Ventilators designed to provide support to patients who do not require complex critical care ventilators. Most devices use positive pressure to deliver gas to the lungs at normal breathing rates and tidal volumes through an endotracheal tube, a tracheostomy cannula, or a mask, typically when ventilation is needed only at night. These ventilators include a control system and alarms; some ventilators also include oxygen accumulators and heating and humidifying capabilities. Portable/home care ventilators may use several methods of cycling (e.g., volume, time) and several ventilation modes, including control, assist/control, and synchronized intermittent mandatory ventilation (SIMV) modes. Power is typically supplied from a power line or from an internal or external battery (e.g., a car batte