Page 324 - Clinical Small Animal Internal Medicine

292 Section 4 Respiratory Disease

transmission. Rapid and fatal reexpansion pulmonary tory crackles, adventitious lung sounds that represent
VetBooks.ir edema may rarely occur in patients with chronic pleural the sudden opening of fluid‐filled alveoli. Alveolar fluid
may be blood, purulent exudate or transudate. Alveolar
effusion. Ideally, pleural fluid and/or air should be
removed until negative pressure is achieved, but this is
coagulopathy. A patient with cardiogenic pulmonary
not always possible. If negative pressure cannot be hemorrhage may occur secondary to trauma and/or
achieved, if more than two thoracocenteses are required edema secondary to left‐sided heart disease may have a
in a one‐hour period, or more than three thoracocente- systolic murmur and hypothermia while a patient with
ses are required in a 24‐hour period, a thoracostomy pneumonia or aspiration pneumonitis may have pyrexia.
tube should be placed. Patients should be efficiently examined for evidence of
Once stable, a thorough physical examination should ecchymoses, obvious soft tissue and/or orthopedic injury
be performed in an effort to determine the underlying and thermal injury (i.e., lingual or oral commissure).
cause. Traumatic pneumothorax commonly resolves Patients should be given appropriate sedation and sup-
without surgical intervention, but injuries may require plemental oxygenation as soon as possible in an effort to
several days to heal. The presence of pneumothorax with- reduce the work of breathing and anxiety. The least
out a history of trauma should always prompt a search for stressful method of supplemental oxygen provision
pulmonary parenchymal disease. Pleural effusion should should be employed. A commonly used sedative protocol
be immediately evaluated in‐house for obvious sepsis for cardiovascularly unstable patients is the combination
and/or neoplastic cells, and one should submit samples of a pure mu opioid (i.e., fentanyl 2–4 μg/kg IV; oxymor-
(i.e., pleural fluid sample in EDTA‐containing tube, phone 0.05–0.1 mg/kg IV/IM; methadone 0.2–0.5 mg/kg
unstained slide, fluid sample on appropriate culture IV; hydromorphone 0.1–0.2 mg/kg IV) with a benzodiaz-
media) to a veterinary reference laboratory for evaluation epine (i.e., diazepam 0.1–0.5 mg/kg IV; midazolam 0.2–
by a board‐certified veterinary clinical pathologist. 0.4 mg/kg IV). A single dose of furosemide (dogs: 2 mg/kg
Echocardiography and cardiac biomarker (i.e., NT‐ IV/IM; cats: 1 mg/kg IV/IM) may be provided to those in
proBNP) measurement may be helpful in those patients which primary heart disease is suspected to be contribut-
suspected of living with cardiac disease, and diaphrag- ing to clinical signs until a definitive diagnosis is made.
matic hernias should be surgically repaired as soon as the While provision of sedation and oxygen is sufficient to
patient is cardiovascularly and metabolically stable. relieve clinical signs, some will not meaningfully respond;
these patients must have their airways captured via oro-
tracheal intubation immediately and mechanical ventila-
Pulmonary Parenchyma tion should be initiated. Provision of positive end‐expiratory
pressure (PEEP) at a level of 3–5 cmH 2 O may promote
The pulmonary parenchyma may be affected by a num- recruitment of collapsed alveoli.
ber of diseases, and a thorough history will help the Diagnostic imaging should be performed once the
astute clinician develop an appropriate diagnostic inves- patient has been appropriately stabilized. Commonly
3
tigation and therapeutic interventions. Dogs frequently employed thoracic imaging modalities include tFAST ,
have a history of a cough that may or may not be produc- veterinary bedside lung ultrasound examination
3
tive, but cats rarely manifest this clinical sign. A history (VetBLUE), and thoracic radiography. A tFAST evalua-
of laryngeal paralysis or recent vomiting should raise tion may be used to detect chest wall, lung, pleural and/
concern for aspiration pneumonitis, and patients with or pericardial pathology, and may be performed in lateral
trauma may develop pulmonary contusions and/or non- or sternal recumbency. Five points are evaluated, and fur
cardiogenic pulmonary edema. Recent generalized is not shaved but rather is simply parted with alcohol or
seizure activity, electrocution, traumatic brain injury, sonographic gel (Table 29.2). Patients with pulmonary
and/or strangulation should also raise concern for non- parenchymal disease may have B‐lines (aka: comet tail
cardiogenic pulmonary edema that develops secondary artifacts, lung rockets) that suggest interstitial disease or
to endothelial injury and vascular leakage into alveoli. interlobar edema is present; thus a clinician should be
Conversely, patients with primary cardiac disease are at suspicious of pulmonary edema (cardiogenic and non-
risk for developing cardiogenic pulmonary edema. cardiogenic) and pneumonia/pneumonitis. A VetBLUE
3
Performing a complete physical examination is invalu- scan is similar to a tFAST , as it is performed rapidly in
able for patients with suspected pulmonary parenchymal sternal recumbency, measures the presence of B‐lines
disease. Affected patients do not have a specific respira- and does not require hair coat shaving; in contrast, eight
tory pattern, and frequently manifest respirations that locations (four per hemithorax) are evaluated during the
are rapid and deep. They may be presented with cyanosis scan (see Table 29.2). The absence of B‐lines in all evalu-
and dyspnea, and increased abdominal effort is relatively ated lung fields rules out pulmonary edema and suggests
common. Auscultation commonly reveals end‐inspira- a nonrespiratory cause of distress.