists about current appropriate use of CCT.
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Cardiologia , Cardiomiopatias , Cardiopatias , Neoplasias , Dor no Peito , Ponte de Artéria Coronária , Humanos , Radiologia Intervencionista , Stents , Tomografia Computadorizada por Raios X/métodosRESUMO
PURPOSE: To describe the effects of timing of intubation in COVID-19 patients that fail helmet continuous positive airway pressure (h-CPAP) on progression and severity of disease. METHODS: COVID-19 patients that failed h-CPAP, required intubation, and underwent chest computed tomography (CT) at two levels of positive end-expiratory pressure (PEEP, 8 and 16 cmH2O) were included in this retrospective study. Patients were divided in two groups (early versus late) based on the duration of h-CPAP before intubation. Endpoints included percentage of non-aerated lung tissue at PEEP of 8 cmH2O, respiratory system compliance and oxygenation. RESULTS: Fifty-two patients were included and classified in early (h-CPAP for ≤2 days, N = 26) and late groups (h-CPAP for >2 days, N = 26). Patients in the late compared to early intubation group presented: 1) lower respiratory system compliance (median difference, MD -7 mL/cmH2O, p = 0.044) and PaO2/FiO2 (MD -29 mmHg, p = 0.047), 2) higher percentage of non-aerated lung tissue (MD 7.2%, p = 0.023) and 3) similar lung recruitment increasing PEEP from 8 to 16 cmH2O (MD 0.1%, p = 0.964). CONCLUSIONS: In COVID-19 patients receiving h-CPAP, late intubation was associated with worse clinical presentation at ICU admission and more advanced disease. The possible detrimental effects of delaying intubation should be carefully considered in these patients.
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COVID-19 , Pressão Positiva Contínua nas Vias Aéreas , COVID-19/terapia , Humanos , Intubação Intratraqueal , Estudos Retrospectivos , Tomografia Computadorizada por Raios XRESUMO
INTRODUCTION: Albeit described since 1948, cardiac herniations still represent an under-recognized clinical entity in the general population, due to their difficult diagnostic detection and to a limited knowledge in clinical practice. This paper aims to provide an updated overview focusing on definition, clinical presentation and diagnostic work-up of cardiac herniations, as well as on further findings concerning prognoses and available therapeutic options. METHODS: This narrative review was performed by following the standard methods of the Cochrane Collaboration and the PRISMA statement. A Pubmed search was conducted using the following keywords (in Title and/or Abstract): ("cardiac" OR "heart") AND ("herniation" OR "hernia"). All available high quality resources containing information on epidemiology, etiopathogenesis, clinical findings, diagnostic tools and therapeutic strategies, were included in our search. RESULTS: Causative agents, location and the degree of haemodynamic impairment were found to play a pivotal role in defining the patient's natural history and prognostic outcomes, and in detecting potential associated clinical conditions which may significantly impact on first line decision-making strategy. CONCLUSIONS: Cardiac herniations remain a rare and life-threatening pathological injury, whose knowledge is still very limited in clinical practice. Clinicians should be aware of such a clinical entity and of its wide spectrum of clinical manifestations, particularly in high-risk subsets of patients, in order to provide the most appropriate decision-making strategy and timely therapeutic approach.
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BACKGROUND AND AIMS: Cardiac outpouchings encounter a series of distinct congenital or acquired entities (i.e. aneurysms, pseudoaneurysms, diverticula, and herniations), whose knowledge is still poorly widespread in clinical practice. This review aims to provide a comprehensive overview focusing on definition, differential diagnosis, and prognostic outcomes of cardiac outpouchings, as well as further insights on therapeutic options, in order to assist physicians in the most appropriate decision-making. METHODS: The material reviewed was obtained by the following search engines: MEDLINE (PubMed), EMBASE, Google Scholar, and Clinical Trials databases, from January 1966 until March 2021. We searched for the following keywords (in title and/or abstract): ("cardiac" OR "heart") AND ("outpouching" OR "outpouch" OR "aneurysm" OR "pseudoaneurysm" OR "false aneurysm" OR "diverticulum" OR "herniation"). Review articles, original articles, case series, and case reports with literature review were included in our search. Data from patients with congenital or acquired cardiac outpouchings, from prenatal to geriatric age range, were investigated. RESULTS: Out of the 378 papers initially retrieved, 165 duplicates and 84 records in languages other than English were removed. Among the 129 remaining articles, 76 were included in our research material, on the basis of the following inclusion criteria: (a) papers pertaining to the research topic; (b) peer-reviewed articles; (c) using standardized diagnostic criteria; and (d) reporting raw prevalence data. Location, morphologic features, wall motion abnormalities, and tissue characterization were found to have a significant impact in recognition and differential diagnosis of cardiac outpouchings as well as to play a significant role in defining their natural history and prognostic outcomes. CONCLUSIONS: Careful recognition of cardiac outpouchings remains a diagnostic challenge in clinical practice. Due to a broad cluster of distinctive and heterogeneous entities, their knowledge and timely recognition play a pivotal role in order to provide the most appropriate clinical management and therapeutic approach.
