Signs Of Respiratory Disease Flashcards
What does the respiratory system defend against?
Inhaled non-infectious particulates
Infectious agents
What non-infectious agents must the respiratory system defend against?
Dust, LPS, allergens
What are the respiratory defence mechanisms?
Airway smooth muscle tone Mucous production and mucociliary clearance Coughing Infiltrating cells Mediators
How can airway smooth muscle tone be altered?
Bronchostriction - prevent pathogens getting further down the respiratory tract
Bronchodilation - physiological e.g. exercise induced
How is airway smooth muscle tone mediated?
Neural mechanisms
Hormones
Mediators
How does the parasympathetic nervous system influence airways?
Smooth muscle contracts - airway constricts
What is the effect of epinephrine on airways?
What receptor does it use ?
Relaxes smooth muscle - dilates airways
B2 receptors
What effects do anti-cholinergics and beta 2 agonists have on airways?
Dilation
How can excess mucous production be treated therapeutically?
Mucolytics
Briefly outline the cough reflex.
Irritant receptors in the respiratory tract stimulated by particulate matter
Vagus nerve transmits to cough centre in brain stem
Efferent motor n. Transmission and cough.
What effects do endorphins and enkephalins have on the cough reflex?
What receptors do they act on?
Where are these located?
Suppress reflex
Opioid receptors in cough centre of brain stem
How can the cough reflex be targeted pharmacologically?
Demulcents (not common)
Opioid receptor agonists
Give examples of opioid receptor agonists which can be used to suppress the cough reflex.
Butorphanol
Codeine
What are the resident cells in the lungs?
Alveolar macrophages
Mast cells
Lymphocytes
What is the role of alveolar macrophages?
—Phagocytosis of foreign particles
—Antigen presentation to lymphocytes
—Formation/ release of mediators
—Clearance of effector cells to turn off inflammation at the end of an infection
What immunoglobulins are involved in respiratory defence?
IgA
IgG
What is the role of IgA in respiratory defence?
Upper airways
Inhibits adherence of bacteria to epithelium
Binds and neutralises foreign particles
Initiates immune response via leukocytes
What is the role of IgG in respiratory defence?
Lower airways
Binds and neutralises foreign particles
Activates compliment cascade
Involved in antibody dependent cytotoxicity
What are the infiltrating cells?
Neutrophils Eosinophils Basophils Lymphocytes Monocytes Platelets
What is the physiological role of mediators in host defence?
Airway smooth muscle tone Blood flow and vascular permeability Cell accumulation and activation Mucous production Neural reflex mechanisms Antibacterial activity
Which drugs are best for addressing problems associated with the presence of excessive mediators in the respiratory tract?
CORTICOSTEROIDS
Anti-inflammatory drugs - steroids better than NSAIDs
What are the clinical manifestations of respiratory disease?
Coughing and bronchoconstriction Sneezing Tachypnoea and hyperpnoea Respiratory distress (dyspnoea) Nasal discharge Epistaxis Haemoptysis Cyanosis Abnormal Respiratory Noise - STRIDOR
What is the definition of ‘cough’?
Sudden noisy expulsion of air through the glottis to clear mucous and other material from the larger airways.
How does coughing aid in mucous clearance?
High velocity of air flow creates shear forces to separate mucous from airway
- helps the mucociliary escalator
What are the stimuli for coughing?
Bronchoconstriction Excessive mucous Inhaled particles Hot or Cold air Intramural or extramural pressure Epithelial sloughing (due to damage) Enhanced epithelial permeability
What type of cough MIGHT you associate with an upper airway problem?
Harsh, loud, non-productive
What type of cough MIGHT you associate with a lower airway condition?
Soft muted, productive
What type of cough MIGHT you associate with painful conditions?
More muted cough
Animal tries not to cough as it hurts
What behaviours would indicate a productive cough?
Swallowing after coughing
Coughing up mucous
How would bronchoconstriction present on auscultation?
Wheezing
How does bronchoconstriction relate to cough?
Separate reflex
Slower onset and longer lasting - may improve the efficiency of coughing
What is meant by the term tachypnoea?
Increased respiratory rate
What is the normal resp rate for a dog?
What is the normal resp rate for cows, and pigs?
