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Jacinda Christie, DVM Affiliated Emergency Veterinary Service
Jacinda Christie, DVM Affiliated Emergency Veterinary Service Overview Respiratory anatomy/physiology Common causes of respiratory distress Initial assessment and stabilization Diagnostics/Therapies Respiratory Anatomy Upper airway Nasal passages Oropharynx Larynx Trachea Lower airway Bronchi/Bronchioles Respiratory Anatomy Pulmonary parenchyma Lung tissue/interstitium Alveoli Pleural space Respiratory Physiology Functions to deliver oxygen from the environment to the blood stream Diffusion of oxygen from the alveoli, across the interstitium, into the blood stream Respiratory Physiology Total blood oxygen is a combination of oxygen carried by hemoglobin and dissolved oxygen Oxyhemoglobin saturation curve Hemoglobin saturation is directly related to the partial pressure of oxygen in the bloodstream Steep dropoff under SpO2 ~94% Respiratory Physiology Disruption in the delivery of oxygen from the environment to the blood stream will result in hypoxemia and lead to respiratory distress Need to try to determine where this disruption is occurring and correct it Causes of Respiratory Distress Upper airway disease Rhinitis Obstructive disease ○ inflammatory, abscess, polyp, foreign body, neoplasia Laryngeal paralysis Collapsing trachea Causes of Respiratory Distress Lower airway disease Inflammatory ○ Chronic bronchitis, feline asthma Infectious Neoplasia Causes of Respiratory Distress Pulmonary parenchymal disease Cardiogenic and non-cardiogenic edema Pneumonia ○ Aspiration ○ Bacterial ○ Fungal Trauma ○ Contusions ○ Hemorrhage Neoplasia Coagulopathy Causes of Respiratory Distress Pleural space disease Trauma ○ Penetrating injury ○ Pneumothorax ○ Diaphragmatic hernia Cardiac disease Infectious ○ Pyothorax ○ FIP Coagulopathy Chylothorax Non-respiratory Causes Metabolic disease Acidosis – renal disease, DKA Anemia Pain Pericardial disease Toxins MetHb, CO Initial Assessment/Stabilization Be prepared Oxygen source ○ Flow by, mask, cage IV catheter supplies Injectable medications ○ Diuretics, bronchodilators, sedatives, glucocorticoids Inhaled medications ○ Bronchodilators, glucocorticoids Initial Assessment/Stabilization Hands off patient evaluation Signalment Brief health history Observation ○ Breathing patterns Open mouth breathing Normal rate vs. tachypnea Paradoxical breathing Inspiratory vs. expiratory ○ Stridor/stertor ○ Cyanosis Initial Assessment/Stabilization Breathing patterns Respiratory rate ○ Normal rate – upper airway disease ○ Tachypnea – short shallow breaths tend to be associated with pulmonary parenchymal or pleural space disease Paradoxical breathing ○ Lack of synchronous movement of the chest and abdominal walls During normal respiration both the chest and abdominal walls move outward Paradoxical breathing is characterized by the abdominal wall being sucked in during inhalation Pleural space disease Initial Assessment/Stabilization Breathing patterns Inspiratory vs. expiratory ○ Prolonged inspiratory time, stridor/stertor Upper airway disease ○ Prolonged expiratory effort, wheezes Lower airway disease ○ Mixed inspiratory/expiratory Pulmonary parenchymal disease Initial Assessment/Stabilization Brief auscultation Heart murmur/arrhythmia ○ May indicate primary cardiac disease Crackles ○ Presence of fluid in the alveoli Wheezes ○ Narrowing of the airways Dull/muffled lung sounds ○ Pleural space disease Disease localization Respiratory distress Upper airway disease Yes Loud upper airway sounds No Laryngeal paralysis Collapsing trachea Other Thoracic auscultation Increased lung sounds Cardiac abnormalities Consider heart failure Cardiac normal Consider parenchymal disease