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Oxygen Supplementation 1147

covers about 80% of the e-collar, with room
left open for elimination of CO 2 and to
VetBooks.ir • An O 2 tubing is run on the inside of the
prevent hyperthermia.
e-collar, and flow rates set at 3-10 L/min,
depending on the size of the patient.
• Both methods are inexpensive and easy to
set up but use a lot of O 2 .
Cages and incubators:
• O 2 cages and incubators offer a low-stress
means of O 2 supplementation for the short
term and for longer durations.
• Immediate placement of a dyspneic animal
into a clear O 2 cage can be calming to the
animal, provide needed O 2 , and can allow safe
observation of respiratory effort and pattern. OXYGEN SUPPLEMENTATION Face masks also Procedures and Techniques
• O 2 cages prevent ready access without offer a simple, rapid, but short-term method of O 2 OXYGEN SUPPLEMENTATION Nasal catheters
supplementation.
opening the door or window, rapidly drop- offer a simple but effective method of O 2 supplementa-
ping the ambient O 2 concentration to that tion for a few to many days. Bilateral catheters can
of room air. be placed if additional O 2 is required.
• Many different models of O 2 cages and
incubators are available, including com-
mercial models and makeshift setups.
• Capable of delivering high concentrations Tracheal catheter:
of O 2 (≥40%-60%), many are sold with O 2 • Patients with upper airway obstruction can
regulator that allows the clinician to set the benefit from tracheal O 2 supplementation.
desired FIO 2 • It may also be helpful when there are con-
• Some cages are able to effectively eliminate traindications to nasal catheter placement
CO 2 and regulate humidity and temperature. (animals with traumatic brain injury or nasal
Incubators are usually not regulated as easily neoplasia).
as cages, but O 2 sensors, thermometers, and • The ventral neck should be shaved and
hygrometers can help monitor internal aseptically prepared.
conditions. • Wearing sterile gloves, a 14- to 20-gauge,
• Ensure incubators are not so tightly sealed 1-1.5 inch over-the-needle catheter is placed
that they prevent CO 2 elimination. into the tracheal lumen through the tracheal
• O 2 cages use large volumes of O 2 . OXYGEN SUPPLEMENTATION O 2 supple- cartilages. It is usually easier to lift up the
3
Nasal prongs: mentation can be achieved by covering ≈ 4 of an skin and pass the catheter through the skin
• Nasal prongs can be used in dogs to supply Elizabethan collar with plastic wrap and inserting the first before passing the catheter through the
O 2 supplementation for hours to days. oxygen tubing under the collar. tracheal ring.
• Various sizes of prongs fit into the nostrils • An O 2 source is attached to the catheter
and are secured behind the ears. after the stylet is removed.
• The tubing can be taped or stapled in place the eye; mark with a permanent marker or • O 2 flow rates of 1-3 L/min can give an FIO 2
but are more easily removed (and replaced) tape. of 60%-80%.
than nasal catheter. • Lubricate the catheter tip with KY gel or • Tracheal catheters are simple to place and
• Compared to nasal catheters (see below), lidocaine gel. are typically well tolerated, but they can be
higher flow rates are typically used with nasal • While the assistant is holding the patient’s challenging to secure and may fall out in
prongs. head with the nose pointed toward the mobile patients.
• Not suitable for cats or small dogs ceiling, the catheter should be advanced in Endotracheal intubation:
Nasal catheter: a ventromedial direction to the premeasured • Requires induction of general anesthesia
• Relatively simple to place and generally well mark. such as propofol 2-6 mg/kg IV or ketamine
tolerated for O 2 supplementation lasting a • The tube is then secured to the nostril with 2-10 mg/kg IV combined with diazepam/
few to many days sutures or staples. The tube should also be midazolam 0.1-0.5 mg/kg IV
• Often performed without, but sedatives secured (with either suture or staples) on • Anesthesia is maintained with inhalant or
may facilitate placement in resistant animals the side of the face or up the bridge of the chemical drugs.
(butorphanol 0.2-0.4 mg/kg IV/IM once). nose. • Mechanical ventilation can be manual or by
An assistant is usually required to help • The end of the tube is then connected to mechanical ventilator machine.
restrain the patient during placement. an O 2 source, usually requiring an adaptor • Can provide 100% O 2 for patients unrespon-
• With the nose pointed up, place a few or Christmas tree. sive to other means of O 2 supplementation
proparacaine drops or topical lidocaine drops • The O 2 flow rate for nasal catheters is usually • Facilitates mechanical ventilation (p. 1185);
inside the nostril. 50-150 mL/kg/min. For a 20-kg dog, flow mechanical ventilation can be lifesaving for
• Red rubber catheters are generally used for rates will be between 1-3 L/min. animals unable to sustain respiratory rate/
nasal insufflation. Small-breed dogs and cats • Bilateral nasal O 2 tubes can be used in dogs effort despite less aggressive means of O 2
may use a 5-Fr catheter (cats may not toler- with severe hypoxemia or dogs that do not supplementation
ate nasal O 2 catheters well); medium-sized respond adequately to one nasal O 2 catheter. • Patient should be intubated if arterial blood
to large-breed dogs do well with an 8-Fr The flow rate can be doubled when two gas or pulse oximetry shows progressive
catheter. catheters are present. hypoxemia with SpO 2 < 90% or PaO 2 <
• Use the catheter to measure from the • An e-collar should be placed to prevent 60 mm Hg despite O 2 supplementation.
external naris to the medial canthus of inadvertent removal. • Prolonged high FIO 2 exposure is toxic.

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