How to care for the rhinoscopy patient
In the penultimate post in our endoscopy series, today we’re looking at upper airway endoscopy (aka rhinoscopy). Like bronchoscopy, upper airway endoscopy can be a little risky, and these patients require close monitoring, careful planning and lots of nursing care to prevent complications. Ready to learn more? Let’s go…
What is rhinoscopy?
Rhinoscopy is the endoscopic examination of the nose. It is performed in two ways, using two different types of endoscope - retroflex or retrograde nasopharyngoscopy is the examination of the caudal aspect of the nose, and is performed using a bronchoscope; and normograde rhinoscopy is performed using a rigid endoscope (rhinoscope). Ideally, in order to fully examine the nasal cavity, a combination of retrograde and normograde rhinoscopy should be performed (depending on the endoscopes available to you in practice).
In addition to visualising both the inner structures of the nose and the nasopharynx, rhinoscopy allows the collection of biopsies, the debridement of fungal plaques (seen with fungal infections) and the removal of foreign material.
How is rhinoscopy performed?
Following anaesthetic induction and patient preparation, the bronchoscope is first inserted into the mouth, flexed upwards, and ‘hooked’ around the soft palate to visualise the nasopharynx. The choanae (bilateral openings into the nasal cavity from the pharynx) can be seen, separated by the vomer bone. In brachycephalic patients, nasal turbinates may also be seen in this view. At this point, the clinician should examine the site and note any abnormalities such as polyps (these are common in cats), narrowings (nasopharyngeal stenosis) or masses. Biopsies are collected as necessary before the flexible endoscope is removed and the clinician switches to the rigid rhinoscope.
The rhinoscope is measured and marked at the level of the medial canthus of the eye before use, to ensure it is not advanced too far into the nose. At this level, the cribriform plate (a thin bone separating the nose and brain) is present; this bone can be compromised where fungal infection or neoplasia is present.
The measured rhinoscope is inserted into the nostril and advanced through the ventral, middle and dorsal meati, between the turbinate bones. As the turbinates are friable, the endoscopist examines the ventral meatus first, moving upwards through the nasal cavity on each side. Visualisation of structures within the nasal cavity is made easier by flushing 0.9% Saline through the rhinoscope whilst it is in use - the veterinary team, therefore, need to be careful to ensure the patient’s throat is packed and the ET tube cuff is appropriately inflated before flushing begins.
After the nasal cavities have been fully inspected on each side, biopsies are collected. This is usually done blind, by inserting biopsy forceps into each nostril and collecting multiple pinch biopsies. These are typically submitted for histopathology, bacterial culture and fungal culture.
How is the patient prepared?
Prior to the procedure the patient’s clotting ability should be confirmed. This is important as rhinoscopies and nasal biopsies cause postoperative haemorrhage, which can be a significant risk in patients with haemostatic disorders. Bloods should be taken to confirm normal platelet count, platelet function (by performing a buccal mucosal bleeding test) and coagulation times (aPTT/PT).
Ahead of the patient’s general anaesthetic, they should be starved according to standard practice protocol, and have a thorough clinical examination and an anaesthetic plan developed. Including local/regional anaesthetic techniques can be useful for these patients, either by performing a maxillary nerve block, or a splash block with lidocaine (personally, I like to use an IV catheter with the stylet removed to splash block the inside of each nostril, and so I discuss this with the veterinary surgeons I work with ahead of the procedure).
Anaesthesia is then induced and, after collecting any required diagnostic images, the patient is positioned in the endoscopy area, in sternal recumbency with their head facing away from the anaesthetic machine. The patient’s neck should be extended and their head supported on a sandbag or rolled towel. The ET tube should be tied to the bottom jaw, to prevent the tie limiting movement of the endoscope, and a mouth gag (not spring-loaded for cats) should be placed to prevent bite-associated endoscope damage.
Following the completion of the retrograde endoscopy, the flexible endoscope is withdrawn. The patient’s mouth gag should be removed, their ET tube cuff should be re-checked and inflated appropriately, and a throat pack should be placed. A fluid collection pouch should also be placed over the end of the table, to catch any saline from the patient’s mouth, or from the rhinoscope.
The veterinary nurse should measure the rhinoscope by placing the tip at the level of the medial canthus of the eye, and placing a tape marker on the rhinoscope level with the nostril. This will remind the clinician not to advance the rhinoscope too far. Following this, fluids are attached to the rhinoscope ready for use.
On recovery, the patient should be closely monitored as residual flushing fluid, haemorrhage, mucous and other fluid may be present, potentially leading to aspiration. Inflammation of the laryngeal tissue can also occur from excessive manipulation, leading to oedema/swelling and other complications such as spasm, particularly in cats. Rhinoscopy patients should be recovered slowly in a quiet, calm area with lots of monitoring. Suction should remain on-hand until they have fully recovered, and SPO2 monitoring should continue until consciousness is regained. These patients can be painful on recovery, with ongoing sneezing and epistaxis, so careful monitoring, cleaning, pain scoring and regular analgesia is indicated.
What about sampling?
The most common method of sample collection during rhinoscopy is via biopsy. These may be endoscope-guided or collected blindly - blind biopsies are generally larger, as larger forceps can be placed directly into the nasal cavity than through the endoscope, but are not endoscope-guided, so are not suitable if you need to biopsy a specific area. Generally, multiple biopsies are collected for histopathology, with one biopsy being stored in sterile saline for bacterial +/- fungal culture.
The veterinary nurse is heavily involved in biopsy collection, whether that be guided biopsies through the endoscope channel, or handling blind biopsies. Here are my tips for handling instruments and collecting tissue samples:
Advance any forceps gradually (2cm at a time) and stop if you feel increased resistance when trying to advance them. Communicate with your clinician, as they may need to un-bend the end of the insertion tube before the forceps will advance.
Ensure that you keep all channel instruments in the ‘closed’ position until you can see the end fully exit the instrument channel. Opening the forceps inside the channel can cause damage to the endoscope.
After exiting the instrument channel, open your forceps and advance them as directed by the clinician, whilst held in the ‘open’ position.
When directed, purposely but carefully push the forceps against the area to be biopsied, and firmly close the forceps.
Holding the forceps in the closed position, withdraw them fully from the instrument channel.
When removing samples from the forceps, this can be done either by carefully ‘hooking’ them out of the forceps using a 25g needle, or by ‘shaking’ the end of the forceps in a sterile pot of saline, to free the biopsies from the forceps.
Transfer the biopsies into an endoscopic biopsy cassette, using one cassette per anatomical region (e.g. nasopharynx, left and right nasal cavity).
Gently close each cassette and place each in a labelled formalin pot for submission to the laboratory.
Place one fresh biopsy in a 1ml plain blood tube filled with sterile saline, for culture and sensitivity.
So that’s this week’s rhinoscopy round-up! I hope it helps you in practice. Don’t forget that you can download a full booklet of endoscopy equipment lists to complement this blog series - simply enter your email address below, and the link to our resource library will be sent straight to your inbox, alongside the password to access it!
References and further reading:
Cox, S. 2016. Endoscopy for the Veterinary Technician. Iowa: Wiley-Blackwell.
Merrill, L. 2012. Small Animal Internal Medicine for Veterinary Technicians and Nurses. Iowa: Wiley-Blackwell.
Disclaimer: Individual endoscope use and maintenance protocols may vary depending on your practice, the endoscopes you use, and clinician preference. The above information is intended as a guide only. Veterinary Internal Medicine Nursing is not responsible for any issues which may arise as a result of their use. Any products mentioned or images included within this post are for reference only and are not product endorsements or recommendations.