Dasgupta - Respiratory Mechanics Flashcards
Venous blood gas tells you ____ about respiratory function
Nothing
The volume of air that you cannot get out of the lung at zero pressure
Residual volume
Flow in large airways is _____
Fast and turbulent
Lesions inside the thoracic cage will be affected to a greater extent by?
Expiration
Trachea tumor is example
destroys the entire alveolus uniformly and is predominant in the lower half of the lungs. generally is observed in patients with homozygous alpha1-antitrypsin (AAT) deficiency or Ritalin-induced lung emphysema. This condition called the Ritalin lung is seen in people who abuse Ritalin. They crush the pills and then inject them intravenously. This pills contain fillers which are insoluble particles. These particles block the fine blood vessels of the lung. Although the lung has millions of blood vessels, routine intravenous administration of Ritalin can block sufficient blood vessels to cause pulmonary hypertension and damage lung tissue to cause _____ emphysema. This is also observed in people who Ritalin by inhalation. In people who smoke, focal ____ emphysema at the lung bases may accompany centrilobular emphysema.
Panacinar emphysema
Normal spontaneous breathing
Eupnea
Low pO2 in ABG
Hypoxemia
The volume of air present in the lungs at the end of passive expiration. At _____ the opposing elastic recoil forces of the lungs and chest wall are in equilibrium and there is no exertion by the diaphragm or other respiratory muscles
Functional residual capacity
A complex mixture of phospholipids (90%) and protein (10%) secreted by type II alveolar cells.
Functions to lower surface tension by inserting itself between water molecules along surface
Pulmonary surfactant
What are the two kinds of dead space?
Anatomical dead space (large airways w/o alveoli)
Physiological dead space (alveoli that are ventilated but not perfused and the anatomical dead space values combined)
If alveolar ventilation is doubled (hyperventilation) but CO2 production remains the same, the alveolar and arterial PCO2 will be _____
Halved
This raises blood pH and causes respiratory alkalosis
In the absence of surfactant (premature infants) lung recoil forces are —______
Very high
The compliance measurements made by spirometry measure ?
Both lung and chest wall compliance (Total compliance)
[if dx can assume chest wall is normal, then you can assume this measure is lung compliance]
The pressure in the lung due to gravity is more negative at the ____
Top
The chest wall exerts and elastic recoil force to _____
Expand the lung
Decrease of respiratory rate
Bradypnea
Expiration is low and prolonged because of high compliance and dynamic collapse in
Obstructive disease
Normal venous blood gas bicarb
24-30meq / mL
Obstructive disease is characterized by?
High airway resistance
Amount of air in lungs which can’t be exhaled or pushed out of lungs
Residual volume (RV)
In adults; 1-2 liters
Obtructions not effected by inspiratory or expiratory effort
Fixed obstructions
[caused by foreign bodies or scarring which makes region of airway too stiff to be affected by transmural pressure gradient]
Bernoulli’s effect:
The faster the airflow, the lower the pressure
The greatest airway resistance is in the ____ airways
Largest
Lung compliance alone can be measured by using ?
Esophageal balloon
Normal ABG bicarb
22-26 meq/mL
_____ % of barometric pressure is exerted by oxygen and ____ % is exerted by N2 Molecules
21
79
Inflammation of the pleural cavity
Pleuritis
Compliance:
Change in volume
_______________
Change in pressure
Normal venous blood gas PO2
38-42mmHg
Restrictive lung diseases are characterized by :
Low lung compliance or increased stiffness of the lung and increased lung recoil
The pattern for FEV1 in restrictive lung disease is described as?
Witch hat shaped
Amount of air that can be exhaled as quickly during a forced exhalation
Normal 4600mL
Forced vital capacity (FVC)
Greatest flow velocities of air are observed in ________ airways
Large
If alveolar ventilation is halved (Hypoventilation) but CO2 production remains the same, the alveolar and arterial PCO2 will ____
Double
This lowers blood pH and causes respiratory acidosis
Main contributor to lung recoil is ?
Surface tension
A rapid rate of breathing
Tachypnea
Reasons for a decrease in compliance of a lung
Interstitial lung disease (fibrosis)
Loss of surfactant
[remember this is things making it harder to fill]
{right shift on PV curve and TLC is reduced}
High pCO2 in ABG
Hypercapnia
Increased depth (volume) of breathing w/ or w/o increased frequency
Hyperpnea
“Accessory muscles” of the shoulder girdle are not involved in quiet breathing, but are involved in ______
Breathing during exercise
Coughing
Sneezing
Volume of air in the lung when the lung and chest wall have equal recoil force
Functional residual capacity
(FRC)
Normal: 2300mL
The lungs elastic recoil forces act to -____
Collapse the lung
Dead space Volume =
150mL
Primary surface tension lowering pulmonary surfactant
DPPC
Dipamitoyl phosphatidyl choline
FEV1 should be about _____ % of FVC
80-100%
When room air is drawn into airways, what other species of gas is added to the mix to change the partial pressure?