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In the past 20 years, Cardiac Computed Tomography (CCT) has become a pivotal technique for the noninvasive diagnostic work-up of coronary and cardiac diseases. Continuous technical and methodological improvements, combined with fast growing scientific evidence, have progressively expanded the clinical role of CCT. Recent large multicenter randomized clinical trials documented the high prognostic value of CCT and its capability to increase the cost-effectiveness of the management of patients with suspected CAD. In the meantime, CCT, initially perceived as a simple non-invasive technique for studying coronary anatomy, has transformed into a multiparametric "one-stop-shop" approach able to investigate the heart in a comprehensive way, including functional, structural and pathophysiological biomarkers. In this complex and revolutionary scenario, it is urgently needed to provide an updated guide for the appropriate use of CCT in different clinical settings. This manuscript, endorsed by the Italian Society of Medical and Interventional Radiology (SIRM) and by the Italian Society of Cardiology (SIC), represents the first of two consensus documents collecting the expert opinion of Radiologists and Cardiologists about current appropriate use of CCT.
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Técnicas de Imagem Cardíaca , Angiografia por Tomografia Computadorizada , Doença das Coronárias/diagnóstico por imagem , Cardiopatias Congênitas/diagnóstico por imagem , Coração/diagnóstico por imagem , Cuidados Pré-Operatórios , Calcinose/diagnóstico por imagem , Estenose Coronária/diagnóstico por imagem , Estenose Coronária/fisiopatologia , Reserva Fracionada de Fluxo Miocárdico , Humanos , Prevenção PrimáriaRESUMO
BACKGROUND: Critically ill COVID-19 patients have pathophysiological lung features characterized by perfusion abnormalities. However, to date no study has evaluated whether the changes in the distribution of pulmonary gas and blood volume are associated with the severity of gas-exchange impairment and the type of respiratory support (non-invasive versus invasive) in patients with severe COVID-19 pneumonia. METHODS: This was a single-center, retrospective cohort study conducted in a tertiary care hospital in Northern Italy during the first pandemic wave. Pulmonary gas and blood distribution was assessed using a technique for quantitative analysis of dual-energy computed tomography. Lung aeration loss (reflected by percentage of normally aerated lung tissue) and the extent of gas:blood volume mismatch (percentage of non-aerated, perfused lung tissue-shunt; aerated, non-perfused dead space; and non-aerated/non-perfused regions) were evaluated in critically ill COVID-19 patients with different clinical severity as reflected by the need for non-invasive or invasive respiratory support. RESULTS: Thirty-five patients admitted to the intensive care unit between February 29th and May 30th, 2020 were included. Patients requiring invasive versus non-invasive mechanical ventilation had both a lower percentage of normally aerated lung tissue (median [interquartile range] 33% [24-49%] vs. 63% [44-68%], p < 0.001); and a larger extent of gas:blood volume mismatch (43% [30-49%] vs. 25% [14-28%], p = 0.001), due to higher shunt (23% [15-32%] vs. 5% [2-16%], p = 0.001) and non-aerated/non perfused regions (5% [3-10%] vs. 1% [0-2%], p = 0.001). The PaO2/FiO2 ratio correlated positively with normally aerated tissue (ρ = 0.730, p < 0.001) and negatively with the extent of gas-blood volume mismatch (ρ = - 0.633, p < 0.001). CONCLUSIONS: In critically ill patients with severe COVID-19 pneumonia, the need for invasive mechanical ventilation and oxygenation impairment were associated with loss of aeration and the extent of gas:blood volume mismatch.
