The use of an ETT has also been explored as a risk factor for anaesthesia in cats . Feline patients have a sensitive tracheal mucosa , which is susceptible to injury by two major mechanisms of action : tube movement ( abrasion ) and pressure necrosis [ 2 ] . Airway management methods must therefore be placed and maintained with care .
Brodbelt et al . [ 11 ] discovered that the cause of anaesthetic death in cats that had been intubated was most often categorised as of respiratory or cardiovascular origin . Laryngeal trauma , spasm and oedema were suggested as common possible causes .
Furthermore , Mitchell et al . [ 12 ] concluded that endotracheal intubation can be a risk factor for tracheal rupture . Of the cats in the study , the cause of the trauma was unknown . Possible explanations listed included over-inflation of the cuff , changing recumbency without disconnecting the ETT from the anaesthetic circuit , traumatic intubation and removal of the ETT without deflating the cuff .
The conclusions drawn from these papers agree that endotracheal intubation should be undertaken and managed carefully in feline patients but that the provision of a patent airway via an ETT remains vital [ 13 ] .
Supraglottic airway devices
The v-gel device is a form of SGAD manufactured for veterinary use , specifically for rabbits and cats [ 3 ] . SGADs provide an alternative to endotracheal intubation in patients with airways that are difficult to intubate or those deemed at high risk of injury . The v-gel device is reported to self-position and is easy to reposition if necessary . Studies have also shown that it creates an equally adequate seal as an ETT and has the advantage of a more comfortable recovery [ 14 ] .
Oostrom et al . [ 4 ] suggest from their results that v-gel devices are easy and quick to place , with the v-gel taking a median of 44.4 seconds to place and ETTs taking a median of 109.0 seconds . However , the v-gel can still cause laryngeal spasms if trying to place it at an inadequate level of anaesthesia .
The results also indicate that the use of an SGAD aids a smoother recovery , with factors such as stridor occurring in 60 % ( n = 6 ) of patients and dyspnoea in 20 % ( n = 2 ) when using ETTs , compared with v-gel patients , where neither of these complications occurred .
Prasse et al . [ 5 ] produced similar results for ease and timing of the placement of the v-gel , in addition to a reduced dose of induction agent being required for placement . A median of 3 mg / kg of propofol was used for v-gel devices and 5 mg / kg for ETTs .
However , fewer adverse effects were recorded , such as coughing and discomfort , when using an ETT . This may be due to the study using a manometer to inflate the cuff on the ETT to a safe pressure of 20 cm H 2
O , whereas Oostrom et al . [ 4 ] inflated the cuff using the minimum occlusive volume technique , where the cuff is inflated until there is no audible leak .
Oostrom et al . [ 4 ] may have their skewed results for negative recovery when using ETTs , due to poor cuff inflation technique , and therefore the v-gel may not be advantageous for patient comfort and recovery . Further study is required .
Face masks
Face masks are a popular form of airway management , as they are quick and easy to use for procedures such as cat castrations [ 3 ] . O ' Dwyer et al . [ 15 ] explain that smaller sensitive airways can cause difficult intubation so practitioners may choose a face mask .
However , it is stressed that masks do not preserve the airway and can make controlled ventilation impossible . Face masks also increase dead space and risk environmental pollution with anaesthetic gases [ 3 ] . Rubbing of the mask or an ill-fitting mask can also cause corneal trauma or drying , leading to ulcers [ 15 ] .
Bednarski et al . [ 8 ] also stress that mask use should be avoided when volatile anaesthetic agents are used , due to pollution of the environment and adverse effects on practice staff . Therefore , masks are not an appropriate choice for an anaesthetic that uses volatile agents .
Tracheostomy tubes
A tracheostomy tube may be used to gain control over a patient ' s airway . However , this is an invasive technique which requires specialist skills , equipment and nursing following its placement , so it is not considered to be a first-line option [ 16 ] .
A tracheostomy tube is usually placed in an emergency when there is an obstruction of airflow in the upper respiratory tract [ 17 ] . Common examples are patients with respiratory distress associated with foreign bodies or laryngeal paralysis [ 16 ] . Placement of a tracheostomy tube is only indicated if endotracheal intubation is not possible .
No airway management
No airway management is considered as an option by Sheppard [ 3 ] for shorter procedures , such as cat castration , and is sometimes justified by the association of increased mortality with the use of ETTs in cats .
However , due to the aforementioned advantage of securing a patient ' s airway , in addition to the risks of an unprotected airway during anaesthesia , it is not an advisable method . Yet it is still selected by some practitioners , due to the speed of the anaesthetic required versus the potential effects of airway management discussed above .
38 Veterinary Nursing Journal