Related Experiment Video
Updated: Jun 12, 2026

Preoxygenation Techniques for Tracheal Intubation in Critically Ill Adults Utilizing Oxygen Mask and Noninvasive Ventilation
Published on: December 5, 2025
Continuous flow biphasic positive airway pressure by helmet in patients with acute hypoxic respiratory failure:
Stefano Isgrò1, Alberto Zanella1, Chiara Sala1
1Department of Experimental Medicine, Azienda Ospedaliera San Gerardo, University of Milano-Bicocca, via Cadore 48, 20048, Monza (MI), Italy.
Purpose:
We investigated the effects of periodical high pressure breaths (SIGH) or biphasic positive pressure ventilation (BIPAP) during helmet continuous positive airway pressure (CPAP) in patients with acute hypoxic respiratory failure.
Methods:
We used a recently developed electromechanical expiratory valve (TwinPAP, StarMed, Mirandola, Italy), which is time-cycled between two customizable positive end-expiratory pressure (PEEP) levels. We studied 21 patients (67 ± 17 years old) undergoing helmet CPAP. Continuous flow CPAP system was set at 60 l/min flow rate while maintaining clinical FiO(2) (51 ± 15%). Five steps, lasting 1 h each, were applied: (1) spontaneous breathing with PEEP 0 cmH(2)O (SB), (2) CPAP with PEEP 8 cmH(2)O (CPAP(basal)), (3) low PEEP, 8 cmH(2)O, for 25 s and high PEEP, 25 cmH(2)O, for 5 s (SIGH), (4) low PEEP, 8 cmH(2)O, for 3 s and high PEEP, 20 cmH(2)O, for 3 s (BIPAP), (5) CPAP with PEEP 8 cmH(2)O (CPAP(final)). We randomized the sequence of SIGH and BIPAP.
Results:
PaO(2) was significantly higher during all steps compared to SB. When compared to CPAP(basal), both SIGH and BIPAP induced a further increase in PaO(2). PaO(2) during SIGH and BIPAP were not different. The oxygenation improvement was maintained during CPAP(final).
Conclusions:
Superimposed, nonsynchronized positive pressure breaths delivered during helmet CPAP by means of the TwinPAP system may improve oxygenation in patients with acute hypoxemic respiratory failure, even at a rate as low as two breaths per minute.
Related Concept Videos
Mechanical Ventilation III: Noninvasive Ventilation
Noninvasive Positive-Pressure Ventilation (NIPPV)
Cardiopulmonary Resuscitation II: ACLS Airway Management
Acute Respiratory Failure-II
The underlying physiological abnormalities that contribute to hypoxemic respiratory failure include:
Treatment for Pulmonary Arterial Hypertension: Oxygen Therapy for Respiratory Failure
Oxygen therapy is vital in increasing and maintaining blood oxygen levels in PAH patients. As a result, it aids in reducing fatigue, improving...
Acute Respiratory Failure-IV
Acute Respiratory Failure-V
Ensure that patients are monitored continuously for their response to therapy, including changes in...
