Plus-Hex CLINICAL
ABSTRACT A veterinary nurse ( VN ) usually prepares a patient for orotracheal intubation and extubation , and the intubation itself is performed by a veterinary surgeon . VNs are trained in these skills but often have limited opportunities to practise them . However , at any point during a patient ' s anaesthesia experience or cardiopulmonary resuscitation , intubation may need to be performed confidently by a VN , without hesitation . VNs should therefore be familiar with the airway anatomy , orotracheal intubation and the cases that may require airway support or emergent intubation .
Keywords anaesthesia , airway , intubation , laryngoscope
Figure 1 . Labelled laryngeal structures .
Introduction
After premedication and induction , the patient ' s airway must be secured and controlled rapidly . Before this , all equipment should be prepared , inspected and tested .
This article discusses the role of the veterinary nurse ( VN ) in preparing for and performing orotracheal intubation . Airway anatomy , types of endotracheal tubes ( ETTs ) and cuff-inflation techniques are discussed , and troubleshooting ETT or airway complications are detailed throughout .
When ‘ intubation ’ is referred to in this article , it will be orotracheal intubation ( through the opening of the mouth and into the trachea ), unless otherwise specified . ‘ Induction ’ will refer to that of anaesthesia .
Learning outcomes
• Prepare and test airway equipment .
• Use different techniques to secure the airway .
• Troubleshoot different patient airway scenarios .
Airway anatomy
The larynx is a complex organ containing cartilaginous structures ( arytenoids , epiglottis , cricoid and thyroid cartilage ), muscles and soft tissue structures , as shown in Figure 1 . The role of the larynx includes vocalisation , controlling the flow of air during respiration and protecting the lower airway during swallowing . The entrance to the trachea is through the vocal cords ( the rima glottidis ), which are attached to the arytenoids .
The trachea is a series of incomplete c-shaped hyaline cartilaginous rings , held between connective tissue and the trachealis muscle ( Figure 2 ). The trachealis muscle runs along the length of the trachea , closing the ‘ c ’ shape and allowing flexibility of the tubular structure .
Brachycephalic patients have airway abnormalities due to redundant pharyngeal soft tissue , such as the soft palate [ 1 ] , which remains despite their reduced skull size . This soft tissue may cause an upper-airway obstruction , known as brachycephalic obstructive airway syndrome ( BOAS ), and can pose a challenge to the anaesthetist when placing the ETT .
Airway devices mucosa trachealis muscle
lumen of trachea
hyaline cartilage
Figure 2 . Incomplete c-shaped cartilage with the trachealis muscle on the top .
General anaesthesia inhibits protective airway reflexes such as coughing and swallowing , which prevent foreign material from entering the lower airway . This may put the patient at risk of aspirating foreign material such as gastroesophageal reflux ( GOR ) or fluid from the dental scaler . These protective reflexes are also present during lighter planes of anaesthesia , especially during induction , which may cause trauma when an airway device is introduced .
Volume 38 ( 3 ) • June 2023
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