8. How will I recognize a patient with severe respiratory distress?

Usually, they aren’t hard to recognize. Abnormal sounds (stridor, wheezes), abnormal posture (orthopnea, head and neck extended, elbows abducted, sternal recumbency), abnormal mucous membrane color (cyanosis or pale), tachypnea, weakness and exhaustion, altered respiratory effort (shallow and rapid, or labored and forceful, or absent), and vigorous resistance to restraint are the typical signs present in animals with respiratory distress. However, pets can have significant respiratory compromise and yet outwardly show minimal clinical signs of distress. Cats are more likely to have this type of presentation. Careful and quiet examination is essential to avoid sending the patient into stress-induced overt distress or respiratory arrest.

9. Are there physical exam findings that might help me differentiate the cause or location of the primary respiratory problem?

YES! Patients with a rapid, shallow respiratory pattern frequently have pleural space disease (pleural effusion, hemothorax, pneumothorax). Patients with end-expiratory effort and wheezes on chest auscultation frequently have small airway obstructive disease (asthma). Patients with deep, labored chest movements frequently have pulmonary parenchymal disease (pulmonary edema, pulmonary contusions, space-occupying masses). Patients with obvious stridor, minimal air movement at the nares or mouth, and marked inspiratory effort typically have upper airway obstruction (laryngeal edema or paralysis, foreign body aspiration). These patterns are hardly exclusive: Often patients have multiple problems, and some patients may have serious underlying respiratory problems and yet clinically appear normal.

10. Define cyanosis, its causes and significance, and the treatment of an emergent patient with cyanosis.

Cyanosis develops 1) when blood is insufficiently oxygenated in the lungs, 2) when hemoglobin is unable to carry oxygen, and 3) when blood stagnates in peripheral capillary beds. To be detected clinically, unoxygenated hemoglobin concentration must be > 5 gm/dL of blood. At this level, significant hypoxemia can already be present (< 50 mmHg), thus reinforcing the significance of cyanosis in a critical patient with respiratory distress. Additionally, anemic patients may not demonstrate cyanosis. Cyanosis is centrally-mediated (right-to-left cardiovascular shunts, hypoventilation, airway obstruction, V/Q mismatching, methemoglbinemia) or peripherally-mediated (arterial thromboembolism, venous obstruction, arteriolar constriction, low cardiac output heart failure, shock). Emergency treatment is provision of supplemental oxygen and rapid identification and correction of the underlying cause.

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