Page 335 - Small Animal Internal Medicine, 6th Edition

CHAPTER 20 Diagnostic Tests for the Lower Respiratory Tract 307

primary complication of BAL is hypoxemia. Hypoxemia laryngoscope is used, and sterile lidocaine is applied topi­
generally can be corrected with oxygen supplementation, but cally to the laryngeal mucosa. The cuff is then inflated suf­
VetBooks.ir animals exhibiting increased respiratory efforts or respira­ ficiently to create a seal, but overinflation is avoided to
prevent tracheal rupture (i.e., use a 3­mL syringe and inflate
tory distress in room air are not good candidates for this
procedure. Patients may have poor lung function without
when gentle pressure is placed on the oxygen reservoir bag).
overt signs, so the ability to provide oxygen supplementation the cuff in 0.5­mL increments only until no leak is audible
for an hour or longer is necessary to minimize the risk of The cat is placed in lateral recumbency with the most
patient decompensation. Patients with hyperreactive airways, diseased side, as determined by physical and radiographic
particularly cats, are treated with bronchodilators, as findings, against the table. Oxygen (100%) is administered
described previously for endotracheal washing. for several minutes through the endotracheal tube. The anes­
In addition to the methods described, other techniques thetic adapter then is removed from the endotracheal tube
for NB­BAL have been reported in which a long, thin, sterile and replaced with a sterile syringe adapter, with caution to
catheter is passed through a sterile endotracheal tube until avoid contamination of the end of the tube or adapter.
the catheter is lodged in a distal airway, and relatively small Immediately, a bolus of warmed, sterile 0.9% saline solution
volumes of saline are infused and recovered. Foster and (5 mL/kg body weight) is infused through the tube over
Martin (2011) used a 6F to 8F dog urinary catheter and two approximately 3 seconds. Immediately after infusion, suction
5­ to 10­mL aliquots of sterile saline. Such methods likely is applied by syringe. Air is eliminated from the syringe, and
result in less hypoxemia than those described here but would several aspiration attempts are made until fluid is no longer
be expected to sample a smaller portion of lung. Critical recovered. The procedure is repeated using a total of two or
evaluation of different techniques for BAL in disease states three boluses of saline solution. The cat is allowed to expand
has not been performed. its lungs between infusions of saline solution. After the last
infusion, the syringe adapter is removed (because it greatly
TECHNIQUE FOR NB-BAL IN CATS interferes with ventilation) and excess fluid is drained from
A sterile endotracheal tube and a syringe adapter are used in the large airways and endotracheal tube by elevating the
cats to collect lavage fluid (Fig. 20.22; see also Fig. 20.21). caudal half of the cat a few inches off of the table. At this
Cats, particularly those with signs of bronchitis, should be point, the cat is cared for as described in the section on
treated with bronchodilators before the procedure, as recovery of patients after BAL.
described previously for tracheal wash (endotracheal tech­
nique), to decrease the risk of bronchospasm. The cat may TECHNIQUE FOR NB-BAL IN DOGS
be premedicated with atropine (0.05 mg/kg subcutaneously) An inexpensive 122­cm 16F Levin­type polyvinyl chloride
to minimize oral secretions, and is anesthetized with ket­ stomach tube can be used in dogs to collect lavage fluid.
amine and acepromazine or diazepam, given intravenously. The tube must be modified for best results. Sterile tech­
The endotracheal tube is passed as cleanly as possible through nique is maintained throughout. The distal end of the tube
the larynx to minimize oral contamination. To achieve suf­ is cut off for removal of the side openings. The proximal
ficient cleanliness, the tip of the tongue is pulled out, a end is cut off for removal of the flange and shortening of

FIG 20.22
Bronchoalveolar lavage using an endotracheal tube in a cat. The fluid retrieved is grossly
foamy because of the surfactant present. The procedure is performed quickly because the
airway is completely occluded during infusion and aspiration of fluid.