Feline Orotracheal Intubation

23/11/2021

Feline orotracheal intubation

Georgina Beaumont
BVSc(Hons.) MANZCVS(VA&CC) Dip.ECVAA MRCVSRCVS Recognised and EBVS® European Veterinary Specialist in Anaesthesia and Analgesia

Beaumont Consulting Ltd

Why intubate?
 Maintain patent airway
 Protect airway
 Deliver anaesthetic gases/vapour
 Prevent anaesthetic leak
 Day 1 Skill

When to intubate
 ASA status ≥3 Major or long procedures
 ETI reduces risk (0.6; CEPSAF 2007) ↑ GOR risk ↑ aspiration risk
 IPPV required©Christopher Beaumont Consulting Limited
2021

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When not to intubate Brief, minor procedures If low GOR risk
 Facemask or SGAD alternative ETI increases risk (2.3; CEPSAF 2007)

 ± airway foreign bodies

Feline concerns Laryngospasm
 Small diameter airway
 Delicate dorsal tracheal ligament Partially complete tracheal rings
 More complete than dogs

 Dental procedures Tracheal damage
 Cortical blindness

Anatomy for orotracheal intubation
PharynxTongue
 Epiglottis
 Vallecular Arytenoids Vocal folds
 Glottis Rima glottides
 Trachea Carina©Christopher Beaumont Consulting Limited
2021

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Equipment Laryngoscope Endotracheal tubes
 ETT anatomy

 Laryngeal desensitisation
 Additional aids

Laryngoscope

Endotracheal tubes
 MACintubation ≠ MACincision
 Sevo 3.55% vs 1.71%

 Autonomic stimulation
 Painful Unpleasant Risk of laryngospasm
 Risk of injury
 ETT selection©Christopher Beaumont Consulting Limited
2021

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ETT anatomy
Machine end
15mm ETT connector
 Shaft
 ± Radiopaque marker
 ± Murphy eye
 ± Cuff & pilot tube
 Bevel Distal tip
Patient endETT selection: material

Polyvinyl chloride (PVC)

Silicone± Low P : high V cuff
± Murphy eye
Medium P : medium V cuff
Murphy eye

Red rubber
High P : low V cuff
No Murphy eye Irritant

ETT selection: material
Kinking

RR>

Si≈

PVC

Ease of inspection

PVC

≥

Si>>

RR

Preformed curve

PVC

≈

RR≠

Si

Softens with heat

Si>

PVC

≠

RR

Flammability

PVC>

Si>

RR

Autoclavable

RR≈

Si≠PVC

Degradation with cleansing

RR≈

Si>

PVC

Perishable

RR>

Si≈

PVCExpense

Si>

RR>

PVC

©Christopher Beaumont Consulting Limited
2021

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ETT selection: diameter
 𝑅=

 𝑅𝛼𝐿
 𝑅𝑟

(½ L = ½ x Raw)(½ r = 16 x Raw)

 Internal diameter ∅ Critical characteristic for Raw
 Tracheal ∅ estimation inaccurate Experience Range of sizes

ETT selection: length Distal tip: proximal trachea
 Below cricoid Above carina

 Proximal tip: incisors
 Minimise VD
 Aim for VD <<< VTETT selection: length If overlong
 Distally: risk obstruction
 Partial / complete Abutting carina
 Bronchial (one-lung) ventilation

 Proximally: ↑ VD
 Rebreathing CO2©Christopher Beaumont Consulting Limited
2021

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ETT selection: seal
 Uncuffed = hydrostatic
 Inflatable cuff
 IPPV High risk aspiration
 GOR/lavage/blood/secreta

 Minimise pollution
 Takes up space Flanges/baffles
 Inappropriate sizes for cats

Cuff inflation
 Cuff manometer 20-30 cmH2O

 Other techniques problematic Inferior to manometer measurement
 Minimum occlusive volume
 Pilot tube palpation

 Impact of N2O

Cuff inflation
 Excessive inflation
 Compromised mucosal perfusion Dorsal ligament rupture Tracheal rupture ↑ harm if movement around tube

 Dental procedures overrepresented©Christopher Beaumont Consulting Limited
2021

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Movement around cETTETT selection: et al Murphy eye Reinforcement
 Shielding

ETT selection
 Minimise risk of airway damage
 𝑅=

 Incisors to proximal trachea
 Generally prefer PVC
 Murphy eyePlace largest diameter ETT possible
without inflicting damage©Christopher Beaumont Consulting Limited
2021

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Laryngeal desensitisation
 Prophylaxis for laryngospasm
 Facilitates atraumatic intubation
 Topical deposition lidocaine NMB is alternative to LA

Laryngeal desensitisation
 One veterinary licensed product Intubeaze®
 Lidocaine 20mg/mL (2%)
 2 – 4 mg per spritz

 Cleanse nozzle between uses
 Alternate EU trade names
 Lidcosal/ Lidcosal Vet

Laryngeal desensitisation
 Beware human alternative products
 Xylocaine® (AstraZenica) Lidocaine 10% 10mg per spritz

 Banana flavouring Anaphylactoid reactions (cats) Contains propylene glycol©Christopher Beaumont Consulting Limited
2021

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Laryngeal desensitisation
 Topical deposition
 Arytenoids/ vocal folds
 2 (– 4) mg/kg lidocaine
 Care locoregional

 Visualise deposition

Laryngeal desensitization: ASEs
 True hypersensitivity/ allergic reactions

uncommon Amide class LA

 Excessive dose → toxicity
 CNS
 Cardiovascular Won’t prevent post-intubation soreness

Neuromuscular blockade Alternative to topical desensitization
 Rocuronium reported
 0.3-0.6mg/kg
 Did not abolish laryngeal reflexes entirely
 MUST be able to provide IPPV©Christopher Beaumont Consulting Limited
2021

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Additional aids
 Positional Bougie Dog urinary catheter Luer slip
 3.5mm ETT connector
 Preload ETT Stylet NEVER within airway

Additional aids

Technique Appropriate anaesthetic depth Visualise & desensitise larynx
 Lubricant
 Atraumatic placement
 Confirm placement
 Secure the tube
 ± Safely inflate cuff

©Christopher Beaumont Consulting Limited
2021

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Confirming placement

Complications of inadequate technique

Laryngospasm

Tracheal mucosal necrosis

Failed airway protectionIschaemic mucosal injury

Oesophageal intubation
Non- intubation

Inadequate seal

Increased work ofbreathingCortical blindnessMalposition



Movement of/around ETT


Fibrinous
pseudomembrane
Dorsal ligament rupture
Tracheal stricture
Tracheal rupture
PneumothoraxPneumomediastinum
SQ emphysema

Sprung mouth gags

Oesophageal
One-lung Mural impaction

Other complications
 Occlusion
 Kink Secreta Impaction
 Cuff herniation

 Inadvertent disconnection
 Connector slip
 Breathing system disconnection

 Damage/breakage/fracture©Christopher Beaumont Consulting Limited
2021

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Specific challenges
 Kittens/small cats
 Abnormal anatomy
 Concurrent locoregional
 Total dose critical Common pitfalls

Q&A
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©Christopher Beaumont Consulting Limited 2021

Georgina Beaumont
BVSc(Hons.) MANZCVS(VA&CC) Dip.ECVAA MRCVSRCVS Recognised and EBVS® European Veterinary Specialist in Anaesthesia and Analgesia

Beaumont Consulting Ltd©Christopher Beaumont Consulting Limited2021

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