Mechanical ventilation or artificial ventilation refers to the mechanical means that are used in assisting or replacing spontaneous breathing. It is generally carried out by a machine called ventilator or by a qualified anesthesiologist and respiratory therapist. The four types of mechanical ventilators are transport ventilators, intensive-care ventilators, neonatal ventilators and positive airway pressure ventilators. Mechanical ventilation can be classified into invasive and non-invasive ventilation. Invasive ventilation involves the use of an instrument inside the trachea through mouth. Non-invasive ventilation includes usage of masks and is done in conscious patients. The two main types of mechanical ventilation include positive pressure ventilation and negative pressure ventilation. In positive pressure ventilation, air is pushed into lungs through airways whereas negative pressure ventilation involves sucking of air into lungs by stimulating movement of the chest. Mechanical ventilation is used in cases of acute severe asthma, acute lung injury, apnea, hypoxemia, etc. The topics covered in this extensive book deal with the core subject of mechanical ventilation. It provides significant information of this discipline to help develop a good understanding of various types that fall under mechanical ventilation. This book will serve as a reference to a broad spectrum of readers.