Non-invasive ventilation

Non-invasive ventilation (NIV) is the use of breathing support administered through a face mask or nasal mask. Air, usually with added oxygen, is given through the mask under positive pressure; generally the amount of pressure is alternated depending on whether someone is breathing in or out. It is termed 'non-invasive' because it is delivered with a mask that is tightly fitted to the face, but without a need for tracheal intubation (a tube through the mouth into the windpipe). While there are similarities with regards to the interface, NIV is not the same as continuous positive airway pressure (CPAP), which applies a single level of positive airway pressure throughout the whole respiratory cycle; CPAP does not deliver ventilation but is occasionally used in conditions also treated with NIV. Non-invasive ventilation is used in acute respiratory failure caused by a number of medical conditions, most prominently chronic obstructive pulmonary disease (COPD); numerous studies have shown that appropriate use of NIV reduces the need for invasive ventilation and its complications. Furthermore, it may be used on a long-term basis in people who cannot breathe independently as a result of a chronic condition. NIV can be used acutely and long-term. In some people who have presented with acute respiratory failure, there is an ongoing need for long-term use of NIV at home. NIV for acute respiratory failure is used particularly for severe exacerbations of chronic obstructive pulmonary disease (COPD) but also for acute decompensated heart failure and other acute conditions. In acute cardiogenic pulmonary oedema caused by decompensated heart failure, the quality of evidence is poor but studies have shown a reduced risk of death and a decreased need for tracheal intubation for both NIV and CPAP. Chronic use of NIV ('home NIV') may be indicated for severe COPD. Home NIV may also be indicated in people with neuromuscular disease and chest wall deformity. People with obesity hypoventilation syndrome often require NIV initially in their care, but many can be switched to CPAP. People with motor neuron disease (MND) may require home NIV in the course of their illness. Guidelines in the United Kingdom stipulate that assessment of respiratory function is part of the multidisciplinary management of MND. A number of terms have been used in the medical literature to describe NIV. The more formal name non-invasive positive pressure ventilation (NPPV or NIPPV) has been used to distinguish it from the use of the now very rare negative pressure ventilator ('iron lung'). The brand name BiPAP/BIPAP has also enjoyed a degree of popularity, after an early NIV machine produced by Respironics, but its use is now discouraged.