4. Ventilation Flashcards
Minute ventilation
Volume of air expired in 1 minute or per minute
Respiratory rate
Frequency of breathing per minute
Alveolar ventilation
Volume of air reaching the respiratory zone per minute
Respiration
Process of generating ATP
Anatomical dead space
Capacity of airways incapable of undertaking gas exchange
Includes entirety of conducting airways and upper respiratory tract
Alveolar dead space
Capacity of airways that should be able to undertake gas exchange but can’t (usually due to absent/ inadequate blood flow)
e.g. hypoperfused alveoli
Physiological dead space
Sum of alveolar + anatomical dead space
Hypoventilation
Deficient ventilation of the lungs; unable to meet metabolic demand
(results in increased PO2 – acidosis)
Hyperventilation
Excessive ventilation of the lungs atop of metabolic demand
results in reduced PCO2 - alkalosis
Hyperpnoea
Increased depth of breathing (to meet metabolic demand)
Hypopnoea
Decreased depth of breathing (inadequate to meet metabolic demand)
Apnoea
Cessation of breathing
Dyspnoea
Difficulty breathing
Bradypnoea
Abnormally slow breathing rate
Tachypnoea
Abnormally fast breathing rate
Orthopnoea
Positional difficulty in breathing
e.g. when lying down
Tidal volume (TV or VT)
Volume of air inspired and expired during regular breathing (not necessarily at rest)
~500mL at rest
Inspiratory reserve volume (IRV)
Volume of air that can be inspired after a tidal inspiration
2.7 L at rest
Expiratory reserve volume (ERV)
Volume of air that can be expired after a tidal expiration.
~1.3 L at rest
Residual volume (RV)
Volume of air that cannot be emptied from the lungs, no matter how hard you expire. This is fixed because of the lung-chest wall interface.
~1.2 L
Equation for total lung capacity (TLC)
TLC = RV + IRV + TV + ERV
Define total lung capacity
Maximum capacity of the lungs
~6L
Functional residual capacity (FRC) equation
FRC= RV + ERV
Define functional residual capacity
Volume of air in the lungs following a tidal expiration at rest.
Represents the “default” volume of the lungs, when the lung recoil (inwards) and chest recoil (outwards) are in equilibrium