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Volume Sanguíneo/fisiologia , COVID-19/diagnóstico por imagem , COVID-19/metabolismo , Pulmão/diagnóstico por imagem , Pulmão/metabolismo , Troca Gasosa Pulmonar/fisiologia , Idoso , Gasometria/métodos , COVID-19/epidemiologia , Estudos de Coortes , Estado Terminal/epidemiologia , Feminino , Humanos , Itália/epidemiologia , Masculino , Pessoa de Meia-Idade , Respiração Artificial/métodos , Estudos Retrospectivos , Tomografia Computadorizada por Raios X/métodosAssuntos
Estenose da Valva Aórtica , Implante de Prótese de Valva Cardíaca , Próteses Valvulares Cardíacas , Valva Aórtica/diagnóstico por imagem , Valva Aórtica/cirurgia , Estenose da Valva Aórtica/cirurgia , Angiografia Coronária/efeitos adversos , Hematoma/diagnóstico por imagem , Hematoma/etiologia , Humanos , Doença IatrogênicaRESUMO
We report the case of a 72-year-old female patient admitted for worsening heart failure. The patient had undergone aortic valve replacement with a mechanical prosthesis 28 years before and since then she had several acute heart failure episodes, with a progressive increase in transprosthetic gradients, without identifying a specific cause.We describe the diagnostic tools used to reach a diagnosis, with particular emphasis on the use of cine-fluoroscopy that allowed to make the decisively diagnosis of prosthetic valve dysfunction, subsequently confirmed by cardiac computed tomography (CT). By cine-fluoroscopy, a widespread, easy, low-cost, and safe tool (no need for medium contrast and low radiation dose), it is possible to precisely define the function of the valve leaflets and measure their opening and closing angles, comparing them to the specific reference angles. To make the correct diagnosis we also performed a cardiac CT demonstrating a sub-aortic fibrous pannus. However, although cardiac CT is highly accurate for the identification of valve leaflet neoformations and abnormalities and for the discrimination between thrombotic formations and fibrous pannus, it is burdened by high costs, use of contrast medium, and limited available dedicated devices.
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Próteses Valvulares Cardíacas , Trombose , Idoso , Valva Aórtica/diagnóstico por imagem , Valva Aórtica/cirurgia , Feminino , Fluoroscopia , Próteses Valvulares Cardíacas/efeitos adversos , Humanos , Pannus , Falha de PróteseRESUMO
INTRODUCTION: The introduction of Cardiac Computed Tomography (CCT) has changed the paradigm in the field of diagnostic cardiovascular medicine. CCT is the primary tool in the assessment of suspected Coronary Artery Disease (CAD) and should be followed by functional assessment when needed to stratify disease and to plan potential interventional or surgical therapy. AREAS COVERED: We provided the current state of the knowledge on the main aspects of technique of examination, image interpretation and clinical indications. We have focused our attention on the basic routine applications and activities. EXPERT OPINION: The primary role of CCT in suspected CAD will progressively become the standard approach. In general, any situation in which anatomy of the heart and thoracic vessels/structures is mandatory must be approached using CT first, whenever possible. The quantity and quality of information that can be provided by CCT is big and the operators should learn how to deal with this information. On the other hand, CCT is only apparently a straightforward and simple examination. It is actually the most complex diagnostic procedure that can be performed on CT and requires highly skilled operators and state-of-art-technology.
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Angiografia por Tomografia Computadorizada/métodos , Doença da Artéria Coronariana/diagnóstico , Angiografia Coronária/métodos , Coração/diagnóstico por imagem , Humanos , Tomografia Computadorizada por Raios X/métodosRESUMO
BACKGROUND: There is a paucity of data concerning the optimal ventilator management in patients with COVID-19 pneumonia; particularly, the optimal levels of positive-end expiratory pressure (PEEP) are unknown. We aimed to investigate the effects of two levels of PEEP on alveolar recruitment in critically ill patients with severe COVID-19 pneumonia. METHODS: A single-center cohort study was conducted in a 39-bed intensive care unit at a university-affiliated hospital in Genoa, Italy. Chest computed tomography (CT) was performed to quantify aeration at 8 and 16 cmH2O PEEP. The primary endpoint was the amount of alveolar recruitment, defined as the change in the non-aerated compartment at the two PEEP levels on CT scan. RESULTS: Forty-two patients were included in this analysis. Alveolar recruitment was median [interquartile range] 2.7 [0.7-4.5] % of lung weight and was not associated with excess lung weight, PaO2/FiO2 ratio, respiratory system compliance, inflammatory and thrombophilia markers. Patients in the upper quartile of recruitment (recruiters), compared to non-recruiters, had comparable clinical characteristics, lung weight and gas volume. Alveolar recruitment was not different in patients with lower versus higher respiratory system compliance. In a subgroup of 20 patients with available gas exchange data, increasing PEEP decreased respiratory system compliance (median difference, MD - 9 ml/cmH2O, 95% CI from - 12 to - 6 ml/cmH2O, p < 0.001) and the ventilatory ratio (MD - 0.1, 95% CI from - 0.3 to - 0.1, p = 0.003), increased PaO2 with FiO2 = 0.5 (MD 24 mmHg, 95% CI from 12 to 51 mmHg, p < 0.001), but did not change PaO2 with FiO2 = 1.0 (MD 7 mmHg, 95% CI from - 12 to 49 mmHg, p = 0.313). Moreover, alveolar recruitment was not correlated with improvement of oxygenation or venous admixture. CONCLUSIONS: In patients with severe COVID-19 pneumonia, higher PEEP resulted in limited alveolar recruitment. These findings suggest limiting PEEP strictly to the values necessary to maintain oxygenation, thus avoiding the use of higher PEEP levels.