Inspiratory effort and lung mechanics in spontaneously breathing patients with acute respiratory failure due to COVID-19. A matched control study.

Several physical and biological mechanisms can drive progression between the different phases of lung injury due to SARS-CoV-2 infection, thus modifying the mechanical properties and behavior of COVID-19 over time. In this research letter we have presented the findings of a registered clinical trial aimed at describing and comparing the inspiratory effort (primary outcome) and the breathing pattern of spontaneously breathing patients with ARF in COVID-19 and historically matched non-COVID-19 patients, either candidate to NIV. Moreover, we reported the response to a 2 hours NIV trial in the two groups. Spontaneously breathing COVID-19 at their early onset of acute respiratory failure with indication for NIV showed different mechanical characteristics and breathing pattern when compared with non-COVID-19

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 (\u394P es ) and nasal (\u394P nos ) as a potential measure of inspiratory effort in spontaneously breathing patients with de novo ARF. Methods- From January 1 st , 2021 to September 1 st , 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 noninvasive respiratory support (NRS) were enrolled. Clinical features and tidal changes in esophageal and nasal pressure were recorded on admission and 24 hours after starting NRS. Correlation between \u394P es and \u394P nos served as primary outcome. The effect of \u394P nos measurements on respiratory rate and \u394P es was also assessed. Results- \u394P es and \u394P nos were strongly correlated at admission (R 2 =0.88, p<0.001) and 24 hours apart (R 2 =0.94, p<0.001). The nasal plug insertion and the mouth closure required for \u394P nos measurement did not result in significant change of respiratory rate and \u394P es . The correlation between measures at 24 hours remained significant even after splitting the study population according to the type of NRS (high-flow nasal cannulas [R 2 =0.79, p<0.001] or non-invasive ventilation [R 2 =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. \u394P nos might warrant further investigation as a measure of inspiratory effort in patients with ARF

Early inspiratory effort assessment by esophageal manometry early predicts noninvasive ventilation outcome in de novo respiratory failure: a pilot study.

Rationale: The role of inspiratory effort has still to be determined as a potential predictors of non-invasive mechanical ventilation (NIV) failure in acute hypoxic de novo respiratory failure (AHRF). Objectives: We explore the hypothesis that inspiratory effort might be a major determinant of NIV failure in these patients. Methods: Thirty consecutive patients with AHRF admitted to a single center and candidates for a 24-hour NIV trial were enrolled. Clinical features, tidal changes in esophageal (ΔPes) and dynamic transpulmonary pressure (ΔPL), expiratory tidal volume, and respiratory rate were recorded on admission and 2-4-12-24 hours after NIV start, and were tested for correlation with outcomes. Measurements and Main Results: ΔPes and ΔPes/ΔPL were significantly lower 2 hours after NIV start in patients who successfully completed the NIV trial (n=18) compared to those who needed endotracheal intubation (n=12) [median=11 (IQR=8–15) cmH2O vs 31.5 (30–36) cmH2O, p<0.0001] while other variables differed later. ΔPes was not related to other predictors of NIV failure at baseline. NIV-induced reduction in ΔPes of 10 cmH2O or more after 2 hours of treatment was strongly associated to avoidance of intubation, and represented the most accurate predictor of treatment success (OR=15, 95%CI 2.8-110, p=0.001, AUC=0.97, 95%CI 0.91–1, p<0.0001). Conclusions: The magnitude of inspiratory effort relief as assessed by ΔPes variation within the first 2 hours of NIV was an early and accurate predictor of NIV outcome at 24 hours

Acute exacerbation of idiopathic pulmonary fibrosis: Lessons learned from acute respiratory distress syndrome?

Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease characterized by progressive loss of lung function and poor prognosis. The so-called acute exacerbation of IPF (AE-IPF) may lead to severe hypoxemia requiring mechanical ventilation in the intensive care unit (ICU). AE-IPF shares several pathophysiological features with acute respiratory distress syndrome (ARDS), a very severe condition commonly treated in this setting. A review of the literature has been conducted to underline similarities and differences in the management of patients with AE-IPF and ARDS. During AE-IPF, diffuse alveolar damage and massive loss of aeration occurs, similar to what is observed in patients with ARDS. Differently from ARDS, no studies have yet concluded on the optimal ventilatory strategy and management in AE-IPF patients admitted to the ICU. Notwithstanding, a protective ventilation strategy with low tidal volume and low driving pressure could be recommended similarly to ARDS. The beneficial effect of high levels of positive end-expiratory pressure and prone positioning has still to be elucidated in AE-IPF patients, as well as the precise role of other types of respiratory assistance (e.g., extracorporeal membrane oxygenation) or innovative therapies (e.g., polymyxin-B direct hemoperfusion). The use of systemic drugs such as steroids or immunosuppressive agents in AE-IPF is controversial and potentially associated with an increased risk of serious adverse reactions. Common pathophysiological abnormalities and similar clinical needs suggest translating to AE-IPF the lessons learned from the management of ARDS patients. Studies focused on specific therapeutic strategies during AE-IPF are warranted

