SMALL ANIMAL MEDICINE
FELINE
Table 2: Monitoring for pulmonary oedema whilst on fluid therapy
Exercise intolerance
Tachypnoea
Referred breath sounds Inspiration is active, expiration is passive based on the elasticity of pulmonary tissue.
Thus increased effort of expiration is an early sign of interstitial fluid accumulation.
Referred breath sounds occur when the sound of normal air turbulence in the large
bronchi is carried to the lung periphery due to interstitial fluid accumulation (sound
travels better through a fluid than air).
Respiratory distress
Crackles on auscultation
Moist soft cough
Cyanosis Fluid is now also building up in the alveoli - causing crackles.
IV fluids in AP patients. Each patient will be different.
Providing balanced fluid support is important, with
each patient being monitored closely and the fluid
rates adapted appropriately. (Table 2)
Oxygen Therapy
Oxygen therapy is indicated if the patient is
hypoxaemic or severely dyspnoeic. The assessment
of a patients oxygenation can be done using arterial
blood gas or pulse oximetry, with a PaO2 < 70mm
Hg or an SPO2 <93% indicating hypoxaemia and the
need for oxygen supplementation. If you do not have
access to blood gas or pulse oximetry, use the clinical
signs to guide you. In my opinion, if you are not sure if
the patient needs oxygen, just supplement it, the only
contraindication for giving oxygen is if the patient “is
on fire”!!
Nebulization
Nebulization with 0.9% saline and coupage is used
by most veterinarians with the thought that the this
will allow the delivery of small drops of water into
the respiratory tract to increase the hydration of the
aqueous layer of the respiratory secretions, which
will enhance the movement of theses secretions by
the mucociliary apparatus. Despite the common use
of nebulization and coupage, there is no evidence
in veterinary medicine to support its use, in fact one
veterinary study found no statistically significant
links between nebulization treatments and survival
to discharge and coupage has been associated with
pulmonary atelectasis and gastroesophageal reflux
in dogs. In human studies there is some evidence
that suggests nebulizing with 3% hypertonic saline
was more effective than normal saline. But even in
the human studies the results are conflicting with
many studies showing no clear benefit for the use
of nebulization. With this in mind, and given the time
and effort that goes into performing nebulization and
coupage, the question is should we still be doing it?
This should be left up to the clinician, to decide, but If
nebulization is going to be used rather use hypertonic
saline.
Conclusion
Aspiration pneumonia is common in canine veterinary
patients and can have high morbidity and mortality
rates if not treated. Apiration pneumonia can be
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prevented by identifying high risk patients and
procedures and reducing risk factors where possible.
High risk patients should be monitored closely
to allow for early diagnosis and treatment when
aspiration does occur. Survival rates of 77 – 82%
have been reported in patients treated for AP so the
prognosis is fair to good for patients treated correctly.
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