Lecture 1 Flashcards
The mucociliary escalator clears dust/pathogens from which areas of the respiratory tract?
Trachea and Bronchi
Why does dust tend to settle in the terminal bronchioles?
There is a rapid decrease in air velocity in the terminal bronchioles, so dust tends to settle here!
Does the respiratory zone or the conducting zone have a greater surface area?
Respiratory zone
If the mucociliary escalator clears dust/debris from the trachea and bronchi, what clears debris from the respiratory zone (respiratory bronchioles, alveolar ducts, alveolar sacs)?
Macrophages clear debris out of the respiratory zone
What type of cell produces surfactant in the lungs?
Type II pneumocyte
What comprises the upper airway?
Pharynx, Larynx, Trachea, Bronchi, Bronchioles
What comprises the lower airway?
Respiratory bronchioles and alveoli
Is the smooth muscle in the respiratory tract in the upper airway or the lower airway?
Upper air way. The bronchi and bronchioles are surrounded by smooth muscle.
What do normal bronchial sounds sound like?
Harsh, hollow, blowing
- airflow through trachea/mainstem bronchi
- loudest over trachea
- both inspiratory and expiratory
What do normal vesicular sounds sound like?
Rustling
- Airflow through lobar bronchi
- Peripheral
- Primarily inspiratory (can be hard to hear!)
Name 4 abnormal breath sounds.
- Crackles
- Wheezes
- Stertor
- Stridor
NOTE: 1 &2: typically heard w/ stethoscope on chest
3&4: more upper resp. issues, audible
What are “crackles”?
Discontinuous “popping” sounds
- Cause: snapping open of small airways that have collapsed or accumulated fluid/debris
- Timing: mostly INSPIRATORY
What are some differentials if you were to hear crackles?
- Pulmonary edema (cardiogenic vs. non-cardiogenic)
- Pneumonia (esp. aspiration)
- Fibrosis
What are wheezes?
A continuous, whistling musical sound (hear w/ stethoscope)
- Cause: airflow through constricted or narrowed airways
- Timing: EXPIRATORY
Wheezes: Differentials
- Lower airway inflammatory disease
- Feline asthma/feline lower airway disease
- Canine chronic bronchitis - Anaphylactic reaction
Stertor?
Snoring, snorting, snuffling noise
- Cause: upper airway obstruction of airflow due to excess tissue or secretions
- Timing: VARIABLE (usually BOTH insp. and expir.)
Overtly audible sound, like snoring..
Where does stertor sugges disease is localized to?
Stertor suggests disease is localized to the nasal cavity and/or nasopharynx
- anything filling nasal cavity or nasopharynx can cause stertor
Stertor: differentials
- Brachycephalic syndrome
- Nasal congestion/infiltration
- Nasopharyngeal polyps
- Nasal/Nasopharyngeal neoplasia
- Inflammatory/infectious rhinitis
- Nasal/nasopharyngeal foreign body
Stridor
Intense, high-pitched wheeze
- Cause: extra-thoracic UPPER airway collapse and/or narrowing
- Timing: virtually always INSPIRATORY (opposite of wheezes!)
- Overtly audible sound
- When stridor is present w/ choice change, suspect laryngeal involvement (ie. dog has less of a bark)
Stidor: differentials
- Laryngeal paralysis
- Laryngeal collapse
- Tracheal collapse
- Laryngeal/tracheal obstruction
- intraluminal (foreign body, mass)
- Extraluminal (mass, soft tissue swelling)
Dyspnea
Respiratory distress - labored breathing in response to:
- Hypoxemia
- Hypercapnia
Top 4 localizations of Dyspnea
- Upper airway
- Lower airway
- Parenchymal
- Pleural space
Dyspnea patterns
- Obstructive (inspiratory and expiratory)
2. Restrictive
Obstructive Dyspnea
Obstruction of airway
- normal to increased respiratory rate
- increased depth of breathing (hyperpnea)
ITS LIKE A MAN UNDERWATER BREATHING THROUGH A STRAW
Obstructive Inpiration
Slow, deep inhalation
+/- stridor
Due to a dynamic EXTRA-THORACIC obstruction
- tracheal or laryngeal obstruction (ie. laryngeal paralysis)
Obstructive expiratory
Slow, prolonged expiration
- Due to INTRA-THORACIC airway disease
- large airway obstruction (intra-thoracic tracheal collapse)
- small airway disease (bronchitis, feline asthma)
Restrictive Dyspnea
Occurs due to disease process that restricts lung INFLATION
- increased respiratory rate
- variable depth, depending on disease state
Example: pleural space disease
PICTURE A BEAR SQUEEZING A MAN - RESTRICTIVE
Does tachypnea equal panting?
NO.
Normal resting respiratory rates
Canine: 18 - 34 brpm
Feline: 16 - 40 brpm
Pulse Oximtry (SpO2)
Emits red and infrared lights
- Detector measures unabsorbed light
- Oxygenated blood ABSORBS infrared light
- Deoxygenated blood absorbs red light
Place on ear, lip, tongue, prepuce/vulva
- a dark pigmented animal may make it difficult to get a reading!
Can the pulse ox differentiate between carboxyhemoglobin and monoxyhemoglobin from oxygenated hemoglobin?
NO!!!
Oxygen supplementation?
- Hypoxemia
- PaO2 < 80 mmHg
- Oxygen desaturation
- SPO2 < 94%
- Respiratory distress/arrest
FiO2 w/ intubaction
intubated FiO2 = 100% oxygen
FiO2 w/ Oxygen Cage
FiO2 oxygen cage = 40-60%
- takes time, expensive, isolation of animal
- non-invasive and non-stressful
NOTE: at 60% we are have a risk of explosion.. Start at 40%
Nasal Oxygen FiO2
Nasal oxygen FiO2 = 40-50%
- quite effective; place in ventral nasal meatus
Pros = good for large dogs; easy to care for patient Cons = uncomfortable, nasal bleeding (not good in thrombocytopenic patients), inadvertent removal
Face mask FiO2
Face mask FiO2 = 50%
- very practical if it’s NOT long term
Pros = convenient Cons = need tight seal, can be stressful
Hood oxygen FiO2
Hood oxygen FiO2 = 40-60%
Pros = easy and economical (saran wrap the front of an E-collar) Cons = gets hot/humid, variable FiO2, may need sedation
Flow-by-oxygen FiO2
Flow-by-oxygen FiO2 = ~30-40%
- hold tube 2-4 cm from nose
Pros = easy, convenient Cons = high flow rates (waste), not long-term solution
