Medical intensivist directed VV ECMO cannulation for the facilitation of tracheostomy in a patient with severe tracheal stenosis: A case report

Objectives: We present a case report of medical intensivist driven ECMO program using ECMO as a pre-procedural tool to maintain oxygenation in a patient with critical tracheal stenosis during tracheostomy placement. Method(s): VV ECMO is primarily used to support patients when mechanical ventilation is unable to provide adequate gas exchange. Alternatively, it has been used pre-procedurally when intubation is required in anticipation of a difficult airway. Described here is the first intensivist preformed awake VV ECMO cannulation to facilitate tracheostomy in a patient with severe tracheal stenosis. Result(s): The patient is a 41-year-old female with the relevant background of COVID19 pneumonia status post tracheostomy and subsequently decannulated after prolonged intubation and ICU stay. As a result, the patient developed symptomatic tracheal stenosis and presented two years after her ICU stay for scheduled bronchoscopy and balloon dilation. However, the patient developed worsening stridor and shortness of breath requiring heliox and BPAP. After multidisciplinary discussion between the critical care team ENT teams, the decision was made to cannulate for VV ECMO as a pre-procedural maneuver to allow for oxygenation during open tracheostomy in the OR. Dexmedetomidine and local anesthesia were used for the procedure with the patient sitting at 30 degrees on non-invasive ventilation and heliox. The patient was cannulated with a 21F right internal jugular return cannula and 25F right common femoral drainage cannula by medical intensivists in the intensive care unit using ultrasound guidance. The patient went for operative tracheostomy the next day and was subsequently decannulated from ECMO the following day without complication. She was discharged home on trach collar. Conclusion(s): Intensivist performed ECMO cannulation has been shown to be safe and effective. We anticipate the indications and use will continue to expand. This case is an example that intensivist driven preprocedural ECMO is a viable extension of that practice.

Omicron driven ECMO in a vaccinated critically ill patient

Objectives: Reporting a case of a COVID-19 vaccinated patient admitted to our intensive care unit with severe acute respiratory failure due to SARSCoV2 - Omicron variant, rapidly deteriorating requiring intubation, prone ventilation, and ECMO support. Method(s): A 62 years old Caucasian male was admitted in ICU for rapidly deranging respiratory failure and fever which occurred over the previous 24h. The patient received two doses of SARS-CoV2 vaccine (Oxford, AstraZeneca), the last one over five months before onset of symptoms. The patient was admitted to the intensive care unit (ICU) with tachypnea, low peripheral saturation (80%), elevated serum creatinine (2.4 mg/dl), and mild obesity (BMI 34,6). Pressure support ventilation trial (2 hours) failed carryng out to orotracheal intubation and protective ventilation. Worsening of respiratory exchanges (5 th day from the admission) required a rescue prone ventilation cycle, in the meantime an indication was given to the placement of veno-venous ECMO. The cannulation site was femoro-femoral and the configuration used was Vivc25- Va21, according to the current ELSO nomenclature;ECMO flow was progressively increased until a peripheral saturation of 95% was obtained. Result(s): The patient passed out after 2 month of extracorporeal support with no sign of recovery of pulmonary and renal function. Conclusion(s): Unlike evidences showing a lower symptomatic engagement of the Omicron variant SARSCoV2 positive patients, we have witnessed a rapid and massive pulmonary involvement. The short time that passed from the onset of symptoms and the rapid decay of respiratory function required rapid escalation of the intensity of care up to extracorporeal support. The patient showed previous pathologies that can lead to suspicion of a loss of immune coverage given by the vaccine, in addition to the long time elapsed since the last dose. (Figure Presented).

The separation membranes in artificial organs

Separation membranes play a crucial role in the functioning of artificial organs, such as hemodialysis machines, membrane oxygenators, and artificial liver models. The current COVID-19 pandemic has highlighted the importance of these technologies in the medical community. However, membrane technology in artificial organs faces significant challenges, such as the clearance of low-middle-molecule and protein-bound toxins and limited blood compatibility. In this review, we will discuss the separation mechanisms, separation performance, and biocompatibility of different types of separation membranes used in artificial organs. We will also highlight the opportunities and challenges for next-generation membrane technology in this field, including the need for improved clearance of toxins and increased blood compatibility, as well as the potential for microfluidic devices.

