1.
Alveolar ventilation equation: 
2.
Average compliance of a healthy adult lung: 
0.2 L/cmH₂O
3.
Causes of alveolar dead space: • Pulmonary embolism
• V/Q mismatch (without perfusion there is no gas exchange)
4.
Characteristics of compliance in patients with emphysema: 
Increased compliance
• ↑ ∆V with small ∆P
• Results from loss of elastic fibers
• Lungs become more distensible, usually resulting in hyperinflation (abnormally increased lung volume)
5.
Characteristics of compliance in patients with pulmonary fibrosis:
Decreased compliance
• ↓ ∆V for any given ∆P
• Results from increase in connective tissue (fibrotic lung)
• Stiffer lungs with reduced volumes
6.
Compare the differences in thoracic expansion from the upper chest to the lower chest: Expansion of the lower chest is approximately 50% greater than that of the upper chest
7.
Compare the expansion of the alveoli in different regions of the upright lung: • Alveoli at the apices have a higher resting volume and expand less during inspiration
• Alveoli at the bases have a lower resting volume and receive approximately 4 TIMES as much ventilation as the apices
8.
Conditions that can increase tissue viscous resistance: • Obesity
• Fibrosis
• Ascites
9.
Dead Space Equation: 
10.
Define airway resistance: Impedance to ventilation caused by the movement of gas through the airways
11.
Define alveolar dead space: The volume of gas ventilating unperfused alveoli
12.
Define alveolar ventilation: The volume of fresh gas reaching the alveoli per minute
13.
Define anatomic dead space: The volume of the conducting airways, including the oro-and nasopharynx
14.
Define compliance: Volume change per unit of pressure change
• Compliance is usually measured under static conditions (no airflow)
15.
Define dead space: Volume of inspired gas that is wasted
16.
Define effective ventilation: Ventilation is effective when it PaCO₂ is maintained at a level that maintains a normal pH
17.
Define elasticity: The physical tendency of an object to return to an initial state after deformation
• When stretched, the structure tends to return to its original shape
18.
Define hyperventilation: Ventilation exceeding metabolic needs
19.
Define hypoventilation: Ventilation that does not meet metabolic needs resulting in respiratory acidosis
20.
Define minute ventilation: Tidal volume per minute
21.
Define Normal VT: • Removes CO₂ and supplies O₂ to meet metabolic needs (≈ 0.5 L or 500 mL)
22.
Define physiological dead space: The sum of anatomical and alveolar dead space
23.
Define the Equal Pressure Point (EPP): 
The point where intrapleural pressure and alveolar pressure are equal.
• This happens sooner in diseased lungs and can lead to collapsed airways at lower levels
24.
Define Tidal Volume (VT): The volume of air inspired or expired in a single breath during regular breathing
25.
Define tissue viscous resistance: The impedance of motion caused by displacement of tissues during ventilation (lungs, ribcage, diaphragm, abdominal organs)
26.
Define work in traditional physical terms: W = F ⋅ d
(Work = Force × distance)
27.
Describe breathing patterns that reduce WOB in individuals with lung diseases: • Restrictive: Rapid, shallow breathing
• Obstructive: Slow, pursed-lip breathing
28.
Describe effective ventilation: A balance between CO₂ production and alveolar ventilation
29.
Describe exhalation below the resting level: Requires muscular effort to overcome the tendency of the chest wall to expand
30.
Describe O₂ cost of breathing with increasing ventilation in the presence of pulmonary disease: O₂ consumption in the presence of pulmonary disease will dramatically increase as ventilation increases due to an increased work of breathing
31.
Describe pulmonary surfactant's effect on surface tension: Pulmonary surfactant changes surface tension according to its area
• This ability is reduced as surface area increases
• This ability is increased as surface area decreases
32.
Describe the affects of alveolar ventilation in comparison to CO₂ production and removal: • Approximately 200 mL of CO₂/min is produced in the body during resting metabolic conditions
• Alveolar ventilation must match CO₂ production per minute to ensure the acid-base balance (homeostasis - 40 mmHg)
33.
Describe the differences in alveolar pressure (intrapulmonary pressure) during the breathing cycle: 
• Alveolar pressure varies during the breathing cycle
• Between +0.5 and -0.5 cmH₂O
34.
Describe the differences in intraplural pressure during the breathing cycle: 
• Intraplural pressure is usually negative during quiet breathing and varies during the breathing cycle
• Between -5 and -10 cmH₂O
35.
Describe the differences in work of breathing (WOB) during inhalation and exhalation: • Inhalation is ACTIVE
• Exhalation is PASSIVE
- Forced exhalation requires additional work by expiratory muscles
36.
