Nasal pressure swings as the measure of inspiratory effort in spontaneously breathing patients with de novo acute respiratory failure.

BACKGROUND: Excessive inspiratory effort could translate into self-inflicted lung injury, thus worsening clinical outcomes of spontaneously breathing patients with acute respiratory failure (ARF). Although esophageal manometry is a reliable method to estimate the magnitude of inspiratory effort, procedural issues significantly limit its use in daily clinical practice. The aim of this study is to describe the correlation between esophageal pressure swings (ΔPes) and nasal (ΔPnos) as a potential measure of inspiratory effort in spontaneously breathing patients with de novo ARF. METHODS: From January 1, 2021, to September 1, 2021, 61 consecutive patients with ARF (83.6% related to COVID-19) admitted to the Respiratory Intensive Care Unit (RICU) of the University Hospital of Modena (Italy) and candidate to escalation of non-invasive respiratory support (NRS) were enrolled. Clinical features and tidal changes in esophageal and nasal pressure were recorded on admission and 24 h after starting NRS. Correlation between ΔPes and ΔPnos served as primary outcome. The effect of ΔPnos measurements on respiratory rate and ΔPes was also assessed. RESULTS: ΔPes and ΔPnos were strongly correlated at admission (R2 = 0.88, p < 0.001) and 24 h apart (R2 = 0.94, p < 0.001). The nasal plug insertion and the mouth closure required for ΔPnos measurement did not result in significant change of respiratory rate and ΔPes. The correlation between measures at 24 h remained significant even after splitting the study population according to the type of NRS (high-flow nasal cannulas [R2 = 0.79, p < 0.001] or non-invasive ventilation [R2 = 0.95, p < 0.001]). CONCLUSIONS: In a cohort of patients with ARF, nasal pressure swings did not alter respiratory mechanics in the short term and were highly correlated with esophageal pressure swings during spontaneous tidal breathing. ΔPnos might warrant further investigation as a measure of inspiratory effort in patients with ARF. TRIAL REGISTRATION: NCT03826797 . Registered October 2016.

Risk Factors for Pulmonary Air Leak and Clinical Prognosis in Patients With COVID-19 Related Acute Respiratory Failure: A Retrospective Matched Control Study.

Background: The role of excessive inspiratory effort in promoting alveolar and pleural rupture resulting in air leak (AL) in patients with SARS-CoV-2 induced acute respiratory failure (ARF) while on spontaneous breathing is undetermined. Methods: Among all patients with COVID-19 related ARF admitted to a respiratory intensive care unit (RICU) and receiving non-invasive respiratory support, those developing an AL were and matched 1:1 [by means of PaO2/FiO2 ratio, age, body mass index-BMI and subsequent organ failure assessment (SOFA)] with a comparable population who did not (NAL group). Esophageal pressure (ΔPes) and dynamic transpulmonary pressure (ΔPL) swings were compared between groups. Risk factors affecting AL onset were evaluated. The composite outcome of ventilator-free-days (VFD) at day 28 (including ETI, mortality, tracheostomy) was compared between groups. Results: Air leak and NAL groups (n = 28) showed similar ΔPes, whereas AL had higher ΔPL (20 [16-21] and 17 [11-20], p = 0.01, respectively). Higher ΔPL (OR = 1.5 95%CI[1-1.8], p = 0.01), positive end-expiratory pressure (OR = 2.4 95%CI[1.2-5.9], p = 0.04) and pressure support (OR = 1.8 95%CI[1.1-3.5], p = 0.03), D-dimer on admission (OR = 2.1 95%CI[1.3-9.8], p = 0.03), and features suggestive of consolidation on computed tomography scan (OR = 3.8 95%CI[1.1-15], p = 0.04) were all significantly associated with AL. A lower VFD score resulted in a higher risk (HR = 3.7 95%CI [1.2-11.3], p = 0.01) in the AL group compared with NAL. RICU stay and 90-day mortality were also higher in the AL group compared with NAL. Conclusion: In spontaneously breathing patients with COVID-19 related ARF, higher levels of ΔPL, blood D-dimer, NIV delivery pressures and a consolidative lung pattern were associated with AL onset.

