Contributors: Danielle Gunn-Moore

 Species: Feline   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading

Introduction

  • Nasopharyngeal disease is common in the cat and direct examination can assist diagnosis.

Uses

  • Examination of the nasopharyngeal mucosal surface.
  • Collection of mucosal biopsy samples from the nasopharynx.
  • Detection and retrieval of foreign bodies from the nasopharynx.
  • Detection/biopsy of nasopharyngeal masses.
  • Definitive diagnosis of nasopharyngeal disease.
  • Investigation of:
    • Nasopharyngeal disease.
    • Acute and chronic upper respiratory tract disease.

Advantages

  • Non invasive technique requiring no surgical intervention.
  • Well tolerated by sick cats which would be unsuitable for exploratory surgery.
  • Reasonable visualization of the nasopharyngeal mucosa.

Disadvantages

  • Will not detect pathology lying deep below the mucosa.
  • Misses disease within the mid nasal area.
  • Expensive equipment.

Technical Problems

  • Technical difficulty in procedures.

Alternative Techniques

  • Radiography and CT/MRI.
  • Exploratory rhinotomy/caudal soft palate split.

Time Required

Preparation

  • Induction of anesthesia and/or sedation   →   10-30 min.

Procedure

  • Depends on the experience of the endoscopist   →   rhinoscopy approximately 30 min.

Decision Taking

Risk assessment

  • Low to moderate risk.
  • See complications.

Requirements

Personnel

Nursing expertise

  • Good level of competence required for assisting in procedures, monitoring anesthetic and assisting in biopsy collection and handling.
  • High competence for care and cleaning of endoscopic equipment Endoscope: cleaning.

Materials Required

Minimum equipment

  • Fully immersible fiber optic flexible or rigid endoscopes (human bronchoscope or pediatric bronchoscope/cystoscope).
  • For rostral rhinoscopy:
    • Rigid endoscope.
      • Up to 20 cm insertion tube length.
      • Insertion tube diameter 2 mm.
  • For caudal rhinoscopy (retroflex rhinoscopy) and for rostral rhinoscopy of larger cats.
    • Flexible endoscope.
      • up to one meter insertion tube length.
      • Insertion tube diameter 3-5 mm.
  • ONLY use an end viewing endoscope.
  • Two or four way tip deflection.
  • MUST have cold light source with air pump and water wash facility.
  • Grab biopsy forceps for collection of mucosal biopsy samples. (To pass down flexible endoscope or to be passed separately to collect biopsies in rostral rhinoscopy when using rigid endoscope).
  • Cleaning brushes for biopsy channels.
  • Water leakage tester.

Ideal equipment

  • video endoscope:
    • Excellent magnified image presented on screen.
    • Detection of lesions much easier.
    • Allows for multiple person viewing.
    • Excellent for recording procedures and/or collecting still images.
    • Excellent as a training aid.
  • Xenon light source.
  • Insertion tube diameter 3-5 mm.
  • Cytology brushes, grasping forceps and biopsy grabs.
  • More than one endoscope for examination of different parts of the respiratory tract.
  • Endoscope cleaning cart and sterilization unit.
  • Ultrasonic cleaner for biopsy forceps.

Minimum consumables

  • Clean water.
  • Endoscope disinfectants.
  • Household detergent.
  • Formal saline, card and containers for preservation of biopsy samples.

Other requirements

Care and maintenance

  • Storage of endoscopes:
    • ALWAYS store endoscopes in a safe location where accidental knocks can be avoided.
    • ALWAYS store endoscopes with insertion tube hanging vertically in a well ventilated area.
    • Do NOT store endoscopes in their carrying case.
    • See supplier for further details of endoscope 'hangers'.
  • Cleaning and disinfection:
    • Follow the manufacturers recommendations at all times.
    • Use an endoscope cleaning bath wherever possible.
    • Use whatever cleaning solution and disinfectant the manufacturer recommends.
    • Follow health and safety rules regarding use of these products.

