Escalation to invasive mechanical ventilation in noninvasive ventilation failure: some insights about methodology

Dear Editor in Chief Noninvasive ventilation (NIV) is defined as ventilatory support with positive pressure in the airway without using an invasive artificial airway, endotracheal or tracheostomy tube. It is essential in cases when we want to avoid some of complications that are characteristic of invasive mechanical ventilation (IMV) such as nosocomial infections, need for sedation, decrease the possibility of developing delirium, and spontaneous pneumomediastinum [1]. According to some authors, NIV is more suitable than IMV in patients with acute hypoxemic respiratory failure (AHRF), but nowadays, it has been proven that high-flow nasal cannula (HFNC) has the same effects as NIV and advantages in terms of easier tolerance, being more physiological, and patients have opportunity to talk, drink, and eat while connected to HFNC [2]. In one prospective randomized trial, which was conducted between March 2019 and May 2020, 100 patients who were hospitalized in the ICU underwent randomization, where 50 patients were connected to NIV and other 50 were assigned to HFNC. The exclusion criteria were coma, hemodynamic instability, life-threatening arrhythmia, pneumothorax, facial burn or trauma, active gastrointestinal bleeding, tracheotomy, PaCO2 more than 45 mmHg, and chronic respiratory failure. They got the following results: the length of ICU stay was lower in the HFNC group (5.06 ± 2.80 vs. 7.42 ± 4.24), and also hospital stay duration was lower in the HFNC group (7.46 ± 3.36 vs. 10.84 ± 5.96). Days from admission to IMV were longer in the HFNC group (6 vs. 3). When they measured the frequency of ventilation interruption in the first and second day, it was significantly lower in the HFNC group. On the contrary, NIV group showed higher hospital mortality, whereas complications also were higher in NIV group. Escalation to IMV was predominantly in the NIV group, and it referred to increased respiratory distress and worsening hypoxemia. Sequential organ failure assessment scores measured at 24, 48, and 72 h after connection were statistically significant in the HFNC group. Regarding the vital parameters, the following results were obtained: values of blood pressure were nonsignificant in both group, whereas after connection to NIV or HFNC, the values of PaCO2 were significantly lower in HFNC, and values of PaO2 and SaO2 were significantly higher. Overall, 50% of patients in the NIV group needed intubation, whereas 18% in the HFNC group [3]. Some studies also have shown that HFNC is more suitable for the treatment of AHRF: Frat et al. [4] also showed that HFNC was associated with lower rates of hospital mortality. Shen and Zhang [5] found lower intubation rates in the HFNC group, whereas Koga et al. [6] found that the HFNC group had a higher rate of failure compared with the NIV group and the most common causes for escalation were worsening of hypoxemia and respiratory distress. Nowadays, a worrying fact is the use of NIV in patients with AHRF with an altered level of consciousness. In a randomized clinical trial, some authors compared the efficacy of NIV versus Venturi mask with FiO2 of 50% based on survival and avoidance of endotracheal intubation in 105 patients with Glasgow coma scale 12–15 and AHRF. NIV was independently associated with a decreased risk of intubation and 90-day mortality [7], whereas Gonçalves et al. [8] found that in patients with a HACOR score more than 5, the risk for NIV failure reached up to 80%. The use of NIV in patients with low levels of consciousness, especially in those with Glasgow coma scale less than 10, must be done cautiously. Conclusion The use of HFNC was accompanied with reduced rate of mortality, length of hospital stay, and rate of escalation to endotracheal intubation in comparison with NIV. HFNC represents a new and efficient option for early treatment of adults with AHRF. Financial support and sponsorship Nil. Conflicts of interest There are no conflict of interest.