Potentially harmful effects of inspiratory synchronization during pressure preset ventilation

• Published in: Intensive care medicine 2013-11, Vol.39 (11), p.2003-2010
• Main Authors: Richard, J. C. M., Lyazidi, A., Akoumianaki, E., Mortaza, S., Cordioli, R. L., Lefebvre, J. C., Rey, N., Piquilloud, L., Sferrazza-Papa, G. F., Mercat, A., Brochard, L.
• Format: Article
• Language: English
• Subjects: Acute respiratory distress syndrome; Anesthesiology; Critical Care Medicine; Emergency Medicine; Female; Humans; Intensive; Intensive care; Lung Compliance - physiology; Male; Medical colleges; Medical research; Medicine; Medicine & Public Health; Medicine, Experimental; Original; Pain Medicine; Patients; Pay-per-view television; Pediatrics; Pneumology/Respiratory System; Positive-Pressure Respiration - adverse effects; Positive-Pressure Respiration - methods; Pulmonary Gas Exchange - physiology; Pulmonary Ventilation - physiology; Respiratory distress syndrome; Respiratory Distress Syndrome, Adult - physiopathology; Respiratory Distress Syndrome, Adult - therapy; Respiratory Mechanics - physiology; Ventilators
• ISSN: 0342-4642; 1432-1238
• DOI: 10.1007/s00134-013-3032-7

Purpose Pressure preset ventilation (PPV) modes with set inspiratory time can be classified according to their ability to synchronize pressure delivery with patient’s inspiratory efforts (i-synchronization). Non-i-synchronized (like airway pressure release ventilation, APRV), partially i-synchronized (like biphasic airway pressure), and fully i-synchronized modes (like assist-pressure control) can be distinguished. Under identical ventilatory settings across PPV modes, the degree of i-synchronization may affect tidal volume ( V T ), transpulmonary pressure ( P TP ), and their variability. We performed bench and clinical studies. Methods In the bench study, all the PPV modes of five ventilators were tested with an active lung simulator. Spontaneous efforts of −10 cmH 2 O at rates of 20 and 30 breaths/min were simulated. Ventilator settings were high pressure 30 cmH 2 O, positive end-expiratory pressure (PEEP) 15 cmH 2 O, frequency 15 breaths/min, and inspiratory to expiratory ratios (I:E) 1:3 and 3:1. In the clinical studies, data from eight intubated patients suffering from acute respiratory distress syndrome (ARDS) and ventilated with APRV were compared to the bench tests. In four additional ARDS patients, each of the PPV modes was compared. Results As the degree of i-synchronization among the different PPV modes increased, mean V T and P TP swings markedly increased while breathing variability decreased. This was consistent with clinical comparison in four ARDS patients. Observational results in eight ARDS patients show low V T and a high variability with APRV. Conclusion Despite identical ventilator settings, the different PPV modes lead to substantial differences in V T , P TP , and breathing variability in the presence spontaneous efforts. Clinicians should be aware of the possible harmful effects of i-synchronization especially when high V T is undesirable.