BACKGROUND: In COVID-19 patients with acute respiratory distress syndrome (ARDS), the effectiveness of ventilatory rescue strategies remains uncertain, with controversial efficacy on systemic oxygenation and no data available regarding cerebral oxygenation and hemodynamics .

METHODS: This is a prospective observational study conducted at San Martino Policlinico Hospital, Genoa, Italy . We included adult COVID-19 patients who underwent at least one of the following rescue therapies: recruitment maneuvers (RMs), prone positioning (PP), inhaled nitric oxide (iNO), and extracorporeal carbon dioxide (CO 2) removal (ECCO 2 R). Arterial blood gas values (oxygen saturation [SpO 2], partial pressure of oxygen [PaO 2] and of carbon dioxide [PaCO 2] ) and cerebral oxygenation (rSO 2) were analyzed before (T0) and after (T1) the use of any of the aforementioned rescue therapies . The primary aim was to assess the early effects of different ventilatory rescue therapies on systemic and cerebral oxygenation . The secondary aim was to evaluate the correlation between systemic and cerebral oxygenation in COVID-19 patients .

RESULTS: Forty-five rescue therapies were performed in 22 patients . The median [interquartile range] age of the population was 62 [57-69] years, and 18/22 [82 %] were male . After RMs, no significant changes were observed in systemic PaO 2 and PaCO 2 values, but cerebral oxygenation decreased significantly (52 [51-54]% vs. 49 [47-50]%, p <0.001). After PP, a significant increase was observed in PaO 2 (from 62 [56-71] to 82 [76-87] mmHg, p = 0.005) and rSO 2 (from 53 [52-54]% to 60 [59-64]%, p = 0.005). The use of iNO increased PaO 2 (from 65 [67-73] to 72 [67-73] mmHg, p = 0.015) and rSO 2 (from 53 [51-56]% to 57 [55-59]%, p = 0.007). The use of ECCO 2 R decreased PaO 2 (from 75 [75-79] to 64 [60-70] mmHg, p = 0.009), with reduction of rSO 2 values (59 [56-65]% vs. 56 [53-62]%, p = 0.002). In the whole population, a significant relationship was found between SpO 2 and rSO 2 (R = 0.62, p <0.001) and between PaO 2 and rSO 2 (R0 0.54, p <0.001).

CONCLUSIONS: Rescue therapies exert specific pathophysiological mechanisms, resulting in different effects on systemic and cerebral oxygenation in critically ill COVID-19 patients with ARDS. Cerebral and systemic oxygenation are correlated . The choice of rescue strategy to be adopted should take into account both lung and brain needs . Registration The study protocol was approved by the ethics review board (Comitato Etico Regione Liguria, protocol n. CER Liguria : 23/2020).