Pulmonology
Pulmonology
Notes & Study aids
LUNG VOLUMES & CAPACITIES
Vital capacity VC =TV+IRV+ERV. Amount of inspiratory air and normal expiratory air in your lungs during normal breathing.
Functional residual capacity FRC = RV + ERV. Volume in lungs after normal, passive exhalation.
Inspiratory capacity IC = TV+IRV
Total Lung Capacity TLC = TV+IRV+ERV+RV
Tidal Volume TV is amount of air moved in/out with each breath
Inspiratory Reserve Volume IRV is amount of air that can be inspired forcibly beyond tidal volume
Expiratory Reserve Volume ERV is amount of air that can be forcibly expelled
Residual Volume RV is amount of air that always remains in lungs
Forced expiratory volume FEV. Amount of gas expelled during specific time interval of FVC (forced vital capacity).
FEV1 = amount of air expelled in 1st second (healthy, ~80% expelled).
Obstructive disease exhale <80% in 1st second, Restrictive disease exhale >80% even with reduced FVC
SPIROMETRY
Spirometry can distinguish between:
Obstructive pulmonary disease (increased airway resistance – bronchitis)
TLC, FRC, RV may increase because of hyperinflation of lungs
Restrictive disease (reduced TLC due to disease – tuberculosis) or exposure to environmental agents (fibrosis)
VC, TLC, FRC, RV decline because lung expansion is compromised
Simple spirometry can NOT determine/measure:
RV, FRC, and TLC
Simple spirometry can determine/measure:
IRV, TV, and ERV
GAS LAWS & EQUATIONS
Boyle’s Law: P1V1 = P2V2
Gases always fill the container they are in. If container volume changes, pressure changes correspondingly
Fick’s Law: Larger alveoli are not as efficient at gas exchange because the gas molecules have further distance to travel before reaching the alveolar cell walls for absorption
Ventilation-Perfusion Ratio (V/Q): is the ratio of the amount of gas reaching alveoli (V) to the blood flow in pulmonary capillaries (Q). According to the NIH, the V/Q ratio of a healthy person ranges from 0.3 (base), 1.0 (middle) and 2.1 (apex).
Airway Resistance: friction (always present in airways) is the major nonelastic source of resistance to gas flow
Flow = DPressure/Resistance
Flow is directly proportional to BP
Flow is inversely proportional to Resistance (low F, high R)
Governing principle of pressure differences in the form of cardiac output and vessel compliance (Ohm’s law of fluid flow)
PRESSURES
Spirometry can distinguish between:
Alveolar pressure (Palv) is the pressure of air inside the lung’s alveoli and affects the flow of air in and out of the lungs. When Palv is negative (during inspiration), air flows from higher pressures of the atmosphere to lower pressures in the alveoli. When Palv is positive (during expiration), air flows out of the alveoli.
Pleural pressure is created by the opposing forces from elastic recoil between the chest wall and lungs, and the forces generated by the respiratory muscles.
Transpulmonary pressure is the difference between pressure in the alveoli (intra-alveolar pressure, PPUL) and the pressure in the pleural cavity (intrapleural pressure PIP). The transpulmonary pressure keeps the lungs open/inflated (TPP = PPUL- PIP)
COPD
Chronic Bronchitis vs Emphysema
Blue bloater and Pink panther
Chronic bronchitis (Blue bloater)
Narrowing of airways caused by overproduction of mucus and swollen tissue
Primary risk factor: smoking
Signs: hypoxia (blue), digital clubbing
Emphysema (Pink panther)
Gradual destruction of alveolar septae & pulmonary capillary bed
Leads to decreased ability to oxygenate blood
Signs: pursed lip breathing, Increase CO2 retention, Thin (muscle wasting)
