Influence of Noninvasive Ventilation Protocol on Intubation Rates in Subjects With De Novo Respiratory Failure

Noninvasive ventilation and high-flow nasal oxygen for acute respiratory failure: is less more?

PURPOSE OF REVIEW

High-flow nasal oxygen and noninvasive ventilation (NIV) are two strategies representing an alternative to standard oxygen in the management of respiratory failure.

RECENT FINDINGS

Although high-flow nasal oxygen has shown promising results in patients with de-novo acute respiratory failure, further large clinical trials are needed to determine the best oxygenation strategy. As NIV may have deleterious effects, especially in patients generating strong inspiratory efforts, protective NIV using higher levels of positive-end expiratory pressure, more prolonged sessions and additional interfaces such as helmets should be assessed in the future. Whereas NIV is the first-line ventilation strategy in patients with acute exacerbation of chronic lung diseases, high-flow nasal oxygen could be an alternative to NIV after partial reversal of respiratory acidosis. To prevent severe hypoxemia during intubation of hypoxemic patients or to prevent postextubation respiratory failure in patients at high-risk of reintubation, NIV is the best strategy for preoxygenation or immediately after extubation in ICUs.

SUMMARY

New large-scale clinical trials are needed to compare high-flow nasal oxygen with standard oxygen in patients with de-novo acute respiratory failure to determine the reference treatment. After which, more protective NIV could be assessed among the more severe patients.

Outcomes of an intermediate respiratory care unit in the COVID-19 pandemic

BACKGROUND

15% of COVID-19 patients develop severe pneumonia. Non-invasive mechanical ventilation and high-flow nasal cannula can reduce the rate of endotracheal intubation in adult respiratory distress syndrome, although failure rate is high.

OBJECTIVE

To describe the rate of endotracheal intubation, the effectiveness of treatment, complications and mortality in patients with severe respiratory failure due to COVID-19.

METHODS

Prospective cohort study in a first-level hospital in Madrid. Patients with a positive polymerase chain reaction for SARS-CoV-2 and admitted to the Intermediate Respiratory Care Unit with tachypnea, use of accessory musculature or SpO2 <92% despite FiO2> 0.5 were included. Intubation rate, medical complications, and 28-day mortality were recorded. Statistical analysis through association studies, logistic and Cox regression models and survival analysis was performed.

RESULTS

Seventy patients were included. 37.1% required endotracheal intubation, 58.6% suffered medical complications and 24.3% died. Prone positioning was independently associated with lower need for endotracheal intubation (OR 0.05; 95% CI 0.005 to 0.54, p = 0.001). The adjusted HR for death at 28 days in the group of patients requiring endotracheal intubation was 5.4 (95% CI 1.51 to 19.5; p = 0.009).

CONCLUSIONS

The rate of endotracheal intubation in patients with severe respiratory failure from COVID-19 was 37.1%. Complications and mortality were lower in patients in whom endotracheal intubation could be avoided. Prone positioning could reduce the need for endotracheal intubation.

Reliability of methods to estimate the fraction of inspired oxygen in patients with acute respiratory failure breathing through non-rebreather reservoir bag oxygen mask

Severity of hypoxaemia can be assessed using the partial pressure of arterial oxygen to fraction of inspired oxygen ratio (FiO2). However, in patients breathing through non-rebreather reservoir bag oxygen mask, accuracy of bedside FiO2 estimation methods remains to be tested. In a post-hoc analysis of a multicentre clinical trial, three FiO2 estimation methods were compared with FiO2 measured with a portable oxygen analyser introduced in the oxygen mask. Among 262 patients analysed, mean (SD) measured FiO2 was 65% (13). The 3%-formula (21% + oxygen flow rate in L/min × 3) was the most accurate method to estimate FiO2. Other methods overestimated FiO2 and hypoxaemia severity, so they should be avoided.