Pulmonary surfactant and COVID-19: A new synthesis

Chapter 1: COVID-19 pathogenesis poses paradoxes difficult to explain with traditional physiology. For instance, since type II pneumocytes are considered the primary cellular target of SARS-CoV-2;as these produce pulmonary surfactant (PS), the possibility that insufficient PS plays a role in COVID-19 pathogenesis has been raised. However, the opposite of predicted high alveolar surface tension is found in many early COVID-19 patients: paradoxically normal lung volumes and high compliance occur, with profound hypoxemia. That 'COVID anomaly' was quickly rationalised by invoking traditional vascular mechanisms-mainly because of surprisingly preserved alveolar surface in early hypoxemic cases. However, that quick rejection of alveolar damage only occurred because the actual mechanism of gas exchange has long been presumed to be non-problematic, due to diffusion through the alveolar surface. On the contrary, we provide physical chemical evidence that gas exchange occurs by an process of expansion and contraction of the three-dimensional structures of PS and its associated proteins. This view explains anomalous observations from the level of cryo-TEM to whole individuals. It encompasses results from premature infants to the deepest diving seals. Once understood, the COVID anomaly dissolves and is straightforwardly explained as covert viral damage to the 3D structure of PS, with direct treatment implications. As a natural experiment, the SARS-CoV-2 virus itself has helped us to simplify and clarify not only the nature of dyspnea and its relationship to pulmonary compliance, but also the fine detail of the PS including such features as water channels which had heretofore been entirely unexpected.Copyright ©

Mechanisms of impaired gas exchange following hospitalisation for severe COVID-19

Introduction/Aim: Reduced carbon monoxide diffusing capacity (DL CO) is common after recovery from severe COVID-19 and cohort studies have found it to be more abnormal than either VC or TLC. There is no specific evidence that this relates to membrane disfunction or vascular injury. Concurrent measurement of nitric oxide diffusing capacity (DL NO) and DL CO can be used to partition gas diffusion into its two components - membrane conductance (D m CO) and capillary blood volume (V C). In this study, we sought to evaluate D m CO and V C in the early and later recovery periods after severe COVID-19. Method(s): Patients attended for post-COVID outpatient clinical review and complex lung function testing including DL NO /DL CO (Hyp'Air;Medisoft, Leeds). Further appointments and repeat testing occurred when indicated. Lung function comparisons were made using t-tests. Result(s): 46 (8 female) subjects (mean+/-SD age 58+/-13, BMI 34+/-8), who had severe COVID pneumonitis, WHO ordinal severity classification of 6+/-1 and prolonged (19+/-22 days) length of hospital stay, were assessed 51+/-29 days post discharge. Mean TLC [z-score -1.64+/-1.31] and D L CO [z-score -1.60+/-1.48] were both reduced. V C and D m CO were reduced to a similar extent (Z-score -1.36+/-1.19 and -1.14+/-1.06, p=0.4). 14 (1 female) patients returned for testing 70+/-35 days later. In this subgroup, D L CO improved but remained below LLN (Z-score -2.98+/-0.73 [Visit 1] Vs -2.17+/-0.69 [Visit 2], p=0.01). D m CO improved (Z-score -1.99+/-0.91 Vs -1.25+/-1.17, p=0.01) but V C was unchanged (Z-score -2.33+/-0.53 Vs -2.03+/-0.76, p=0.17). Conclusion(s): Gas exchange is persistently abnormal after severe COVID. Membrane conductance is abnormal in the earlier recovery phase but improves to a significant extent. In contrast, reduced capillary blood volume persists. Repeat testing at longer intervals after recovery from acute illness is still required but these data raise the possibility that persisting effects of acute vascular injury will contribute to physiological impairment long after severe COVID pneumonitis.

