Non-invasive ventilation

Non-invasive ventilation (NIV) refers to the delivery of mechanical ventilation to the lungs using techniques that do not require an endotracheal airway. Essentially, there are two modalities: continuous positive airway pressure (CPAP) and pressure support ventilation (NIPSV). In acute pulmonary edema (APE) both modalities have shown a faster improvement in gas exchange and physiologic parameters with respect to conventional oxygen therapy. CPAP is a simple technique that may reduce preload and afterload, increasing cardiac output in some patients. It has been successfully used in APE in the last 30 years, demonstrating a reduction in the intubation rate and mortality. The most common level of pressure is 10 cmH(2)O. NIPSV is a more complex mode that requires a ventilator and experience. It is usually applied with an expiratory pressure (EPAP or PEEP), resulting in a bilevel pressure modality (BIPAP). This technique has been introduced most recently in APE and has also shown a reduction in the intubation rate and a tendency to reduce mortality. The inspiratory help may be particularly useful in those patients with fatigue and hypercapnia. However, this hypothetical advantage over CPAP has not been demonstrated in comparative trials. The ventilator is usually set at 5 cmH(2)O of EPAP and inspiratory pressure between 12 and 25 cmH(2)O, although initially, the level of pressure support is lower. It is essential to achieve a good adaptation and synchronicity between the patient and the ventilator, reducing leakage to a minimum. The use of facial masks, high FiO(2), and sedation with opiates are complementary maneuvers that may be recommended in this context in the majority of patients.