Mechanical Ventilation to Minimize Progression of Lung Injury in Acute Respiratory Failure

Mechanical Ventilation (MV) is used to sustain life in patients with acute respiratory failure. A major concern in mechanically ventilated patients is the risk of Ventilator-Induced Lung Injury (VILI), which is partially prevented by lung protective ventilation. Spontaneously breathing, non-intubated, patients with acute respiratory failure may have a high respiratory drive and breathe with large tidal volumes and potentially injurious transpulmonary pressure swings. In patients with existing lung injury, regional forces generated by the respiratory muscles may lead to injurious effects on a regional level. In addition, the increase in transmural pulmonary vascular pressure swings caused by inspiratory effort may worsen vascular leakage. Recent data suggest that these patients may develop lung injury that is similar to the VILI observed in mechanically ventilated patients. As such, we argue that application of a lung protective ventilation, today best applied with sedation and endotracheal intubation, might be considered a prophylactic therapy, rather than just a supportive therapy, to minimize the progression of lung injury from a form of patient-self inflicted lung injury (P-SILI). This has important implications for the management of these patients

Progression of regional lung strain and heterogeneity in lung injury: assessing the evolution under spontaneous breathing and mechanical ventilation

Indexación ScopusBackground: Protective mechanical ventilation (MV) aims at limiting global lung deformation and has been associated with better clinical outcomes in acute respiratory distress syndrome (ARDS) patients. In ARDS lungs without MV support, the mechanisms and evolution of lung tissue deformation remain understudied. In this work, we quantify the progression and heterogeneity of regional strain in injured lungs under spontaneous breathing and under MV. Methods: Lung injury was induced by lung lavage in murine subjects, followed by 3 h of spontaneous breathing (SB-group) or 3 h of low Vt mechanical ventilation (MV-group). Micro-CT images were acquired in all subjects at the beginning and at the end of the ventilation stage following induction of lung injury. Regional strain, strain progression and strain heterogeneity were computed from image-based biomechanical analysis. Three-dimensional regional strain maps were constructed, from which a region-of-interest (ROI) analysis was performed for the regional strain, the strain progression, and the strain heterogeneity. Results: After 3 h of ventilation, regional strain levels were significantly higher in 43.7% of the ROIs in the SB-group. Significant increase in regional strain was found in 1.2% of the ROIs in the MV-group. Progression of regional strain was found in 100% of the ROIs in the SB-group, whereas the MV-group displayed strain progression in 1.2% of the ROIs. Progression in regional strain heterogeneity was found in 23.4% of the ROIs in the SB-group, while the MV-group resulted in 4.7% of the ROIs showing significant changes. Deformation progression is concurrent with an increase of non-aerated compartment in SB-group (from 13.3% ± 1.6% to 37.5% ± 3.1%), being higher in ventral regions of the lung. Conclusions: Spontaneous breathing in lung injury promotes regional strain and strain heterogeneity progression. In contrast, low Vt MV prevents regional strain and heterogeneity progression in injured lungs. © 2020, The Author(s).https://annalsofintensivecare.springeropen.com/articles/10.1186/s13613-020-00725-

Effects of Thoracic Spine Position during Cycle Sprint Recovery

There is a paucity of research on how to recover during a race or practice immediately between cycling sprints. The subjects of this study included 13 competitive male cyclists recruited from local bicycle shops. This study utilized a pretest-posttest experimental design. Participants completed two 30-s maximal effort sprints on a cycle ergometer followed by two four-min active recovery intervals. They were randomly assigned to either a flexed thoracic spine position greater than 14° (FC) or a neutral thoracic spine position (NC) during cycling sprint recovery intervals on the first testing day and completed the other no less than 48 hours later. Recorded variables included heart rate recovery (HRR), tidal volume (VT), carbon dioxide output (VCO2), change in sprint mean power (ΔMP), and change in sprint fatigue index (ΔFI). There were no significant differences between conditions in any of the variables (p\u3e0.05). Using the Cohen’s d statistic, there was a small effect of thoracic spine position during recovery on HRR (p=0.293; d=0.33), VT (p=0.121; d=0.34), and ΔFI (p=0.289; d=0.45) from one sprint to another. However, there was no effect of thoracic position on VCO2 (p=0.794; d=0.062) or the ΔMP (p=0.853; d=0.051) from sprint to sprint. HRR was 23.5±0.40 bpm in FC and 21.3±5.0 bpm in NC. VT was 3.0±0.51 L in FC and 3.19±0.54 L in NC. VCO2 was 3.28±0.25 L/min in FC and 3.26±3.61 L/min in NC. ΔMP was -29.7±17 W in FC and -28.8±19 W in NC. ΔFI was 0.59±3.6 W/s in FC and -0.429±1.9 L in NC. There may be little to no benefit in assuming a more flexed thoracic position between cycling sprints