Dysfunctional breathing induces vocal cord dysfunction following COVID-19 infection

Introduction/Aim: SARS-CoV-2 (COVID-19) has affected over 60 million people world-wide. In most cases symptoms are mild, however some people have ongoing symptoms lasting longer known as 'long COVID'. Exertional breathlessness is a common complaint in these patients. Dysfunctional breathing (DB) and vocal cord dysfunction (VCD) are two underappreciated causes of breathlessness. We hypothesized that in individuals who had experienced COVID-19, dysfunctional breathing could give rise to VCD. Method(s): Nine convenience-sampled participants with confirmed COVID-19 infection were included following resolution of the acute illness. Vocal cords movements were visualised via continuous laryngoscopy. Hyperventilation was employed as a surrogate for DB, using a standard protocol of 40 breathes per minute (bpm). Participants breathed through a flow sensor with concomitant laryngoscopy, and we monitored hyperventilation, gas exchange measurements and laryngeal movements. After 12-weeks patients returned for repeat hyperventilation testing. Result(s): The nine participants consisted of five females and four males, age range 24-66 years. Three of the nine participants developed classic inspiratory VCD during hyperventilation. Patients with VCD were female, younger (<45), reported significantly reduced exercise tolerance post infection and had been physically very active prior to COVID infection. In two participants VCD associated with hyperventilation had resolved on laryngoscopy at 12-weeks. In these two participants who had VCD, breathlessness and reduced exercise tolerance resolved at 12-weeks following laryngeal retraining. In one person evidence of VCD and reduced exercise tolerance persisted post 12-weeks review. Conclusion(s): This study provides the first evidence that COVID-19 may facilitate VCD via DB, causing unexplained breathlessness. Our findings suggest that this disease process may be implicated in 'long COVID' and provide a rationale for therapies such as breathing and laryngeal retraining.

Mechanisms of impaired gas exchange following hospitalisation for COVID-19

Introduction/Aim: Reduced carbon monoxide diffusing capacity (DL CO) is the most prevalent lung function abnormality post COVID-19 infection. Two studies suggested this relates to alveolar unit loss with preserved capillary blood volume. The measurement of nitric oxide diffusing capacity (D L NO) concurrently with D L CO allows for the quantitation of the membrane component of gas diffusion (D m CO) and capillary blood volume (V C). We sought to monitor D m CO and V C in the recovery period of patients hospitalised for severe COVID-19. Method(s): Patients attended outpatient clinical review and lung function testing including DL NO /DL CO (Hyp'Air;Medisoft, Leeds), with further appointment if indicated. Lung function comparisons were made using t-tests and clinical associations using Pearson correlation. Result(s): 46 (8 female) patients (mean+/-SD) (age 58+/-13, BMI 34+/-8), were assessed 51+/-29 days post discharge. WHO ordinal severity classification was 6+/-1, suggesting severe disease, with prolonged (19+/-22 days) length of admission. V C and D m CO were similarly reduced (Z-score -1.36+/-1.19 Vs -1.14+/-1.06, p = 0.4). V C was negatively correlated with length of stay (r=-0.42, p < 0.01). TLC (Z-score -1.64+/-1.31) and D L CO (-1.60+/-1.48) were significantly reduced and negatively correlated with length of stay (r>-0.41, p<=0.02). WHO severity negatively correlated with TLC only (r=-0.45, p < 0.01). Demographic and biochemical data did not correlate with lung function.14 (1 female) patients returned for repeat testing 70+/-35 days later. D m CO improved (Z-score -1.99+/-0.91 Vs -1.25+/-1.17, p = 0.01). V C was unchanged (Z-score -2.33+/-0.53 Vs -2.03+/-0.76, p = 0.17). D L CO improved but remained below LLN (Z-score -2.98+/-0.73 Vs -2.17+/-0.69, p = 0.01). Conclusion(s): Similar reductions in D m CO and V C following hospitalisation for COVID-19 were identified. In those who returned for repeat testing, D m CO values normalised, but V C did not improve. Abnormal lung function related to increasing severity and length of stay. These findings suggests vascular injury may play a more important role rather than alveolar unit loss as the primary contributor to gas exchange impairment following COVID-19.

