Page 1753 - Cote clinical veterinary advisor dogs and cats 4th

880 Respiratory Distress

CONTAGION AND ZOONOSIS • Ocular/nasal discharge (suggestive of an • Causes of hypoxemia
Pathogens of tracheobronchitis (pp. 271 and infectious process; may warrant containment ○ Decreased fraction of inspired oxygen
VetBooks.ir chiseptica infects immunosuppressed people. • Consider pattern of distress: inspiratory, ○ Ventilation-perfusion (VQ) mismatching
to prevent contagion)
(FIO 2 )
987) are contagious; rarely, Bordetella bron-
(e.g., PTE, asthma, pulmonary veno-
expiratory, mixed, paradoxical (see Disease
Other systemic contagions occasionally cause
occlusive disease [PVOD], PCH)
respiratory distress (e.g., leptospirosis [p. 583],
Forms/Subtypes above)
feline infectious peritonitis [p. 327]), and some • Muddy or cyanotic mucous membranes with ○ Hypoventilation (e.g., central nervous
are also zoonotic (e.g., plague). severe hypoxemia (p. 231) system disease, sedation)
• Audible noises (p. 945) ○ Diffusion impairment across the alveo-
ASSOCIATED DISORDERS ○ Stertor: seldom associated with cause of locapillary membrane (e.g., pulmonary
Stridor, syncope, cyanosis, orthopnea, regurgita- distress because it reflects obstruction fibrosis); rarely causes hypercarbia due
tion, exercise intolerance, dysphonia, or others, above the larynx to differences in solubility of gasses.
depending on cause of distress ○ Stridor: laryngeal or upper tracheal ○ Shunt (blood from the right heart enters
obstruction; inspiratory the left side without taking part in gas
Clinical Presentation • Thoracic palpation exchange) (e.g., acute respiratory distress
DISEASE FORMS/SUBTYPES ○ Evidence of trauma (e.g., rib fracture, fail syndrome [ARDS], alveolar collapse)
• Inspiratory distress: upper airway obstruc- segment) • Causes of hypercarbia
tion (above the thoracic inlet), severe ○ Lack of compressibility (cats) suggests ○ Hypoventilation
abdominal distention, or pleural space cranial mediastinal masses or pleural ○ VQ mismatching
disease. Upper airway obstruction may also effusion.
be associated with an externally audible ○ Palpable thrill from high-grade heart DIAGNOSIS
noise (e.g., stridor/stertor). A history of dys- murmur
phonia localizes disease to the upper airway • Thoracic percussion Diagnostic Overview
(larynx). ○ Hyporesonance suggests effusion, consoli- Disease localization is critical to prompt treat-
• Expiratory distress: lower airway disease dation, or mass effect. ment in an emergency setting. Upper airway
(below the thoracic inlet); may be associated ○ Hyperresonance suggests pneumothorax. obstruction (inspiratory effort with stridor),
with expiratory wheeze, expiratory effort is • Thoracic auscultation lower airway obstruction (expiratory effort,
associated with abdominal contraction during ○ Murmurs/arrhythmias due to heart wheeze), pleural space disease (inspiratory/
exhalation disease paradoxical effort, decreased ventral/dorsal lung
• Inspiratory-expiratory distress: mixed ○ Crackles suggest edema, pneumonia, sounds), flail chest, and abdominal distention
inspiratory and expiratory effort is typically contusions, or fibrosis; often inspiratory are identifiable during initial physical exam,
associated with pulmonary parenchymal or ■ Cough may enhance ability to auscul- allowing specific intervention before extensive
mixed disorders. tate crackles (post-tussive crackle). diagnostics.
• Paradoxical breathing: pleural space disease, ○ Wheezes suggestive of airway narrowing
airway obstruction, and diaphragmatic (e.g., bronchoconstriction, exudate); often Differential Diagnosis
paralysis; dyssynchronous movement of expiratory • Panting
the chest and abdomen. A focal paradoxical ○ Increased bronchovesicular sounds • Reverse sneezing
pattern of chest movement is seen with flail suggest increased airflow, early edema, • Look-a-like diseases: abnormal respiratory
chest. or pneumonia. rate/pattern without respiratory pathol-
• Respiratory effort in vascular disorders ○ Dull or absent bronchovesicular sounds ogy (e.g., anemia, acidemia, stress, pain,
(e.g., pulmonary thromboembolic disease ventrally or dorsally may suggest pleural methemoglobinemia)
[PTE], pulmonary capillary hemangiomatosis fluid or pneumothorax, respectively. ○ Differentiated from respiratory disease
[PCH]) varies. ○ Tracheal auscultation to assess referred by normal arterial blood gas or pulse
• Look-a-like diseases, including anemia, upper airway sounds oximetry (pulse oximetry reads low with
stress, pain, or metabolic disorders, may be • Hyperthermia may be identified with methemoglobin) on room air
mistaken for respiratory distress. upper airway obstruction or infectious
disease. Initial Database
HISTORY, CHIEF COMPLAINT • Profound abdominal distention (e.g., ascites, Provide supplemental oxygen immediately,
Labored, rapid, or noisy breathing, open-mouth gastric distention) can cause shallow, inspira- including during all diagnostic testing.
breathing (cats), and collapse are common tory distress. • CBC/serum biochemical profile/urinalysis:
presenting complaints. Anorexia, restlessness, • Poor body condition may be seen in cases changes depend on underlying disorder, often
exercise intolerance, and hiding behavior (cats) of chronic disease (e.g., neoplasia, fungal nonspecific
may be reported. Cough, hemoptysis, and pneumonia). • Thoracic/cervical radiographs: minimum
cyanosis are sometimes reported. Many cat • Other findings may reflect underlying disease of three-view thoracic radiographs recom-
owners fail to recognize cough, and cats with (e.g., skin lesions due to blastomycosis, mended; inspiratory and expiratory views
paroxysms of cough may present for vomiting abdominal mass associated with metastatic that include the thoracic and cervical trachea
or hairballs. pulmonary neoplasia). are needed in cases of collapsing trachea
(p. 1155)
PHYSICAL EXAM FINDINGS Etiology and Pathophysiology ○ Radiographic positioning may not be
Special attention should be paid early in the • Respiration depends on coordination tolerated until respiratory distress is
exam (before excessive handing) to phase of central and peripheral O 2 and CO 2 improved.
of respiratory effort, rate, and depth of excur- sensors, the respiratory control center • Pulse oximetry: ensure a good waveform
sions. (medulla oblongata and pons), and corresponding to auscultated heart rate;
• Features of respiratory distress may include external effector muscles (diaphragm, anemia should not cause interference when
an anxious facial expression, abducted elbows, intercostal muscles). packed cell volume > 15%-18%
neck extension, flaring nostrils, and restless- • Respiratory distress may be triggered by • Thoracic focused assessment of sonography
ness, orthopnea, or open-mouth breathing hypoxemia or hypercarbia (PaO 2 < 60 mm for trauma (TFAST) scan if pneumothorax
(cats). Hg; PaCO 2 > 50 mm Hg) or pleural effusion is suspected (p. 1102)

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