Airway Management Devices

Abstract

The most important interface between the breathing system and the patient’s lungs is an airway management device (AMD). Post-operatively it can be considered to be a means of delivering oxygen enriched air to the patient. Intraoperatively it is intended to secure the patient’s airway, which might otherwise obstruct due to deep anaesthesia, to provide a reasonably gas tight seal to ensure accurate delivery of anaesthetic gases and, if necessary, to protect the lungs against aspiration of gastric contents. Postoperatively, the AMD can be nasal prongs or a variable performance mask, whose efficiencies may not be predictable [Wagstaff et al. 2007]. Intraoperatively it might be an artificial airway with a facemask, a supraglottic airway of one of the many types now available or an endotracheal tube (ETT). A supraglottic airway is one that sits in the pharynx or larynx above the vocal cords and these days is usually a laryngeal mask airway (LMA) of the numerous types now available, a cuffed oropharyngeal airway (COPA), or a Combitube. The LMA types available consist of: the classical LMA; the flexible (reinforced) LMA with a flexible tube to the breathing system; the ‘Proseal’, which has a gastric drainage tube as well as a gas transport tube; the intubating LMA, a device with a rigid right angled tube that acts as a ventilation conduit in the usual way, but through which an endotracheal tube may also be blindly introduced into the trachea; the ‘I-gel’ which has a gastric and a respiratory port as does the Proseal, but is less bulky, and whose bowl does not require inflation with air, but is filled with a gel that expands with body heat to form a seal. These days, almost all devices are made of material that excludes latex, but care should be taken to ensure this is indeed the case when there is a latex sensitive patient. Depending on the exact surgical and anaesthetic circumstances, the anaesthetist’s experience and equipment availability, a choice is made between these devices to secure the airway for a given operation. Additionally, there are other devices available to assist in securing the airway, such as the laryngoscope, the fibre optic bronchoscope and the cricothyrotomy tube.