Noninvasive Ventilation for Acute Hypoxemic Respiratory Failure/ARDS - is There a Role?

Electrical impedance tomography: Usefulness for respiratory physiotherapy in critical illnesses

Respiratory physiotherapy, including the management of invasive mechanical ventilation (MV) and noninvasive mechanical ventilation (NIV), is a key supportive intervention for critically ill patients. MV has potential for inducing ventilator-induced lung injury (VILI) as well as long-term complications related to prolonged bed rest, such as post-intensive care syndrome and intensive care unit acquired weakness. Physical and respiratory therapy, developed by the critical care team, in a timely manner, has been shown to prevent these complications. In this pathway, real-time bedside monitoring of changes in pulmonary aeration and alveolar gas distribution associated with postural positioning, respiratory physiotherapy techniques and changes in MV strategies can be crucial in guiding these procedures, providing safe therapy and prevention of potential harm to the patient. Along this path, electrical impedance tomography (EIT) has emerged as a new key non-invasive bedside strategy free of radiation, to allow visualization of lung recruitment. This review article presents the main and potential applications of EIT in relation to physiotherapy techniques in the ICU setting.

Risk factors for non-invasive ventilation failure in influenza infection with acute respiratory failure in emergency department

OBJECTIVE

Non-invasive ventilation (NIV) has been widely used in hypoxemic acute respiratory failure (ARF) due to influenza pneumonia in the emergency department (ED). However, NIV used in influenza-associated acute respiratory failure had a variable rate of failure. Previous studies have reported that prolonged use of NIV was associated with increased mortality. Our study aimed to identify risk factors for NIV failure in influenza infection with acute respiratory failure in ED.

METHOD

We performed a retrospective cohort observational study. Enrolled patients were older than 18 years who used NIV due to influenza infection with ARF between 1 January 2017 to 31 December 2018 in Ramathibodi Emergency Department. Patients characteristics, comorbidity, clinical, laboratory outcome, chest imaging, initial NIV setting, and parameters were collected in ED setting. Sequential organ failure assessment (SOFA) score and PaO2/FiO2 (PF) ratio were calculated from the first arterial blood gas in ED. We followed the outcome success or failure of the NIV used.

RESULTS

A total of 162 patients were enrolled and 72 (44%) suffered NIV failure in influenza infection with ARF. We used univariate and multivariate logistic analyses to assess risk factors for NIV failure. The ability of risk factor to predict NIV failure was analyzed using the area under the receiver operating characteristic (AUROC). Risk factors of NIV failure included SOFA score (P = 0.001), PF ratio (P = 0.001) and quadrant infiltrations in chest x-rays (CXR) (P = 0.001). SOFA score, PF ratio, and number quadrant infiltrations in chest radiography have good ability to predict NIV failure, AUROC 0.894 (95%CI 0.839-0.948), 0.828 (95%CI 0.764-0.892), and 0.792 (95%CI 0.721-0.863), respectively and no significant difference in the ability to predict NIV failure among three parameters. The use of PF ratio plus number quadrant infiltrations in chest radiography demonstrated a higher predictive ability for NIV failure in influenza infection with ARF.

CONCLUSIONS

SOFA score, PF ratio, and quadrant infiltrations in chest radiography were good predictors of NIV failure in influenza infection with ARF.

Noninvasive ventilation for acute hypoxemic respiratory failure in patients with COVID-19

Aim

Noninvasive ventilation (NIV) is known to reduce intubation in patients with acute hypoxemic respiratory failure (AHRF). We aimed to assess the outcomes of NIV application in COVID-19 patients with AHRF.

Materials & methods

In this retrospective cohort study, patients with confirmed diagnosis of COVID-19 and AHRF receiving NIV in general wards were recruited from two university-affiliated hospitals. Demographic, clinical, and laboratory data were recorded at admission. The failure of NIV was defined as intubation or death during the hospital stay.

Results

Between April 8 and June 10, 2020, 61 patients were enrolled into the final cohort. NIV was successful in 44 out of 61 patients (72.1%), 17 patients who failed NIV therapy were intubated, and among them 15 died. Overall mortality rate was 24.6%. Patients who failed NIV were older, and had higher respiratory rate, PaCO₂, D-dimer levels before NIV and higher minute ventilation and ventilatory ratio on the 1-st day of NIV. No healthcare workers were infected with SARS-CoV-2 during the study period.

Conclusions

NIV is feasible in patients with COVID-19 and AHRF outside the intensive care unit, and it can be considered as a valuable option for the management of AHRF in these patients.

Medical Conditions

An acute hypoxemic respiratory failure (AHRF) has high possibilities to develop acute respiratory distress syndrome (ARDS) and increased death risk. AHRF which represents a common end-point to multiple pathological processes either local or systemic may have many medical conditions as aetiology. The causes may be pulmonary and extrapulmonary. Between pulmonary determinants, pneumonia and bacterial and virus infection diseases are the most frequent disease associated with AHRF. On the other hand, many non-infectious etiologic conditions, such as blunt chest contusion, multiple injuries, aspiration of gastric contents, inhalation burns, pancreatitis, and blood transfusions may cause ARDS.