Neurally adjusted ventilatory assist preserves cerebral blood flow velocity in patients recovering from acute brain injury

Neurally adjusted ventilatory assist (NAVA) has never been applied in patients recovering from acute brain injury (ABI) because neural respiratory drive could be affected by intracranial disease with detrimental effects on cerebral blood flow (CBF) velocity. Our primary aim was to assess the impact of NAVA and pressure support ventilation (PSV) on CBF velocity. In fifteen adult patients recovering from ABI and undergoing invasive assisted ventilation, PSV and NAVA were applied over 30-min-lasting trials, in the following sequence: PSV1, NAVA, and PSV2. While PSV was set to deliver a tidal volume ranging between 6 and 8 ml kg−1 of predicted body weight, in NAVA the level of assistance was chosen to achieve the same inspiratory peak airway pressure as PSV. At the end of each trial, a sonographic evaluation of CBF mean velocity was bilaterally obtained on the middle cerebral artery and an arterial blood gas sample was taken for analysis. CBF mean velocity was 51.8 [41.9,75.2] cm  s−1 at baseline, 51.9 [43.4,71.0] cm s−1 in PSV1, 53.6 [40.7,67.7] cm s−1 in NAVA, and 49.5 [42.1,70.8] cm s−1 in PSV2 (p = 0.0514) on the left and 50.2 [38.0,77.7] cm s−1 at baseline, 47.8 [41.7,68.2] cm s−1 in PSV1, 53.9 [40.1,78.5] cm s−1 in NAVA, and 55.6 [35.9,74.1] cm s−1 in PSV2 (p = 0.8240) on the right side. No differences were detected for pH (p = 0.0551), arterial carbon dioxide tension (p = 0.8142), and oxygenation (p = 0.0928) over the entire study duration. NAVA and PSV preserved CBF velocity in patients recovering from ABI.