Page 283 - Small Animal Internal Medicine, 6th Edition

CHAPTER 14 Diagnostic Tests for the Nasal Cavity and Paranasal Sinuses 255

localizable lesion is identified radiographically or rhinoscop- be in place during the procedure, and the caudal pharynx
ically, multiple biopsy specimens (usually 6-10) are obtained should be packed with gauze after visual assessment of the
VetBooks.ir randomly from both sides of the nasal cavity. oral cavity and nasopharynx. The cuff should be sufficiently
inflated to prevent audible leakage of air during gentle com-
TURBINECTOMY
Overinflation of the cuff may lead to tracheal trauma or tear.
Turbinectomy provides the best tissue specimens for histo- pression of the reservoir bag of the anesthesia machine.
logic examination and allows the clinician to remove abnor- The nose is pointed toward the floor over the end of the
mal or poorly vascularized tissues, debulk fungal granulomas, examination table, allowing blood and fluid to drip out from
and place drains for subsequent topical nasal therapy. Turbi- the external nares after rhinoscopy and biopsy. Finally, the
nectomy is performed through a rhinotomy incision and is caudal pharynx is examined during gauze removal and
a more invasive technique than those previously described. before extubation for visualization of continued accumula-
Turbinectomy is a reasonably difficult surgical procedure tion of fluid. Gauze sponges are counted during placement
that should be considered only when other less invasive tech- and then re-counted during removal so that none are inad-
niques have failed to establish the diagnosis. Potential opera- vertently left behind.
tive and postoperative complications include pain, excessive
hemorrhage, inadvertent entry into the cranial vault, and
recurrent nasal infections. Cats may be anorectic postopera- NASAL CULTURES: SAMPLE COLLECTION
tively. Placement of an esophagostomy or gastrostomy tube AND INTERPRETATION
(see Chapter 28) should be considered if necessary to provide
a means for meeting nutritional requirements during the Microbiologic cultures of nasal specimens are often per-
recovery period. (See Suggested Readings in Chapter 13 for formed but can be difficult to interpret. Aerobic and anaer-
information on the surgical procedure.) obic bacterial cultures, mycoplasmal cultures, and fungal
cultures can be performed on material obtained by swab,
Complications nasal flush, or tissue biopsy. However, a wide range of organ-
The major complication associated with nasal biopsy is hem- isms that may be pathogenic in some settings can be present
orrhage. The severity of hemorrhage depends on the method in the proximal nasal cavity in healthy dogs and cats, includ-
used to obtain the biopsy, but even with aggressive tech- ing Pseudomonas, Mycoplasma, and Aspergillus organisms,
niques the hemorrhage is rarely life-threatening. When any along with a variety of other aerobic and anaerobic bacteria
technique is used, the floor of the nasal cavity is avoided to and fungi. Thus bacterial or fungal growth from nasal speci-
prevent damage to major blood vessels. For minor hemor- mens does not necessarily confirm the presence of infection.
rhage, the rate of administration of intravenous fluids should Cultures should be performed on specimens collected
be increased and manipulations within the nasal cavity within the caudal nasal cavity of anesthetized patients. Bac-
should be stopped until the bleeding subsides. Cold saline terial growth from superficial specimens, such as nasal dis-
solution with or without diluted epinephrine (1 : 100,000) charge or swabs inserted into the external nares of
can be gently infused into the nasal cavity. Persistent severe unanesthetized patients, is unlikely to be clinically signifi-
hemorrhage can be controlled by packing the nasal cavity cant. It is difficult for a culture swab to be passed into the
with umbilical. The tape must be packed through the naso- caudal nasal cavity without its being contaminated with
pharynx as well as through the external nares, or the blood superficial (insignificant) organisms. Guarded specimen
will only be redirected. Similarly, placing swabs or gauze in swabs can prevent contamination but are relatively expensive
the external nares serves only to redirect blood caudally. In and may be too long to safely extrude into the nasal cavity
the rare event of uncontrolled hemorrhage, the carotid artery of cats and small dogs. Alternatively, mucosal biopsies from
on the involved side can be ligated without subsequent the caudal nasal cavity can be obtained for culture using
adverse effects. Rhinotomy should not be attempted. In the sterilized biopsy forceps; the results may be more indicative
vast majority of animals, only time or cold saline infusions of true infection than those from swabs because, in theory,
are required to control hemorrhage. The fear of severe hem- the organisms have invaded the tissues. Superficial contami-
orrhage should not prevent the collection of good-quality nation may still occur.
tissue specimens. Regardless of the method used, the growth of many colo-
Trauma to the brain is prevented by never passing any nies of one or two types of bacteria rather than the growth of
object into the nasal cavity beyond the level of the medial many different organisms more likely reflects infection. The
canthus of the eye without visual guidance. The distance microbiology laboratory should be asked to report all growth.
from the external nares to the medial canthus is noted by Otherwise, the laboratory may report only one or two organ-
holding the instrument or catheter against the face, with the isms that more often are pathogenic and provide misleading
tip at the medial canthus. The level of the nares is marked on information about the relative purity of the culture. The pres-
the instrument or catheter with a piece of tape or marking ence of septic inflammation based on histologic examina-
pen. The object should never be inserted beyond that mark. tion of nasal specimens and a positive response to antibiotic
Aspiration of blood, saline solution, or exudate into the therapy support a diagnosis of bacterial infection contribut-
lungs must be avoided. A cuffed endotracheal tube should ing to clinical signs. Although bacterial rhinitis is rarely a