Evaluation of different CPAP systems in ICU population

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The aim of this study was to evaluate the effects of different CPAP delivery systems in ICU patients. We tested four systems: 1) a home-made CPAP low flow circuit with an inspiratory reservoir and expiratory water valve (LW); 2) the same system with an expiratory mechanical valve (Vital Sign's) (LM); 3) a high flow CPAP system (Jet Venturi) with an expiratory mechanical valve (Vital Sign's) (HM); 4) the CPAP of the mechanical ventilator Servo 300 (Siemens); 5) the CPAP of Servo 300 plus three additional breaths per min delivered in pressure control ventilation (i.e. plateau airway pressure of 30 cmH₂O) (ServoPC). In 13 intubated patients (9 males, PEEP level of 6 ± 2 cmH₂O and PaO₂/FiO₂ 250 ± 10) during the weaning phase we measured the breathing pattern, work of breathing, gas exchange and functional residual capacity. Data are expressed as mean ± sd.

We found no differences between the low flow, either water or mechanical valve, and the high flow CPAP systems. The Servo 300 reduced the work of breathing, while the same CPAP system plus three additional breaths caused a further reduction in work of breathing and improvement in gas exchange and FRC.

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