Increased shunt and dead space in recovered COVID-19 pneumonitis patients

Introduction/Aim: We previously reported impaired pulmonary gas exchange in acute COVID-19 patients resulting from both increased intrapulmonary shunt (SH) and increased alveolar dead space (AD) 1 . The present study quantifies gas exchange in recovered patients. Method(s): Unvaccinated patients diagnosed with acute COVID-19 infection (March-December 2020) were studied 15 to 403 days post first SARS-CoV-2 positive PCR test. Demographic, anthropometric, acute disease severity and comorbidity data were collected. Breathing room air, steady-state exhaled gas concentrations were measured simultaneously with arterial blood gases. Alveolar CO 2 and O 2 (P A CO 2 and P A O 2 ;mid-exhaled volume) determined;AaPO2, aAPCO2, SH% and AD% calculated. 2 Results: We studied 59 patients (33 males, Age: 52[38-61] years, BMI: 28.8[25.3-33.6] kg/m 2 ;median[IQR]). Co-morbibities included asthma (n = 2), cardiovascular disease (n = 3), hypertension (n = 12), and diabetes (n = 9);14 subjects smoked;44 had experienced mild-moderate COVID-19 (NIH category 1-2), 15 severe-critical disease (NIH category 3-5). PaCO 2 was 39.4[35.6-41.1] mmHg, PaO 2 92.1[87.1-98.2] mmHg;P A CO 2 32.8[28.6-35.3] mmHg, P A O 2 112.9[109.4-117.0] mmHg, AaPO 2 18.8[12.6-26.8] mmHg, aAPCO 2 5.9[4.3-8.0] mmHg, SH 4.3 [2.1-5.9]% and AD 16.6 [12.6-24.4]%. 14% of patients had normal SH (<5%) and AD (<10%);1% abnormal SH and normal AD;36% both abnormal SH and AD;49% normal shunt and abnormal AD. Previous severe-critical disease was a strong independent predictor for increased SH (OR 14.8[2.28-96], [95% CI], p < 0.01), increasing age weakly predicted increased AD (OR 1.18[1.01, 1.37], p < 0.04). Time since infection, BMI and comorbidities were not significant predictors (all p > 0.11). Conclusion(s): Prior COVID-19 was associated with increased intrapulmonary shunt and/or increased alveolar dead space in 86% of this cohort up to ~13 months post infection, with those with more severe acute disease, and older patients, at greater risk. Increased intrapulmonary shunt suggests persistent alveolar damage, while increased alveolar dead space may indicate persistent pulmonary vascular occlusion.

TSANZSRS 2023 Australia and New Zealand Society of Respiratory Science and The Thoracic Society of Australia and New Zealand (ANZSRS/TSANZ) Annual Scientific Meeting for Leaders in Lung Health and Respiratory Science

The proceedings contain 360 papers. The topics discussed include: comparison of three methods assessing spirometry bronchodilator responsiveness in children;the quality of spirometry testing: a systematic review;airflow severity in asthma minimally affects within-session oscillometry variability;corrected normative multiple breath washout data in pre-school aged children;prevalence and predictors of tidal expiratory-flow-limitation in healthy adolescents/young adults;impact of change of significant bronchodilator response definition;volume-dependence of reactance as a measure of ventilation inhomogeneity;mechanisms of impaired gas exchange following hospitalization for severe COVID-19;increased shunt and dead space in recovered COVID-19 pneumonitis patients;airway hyperresponsiveness detection in atopic asthma using exhaled nitric oxide;increased conductive ventilation heterogeneity following exposure to coal-mine fire smoke;accuracy of transcutaneous carbon dioxide monitoring during sleep studies;and effect of hematopoietic stem cell transplant on small airways function.

Evaluation of myocardial work in patients recovered from the severe form of COVID-19