Early awake proning in critical and severe COVID-19 patients undergoing noninvasive respiratory support: A retrospective multicenter cohort study.

BACKGROUND/MATERIALS AND METHODS: This retrospective cohort study was conducted in two teaching hospitals over a 3-month period (March 2010-June 2020) comparing severe and critical COVID-19 patients admitted to Respiratory Intensive Care Unit for non-invasive respiratory support (NRS) and subjected to awake prone position (PP) with those receiving standard care (SC). Primary outcome was endotracheal intubation (ETI) rate. In-hospital mortality, time to ETI, tracheostomy, length of RICU and hospital stay served as secondary outcomes. Risk factors associated to ETI among PP patients were also investigated. RESULTS: A total of 114 patients were included, 76 in the SC and 38 in the PP group. Unadjusted Kaplan-Meier estimates showed greater effect of PP compared to SC on ETI rate (HR = 0.45 95% CI [0.2-0.9], p = 0.02) even after adjustment for baseline confounders (HR = 0.59 95% CI [0.3-0.94], p = 0.03). After stratification according to non-invasive respiratory support, PP showed greater significant benefit for those on High Flow Nasal Cannulae (HR = 0.34 95% CI [0.12-0.84], p = 0.04). Compared to SC, PP patients also showed a favorable difference in terms of days free from respiratory support, length of RICU and hospital stay while mortality and tracheostomy rate were not significantly different. CONCLUSIONS: Prone positioning in awake and spontaneously breathing Covid-19 patients is feasible and associated with a reduction of intubation rate, especially in those patients undergoing HFNC. Although our results are intriguing, further randomized controlled trials are needed to answer all the open questions remaining pending about the real efficacy of PP in this setting.

Spontaneous Breathing and Evolving Phenotypes of Lung Damage in Patients with COVID-19: Review of Current Evidence and Forecast of a New Scenario.

The mechanisms of acute respiratory failure other than inflammation and complicating the SARS-CoV-2 infection are still far from being fully understood, thus challenging the management of COVID-19 patients in the critical care setting. In this unforeseen scenario, the role of an individual's excessive spontaneous breathing may acquire critical importance, being one potential and important driver of lung injury and disease progression. The consequences of this acute lung damage may impair lung structure, forecasting the model of a fragile respiratory system. This perspective article aims to analyze the progression of injured lung phenotypes across the SARS-CoV-2 induced respiratory failure, pointing out the role of spontaneous breathing and also tackling the specific respiratory/ventilatory strategy required by the fragile lung type.

Machine learning in predicting respiratory failure in patients with COVID-19 pneumonia-Challenges, strengths, and opportunities in a global health emergency.

AIMS: The aim of this study was to estimate a 48 hour prediction of moderate to severe respiratory failure, requiring mechanical ventilation, in hospitalized patients with COVID-19 pneumonia. METHODS: This was an observational prospective study that comprised consecutive patients with COVID-19 pneumonia admitted to hospital from 21 February to 6 April 2020. The patients' medical history, demographic, epidemiologic and clinical data were collected in an electronic patient chart. The dataset was used to train predictive models using an established machine learning framework leveraging a hybrid approach where clinical expertise is applied alongside a data-driven analysis. The study outcome was the onset of moderate to severe respiratory failure defined as PaO2/FiO2 ratio <150 mmHg in at least one of two consecutive arterial blood gas analyses in the following 48 hours. Shapley Additive exPlanations values were used to quantify the positive or negative impact of each variable included in each model on the predicted outcome. RESULTS: A total of 198 patients contributed to generate 1068 usable observations which allowed to build 3 predictive models based respectively on 31-variables signs and symptoms, 39-variables laboratory biomarkers and 91-variables as a composition of the two. A fourth "boosted mixed model" included 20 variables was selected from the model 3, achieved the best predictive performance (AUC = 0.84) without worsening the FN rate. Its clinical performance was applied in a narrative case report as an example. CONCLUSION: This study developed a machine model with 84% prediction accuracy, which is able to assist clinicians in decision making process and contribute to develop new analytics to improve care at high technology readiness levels.

