INTUBATION OF DOGS AND CATS AA Page 245

INTUBATION OF DOGS AND CATS A&A Page 245

Intubation Flexible tube, placed inside trachea of an anesthetized patient, used to transfer gases directly from anesthesia machine to patient’s lungs. Usually after induction Page 2

Advantages Patient airway is assured ◦ Free from obstruction Artificial ventilation can be provided ◦ Flow of O 2 and iso from the machine will fill the reservoir bag, which can be used to provide a breath ◦ When should this be done other than emergencies? Dead air space reduced increase efficiency of gas exchange ◦ Dead air space describes the breathing passages that contain air but no gas exchange can occur 3

More advantages “Cuffed” ET tubes reduces the risk of vomit/saliva/water being aspirated ◦ Where would water come from? Vomit? Secretions can be removed with suction catheter through the ET tube Efficient delivery of inhalant anesthetics ◦ Gas rates can be lowered (safe personnel) ◦ Anesthetic gas stays in the system, not the sx suite Drugs can be easily administered in emergency ◦ Must give double the IV dosage

PROBLEMS Difficult to intubate certain patients ◦ Brachycephalic, tiny animals, bull dogs Overzealous efforts to intubate can damage larynx, pharynx, soft palate ◦ Cats especially with small glottis Blind intubation (esophagus) Tubes can be inserted too far Ventilation of only one lung Pressure necrosis from over inflation

Types of ET Tubes PVC, red rubber, or silicone Non-cuffed ◦ Used in birds/reptiles due to their tracheal rings Cuffed ◦ Balloon type structure on the lower half of tube ◦ Inflated with air in a syringe AFTER tube has been placed in the trachea ◦ Need a designated “cuff inflator” ◦ Murphy eye-beveled, with a side hole

Purpose of Cuff on Tube Positive pressure ventilation Easier achievement of anesthesia ◦ P isn’t breathing in room air too Prevent foreign material from entering lungs Less waste gases in room *Inflating the cuff should not take the place of using a larger tube

Laryngoscope Blade Light source Handle Responsible for maintenance: batteries/charging and light bulbs

Selecting an ET Tube DIAMETER Should be a snug, easy fit ◦ Should not “fall” in OR be forced into trachea ◦ The cuff being inflated will “seal” the trachea General ideas: CATS = 3. 0 -4. 5 mm DOGS = based on weight (table in A&A book) Remember: 20 kg = 9. 5 -10 mm

Tips for Tube Size Weight based is a guideline Always prep 3 tubes (choice, 1 smaller, 1 bigger) Brachycephalics may need smaller than you think ◦ Long soft palate with extra tissue and narrow tracheas Use width of space between the nostrils as a guide

Selecting an ET Tube LENGTH Extend from the tip of the nose to the thoracic inlet ◦ ABOVE THE TRACHEAL BIFURCATION If you extend into only one lung: ◦ Hypoventilation and hypoxemia ? ? ? If you extend tube too far past patient’s nose Increased dead space

Prior to Intubation Check several tubes for loose connectors, excessive wear, cuff leaks, debris Cuff leak check: inflate cuff fully and let it sit Remember to deflate cuff completely prior to intubation Apply lubrication- very small amount and optional ◦ Larger tubes – KY jelly or saliva Do not allow it to dry on tube ◦ Smaller tubes (<4. 0 mm) – water or saliva Check patient jaw tone ◦ Swallow reflex

Intubation Techniques 1. Visual Preferred technique for dog and cat Direct visualization of larynx minimizes possibility of traumatic or improper intubation Position: Sternal, Dorsal, Lateral recumbency ◦ Position is preference

Visual Technique Assistant holds hand placed on the muzzle with fingers behind front canine teeth (like you would for pilling) pulling upward to open the mouth Neck should be slightly extended and in line with body Pull out tongue to visualize back of throat ◦ May need gauze to hold tongue- slippery 14

Tongue is pulled forward and off to the side, then held in place with thumb – moves epiglottis forward and down ◦ Tongue can be held by you or restrainer Move soft palate up and out of the way with ET tube and at the same time… Move epiglottis down out of the way with the tube – this brings tracheal opening into view Under direct vision, tube is passed through tracheal opening Tech note: You may need to wait for a breath or stimulate animal’s body to inhale to see opening

