Respiratory System Flashcards
What are things to evaluate in relation to the hands when doing a respiratory exam?
Pallor-
Flapping tremour- Carbon dioxide retention (impacts muscle contraction)
Blueing- peripheral cyanosis
What are things to evaluate in relation to the face when doing a respiratory exam?
Pallor of conjunctive- anaemia
Mucous Membrane blueing- central cyanosis
What are things to evaluate in relation to the neck when doing a respiratory exam?
Trachea- should feel central
Lymph nodes- looks for lymphatanotomy (neck masses), and palpate (patient sits up and you go behind to feel)
What are things to evaluate in relation to the chest when doing a respiratory exam?
Barrel chest- COPD, emphysema (prominent chest cavity)
Pectus excavatum/ carinatum- inward/outward sternum
Symmetry
Apex beat
Percussion- Should sound hollow
Chest expansion- place hands on chest wall with fingers meeting in middle, laying over, not on. Front and back
Tactile vocal phremitis- say 1-1-1 and listen for vibrations (pleural effusion, pneumothorax, pneumonia)
What are things to evaluate in relation to the auscultations when doing a respiratory exam?
Starting at apex of lungs, and moving side to side as you move down the chest wall.
3 on front, 4 on back, and in apex
Crackling course- noisy, sounds like crunchy leaves, found at base
Fine crackles- pulmonary fibrosis, found at base
Wheezing- all throughout chest- caused by narrowed airways (COPD, asthma)
Strider- upper airway obstruction, severe
Vocal phremitis- vibrations
What do you do at the end of respiratory exam?
Summarize and thank patient
What is chylothorax?
Chyle (lipid rich fluid) in thorax
Commonly found in paediatric oncology patients
What is empyema?
Collection of pus in pleural sac
What atelectasis?
Inability to expand
Can occur due to obstruction, i.e. chocking
Where does looping of the vagus nerve occur?
Left: Arch of aorta (giving off the left recurrent laryngeal branch)
Right: Level of right subclavian artery
How do you differentiate the phrenic and vagus nerves when examining the thorax?
Vagus travels in thoracic cavity posterior to the hilum, phrenic travels anteriorly
What is effusion?
Accumulation of fluid in a space (i.e. the pericardial cavity)
What physiological changes are associated with asthma?
Loss of normally functioning of airway epithelium, thickening of basement membrane, hypertrophy of smooth muscle layer.
What impact does the pathophysiology of asthma have?
Causes hyper-responsiveness to normal triggers of contraction (histamine and/or acetylcholine).
Abnormal contraction in response to usually benign triggers.
What are possible triggers for asthma?
Acute Inflammation: Allergy, Viral/bacterial infection, exercise
Drugs (that interfere with normal regulation of airway): beta-blockers, non-steroidal anti-inflammatory drugs
Cold air and scents
How are asthma symptoms managed?
Bronchospasm- treated with bronchorelaxation (beta 2 agonists like salbutamol)
Inflammation- treated with anti-inflammatories (corticosteroids, leukotriene receptor blockade, monoclonal antibodies)
What is the typical presentation of asthma?
Bronchospasm (causes wheeze, dyspnoea, exercise intolerance), and Inflammation (cough)
What limits ability to take a breathe?
Breathing is a single orifice system, so need for oxygen is balanced with need to eliminate waste
What are the 2 different types of airway narrowing, explain each briefly?
Dynamic- Rapid muscle contraction (due to histamine or acetylcholine), medium-secretions
Fixed (stiff airway wall)- smooth muscle bulking, thickened basement membrane
How do the pathophysiological changes associated with asthma impact the physiological response?
Increased smooth muscle: increased force of contraction
Mast cells in smooth muscle: Twitchy smooth muscle with variable airway calibre (big changes in sensitivity and activity of muscle impacting radius)
Increased basement membrane: loss of relaxation following contraction (loss of elasticity, chronic reduction in airway calibre leading to damage of airways)
What is diurnal variability?
Variability in smooth muscle contraction throughout the day.
Usually worse at night.
What type of inflammation is seen in physiological response of asthma, and how is it mearsured?
Eosinophilic inflammation
It causes increase in production of exhaled nitric oxide which can be measures (30ppb is normal).
What is reversible airflow and how is its measure related to asthma?
Asthma should always have reversible airflow obstruction.
Asthmatic patients should experience bronchodilation following use of nebulised salbutamol, whereas someone with chronic destructive lung disease would not have any dilation. Confirmatory test
What are the 3 phases needed for diagnosing asthma?
Smooth muscle only- trigger by direct mediator release (histamine) causing rare wheezy episodes
Chronic Inflammation- irritates smooth muscle, causes regular wheezy episodes
Acute inflammation- viral infection, ‘clinical exacerbations’
In type 2 inflammation relating to asthma, what are the associated cells, cytokines, prostanoids, and Igs?
Cells- lymphocytes H2, eosinophils, mast cells
Cytokines- IL-4/5
Prostanoids- PGE2, leukotriene D4
Ig- specific IgE (typically driving type 1 allergy)
What is a driving factor in terms of the immunological response during first exposure to a potential asthmatic trigger?
The cytokines involved during first exposure will determine response.
IL-4/5/33 will lead to mast cell response (immediate), whereas IL-12 & IFN would lead to reactive T cells (delayed, protective)
What receptor does histamine bind to and what is its effect on the airway?
Binds H1 receptor
Causes smooth muscle contraction
What receptor does Leukotriene D4 bind to and what is its effect on the airway?
Cyst LKTR
Smooth muscle contraction, airway wall oedema
What receptor does prostaglandin bind to and what is its effect on the airway?