Describe the effect of changes in compliance and resistance on driving pressure and alveolar inflation: In an obstructed lung there is the possibility of increased airway resistance in local areas
• More driving pressure is needed to flow through airways
• Less driving pressure is available for alveolar inflation
• There is less alveolar volume change for a given pressure
37.
Describe the effect that patient/lung position has on ventilation: The regions and/or lung closest to the resting surface becomes dependent (better ventilation).
38.
Describe the opposing forces that determine the lung volume equivalent to the functional residual capacity (FRC): The lungs and chest wall recoil (in opposite directions) to a resting volume, or Functional Residual Capacity (FRC)
• FRC is the total amount of gas left in the lungs after a resting expiration
• Opposing forces are balanced (Palv = Pao)
• Normal FRC is 40% (1200 mL) of total lung capacity (TLC)
39.
Describe the pressure changes during inspiration and expiration: • Pbs and Pao remain at 0 throughout cycle
• Palv and Ppl are changing throughout cycle
40.
Describe the transpulmonary pressure gradient: • The difference in pressure between the alveoli and the pleural space
• Pl = Palv - Ptp
41.
Describe the transresipiratory pressure gradient (Prs): • The difference in pressure between the atmosphere and the alveoli
• Prs = Palv - Pao
• In a spontaneously breathing patient, Pao = Pbs = 1 atm (760 mmHg)
42.
Describe the transthoracic pressure gradient: • The difference in pressure between the plural space and the body surface
• Pw = Ppl - Pbs
• In a spontaneously breathing patient, Pbs = Pao = 1 atm (760 mmHg)
43.
Factors that affect the efficiency of ventilation: • Regional differences in ventilation
• Dead space (anatomic and alveolar)
• Alveolar ventilation
• Efficiency = consume little oxygen and produce minimum CO₂
44.
Factors that increase the elastic component of the work of breathing: 
Restrictive lung diseases, like pulmonary fibrosis; tidal volume
45.
Factors that increase the frictional component of work of breathing: 
Obstructive lung diseases, like COPD (emphysema, chronic bronchitis); shallow breathing
46.
Formula for airway resistance: 
The ratio of driving pressure responsible for gas movement to the flow of the gas
• cmH₂O/L/sec (cmH₂O per liter per second)
• Think Pressure/Flow
47.
Formula or measurement of lung compliance: 
• ∆V (liters) is the inspired volume
• ∆P (cmH₂O) is the transpulmonary pressure gradient
• Units are L/cmH₂O
48.
Formula to compute mechanical work of breathing: WOB = ∆P × ∆V
49.
Formula to compute the time constant of a lung unit: Time Constant = R × C
• R = Resistance (cmH₂O/L/sec)
• C = Compliance (L/cmH₂O)
• All units cancel except seconds
50.
Identify all forces that must be overcome to move into the respiratory system: • Elastic forces
• Frictional forces
51.
Identify the causes of long time constants: • Resistance or compliance is high
• Lung unit will fill and empty more slowly
52.
Identify the causes of short time constants: • Resistance or compliance is low
• Lung unit will fill and empty more rapidly
53.
Identify the distribution of airway resistance by location: • 80% in nose, mouth, and large airways
• 20% in airways > 2mm in diameter where flow is mainly laminar
54.
Identify the elastic forces opposing lung inflation: • Tissues of the lungs and thorax
• Surface tension in the alveoli
55.
Identify the factors that affect the dead space/tidal volume ratio during normal breathing and during exercise: • Physiological dead space is approximately 1/3 of tidal volume (30%)
• During exercise, both increase, but tidal volume increases more, reducing the dead space/tidal volume ratio.
56.
Identify the frictional forces opposing lung inflation: • Resistance caused by gas flow (80%)
• Tissue movement during breathing (20%)
57.
Identify the normal total lung-thorax compliance of a healthy subject: 0.1 L/cmH₂O
58.
Identify the proportions attributed to the total work of breathing: 
• Approximately 2/3 of WOB is attributed to elastic forces
• Remaining 1/3 is attributed to frictional forces
Total mechanical WOB is the sum of areas 1 + 2 above
59.
Minute ventilation equation: 
60.
Normal range of airway resistance in healthy adults: 0.5 - 2.5 cmH₂O/L/sec
61.
Primary Function of the Lungs: • Supply O₂
• Remove CO₂
62.
Rule of thumb for changes in caliber of airway: A change in the caliber of an airway by a factor of 2 causes a 16-fold change in resistance (r⁴ = 16, if r = 2)
63.
The best indicator of effective ventilation: Normal PaCO₂ and pH
64.
The point during inspiration that the chest wall reaches natural resting level: 
70% of vital capacity (VC)