Preparation

Pre-medication

Dietary Preparation

  • Nil by mouth for 6 hours prior to procedure.

Restraint

Procedure

Approach

Step 1 - Patient preparation

  • Following induction of anesthesia - it is essential to intubate patient with cuffed endotracheal tube.
  • Tie endotracheal tube to maxilla to ensure that ET tube is not accidentally dislodged.
  • Lay patient in sternal recumbency.
  • Place mouth gag to protect endoscope.

Core Procedure

Step 1 - Endoscopic examination

  • Examine and biopsy caudal nasopharynx before rostral as hemorrhage from rostral biopsies will obscure the view.
  • Insert endoscope along hard palate and into proximal esophagus.
  • Once within the proximal esophagus, retroflex the endoscope and withdraw slowly so that the hooked end catches over the soft palate.
  • Withdraw slightly more so that the floor of the soft palate and the caudal nasopharynx can be seen.

Step 2 - Biopsy collection

  • The biopsy forceps can then be gently advanced through the endoscope and biopsies can be collected.
  • If they will not advance easily, withdraw endoscope and pass forceps with the scope so their tip is at the tip and passed into the nose. The biopsies are then collected blindly.
  • Try and advance biopsy forceps perpendicular to the mucosa.
  • Deeper samples can be collected by sampling repeatedly at the same site.
  • Capillary bleeding from biopsy sites is normal.

Exit

Step 1 - Remove endoscope

  • Gently withdraw endoscope.
  • Support end of scope as it is withdrawn to prevent damage of the endoscope.
  • Repeat the procedure to gain access to the caudal nasopharynx.

Step 2 - Endoscopic examination of the nasal chambers

  • Pack pharynx with a gauze swab to prevent blood leaking into trachea.
  • Measure endoscope against cat's face and place a marker tape at the point where the endoscope extends from the medial canthus of the eye to the nostril of the same side. (This prevents iatrogenic brain damage or the over-insertion of rigid endoscope).
  • Insert endoscope into each nostril in turn.
  • Slowly pass endoscope into the nasal chambers examining the mucosa as you proceed.
  • Examine the entire extent of the nasal chambers.

Step 3 - Biopsy collection

  • When using a flexible endoscope pass the biopsy forceps within the biopsy channel.
  • When using a rigid endoscope that does not have a biopsy channel, the scope is removed from the nose before taking the biopsies after first noting how far into the nose the area of interest is. Flexible endoscope grabs (the largest that can be fitted into the nose) are then marked as above (to prevent iatrogenic brain damage) and passed into the nose. The biopsies are then collected blindly.
  • Advance biopsy forceps perpendicular to the mucosa.
  • Deeper samples can be collected by sampling repeatedly at the same site.
  • Significant bleeding from biopsy sites is normal.

Step 4 - Remove endoscope

  • Gently withdraw endoscope.
  • Temporarily pack the nose to stop excessive hemorrhage.
  • Support end of scope as it is withdrawn to prevent damage.

Aftercare

Immediate

Monitoring

  • Routine post anesthetic observation.
  • Check mucus membrane color, heart and respiratory rates in case of hemorrhage.
  • Check there is no evidence of aspiration.

Potential complications

  • Arterial bleeding from biopsy sites.
  • Iatrogenic damage to brain caused by advancing endoscope too far.

Outcomes

Further Reading

Publications

Refereed papers

Other sources of information

  • Tams T R (1990) Small Animal Endoscopy. C V Mosby, St Louis.

Organizations

  • Key-Med UK Ltd., Keymed House, Stock Road, Southend on Sea. Essex. SS2 5QH, UK.
  • Arnolds Veterinary Products, Cartmel Drive, Harlescott, Shrewsbury SY1 3TB, UK.
  • Veterinary Endoscope Services, Alder House, High Road, Rayleigh, Essex SS6 7SA, UK.