Background/Introduction: The impact of COVID-19 goes beyond its acute form, and can lead to the persistence of symptoms and the emergence of systemic disorders, defined as Post-Covid or Long-Covid. Purpose(s): Assess the late impact on the cardiorespiratory system of patients recovered from severe Covid. Method(s): We performed cross-sectional study that included patients over 18 years of age who recovered from the severe form of COVID-19 after at least 60 days of their discharge. Patients and healthy controls were enrolled to perform transthoracic echocardiography (TTE) and cardiopulmonary exercise testing (CPET). Result(s): A total of 52 patients and 24 controls were enrolled. The standard TTE parameters (end diastolic diameters, left ventricular ejection fraction, diastolic function and right ventricular systolic function) showed no difference when compared to the control group. When analyzing the myocardial work, there was a higher Wasted MW (GWW): 135 mmHg% vs 84.5 mmHg% (p=0.002), with lower MW Efficiency (GWE): 94 vs. 96 (p=0.003);as well as lower values of global strain: Cases = 18.6% vs. 20.1% (p=0.009). No differences were found in the Constructive MW (GWC) and MW Global Index (GWI). In the CPET data we found lower peak values for the VO2: 24 ml/kg/min vs. 32.75 ml/kg/min (p<0.001);for the Heart Rate: 162 bpm vs. 175 bpm (p<0.001);for the Ventilation: 79.3 L/min vs. 109.85 L/min (p<0.001) and Respiratory Exchange Ratio: 1.12 vs. 1.19 (p=0.004). There was no difference in the maximum load reached, neither in the oxygen pulse values and in the Ve/CO2 slope. In relation to the oxygen kinetics, there was a significant reduction in OUES%: 85% vs. 98% (p=0.03);as well as an extended T1/4: 112 s vs. 88.5 s (p<0.001);and a slowing of the fall in heart rate in recovery time, as measured by the Heart Rate decay: -17.32 bpm vs. -22.08 bpm (p=0.005). Conclusion(s): Patients recovered from the severe form of COVID-19 had higherGWWwith lower efficiency (GWE). Such findings, added to changes in oxygen kinetics during exercise, may point to a possible cardiocirculatory mechanism associated with decreased aerobic capacity.

Is COVID-19 different from other causes of acute respiratory distress syndrome?

Coronavirus disease 2019 (COVID-19) pneumonia can lead to acute hypoxemic respiratory failure. When mechanical ventilation is needed, almost all patients with COVID-19 pneumonia meet the criteria for acute respiratory distress syndrome (ARDS). The question of the specificities of COVID-19-associated ARDS compared to other causes of ARDS is of utmost importance, as it may justify changes in ventilatory strategies. This review aims to describe the pathophysiology of COVID-19-associated ARDS and discusses whether specific ventilatory strategies are required in these patients.

Shunt fraction in Covid-19 related Acute Respiratory Failure

Background: Failing autoregulation of pulmonary vessels and higher shunt have been described in Covid-19 related Acute respiratory failure (ARF). The aim was to investigate shunt fraction in patients with Covid-19-ARF compared to patients with other causes of ARF. Method(s): Observational study of hospitalized patients with Covid-19-ARF and other causes of ARF at Papa Giovanni XXIII Hospital, Bergamo, Italy between June 2020 and November 2021. Shunt fraction was measured by a non-invasive system during spontaneous breathing (BeaconCaresystem). Result(s): We enrolled 51 adult patients (8 female), mean age (+/-SD) 65+/-13 years and mean BMI 28,3+/-5,3 Kg/m2. Covid-19-ARF patients represented 71% (36/51). Community acquired pneumonia was the most common cause of other ARF (11/15). No differences in terms of age and BMI were described between the two groups. Pulmonary gas exchange impairment was similar, median PaO2/FIO2 ratio was 254 [IQR 162,297] in Covid-19-ARF and 269 [IQR 201,296] in other causes of ARF patients (p=0.41). Nevertheless, mean shunt fraction resulted significantly increased in Covid-19-ARF (18+/-6%) than other causes of ARF patients (12+/-9%;p=0.03) Fig. 1. Conclusion(s): Shunt fraction appears to be increased in Covid-19-ARF if compared to patients with other causes of ARF. However, this is the first study proposing this non-invasive method to measure shunt fraction in ARF and further investigations are needed to validate this technique.

Gas exchange after Covid-19 pneumonia

Introduction : Functional follow-up of patients after Covid-19 pneumonia is essential, not only to adapt patient care but also to better understand the medium and long-term consequences of the virus on respiratory function. Among the respiratory function tests, DLCO allows to evaluate the sequelae on the quality of gas exchanges. Methods : The DLCO was measured as part of a respiratory function assessment, 3 months after recovery from Covid-19 pneumonia in a group of 469 patients. Result(s): Study population was composed of 262 males and 207 females. Mean age and body mass index (BMI) were respectively 59.45+/-12.85 years-old and 31.24+/-5.83 kg/m2. Smoking was reported in 32.9% of cases. Hospitalization was needed on 92.3%, oxygen supply in 91.8% and respiratory aid in 11.1% of cases. Mean DLCO was 74.24%+/-17.7 and was abnormal in 43% of cases whereas restriction and obstruction were found respectively in 14.8% and 4.9% of spirometry. DLCO was correlated with age (r=0.236;p<10-3), BMI (r=-0.097;p=0.036), dyspnea severity according to the mMRC score (r=-0.318;p<10-3), duration of hospitalization (r=-0.13;p=0.008), respiratory aid (r=-0.159;p=0.01), duration of oxygen need (-0.364;p<10-3), extension of pneumonia on the CT scan (r=-0.245;p<10-3), FVC (r=0.521;p<10-3), FEV1 (r=0.479;p<10-3) and TLC (r=0.290;p<10-3). Conclusions : DLCO seems to be one of the first functional parameters to be altered after Covid-19 pneumonia, which justifies its regular measurement in patient follow-up.

