08.12 - Ventilation, Mechanics, Volumes (Waters) Flashcards
Inspiratory Capacity = ___ + ___
Inspiratory Reserve Volume + Resting Tidal Volume
Inspiratory Reserve Volume + Resting Tidal Volume
Inspiratory Capacity
Functional Residual Capacity = ___ + ___
Expiratory Reserve Volume + Residual Volume
Expiratory Reserve Volume + Residual Volume
Functional Residual Capacity
Vital Capacity is composed of
Inspiratory Capacity + Expiratory Reserve Volume
Inspiratory Capacity + Expiratory Reserve Volume
Vital Capacity
FEV1 values less than 70% of FVC
Obstructive Lung Disease
Forced Vital Capacity
TV + IRV + ERV
TV + IRV + ERV
Forced Vital Capacity
Normal FEV1/FVC
80%
FEV1 in Obstructive Lung Disease
FEV1 less than 70% of Forced Vital Capacity (both decreased)
Reduced FVC with normal or increased FEV1 to FVC ratio
Restrictive Lung Disease
FEV1/FVC in Restrictive Lung Disease
Normal or Increased FEV1 to FVC Ratio
Physiologic Dead Space can be estimated as
Fraction of TV by measuring End-Tidal PCO2 and Arterial PCO2
Minute Ventilation =
Vmv = Tidal Volume x RR
Alveolar Ventilation (Valv) =
(TV - Dead Space) x RR
(TV - Dead Space) x RR
Alveolar Ventilation (Valv)
Trans-Respiratory System Pressure =
Palv - Patm
Trans-Pulmonary Pressure =
Ptp = Palv - Pip
Accessory muscles of Inspiration
Scalenes, Sternocleidomastoids
Expiratory Muscles
Abdominals, Internal Intercostals
Slope of the Pressure-Volume curve for the lung
Compliance
Compliance in Inhalation vs Exhalation
Greater during inhalation (slope greater)
Compliance in Restrictive Lung Diseases
Decreased - Can’t get air in
Compliance in Obstructive Ventilatory Defects
Increased Compliance - Can’t get air out
How to normalize Compliance
Divide by FRC -> provides a measure of elastic properties of lung tissue regardless of individual differences in lung volume
Vital Capacity in Obstructive vs Restrictive Ventilatory Defects
Normal in Obstructive, Decreased in Restrictive
How does surfactant affect lung compliance
Increases Lung Compliance
Compliance in Respiratory Distress Syndrome of the Newborn
Decreased
What is atalectasis
Unstable alveoli that collapse on expiration
The larger the radius, the ___ the pressure needed to keep it open
smaller
Laplace’s Law = P = (T x 2 x pi x r)/(pi x r^2)
P = (T x 2 x pi x r)/(pi x r^2)
Poiseulle’s Equation
R = 8nl/pir^4
Where is major resistance to air flow in respiratory system
Upper airways, even though radius larger
Lung Volume in Asthmatics
Pts with increased airway resistance often breathe at high lung volumes, which helps keep airway resistance lower
