Continuous flow biphasic positive airway pressure by helmet in patients with acute hypoxic respiratory failure: effect on oxygenation.
OBJECTIVE
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.
Isgrò
Stefano
S
Department of Experimental Medicine, Azienda Ospedaliera San Gerardo, University of Milano-Bicocca, via Cadore 48, 20048, Monza (MI), Italy.
Zanella
Alberto
A
Department of Experimental Medicine, Azienda Ospedaliera San Gerardo, University of Milano-Bicocca, via Cadore 48, 20048, Monza (MI), Italy.
Sala
Chiara
C
Department of Experimental Medicine, Azienda Ospedaliera San Gerardo, University of Milano-Bicocca, via Cadore 48, 20048, Monza (MI), Italy.
Grasselli
Giacomo
G
Department of Perioperative Medicine and Intensive Care, San Gerardo Hospital, Via Pergolesi 33, 20052, Monza (MI), Italy.
Foti
Giuseppe
G
Department of Perioperative Medicine and Intensive Care, San Gerardo Hospital, Via Pergolesi 33, 20052, Monza (MI), Italy.
Pesenti
Antonio
A
Department of Experimental Medicine, Azienda Ospedaliera San Gerardo, University of Milano-Bicocca, via Cadore 48, 20048, Monza (MI), Italy.|Department of Perioperative Medicine and Intensive Care, San Gerardo Hospital, Via Pergolesi 33, 20052, Monza (MI), Italy.
Patroniti
Nicolò
N
Department of Experimental Medicine, Azienda Ospedaliera San Gerardo, University of Milano-Bicocca, via Cadore 48, 20048, Monza (MI), Italy. nicolo.patroniti@unimib.it.|Department of Perioperative Medicine and Intensive Care, San Gerardo Hospital, Via Pergolesi 33, 20052, Monza (MI), Italy. nicolo.patroniti@unimib.it.
D000368:Aged; D045422:Continuous Positive Airway Pressure / Q000295:instrumentation*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010100:Oxygen / Q000378:metabolism*; D012131:Respiratory Insufficiency / Q000503:physiopathology / Q000628:therapy*
D010100:Oxygen