Endotracheal Intubation of Dogs and Cats

(Anesthetist)A&A Pages 97-99 & 245-251

Endotracheal Intubation

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Flexible tube, placed inside trachea of an anesthetized patient, used to transfer gases directly from anesthesia machine to patient’s lungs.

Usually after induction

Advantages Patient airway is assured

◦ Free from obstruction

Artificial ventilation can be provided◦ Manual or mechanical◦ Flow of O2 and iso from the machine will fill the

reservoir bag, which can be used to provide a breath

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

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“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

More advantages

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

◦ More so in cats

PVC◦ Transparent◦ Rigid

Red rubber◦ Flexible/floppy◦ Absorbs disinfectants

Silicone- happy medium but expensive

Types of ET Tubes

Types of ET Tubes Cole tubes

◦ Non-cuffed◦ Used in birds/reptiles due to their tracheal rings…what about them?

Murphy tubes◦ Balloon type structure on the lower half of tube◦ Inflated with air in a syringe AFTER tube has been

placed in the trachea *Once inflated, DO NOT move tube◦ Need a designated “cuff inflator”

Murphy Eye

Purpose of Cuff on Tube

Positive pressure ventilation Efficient delivery of inhalant anesthetics◦P isn’t breathing in room air too◦Less waste gases in room

Prevent foreign material from entering lungs

*Inflating the cuff should not take the place

of using a larger tube

Laryngoscope

Light source

Blade

Handle

Responsible for maintenance:

batteries/charging and light bulbs

*Handle must match blade

http://www.youtube.com/watch?v=cK8fdHHyCPY&NR=1 - visual of epiglottis

http://www.youtube.com/watch?v=3EDRvvGpOZk&NR=1 - intubation of a dog

http://www.youtube.com/watch?v=CGjGTfP_Bs0 – intubation with cuff

Videos

DIAMETER (measured in mm) 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 = 3.0-4.5mm

DOGS = based on weight (table in A&A book)Remember: 20 kg = 9.5-10 mm

Selecting an ET Tube

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

Tips for Tube Size

Use width of space between thenostrils as a guide

LENGTH (measured in centimeters) Extend from the tip of the nose to the thoracic inlet

◦ ABOVE THE TRACHEAL BIFURCATION

If you extend into only one bronchus:◦ Hypoventilation and hypoxemia???

If you extend tube too far past patient’s nose

Increased dead space

Selecting an ET Tube

Prior to Intubation Check several tubes for loose connectors,

excessive wear, cuff leaks, debrisCuff leak check: inflate cuff fully and let it sit Remember to deflate cuff completely prior to intubation

Immediately before intubating: Apply lubrication- very small amount and optional

◦ Larger tubes – KY jelly or saliva Do not allow it to dry on tube

◦ Smaller tubes (<4.0mm) – water or saliva Check patient jaw tone

◦ Swallow reflex

Intubation Techniques Procedure 8-6 on Page 260

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 extended and in line with body

Pull out tongue to visualize back of throat

◦ May need gauze to hold tongue- slippery

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Move soft palate up and out of the way with ET tube and at the same time…

Move epiglottis down and out of the way with the ET tube (or blade of laryngyscope)◦ This brings tracheal opening into view

Under direct vision, ET 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 can obstruct view

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With Stylet Stylet runs inside the ET tube Made of strong wire/metal

◦ Stiffens the tube and molds the tube Can stick 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?

Intubation Techniques2. 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)

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

More difficult Small mouth and sensitive larynx Dome shaped vocal cords tend to quickly

close and push tube to side Swallowing reflex or contact with end of

ET 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

Feline Intubation

Tips for cats

Sternal recumbency, neck extended 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 metalat 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

Using Machines

Give a breath = chest should rise (stomach should NOT)◦ Listen to BOTH lung sounds

Rebreathing bag and flutter valves should move with respirations

Capnograph should give appropriate reading

Radiographs

How Do You Know You’re In?

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Cuff Inflation Cuff is attached to a pilot balloon with a

spring loaded inflation valve Must depress spring in order to inflate Cuff should inflate, but not be maximally full

of air

*If more than 10 cc of air needed: Leaky cuff or need a larger ET

tube

Cuff Inflation

Recheck every 30 min of surgery – especially after moving or repositioning patient◦ Most important for which type of procedure??

If you are running anesthesia for longer than 2 hours, you can reposition the tube slightly so pressure necrosis does not happen.◦ Must deflate cuff before moving tube!

*Even in emergencies

Secure Tube in Place Roll gauze

Rubber Band IV line tubing

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 LW A Y S disconnect the patient from the anesthetic tubes when moving OR repositioning

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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 such as??

Remove ET tube after 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*

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

Extubation Note

Bulldog video

Post-op Advice to Owner

Patients may cough for 1 – 2 days post-op◦ 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 in Ultra Sonic Cleaning soln. or

DILUTE chlorhexidine Rinse VERY well Hang upright to dry over night Deflate cuff

Unclean equipment (we reuse ET tubes!)◦ Disease transmission ex. Kennel cough

Leaky cuff◦ Check before use, during surgery, and while cleaning

Complications Before You Even Start

Complications While Placing

Tube too small◦ Failure to achieve desired depth of anesthesia

“light”◦ Like breathing through a straw increased resp.

effort◦ Easily become blocked with mucus

Tube too large◦ Damage to anatomy

Tube is too long◦ Hypoxemia and atelectasis decreased tissue

perfusion and difficulty breathing on recovery

Over-inflation of cuff◦ Necrosis, anatomical damage

Under inflating cuff = No seal created◦ Breathing room air light◦ Staff breathing iso high◦ Aspiration likely, especially if dental procedure

Vagus nerve stimulation◦ Parasympathetic response bradycardia, apnea,

cardiac arrhythmias ◦ What class of premed can help prevent this

response?

Complications While Placing

Dislodged tube◦ Not tied securely◦ Coughs out (cats)◦ Not disconnected while repositioning◦ Weight of hoses & machine pulls out

Restricted air flow◦ Bevel against wall of trachea, reason for

additional “Murphy eye” on other side◦ Kinks- extreme head position, over edge of table,

floppy tube used

Complications During Ax