DAS Project Grant
Developing a framework for the assessment of introducers used for difficult airway management
Dr Anthony Wilkes
Background
Prior to surgery, an anaesthetist will commonly place a short tube (called a tracheal tube) into the windpipe of a patient to allow the delivery of oxygen-enriched anaesthetic gases to the patient's lungs. The placement of the tracheal tube is called intubation. During intubation, the tracheal tube is passed through the vocal cords, so the anaesthetist needs to be able to see the vocal cords clearly. To achieve this, the anaesthetist uses a laryngoscope, which is an instrument that the anaesthetist can use to move and lift the patient's tongue to gain a view of the vocal cords. In some patients, the anaesthetist is not able to obtain a clear view and this is known as difficult intubation. When this occurs, the patient is typically already anaesthetised and paralysed, so the patient is unable to breathe for themselves. It is therefore imperative that the tracheal tube is placed correctly and rapidly to allow oxygenation to start as quickly as possible. Due to the anatomy at the back of the throat, it is easier to place the tracheal tube incorrectly into the oesophagus than the windpipe; if this occurs, then supplying oxygen to the patient's lung is clearly impossible and the patient will suffer and could die.
In this scenario, the anaesthetist commonly uses an introducer which is a long curved thin piece of plastic which can be inserted around the base of the tongue blindly through the vocal cords. The curvature is important, as a straighter introducer will pass through the oesophagus. The tracheal tube is then threaded over the introducer into the windpipe, the introducer removed, and the breathing system attached to the tracheal tube so that oxygenation can commence.
There are many different models of introducer on the UK market. Each introducer is different in terms of its length, flexibility and memory (ability to remain in the same shape when curved by the anaesthetist). A stiffer introducer can cause damage to the patient's throat and windpipe during insertion and, if pushed too far, to the patient's lungs. Incidents have been reported where this has occurred. Not only is damage to the patient's throat, windpipe and lungs detrimental to the patient, but the resulting blood can further reduce the clear view of the vocal cords, resulting in further delay to delivering oxygen.
Aims
Currently there is no standard for introducers and no agreed framework for assessment of these devices. We therefore intend to develop a framework for assessment and trial this framework on a selection of introducers currently available in the UK. From this we hope to assess whether the methodology gives useful information to clinicians to the operational characteristics of bougies. Following on from this, we will then seek further funding to develop the framework into a standard, which we will propose to the relevant British Standards technical committee. We will involve experts from the relevant sub-specialty Professional Bodies to assist us in developing the standard based on the data obtained in the current study.
