21 – Pathophysiology: Respiratory System Flashcards
What are the 3 body systems that sustain life min-by-min?
- CNS
- Respiratory system
- CV system
- *if stop working=life threatening!
Upper airways include
- Nose, nasal cavity and sinuses, nasopharynx
- Mouth, oropharynx, larynx
Lower airways (lungs) zones
- Conducing zone
a. Trachea, bronchi, bronchioles, tertiary bronchi - Respiratory zone
a. Tertiary bronchi, alveoli
Upper airway functions
- Thermoregulation
- Filtration
- Humidification
- Olfactory
- Air conduction
- Phonation
- Swallowing (airway protection)
What are the 2 main functions of the lower airways?
- Non-respiratory
- Respiratory
Non-respiratory functions of the lower airways
- Immunological (mucociliary)
- Acid-base regulation
- Vascular, metabolic, endocrine, etc.
Respiratory functions of the lower airways
- GAS EXCHANGE
o Works closely with CV system - Surfactant synthesis
What is ventilation primarily controlled by?
- CO2
Respiratory center provides
- Slow, steady ventilation control
2 areas of the respiratory center
- Medulla oblongata
- Pons
Medulla oblongata (respiratory centre)
- Dorsal and ventral respiratory groups
o Control inspiration and expiration
Pons (respiratory center)
- Pneumotaxic center and apneustic center
o Adjust ventilation controlled by medulla oblongata respiratory groups
Central chemoreceptors
- Min-by-min changes in ventilation
- Floor of ventral medulla
- Dissolved CO2 passed through semipermeable membrane (BBB) and enters CSF
What is the normal CSF pH and what happens if it changes?
- 7.32
- If changes=control breathing
- Increased CO2=decrease pH=STIMULATE breathing
- *less buffering capacity than blood=greater changes in pH based on PCO2
Peripheral chemoreceptors
- Rapid, fine-tunning ventilation
- Aortic and carotid bodies!
- Sense PaCO2, PaO2, pH and perfusion of carotid/aortic bodies
- *overrides ventilation controlled by respiratory center
When do you get an increased ventilation from the peripheral chemoreceptors in response?
- Increased PaCO2
- Decreased blood pH
- Decreased PaO2
What are the positives of endotracheal intubation?
- Prevent aspiration of gastric contents
- Prevent upper airway obstruction (due to muscle relaxation of laryngeal muscles=sedatives and tranquilizers)
- Ability to manually ventilate for patient experiencing hypoventilation or apnea
What are the negatives of endotracheal intubation?
- Bypass humidification and heating mechanisms of upper airways
- Increased resistance to breathing
o if too small tube, connectors or one-way valves in breathing circuit
What are ways to treat for heat and water losses with endotracheal intubation?
- Passive: COMMON
- Active
- Active warming
Passive ways to treat heat and water losses with endotracheal intubation?
- Implement low fresh gas flow rates
- Use HME filters
Active ways to treat heat and water losses with endotracheal intubation?
- Humidifiers/nebulizers
- Heated anesthesia breathing circuits
How can you treat for increased resistance to breathing with endotracheal intubation?
- Choose largest tube possible
o *Poiseuille’s’ law: airway resistance through a tube is INVERSELY proportional to radius to the power of 4
What is the normal PaCO2?
- 35-45 mmHg
When awake, alveolar ventilation changes _______with changes in PaCO2
- LINEARLY
o Max response at PaCO2=100mmHg
What is involved with hypoventilation?
- Inadequate CO2 elimination detected by increased PaCO2 or ETCO2
- *PaCO2 is MORE THAN 45mmHg