A crucial step in the transition from mechanical ventilation to extubation is the successful performance of a spontaneous breathing trial (SBT). The American College of Chest Physicians (ACCP) Guidelines recommend removal of the endotracheal tube upon successful completion of a SBT. However, this does not guarantee successful extubation as there remains a risk of re-intubation. Guidelines have outlined ventilator liberation protocols, selected use of non-invasive ventilation on extubation, early mobilization, and dynamic ventilator metrics to prevent and better predict extubation failure. However, a significant percentage of patients still fail mechanical ventilation discontinuation. A common reason for re-intubation is having a weak cough strength, which reflects the inability to protect the airway.Evaluation of cough strength via objective measures using peak expiratory flow rate is a non-invasive and easily reproducible assessment which can predict extubation failure. We conducted a narrative review of the literature regarding use of cough strength as a predictive index for extubation failure risk. Results of our review show that cough strength, quantified objectively with a cough peak expiratory flow measurement (CPEF), is strongly associated with extubation success. Furthermore, various cutoff thresholds have been identified and can provide reasonable diagnostic accuracy and predictive power for extubation failure.These results demonstrate that measurement of the CPEF can be a useful tool to predict extubation failure in patients on MV who have passed a SBT. In addition, the data suggest that this diagnostic modality may reduce ICU length of stay, ICU expenditures, and morbidity and mortality.

Introduction In COVID-19 associated hypoxemic acute respiratory failure (ARF) without mandatory indication for urgent endotracheal intubation, a trial of CPAP may be considered. We aimed to evaluate HACOR (heart rate, acidosis, consciousness, oxygenation, respiratory rate) score performance in these patients as predictor of CPAP failure. Methods Prospective observational multicentric study (three centers in different countries), including adult patients with SARS-CoV-2 pneumonia admitted to a respiratory intermediate care unit, presenting PaO 2 /FiO 2 < 300 and PaCO 2 < 45 mmHg, who received CPAP. One hour after starting CPAP, HACOR was calculated. Results We enrolled 128 patients, mean age 61,7 years. Mean HACOR at one hour after starting CPAP was 3,27 ± 3,84 and mean PaO 2 /FiO 2 was 203,30 ± 92,21 mmHg; 35 patients (27,3%) presented CPAP failure: 29 underwent oro-tracheal intubation and 6 died due to COVID-19 (all having a do-not-intubate order). HACOR accuracy for predicting CPAP failure was 82,03%, while PaO 2 /FiO2 accuracy was 81,25%. Conclusion Although HACOR score had a good diagnostic performance in predicting CPAP failure in COVID-19-related ARF, PaO 2 /FiO 2 has also shown to be a good predictor of failure.

Unlike general anaesthesia, neuraxial anaesthesia (NA) reduces the burden and risk of respiratory adverse events in the post-operative period. However, both patients affected by chronic obstructive pulmonary disease (COPD) and chest wall disorders and/or neuromuscular diseases may experience the development or the worsening of respiratory failure, even during surgery performed under NA; this latter negatively affects the function of accessory respiratory muscles, resulting in a blunted central response to hypercapnia and possibly in an exacerbation of cardiac dysfunction (NA-induced relative hypovolemia). According to European Respiratory Society (ERS) and American Thoracic Society (ATS) guidelines, non-invasive ventilation (NIV) is effective in the post-operative period for the treatment of both impaired pulmonary gas exchange and ventilation, while the intra-operative use of NIV in association with NA is just anecdotally reported in the literature. Whilst NIV does not assure a protected patent airway and requires the patient's cooperation, it is a handy tool during surgery under NA: NIV is reported to be successful for treatment of acute respiratory failure; it may be delivered through the patient's home ventilator, may reverse hypoventilation induced by sedatives or inadvertent spread of anaesthetic up to cervical dermatomes, and allow the avoidance of intubation in patients affected by chronic respiratory failure, prolonging the time of non-invasiveness of respiratory support (i.e., neuromuscular patients needing surgery). All these advantages could make NIV preferable to oxygen in carefully selected patients.

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