Does helmet CPAP reduce carotid flow compared to oronasal mask CPAP? A randomized cross-over trial in healthy subjects.

This study aimed to assess whether delivering Continuous Positive Airway Pressure (CPAP) through a Helmet interface (H-CPAP) reduces common carotid artery flow (CCAF), compared to breathing room air (RA) or using an oronasal mask (M-CPAP). This trial is an unblinded, randomized, controlled crossover trial. The primary outcome was CCAF, measured using Doppler ultrasound. The secondary outcome was mean arterial pressure (MAP). A convenient sample of adult healthy volunteers was enrolled. Subjects were enrolled and randomized to receive either H-CPAP or M-CPAP first at + 10 cmHO, followed by the alternate intervention, each for 5 min. CCAF, mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), oxygen saturation (SpO₂), and anxiety score (AS) were recorded at baseline (RA) and after 5 min under each CPAP condition. Results showed a significant 14% reduction in CCAF between RA and H-CPAP (p = 0.001) and a 13% reduction between M-CPAP and H-CPAP (p = 0.004), with no significant difference between RA and M-CPAP. MAP remained unchanged across treatments, suggesting that the reduction in cerebral perfusion observed with H-CPAP was independent of systemic blood pressure changes. Helmet CPAP significantly reduces CCAF compared to RA and M-CPAP. While H-CPAP may offer advantages in respiratory support, its effect on cerebral perfusion suggests caution in patients with impaired cerebral autoregulation, such as those with stroke.