Mechanical ventilation

Mechanical ventilation is used to assist or replace spontaneous respiration. Gas flow can be generated by negative pressure techniques, but it is positive pressure ventilation that is the most efficacious in intensive care. There are numerous pulmonary and extrapulmonary indications for mechanical ventilation, and it is the underlying pathology that will determine the duration of ventilation required. Ventilation modes can broadly be classified as volume- or pressure-controlled, but modern ventilators combine the characteristics of both in order to complement the diverse requirements of individual patients. To avoid confusion, it is important to appreciate that there is no international consensus on the classification of ventilation modes. Ventilator manufacturers can use terms that are similar to those used by others that describe very different modes or have completely different names for similar modes. It is well established that ventilation in itself can cause or exacerbate lung injury, so the evidence-based lung-protective strategies should be adhered to. The term acute lung injury has been abolished, whilst a new definition and classification for the acute respiratory distress syndrome has been defined.