Background: Noninvasive ventilation (NIV) is recognized as first line ventilatory support for the management of acute pulmonary edema (APE) and chronic obstructive pulmonary disease (COPD) exacerbations. We aimed to study the prehospital management of patients in acute respiratory distress with an indication for NIV and whether they received it or not.
Methods: This retrospective study included patients ≥18 years old who were cared for acute respiratory distress in a prehospital setting. Indications for NIV were oxygen saturation (SpO2) <90% and/or respiratory rate (RR) >25/min with a presumptive diagnosis of APE or COPD exacerbation. Study population characteristics, initial and at hospital vital signs, presumptive and definitive diagnosis were analyzed. For patients who received NIV, dyspnea level was evaluated with a dyspnea verbal ordinal scale (D-VOS, 0-10) and arterial blood gas (ABG) values were obtained at hospital arrival.
Results: Among the 187 consecutive patients included in the study, most (n = 105, 56%) had experienced APE or COPD exacerbation, and 56 (30%) received NIV. In comparison with patients without NIV, those treated with NIV had a higher initial RR (35 ± 8/min vs 29 ± 10/min, p < 0.0001) and a lower SpO2 (79 ± 10 vs 88 ± 11, p < 0.0001). The level of dyspnea was significantly reduced for patients treated with NIV (on-scene D-VOS 8.4 ± 1.7 vs 4.4 ± 1.8 at admission, p < 0.0001). Among the 131 patients not treated with NIV, 41 (31%) had an indication. In the latter group, initial SpO2 was 80 ± 10% in the NIV group versus 86 ± 11% in the non-NIV group (p = 0.0006). NIV was interrupted in 9 (16%) patients due to either discomfort (n = 5), technical problem (n = 2), persistent desaturation (n = 1), or vomiting (n = 1).
Conclusions: The results of this study contribute to a better understanding of the prehospital management of patients who present with acute respiratory distress and an indication for NIV. NIV was started on clinically more severe patients, even if predefined criteria to start NIV were present. NIV allows to improve vital signs and D-VOS in those patients. A prospective study could further elucidate why patients with a suspected diagnosis of APE and COPD are not treated with NIV, as well as the clinical impact of the different strategies.
Trial registration: The study was approved by our institutional ethical committee ( CER-VD 2020-01363 ).
Keywords: Acute pulmonary edema; Acute respiratory failure; Chronic obstructive pulmonary disease exacerbation; Emergency medical services; Noninvasive ventilation; Prehospital; Respiratory distress.