10-30
10-30
What is the normal resp rate for a cat?
24-42
What is the normal resp rate for a horse?
8-16
What is the normal resp rate for a rabbit?
30-60
What is the normal resp rate for a foal or calf?
20-40
What are the physiological causes of tachy/hyperpnoea?
Pain, exertion, heat, anxiety
Stimulation of autonomic nervous system
What are the pathological causes of tachy/hyperpnoea?
High CO2, low pH, low O2 Metabolic acidosis Excessive environmental heat Damaged or diseases CNS (resp. Centres) Pain or restriction in structures involved in breathing
What are the signs of respiratory distress?
-Abnormal rate, rhythm and character
-Nostril flaring
-Exaggerated intercostal and/or abdominal effort,
-abducted elbows,
-stridor,
-Anxious expression,
Inactivity
When would you not expect to see mouth breathing in respiratory distress?
HORSES
Obligate nasal breathers
What are the causes of inspiratory distress?
Extrathoracic non-fixed airway obstruction
Restrictive disease
How can extrathoracic non fixed airway obstructions cause inspiratory distress?
The negative pressure of breathing in draws the obstructing thing into the airway to obstruct them.
This is then pushed away when breathing out.
Give an example of an extrathoracic non-fixed airway obstruction
Upper airway obstructions
Laryngeal hemiplegia
Soft palate disorders
How can restrictive diseases lead to inspiratory distress?
Give an example
Limit lung expansion
Pleural effusion
What can cause intrathoracic airway obstruction?
Severe Equine Asthma in horses
Farmers disease in cattle
Tracheal collapse in dogs and horses
What can cause expiratory distress?
Intathoracic airway obstruction
Hypertrophy of the body wall
What can cause both inspiratory and expiratory distress?
Extrathoracic fixed obstruction
Give examples of an extrathoracic fixed obstruction
Fb
Intraluminal mass
What is orthopnoea?
Difficulty breathing while recumbent
What might cause orthopnoea?
Pleural fluid accumulation
Neonates
Diaphragmatic hernia
CHF
How can you avoid orthopnoea in neonates?
Place them in sternal recumbency if lying down
How can you describe the appearance of nasal discharge?
Serous
Mucoid
Purulent
Sanguinous
(Or a combination of these)
How can nasal discharge be characterised?
Serous/mucoid/purulent/sanguinous
Profuse or scant
Continuous or intermittent
Unilateral or bilateral
When might you see ingested food in nasal discharge?
GI disease
Dysphagia
Communication between oral and nasal cavities e.g. cleft palate
When do you tend to see unilateral nasal discharge?
Originates in structures rostral to the caudal end of the nasal septum
— easier to drain forward due to gravity
When do you tend to see bilateral discharge?
From caudal structures or bilaterally affected rostral structures
What might a foul odoured nasal discharge indicate?
Anaerobic infections
Necrotising conditions
Connection to the oral cavity e.g. tooth root infections in horses
What can cause epistaxis and/or haemoptysis?
Trauma Coagulopathies Vasculitis Erosive or invasive conditions (parasites, fungi) EPIH in horses
What is EPIH?
What region does it tend to affect?
Exercise induced pulmonary haemorrhage
Caudo-dorsal lung lobe
What arterial oxygen concentration is required for cyanosis to be seen?
Less than 50 mmHg
What is the normal arterial oxygen concentration?
100 mmHg
When is cyanosis evident?
When Hb is normal or near normal
When would low arterial O2 not be evident as cyanosis?
Anaemic patients - has to fall lower than 50
Polycythaemic patients - may appear cyanosic at higher O2 concentrations
When can peripheral cyanosis occur?
Poor peripheral perfusion - e.g. shock, heart failure
What can cause pulmonary cyanosis?
Ventilation/ perfusion mismatch
Alveolar hypoventilation
Shunting
Diffusion impairment
What can cause cardiac cyanosis?
Shunting (R-L)
What can cause acquired cyanosis?
Reducing chemical e.g. nitrates, red maple leaf
What is the term for abnormal respiratory noise?
Stridor
What can cause respiratory stridor?
Fixed or dynamic obstructions
E.g. Laryngeal paralysis Stenotic/paralysed nerves Nasal masses Soft palate elongation - BOAS
