Use of non-invasive ventilation in acute pulmonary edema and chronic obstructive pulmonary disease exacerbation in emergency medicine: predictors of failure.

OBJECTIVE: This study analyzed acute respiratory failure caused by acute pulmonary edema, as well as chronic obstructive pulmonary disease exacerbation, that was treated with non-invasive mechanical ventilation to identify the factors that are associated with the success or failure non-invasive mechanical ventilation in urgent and emergency service.

METHODS: This study was a prospective, descriptive and analytical study. We included patients of both genders aged >18 years who used non-invasive mechanical ventilation due to acute respiratory failure that was secondary to acute pulmonary edema or chronic obstructive pulmonary disease exacerbation. Patients with acute respiratory failure that was secondary to pathologies other than acute pulmonary edema and chronic obstructive pulmonary disease or who presented with contraindications for the technique were excluded. Expiratory pressures between 5 and 8 cmH2O and inspiratory pressures between 10 and 12 cmH2O were used. Supplemental oxygen maintained peripheral oxygen saturation at >90%. The primary outcome was endotracheal intubation.

RESULTS: A total of 152 patients were included. The median non-invasive mechanical ventilation time was 6 hours (range 1 - 32 hours) for chronic obstructive pulmonary disease patients (n=60) and 5 hours (range 2 - 32 hours) for acute pulmonary edema patients (n=92). Most (75.7%) patients progressed successfully. However, reduced APACHE II scores and lower peripheral oxygen saturation were observed. These results were statistically significant in patients who progressed to intubation (p<0.001). BiPAP (Bi-level Positive Airway Pressure portable ventilator), as continuous positive airway pressure use increased the probability of endotracheal intubation 2.3 times (p=0.032). Patients with acute pulmonary edema and elevated GCS scores also increased the probability of success.

CONCLUSION: Respiratory frequency >25 rpm, higher APACHE II scores, BiPAP use and chronic obstructive pulmonary disease diagnosis were associated with endotracheal intubation. Higher GCS and SpO2 values were associated with NIV success. Non-invasive mechanical ventilation can be used in emergency services in acute respiratory failure cases caused by acute pulmonary edema and chronic obstructive pulmonary disease exacerbation, but patients with variables related to a higher percentage of endotracheal intubation should be specially monitored.