Seminars Respiratory Flashcards
What is the single largest contributor to an increased resistance in airflow?
Reduction in airway diameter
What is the hallmark of an upper respiratory tract obstruction?
Respiratory noise (stridor) usually an inspiratory noise and prolonged inspiration
What is dyspnoea?
Difficulty breathing- can happen with upper or lower respiratory tract issues
What occurs with regards to sound in a lower respiratory obstruction or severe lung disease?
Silent dyspnoea, with exaggerated expiratory effort and prolonged expiration
What is the narrowest part of the URT?
Larynx
What is Poiseuille’s Law?
Airflow is proportional to r^4 (.5 obstruction- 1/16 the flow). A small obstruction can have a big impact on airflow.
Recurrent Laryngeal Neuropathy (Laryngeal hemiplegia)
An arytenoid cartilage that does not maximally open or does not open with sustained strength during exercise
Dorsal displacement of the soft palate
Large negative pressures during exercise dislodge the soft palate from its normal position
Collapse of the pharyngeal roof
causes obstruction URT
Axial collapse of the ariepiglottic folds
causes obstruction URT
Which species cannot mouth breathe?
Horses, rabbits, and rodents. They have a long soft palate which sits underneath the epiglottis forming an airtight seal around the larynx. Severe bilateral nasal obstruction is life threatening in these species.
Which species only mouth breathe when they are having difficulty breathing?
Cats, cattle, and sheep
Why might it be difficult to see nasal discharge in cattle?
They lick their noses
What is strangles?
high contagious bacterial infection (horses) caused by Streptococcus equi. Causes large abscesses in the URT lymph nodes. If the retropharyngeal lymph nodes are involved and they continue to enlarge without rupture, they push the roof of the pharynx down obstructing the airway.
Bovine nasal granuloma (allergic rhinitis)
Hypersensitivity reactions in the nasal mucosa cause extreme irritation and itching which leads to FBs lodged deep in the nasal passages
Calf diphtheria (laryngeal and oral necrobacillosis)
Anaerobic bacterium Fusobacterium necrophorum invade superficial ulcers in the larynx (or mouth) causing large proliferative necrotic lesions that obstruct the larynx. Ulcers can develop as a result of continual coughing, or mild URT infections, constant vocalization or inhaled irritants.
Brachycephalic Syndrome- dogs
Flattened faces (shortened noses)- stenotic nares, long soft palate, everted laryngeal saccules. Abnormal narrowing of the nostrils creates a need for greater inspiratory effort at rest and a larger negative pressure inside the airways. This helps to displace the elongated soft palate which flaps in front of the larynx, obstructing (getting sucked into) the airway, causing dyspnoea and a bigger inspiratory effort. Negative pressure also evert the laryngeal saccules, which cause greater laryngeal obstruction and dyspnoea.
What does pulse oximetry measure?
Determines the degree of saturation of haemoglobin with oxygen
Where do we clip pulse oximeters on animals?
Tongue, paw, lip, or oesophagus or cloaca
What is a normal percentage saturation of Hb with oxygen?
95%
What does a capnogram measure?
Expired CO2 in gases continuously sampled near the patients respiratory tract. End tidal CO2 tension reflects systemic arterial CO2 tension (more accurately measured by arterial blood gas analysis).
What does the level of end tidal CO2 depend on?
Rate of production of CO2, the alveolar ventilation, and the CO and pulmonary perfusion. Thus monitoring end tidal CO2 tells us about metabolism, ventilation, and circulation
What is a normal tidal CO2 value?
30-45 mm Hg
What is blood gas analysis?
pH, partial pressure of oxygen (pO2), and pCO2. Also, bicarbonate, base excess, and percentage saturation of Hb with oxygen. (can also measure lactate, glucose and electrolytes) Arterial blood gas analysis is the gold standard for monitoring the respiratory system. Venous blood gas can also give information.
