Noninvasive positive pressure ventilation delivered by helmet vs. standard face mask.

OBJECTIVE: This bench and human study compared large and small helmets with face mask (FM) for delivery of noninvasive positive pressure ventilation. DESIGN: A lung simulator was employed, and the human study involved six healthy subjects. We evaluated a continuous high-flow (CPAPHF), low flow (CPAPLF), ventilator (CPAPVENT) CPAP, and pressure support ventilation (PSV 10 and 20 cmH2O). In the human study we used CPAPHF, CPAPVENT, and PSV 5 cmH2O. PEEP was 5 cmH2O. MEASUREMENTS: In the bench study during CPAP we measured the negative airway pressure time product (areaCPAP), i.e., the area of airway pressure (Paw) under PEEP and during PSV the pressure airway time product (areaPSV), i.e., the area of Paw from onset to end of inspiratory flow. In the human study we measured the breathing pattern and work of breathing (WOB). RESULTS: In the bench study during CPAPLF the helmets had a lower areaCPAP than the FM, while during CPAPHF the three interfaces had similar areaCPAP. Using CPAPVENT and PSV the FM reduced areaCPAP and increased areaPSV compared to helmets. At 20 cmH2O of PSV using helmets areaPSV was similar to that obtained at 10 cmH2O of PSV using the FM. In human study using CPAPHF and CPAPVENT the tree interfaces had similar effects on breathing pattern and WOB, while using PSV the FM reduced WOB more than helmets. CONCLUSIONS: During CPAPLF helmets were more efficient than FM, while during CPAPHF the three interfaces were comparable. Using CPAPVENT and PSV, FM was more efficient than helmets

Non-invasive ventilation delivered by conventional interfaces and helmet in the emergency department.

Non-invasive positive pressure ventilation is increasingly used as a first-line treatment for respiratory failure. Non-invasive positive pressure ventilation can reduce the complications of endotracheal intubation such as barotrauma, nosocomial infections and the need for sedation. Non-invasive positive pressure ventilation has been shown to reduce the rate of endotracheal intubation in acute cardiogenic pulmonary oedema (27%), in chronic obstructive pulmonary disease (21%), and in acute respiratory failure (17%). Non-invasive positive pressure ventilation can be successfully delivered in the emergency department or in the general ward. However, the criteria for interrupting non-invasive positive pressure ventilation must be stricter (i.e. failure to improve gas exchange within 30 min) than in the general ward. One of the main reasons for the failure of non-invasive positive pressure ventilation lies in the technical problems caused by the face mask. We recently developed a new interface, the 'helmet', to deliver non-invasive positive pressure ventilation. When using the helmet instead of a face mask an increase of 10 cm H(2)O of pressure support and a fast pressurization rate are recommended. In a lung model and in healthy individuals the helmet reduced inspiratory effort. In hypoxemic patients the helmet reduced the intubation rate and the incidence of face mask-related complications. We believe that the helmet can extend the application of non-invasive positive pressure ventilation in different categories of patients with respiratory failure.

Sigh in supine and prone position during acute respiratory distress syndrome.

Interventions aimed at recruiting the lung of patients with acute respiratory distress syndrome (ARDS) are not uniformly effective. Because the prone position increases homogeneity of inflation of the lung, we reasoned that it might enhance its potential for recruitment. We ventilated 10 patients with early ARDS (PaO2/FIO2, 121 +/- 46 mm Hg; positive end-expiratory pressure, 14 +/- 3 cm H2O) in supine and prone, with and without the addition of three consecutive "sighs" per minute to recruit the lung. Inspired oxygen fraction, positive end-expiratory pressure, and minute ventilation were kept constant. Sighs increased PaO2 in both supine and prone (p < 0.01). The highest values of PaO2 (192 +/- 41 mm Hg) and end-expiratory lung volume (1840 +/- 790 ml) occurred with the addition of sighs in prone and remained significantly elevated 1 hour after discontinuation of the sighs. The increase in PaO2 associated with the sighs, both in supine and prone, correlated linearly with the respective increase of end-expiratory lung volume (r = 0.82, p < 0.001). We conclude that adding a recruitment maneuver such as cyclical sighs during ventilation in the prone position may provide optimal lung recruitment in the early stage of ARDS.