The ins and outs of ventilation 1. Basic principles

Broadly speaking, patients that have difficulty ventilating and/or difficulty oxygenating could benefit from mechanical ventilation. Hypoventilation for the purposes of this article is defined as partial pressure of carbon dioxide (PaCO2) in arterial blood that is greater than 60 mmHg. Oxygenation difficulties may exist when the partial pressure of oxygen (PaO2) in arterial blood falls below 60 mmHg on room air, and especially if it remains low despite oxygen supplementation. Under anaesthesia with volatile agents or injectable agents (especially if potent opioids such as fentanyl or remifentanil are administered by infusion), hypoventilation occurs when spontaneous breathing becomes excessively depressed. In addition, the administration of neuromuscular blockers will abolish the patient’s ability to breathe spontaneously. In the intensive care setting, mechanical ventilation of the lungs may be required to support patients with a variety of conditions (eg, pulmonary parenchymal diseases such as acute respiratory distress syndrome or E Q U IP M E N T