Marked T cell activation, senescence, exhaustion and skewing towards TH17 in patients with COVID-19 pneumonia.

The immune system of patients infected by SARS-CoV-2 is severely impaired. Detailed investigation of T cells and cytokine production in patients affected by COVID-19 pneumonia are urgently required. Here we show that, compared with healthy controls, COVID-19 patients' T cell compartment displays several alterations involving naïve, central memory, effector memory and terminally differentiated cells, as well as regulatory T cells and PD1+CD57+ exhausted T cells. Significant alterations exist also in several lineage-specifying transcription factors and chemokine receptors. Terminally differentiated T cells from patients proliferate less than those from healthy controls, whereas their mitochondria functionality is similar in CD4+ T cells from both groups. Patients display significant increases of proinflammatory or anti-inflammatory cytokines, including T helper type-1 and type-2 cytokines, chemokines and galectins; their lymphocytes produce more tumor necrosis factor (TNF), interferon-γ, interleukin (IL)-2 and IL-17, with the last observation implying that blocking IL-17 could provide a novel therapeutic strategy for COVID-19.

Tocilizumab in patients with severe COVID-19: a retrospective cohort study.

BACKGROUND: No therapy is approved for COVID-19 pneumonia. The aim of this study was to assess the role of tocilizumab in reducing the risk of invasive mechanical ventilation and death in patients with severe COVID-19 pneumonia who received standard of care treatment. METHODS: This retrospective, observational cohort study included adults (≥18 years) with severe COVID-19 pneumonia who were admitted to tertiary care centres in Bologna and Reggio Emilia, Italy, between Feb 21 and March 24, 2020, and a tertiary care centre in Modena, Italy, between Feb 21 and April 30, 2020. All patients were treated with the standard of care (ie, supplemental oxygen, hydroxychloroquine, azithromycin, antiretrovirals, and low molecular weight heparin), and a non-randomly selected subset of patients also received tocilizumab. Tocilizumab was given either intravenously at 8 mg/kg bodyweight (up to a maximum of 800 mg) in two infusions, 12 h apart, or subcutaneously at 162 mg administered in two simultaneous doses, one in each thigh (ie, 324 mg in total), when the intravenous formulation was unavailable. The primary endpoint was a composite of invasive mechanical ventilation or death. Treatment groups were compared using Kaplan-Meier curves and Cox regression analysis after adjusting for sex, age, recruiting centre, duration of symptoms, and baseline Sequential Organ Failure Assessment (SOFA) score. FINDINGS: Of 1351 patients admitted, 544 (40%) had severe COVID-19 pneumonia and were included in the study. 57 (16%) of 365 patients in the standard care group needed mechanical ventilation, compared with 33 (18%) of 179 patients treated with tocilizumab (p=0·41; 16 [18%] of 88 patients treated intravenously and 17 [19%] of 91 patients treated subcutaneously). 73 (20%) patients in the standard care group died, compared with 13 (7%; p<0·0001) patients treated with tocilizumab (six [7%] treated intravenously and seven [8%] treated subcutaneously). After adjustment for sex, age, recruiting centre, duration of symptoms, and SOFA score, tocilizumab treatment was associated with a reduced risk of invasive mechanical ventilation or death (adjusted hazard ratio 0·61, 95% CI 0·40-0·92; p=0·020). 24 (13%) of 179 patients treated with tocilizumab were diagnosed with new infections, versus 14 (4%) of 365 patients treated with standard of care alone (p<0·0001). INTERPRETATION: Treatment with tocilizumab, whether administered intravenously or subcutaneously, might reduce the risk of invasive mechanical ventilation or death in patients with severe COVID-19 pneumonia. FUNDING: None.