With laryngoscope RIGHT HANDED PERSON Hold laryngoscope w/ left hand Hold ET tube in right hand Press blade against pulled out tongue, exposing trachea Can be used to hold epiglottis down ◦ Lightly! Blade too far forward will obstruct view

Page 18

With Stylet runs inside the ET tube Made of strong wire/metal ◦ Stiffens the tube and molds the tube Sticks out past the ET tube ◦ Provides smaller, blunt point to first pass through the vocal cords ◦ Allows larger ET tube to slide into trachea Stylet should be longer than ET tube! ◦ Why? 19

Intubation Techniques 2. Blind Used in dogs and horses NOT suitable for cats, very small dogs, or patients with edema, swelling or trauma Lateral recumbency (RIGHT lateral in dogs) Head and neck extended and mouth open Advance tube with bevel parallel to vocal cords Move soft palate up and out of the way and epiglottis down Advance upon expiration Rotating tube to follow curve and point tip down

Intubation Techniques 3. Tactile Cattle, large exotics, a few large dogs Finger holds down the epiglottis Slide tube into trachea using your finger as a guide

Feline Intubation More difficult Small mouth and sensitive larynx Dome shaped vocal cords tend to close and push tube to side Swallowing reflex or contact with end of tube causes laryngospasm

Feline Intubation Laryngeal sensitivity ◦ Can be reduced by application of topical anesthetic Apply 0. 1 cc of 2% Lidocaine soln. on glottis (without the needle!) ◦ Or use cotton swab Can also coat the end of the tube w/ lidocaine gel

Tips for cats Sternal recumbency Good light source Use direct visualization technique-must be able to see vocal cord opening before inserting tube Stylet is helpful! Cats often cough – don’t let go!

How Do You Know You’re In? Condensation seen in ET tube Feel air through tube ◦ Place something light or metal at end of ET tube Palpate throat ◦ One tube – you’re in ◦ Two tubes – you’re in esophagus Normal breathing sounds ◦ No gurgling Patient can not vocalize

How Do You Know You’re In? Using Machines Give a breath = chest should rise (stomach should NOT) ◦ Listen to BOTH lung sounds Rebreathing bag and flutter valve should move with respirations Capnograph should give appropriate reading Radiographs

Page 32

Secure Tube in Place Roll gauze Rubber Band IV line Paper tape-birds/reptiles Tie around tube first, then around patient Do not include small tube used for cuff inflation ALWAYS use a bow tie, not a knot A L W A Y S disconnect the patient from the anesthetic tubes when moving OR repositioning

Page 34

Cuff Inflation Cats: 1 – 2 cc of air Dogs: 2 – 10 cc of air ◦ Valve port should inflate, but not be maximally full of air ◦ If more than 10 cc needed: Leak or need a larger ET tube

Cuff Inflation Recheck every 30 min of surgery – especially after moving or repositioning patient If you are running anesthesia for longer than 2 hours reposition the tube slightly so pressure necrosis does not happen. ◦ Must deflate cuff before moving tube!

Extubation Your patient will be in recovery ◦ Sternal or lateral recumbency ◦ Head and neck extended Deflate the cuff when the patient shows signs of waking up Remove ET tube after un-stimulated swallowing has returned Prevent obstruction of airway with tongue by pulling tongue forward during and after pulling the tube *Waiting too long can cause patient to bite tube in half*

Extubation Note Brachycephalic animals – should be head up, chewing on tube before it is pulled

Post-op Advice to Owner Patients may cough for 1 – 2 days post operatively Should not be severe or continue to get worse Advising owner will avoid phone calls and later explanations!

ET Tube Cleaning Inflate cuff and leave inflated until dry Wash inside AND outside of endotracheal tube Use warm soapy water to get mucus off ◦ Commercial brushes available, cotton swabs, pipe cleaners Rinse Disinfect for minimum of 15 minutes in Ultra Sonic Cleaning soln. with DILUTE chlorhexidine Rinse VERY well Hang upright to dry over night Deflate cuff