Clinical Findings and Outcomes from 1306 Patients with Covid-19 Pneumonia in an Intermediate Respiratory Care Unit: A Prospective, Observational Study

Background: An intermediate respiratory care unit (IRCU) may be a valuable tool for optimizing patient care, allowing to implement standardized algorithm management to decrease clinical failure and mortality. We aimed to describe the practice of noninvasive respiratory strategies (NRS) in a novel facility fully dedicated to COVID-19 and to establish outcomes of these patients Methods: Prospective, observational study performed at one hospital in Spain. We included consecutive patients admitted to IRCU due to COVID-19 requiring NRS between December 2020 and September 2021. Data collected included mode and usage of NRS, endotracheal intubation and mortality to day 30. A multivariable Cox proportional hazards method was used to assess risk factors associated with clinical failure and mortality Findings: 1306 patients with COVID-19 were included. Of them, 64.6% were men and mean age was 54.7 years. During IRCU stay, 345 patients presented a clinical failure, (89.6% intubated;14.5% died). Cox model showed a higher clinical failure in IRCU when time between symptoms onset and hospitalization < 10 days (HR 1.59;95% CI 1.24-2.03;p<0.001) and PaO2/FiO2 <100 (HR 1.59;95% CI 1.27-1.98;p<0.001). Conversely, these variables were not associated with an increased mortality to day 30 Interpretation: IRCU may be a useful option for the multidisciplinary management of COVID-19 patients requiring NRS;thus, reducing ICU overcharge. Men gender, gas-exchange and blood chemistry at admission are associated with worse clinical outcomes, while older age, gas-exchange and blood chemistry are associated with 30-day mortality.

Impact of SARS CoV2 infection on pulmonary gas exchange and exercise capacity in patients with mild to severe COVID-19

Since beginning of 2020, SARS-CoV2 pandemic has been prevailing in humans causing COVID-19. Airways are strongly impacted during virus mediated inflammation and damage. Exact pathomechanisms during COVID-19 are still under investigation. We now further characterized limitations in exercise capacity in outpatient patients after symptomatic infection with SARS-CoV2 using bicycle cardiopulmonary exercise testing (CPET). 45 patients (21female/24 male) underwent standard pulmonary function testing (PFT) including spirometry, bodyplethysmography, CO-diffusion-measurement (DLCO, DLCO/VA), capillary blood gas-analysis (BGA) and symptom limited CPET on a bicycle. Patients' disease history was evaluated in advance. Severity of the disease was quantified according to reported data. At rest, there were no statistically relevant abnormalities in spirometry, bodyplethysmography, CO-diffusion-measurement or blood gas-analysis, even in those patients less than 40 days post infection. We found significantly impaired alveolar-arterial oxygen gradients (A-aO2) and decreased peak V'O2 level post-COVID-19 patients up to up to 80days post infection. Reevaluating 10 patients 3 month later, a markedly increase in peak oxygen-uptake (V'O2) and a normalized A-aO2 at rest was noted. We conclude that COVID-19 resulted in decreased cardiopulmonary exercised capacity as demonstrated by CPET (significantly decreased peak V'O2). The underlying mechanism is limitation of oxygen-diffusion indicated by significantly elevated A-aO2 level in post-COVID-19 patients. Limitation was temporary and patients reached age-appropriate level 3 month later.