Pneumonia, Hemorrhage, Neoplasia, Inflammatory Decreased lung sounds Consider pleural space disease Pneumothorax Effusion Hernia Initial Assessment/Stabilization Oxygen support First therapy instituted Can be provided many ways Considerations ○ Stress level of patient ○ Size ○ Capabilities Initial Assessment/Stabilization Oxygen support Flow by ○ Easily provided in most situations ○ Short term ○ 25-40% FiO2 Mask ○ Patient tolerance ○ Loose vs. tight fitting ○ Short term ○ 40-50% FiO2 Initial Assessment/Stabilization Oxygen support Hood/Tent ○ E-collar with plastic wrap ○ Patient tolerance ○ Short or longer term ○ 40%+ FiO2 Initial Assessment/Stabilization Oxygen support Oxygen cage ○ Clinic capabilities ○ Short and long term ○ 40%+ FiO2 Initial Assessment/Stabilization Oxygen support Nasal cannula ○ Long term ○ Single or bilateral ○ Red rubber catheter Placed ventromedially Topical anesthetic ○ Humidify oxygen ○ 40-50% FiO2 Initial Assessment/Stabilization Oxygen support Tracheal catheter/tracheostomy ○ Direct delivery of oxygen into the trachea ○ Consider in cases of severe upper airway obstruction Initial Assessment/Stabilization Oxygen support Intubation ○ Severe respiratory distress ○ Upper airway disease ○ Can provide 100% FiO2 ○ Can be helpful to maintain control of airway while other emergency procedures are being performed Tracheostomy, thoracocentesis, chest tube placement Initial Assessment/Stabilization Vascular access Limit stress Peripheral IV catheter ○ Allows for administration of medications Baseline bloodwork Minimum database or at least a big 4 Initial Assessment/Stabilization Injectable medications Sedatives ○ Opioids – butorphanol, buprenorphine ○ Benzos, Acepromazine Diuretics ○ Suspicion of CHF Glucocorticoids/Bronchodilators ○ Suspicion of feline asthma, chronic bronchitis Initial Assessment/Stabilization Inhaled medications Aerokat/Aerodawg Easy to administer in an emergency Bronchodilator ○ Albuterol Glucocorticoids Suspicion of feline asthma or chronic bronchitis Initial Assessment/Stabilization Thoracocentesis Consider performing prior to obtaining radiographs or other diagnostics ○ Paradoxical breathing ○ Dull lung sounds ○ Ultrasound confirmation of pleural space disease ○ R/O coagulopathy Initial Assessment/Stabilization Thoracocentesis 22g catheter or needle ○ Can use larger if needed Extension set 3-way stopcock Syringe Initial Assessment/Stabilization Thoracocentesis Right and/or left hemithorax 7-9th intercostal space ○ Directly in front of the rib Angle dorsally if air is expected Angle ventrally if fluid is expected Ultrasound guidance if available Local anesthesia and/or sedation as needed Diagnostics Radiographs Ensure patient is stable enough Continue supplemental oxygen Consider DV view rather than VD in stressed patients Evaluation of cardiac size/VHS ○ Normal dogs <10.5-11.0 ○ Cats 6.7-8.1 Evaluate pulmonary pattern and pleural space Diagnostics Bloodwork Minimum database once patient is stable ○ R/O anemia, severe metabolic disease as causes of respiratory distress Coagulation panel ○ Especially if rodenticide toxicity or other coagulopathy is suspected Blood gas ○ Ideal for evaluating how well the patient is ventilating and determining the need for manual ventilation Diagnostics Cytology Can be helpful for determining cause of pleural effusion Echocardiography Airway sampling TTW, BAL Cardiac biomarkers?? Additional Therapies IV fluids Antibiotics Nebulization ACE inhibitors/Pimobendan Pain management Plasma transfusion/Vitamin K1 Chest tube placement Surgery Summary Respiratory distress is a common presenting complaint Be prepared! Hands off and brief assessment can help localize the disease and determine the best initial therapy Any Questions??