PC2
Airway wall oedema
Inflammation and mucous secretions
What receptor does VEGF bind to and what is its effect on the airway?
VEGFR
Angiogenesis
What are mast cell mediators involved in asthma?
Histamine, Leukotriene D4, prostaglandin, VEGF
What are chemical ways of triggering Mast cells?
IgE
Salicylates (aspirin and other NSAIDs)
Strong scents
How does exercise trigger mast cells?
Increases ventilation
As humidification capacity is exceeded, drying of airway occurs causing osmotic rupture of mast cells
Mimicked by mannitol in bronchoconstriction test
What are other inflammatory stimuli (besides mast cells)?
Viral infection (neutrophils/ lymphocytes) Parasitic infection (eosinophils) Bacterial (neutrophils)
What are inflammatory and non-inflammatory triggers of asthma?
Inflammatory: Allergy, infection, exercise
Non-inflammatory: scents, perfumes
What is a treatment for the smooth muscle contraction-aspect of asthma?
Beta 2 agonist
Beta-2 adrenergic receptor (7 trans-membrane unit) is bound and activated by agonist causing cAMP second messenger production resulting in smooth muscle relaxation
What is a treatment for the inflammation-aspect of asthma and what does the treatment do?
Corticosteroids: Reduces airway twitches and exhaled nitric oxide. Effective on eosinophils, lymphocytes, but macrophages are slightly resistant.
Anti-leukotriene receptor drugs: More selective. Direct effect on leukotriene D4 in airway. Effect on mast cells and smooth muscle. Good for exercise asthma
What are emerging treatments in asthma?
Monoclonal Abs
Anti-IgE biological therapy- Downregulation of IgE in mast cells
Biological therapies targeting TNF, IL-5, IL-13
What is bronchothermoplasty?
Involves sending probe into lung that heats airway, causing reduction in bulking of smooth muscle, causing reduction in twitching
How is nerve ablation related to asthma treatment?
Nerve ablation of branches of vagus nerve to reduce over-use, and result in decreased bulking
At rest, what are the partial pressures for oxygen and Co2, and amounts used?
PO2= 13.3kPa, 250ml O2/min PCO2= 5.3 kPa, 200mL CO2/min
When is breathing modulated?
During vocalization, emotional events, volitional control, reflexes (coughing), physiological changes (exercise, sleeping)
What role do chemo/mechanoreceptors provide in terms of breathing?
Chemo- detect chemical changes and feedback to brain on blood PO2, CO2 and pH
Mechano- feedback on mechanical status of lungs, chest wall, and airways
Where in the brain does breathing regulation occur?
Brainstem
Different neuronal groups control different aspects of breathing (i.e. respiration, upper-airway control)
What are peripheral chemoreceptor?
Small, highly vascularised, found in aortic arch (use vagus nerve to send signals to brain) and bifurcation of carotid artery (use glossopharyngeal nerve).
Send signals to nucleus tractus solitarius in brainstem.
What do the peripheral chemoreceptors primarily respond to?
Decreases in PO2.
Begins around arterial PO2 of 60 mmHg, and increases drastically at PO2 of around 45 mmHg
What are the central chemoreceptors?
Clusters of neurons in brainstem (posterior to NTS) that are activated by increases in PCO2 (hypercapnia) or decrease in pH
What is the relationship between PCO2 and ventilation?
Small changes in PCO2 have large, and immediate change to ventilation (more CO2= more acidic blood -> increased ventilation).
Large role in moment-to-moment breathing
What are mechanoreceptors and what do they sense?
Sensory receptors detecting changes in pressure, movement, and touch.
In resp. system, will detect movement of lungs and chest walls.
What nerve do the mechanoreceptors of the respiratory system utilize and where does this nerve go?
Send signals via vagus nerve to Nucleus Tractus Solitarius in dorsal brainstem.
What are mechanoreceptors important for?
Adapting and adjusting breathing
Integrating with other movements, i.e. posture
Where are some respiratory mechanoreceptors found, what is their stimulus, and what is their reflex?
Airway smooth muscle -> inflation/distension of airways -> termination of inspiration
Airway epithelium -> rapid lung inflation/deflation, or oedema -> sigh, shortened expiration
What is the centre in brain receiving mechano-chemoreceptor signals?
Nucleus Tractus Solitarius on dorsum of brainstem.
Processed by respiratory neurons (apart of ventral respiratory group) that are responsible for generating rhythm of breathing.
Also receives proprioceptive
What are pattern generating neurons and what are the types?
Pneumotaxic neurons within Pontine centre of brain
They regulate the pattern (inhale, then exhale) of inhalation and exhalation associated with breathing
Inspiratory neurons fire during inspiration
Expiratory neurons active during expiration
Vasospaning neurons fire between inhalation and exhalation
What are the respiratory rhythm neurons?
Bilateral clusters of neurons with rhythm generating patterns within pontine centre
They underlie basic rhythm (speed) of breathing
How do rhythmic breathing signals (innervations) move from the brain to target (describe the locations/nerves involved in transmission)?
Brainstem neurones produce rhythmic output
Output signal sent to spinal cord
Phrenic nerve exits spinal cord at C3-5 to innervate diaphragm
Nerves exiting at thoracic levels innervate intercostals
What do the ventral, pontine, and dorsal respiratory groups consist of?
Dorsal: Nucleus Tractus Solitarius Ventral: Nucleus Ambiguos, Nucleus Retroambiguous, Prebotzinger Complex, Botzinger Complex Pontine: Pneumotaxic Centre, Apneuistic Centre