The ability of Lung High-Resolution Computed Tomography Severity Score to early identify COVID-19 patients who need respiratory support. A retrospective analysis of a monocentric Italian COVID-19 cohort

Objectives: to evaluate the relationship of a quantitative severity score (SS) of lung involvement, derived from nonenhanced Chest High-Resolution Computed Tomography (HRCT), with COVID-19 disease severity and the ability to early identify patients who need respiratory support with continuous positive airway pressure (CPAP) and/or noninvasive mechanical ventilation (NIMV) during follow-up. Method(s): We retrospectively evaluated a cohort of consecutive enrolled patients hospitalized for COVID-19 in an academic hospital in Rome during the first spread of SARS-CoV2 infection. All the enrolled patients underwent HRCT at admission and standardized evaluation of the SS. The study outcome was the need of CPAP and/or NIMV during follow-up. Result(s): We enrolled 39 patients with a median disease duration of 5 days. The median (25degree-75degree percentile) SS at baseline was 5 (2-7). We grouped patients according to tertile distribution of SS. Median pO2/FIO2 ratio progressively decreased from low SS group (SS 0-3) to high SS group, p 0.02. SS positively correlated with pneumonia prognostic scores SOFA (r=0.36, p 0.044) and MEWS (r = 0.33, p 0.038). The SS ROC AUC in predicting the need of respiratory support was 0.74 (95% CI, 0.58-0.90). Using 5 as Youden index cut-off, the sensitivity and specificity of SS were 0.83 and 0.59 respectively. Conclusion(s): The SS obtained from baseline lung CT is related to the clinical and laboratory severity of lung involvement in COVID-19 and with the impairment of gas exchange.

Flexible bronchoscopy in a critically ill-improving patient and operator safety

Flexible bronchoscopy is an indispensable diagnostic and therapeutic tool in respiratory critical care. In a critically ill hypoxemic patient, bronchoscopy is challenging due to interference with ventilation and oxygenation. During repeated disconnections, there is a risk of worsening gas exchange, cardiac arrythmias, hemodynamic instability and increased aerosol generation. As with COVID pandemic, prevention of transmission of infection in healthcare setting is important. This equally holds true for other airborne infections. We propose the use of a novel accessory - closed bronchoscopy device during bronchoscopy in ventilated patients, to reduce the procedure related risk to patient and health care workers. The bronchoscopy valve and sheath in close connection helps to prevent loss of volume, minimize disconnections and desaturation, prevent direct handling of soiled bronchoscope and reduces aerosol generation. This in turn reduces risk of introducing new infection in an airway during the procedure. Overall improved procedure safety, reduced time required without much handling difficulties. This requires scope-valve fit test. The disadvantage during therapeutic bronchoscopy where disconnections are necessary to clear blocked channels or remove large plugs can be managed at the valve level as shown in figure 1. This novel device will prove useful for reducing complications during flexible bronchoscopy in a critically ill.

Persisting exertional dyspnea and perceived exercise intolerance after mild Covid-19: a critical role for breathing dysregulation?

Background: After mild Covid-19, a subgroup of patients reports post-acute sequelae of Covid-19 (PASC), in which exertional dyspnea and perceived exercise intolerance are common. Underlying pathophysiological mechanisms remain incompletely understood. We studied outcomes from cardiopulmonary exercise test (CPET) in these patients. Method(s): In this observational study, we included patients referred for the analysis of PASC after mild Covid-19 in whom CPET was performed after standard clinical work-up turned out unremarkable. Cardiocirculatory, ventilatory and metabolic response to, and breathing patterns during exercise at physiological limits were analyzed. Result(s): Twenty-one patients (76% female, mean age 40y) who reported severe fatigue (CIS-fatigue >= 35), dyspnea (mMRC 2 (IQR1-2)) and disability in physical role functioning (SF-36) underwent CPET at 32 weeks (IQR 22-52) after Covid-19. Mean peak oxygen uptake was 99% (SD13) of predicted with normal anaerobic thresholds at 62% (SD11) of predicted oxygen uptake. No cardiovascular or gas exchange abnormalities were detected. Twenty out of the 21 patients (95%) demonstrated breathing dysregulation, existing of ventilatory inefficiency (29%), abnormal course of breathing frequency and tidal volume (57%), and acute or chronic respiratory alkalosis in resting blood gases (67%). Conclusion(s): In the absence of deconditioning, breathing dysregulation may explain the experienced exertional dyspnea and exercise intolerance in patients with PASC after mild Covid-19.