Venturi Oxygen Delivery
Oxygen supplementation during emergencies is a life-saving treatment. The atmospheric air contains 21% oxygen, which is inadequate for those with some types of breathlessness. We can enhance the amount of oxygen delivered to a patient in distress using specific devices. The most popular among such devices are the Venturi devices.
Venturi masks work on the Bernoulli’s principle, which states that there is a decrease in pressure as the velocity increases (in a tube with either liquid or air). Controlling the velocity of pure oxygen flow into the Venturi device determines the amount of atmospheric air mixed with oxygen inside these devices. This controlled mixing helps to deliver a predetermined fraction of oxygen in inhaled air (FiO2) to the patient.
Venturi devices are usually available in the following FiO2 delivery options: 24%, 28%, 31%, 35%, 40% and 60%. If a patient requires more than 60% of FiO2, then we will need to consider other modes of oxygen delivery. These include non-rebreathing masks, non-invasive ventilation (NIV), endotracheal intubation and tracheostomy.
Intensive care units and other emergency units, including mobile ICUs, use venturi devices frequently for patient care. Here is a chart for ICU use, depicting all the required details for oxygen therapy using Venturi devices. We are using this chart in ICU for more than four years.
Colour coding of these Venturi connectors helps in easily identifying the FiO2 that they can deliver. The attached chart prominently displays the oxygen flow to be set (from a wall supply or oxygen cylinder), for each colour of the Venturi device.
Shashikiran teaches Internal Medicine at MMMC, Manipal Academy of Higher Education, and has clinical responsibilities at the Department of Medicine, Dr TMA Pai Hospital, Udupi, Karnataka, India.