Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.
Issue link: http://todaysveterinarypractice.epubxp.com/i/591321
Today's VeTerinary PracTice | november/december 2015 | tvpjournal.com aPProach To resPiraTory disTress Peer reviewed 54 History History can also be extremely useful; for example: • History of blunt trauma (eg, hit by a car) should prompt concern for pulmonary contusions, pneumothorax, diaphragmatic hernia, or fail chest. • In cats, a history of cough is consistent with asthma, while in dogs, a cough might suggest tracheobronchial disease, interstitial lung disease, or pulmonary edema. Physical Examination Examining a patient with respiratory distress should involve: 1. Initial observation: Consider breathing pattern, presence of externally audible noise with breathing, any signs of trauma, or abdominal distension 2. Lung auscultation: » Increased adventitial lung sounds (eg, crackles, wheezes, harsh lung sounds) are associated with lower airway and pulmonary parenchymal disease » Decreased lung sounds, in an animal with respiratory distress, are associated with pleural space disease. 3. Cardiac auscultation: A murmur, gallop, or other arrhythmia may indicate underlying cardiac disease and the potential for cardiogenic pulmonary edema or pleural effusion. In general, breathing patterns help narrow the list of differential diagnoses (Table 1). For example, upper airway obstruction is associated with inspiratory dyspnea and an externally audible noise. In contrast, lower airway obstruction tends to be associated with expiratory dyspnea and wheeze, with the wheeze generally just audible on thoracic auscultation with a stethoscope, rather than externally audible. Diagnostic Tests Extensive diagnostics should not be performed until the patient has been stabilized as much as possible, a brief physical examination has been performed, and the practitioner has localized the disease to the most likely anatomic location (Table 1). Diagnostic tests may subsequently involve: • Blood analysis: Screening blood tests, blood gases • Imaging: Thoracic ultrasound, including focused assessment with sonography for trauma, triage, and tracking (tFAST); thoracic radiographs; thoracic computed tomography (CT); or echocardiography • Respiratory fluid analysis: Bronchoalveolar lavage, thoracocentesis Categories of Respiratory Disease Dogs and cats with respiratory distress can be classifed into 8 disease categories, some of which are associated with distinct breathing patterns observed during physical examination. 1,2 These categories include both primary respiratory diseases and secondary causes of respiratory diffculty. Diagnostic approach is determined by the category of disease causing respiratory distress. Table 1. Anatomic Classifcation: Causes of Respiratory Distress DISEASE CATEGORY EXAMPLES BREATHING PATTERN 1. Upper Airway Obstruction • Brachycephalic airway disease • Laryngeal paralysis • Inspiratory dyspnea • Externally audible noise (eg, stertor, stridor) 2. Lower Airway Obstruction • Asthma • Expiratory dyspnea • Wheeze (audible with stethoscope) 3. Pulmonary Parenchymal Disease • Pneumonia • Interstitial lung disease • Pulmonary edema • Pulmonary contusions • Not consistent; may be rapid, shallow, or both, and have both inspiratory and expira- tory components 4. Vascular • Pulmonary thromboembolism • Not specifc 5. Pleural Space Disease • Pneumothorax • Pleural effusion • Inspiratory dyspnea, rapid shallow breathing, or generalized paradoxical breathing • Reduced lung sounds on auscultation 6. Flail Chest • Focal paradoxical breathing 7. Abdominal Distension • Ascites • Organomegaly • Inspiratory dyspnea 8. Look-alike Diseases • Not specifc