Water vapor
The pressure difference inside and outside of a given system
Transmural pressure (Ptm)
During gas exchange, the oxygen consumption is _____ mL/min and the CO2 production is ____ mL / min
250
200
Lungs are stiffer and only a small volume is inhaled and expired quickly in
Restrictive disease
Specific compliance =
Compliance / functional residual capacity
The air which a person breathes but is not used for gas exchange. It fills respiratory passages like the nose pharynx and trachea
Dead space volume (Vd)
Normal adult value (150mL)
Dyspnea which occurs when lying flat, causing the person to have to sleep propped up in bed or sitting in a chair
Orthopnea
Normalizes compliance value to the FRC
Specific compliance
Volume of air inspired or expired with each breath
Tidal volume
Normal adult (500mL)
Pneumothorax will cause a mediastinum shift to the
Side opposite the collapse
Partial or total collapse of the lung without air entering the pleural space
Atelectasis
Amount exhaled in the first second.
Should be 80% of FVC
FEV1
Forced expiratory volume in 1 second
Normal: 3800 liters
The lowest part of the lung is ventilated _____ than the uppermost part
More
(This holds true whether standing or supine, and does not refer to the apex of the lung, but the part of the lung that is lower to earth)
Increases in age lead to a ______ in FRC
Increase in FRC because there is a decrease in elastic recoil of lung and an increase in compliance leading to increase in FRC
Obstructions in which the cross-sectional area of the obstruction is dependent on inspiratory or expiratory effort
Variable obstructions
As airway size decreases, velocity of flow is ___________
Increased
What is the methacholine challenge test used to detect?
Hyperactive airways. It is a sensitive test for asthma
Lying down decreases functional residual capacity by _____
10-15%
Forced exhalation uses what extra muscles?
Abdominal muscles (internal oblique, rectus abdominus, and transverse abdominus these push gut into the diaphragm)
Internal intercostals (move ribs down and back
Difficulty breathing that the individual is aware of
Dyspnea
Respiratory problems associated with kyphoscoliosis?
Underventilation of the lungs —> FRC and RV lower
Laplace’s Law states that Pressure is inversely proportional to _______
Radius
Normal arterial blood pH
7.35 - 7.45
Factors involved in lung elastic recoil forces.
Lung tissue elastic recoil (from collagen and elastin)
Surface tension forces (each alveolus is water lined and surface tension forces reduce size of surface)
What is a shunt through the lung?
A vascular pathway in which there is no gas exchange
Normal arterial blood gas PO2
80-100mmHg
Volume of air left in unperfused alveoli which is a measure of lung disease or ventilation-perfusion mismatch
Alveolar dead space
Alveolar ventilation is always ______ than total ventilation
Less
Because it subtracts the volume of dead space in the lung and therefore considers only the volume of air actually participating in gas exchange.
is the most common morphological subtype of emphysema This affects the central portion of secondary pulmonary lobules, around the central respiratory bronchioles, typically involving the superior part of the lungs or lobes. It begins in the respiratory bronchioles and spreads peripherally. this form is associated with long-standing cigarette smoking, occupational exposure to chemicals, dust etc. and predominantly involves the upper half of the lungs.
Centrilobar emphysema
Flow in small airways is ____-
Slow and laminar
Type of pneumothorax in which there is air in the pleural cavity but it does not accumulate with every breath
Non-tension pneumothorax
Complete absence of spontaneous ventilation
Apnea
Doubling radius increases surface tension of alveoli by a factor of _
4
Normal ABG PCO2
35-45mmHg
The measurement of physiological dead space with Bohr’s method is based on which 3 assumptions:
The content of CO2 in atmosphere is 0.04% and negligible
All expired CO2 comes from alveoli
All CO2 comes from the ventilated and perfused alveoli and not from dead space
Complete atelectasis is accompanied with a mediatinum shift to the
Side of the collapse
Why is tension pneumothorax a medical emergency?
Because the air that accumulates with each breath puts pressure on the organs of the chest
The intrapleural pressure is ______
Negative
[subatmospheric]
Type of pneumothorax due to medical procedure
Iatrogenic pneumothorax
Volume of air in lungs after the maximum inspiratory effort
TLC
Total lung capacity
What molecules that make up the physical lung will cause lung tissue elastic recoil forces which act to deflate the lung
Elastin and collagen
Surfactant has a hydrophilic and hydrophobic region, allowing it to reside _________
At the air-water interface
Venous blood gas pH
Normal
7.34 - 7.37
O2 exchange takes place where?
Alveolar sacs
Alveolar ducts
These are the last 4 divisions of the airways
Forced exhalation in emphysema patients can cause
Airway collapse
Which leads to increased resistance and decreased exhalaltion
Type of pneumothorax in which air accumulates within the chest with every breath
Tension pneumothorax
The reduced area in a PEF graph suggests
Some ventilatory limitation
Airways or alveoli being attached to their neighbors
Tethering
Rate of alveolar ventilation depends on:
Respiratory rate
Tidal volume
Dead space volume
What do surgical removal of a lobe, obesity, pulmonary vascular congestion, and decreased pulmonary surfactant do to the pressure - volume curves ?
(PV curve, pressure on x axis)
Right shift
Examples of variable extrathoracic lesions:
Vocal cord paralysis, fat deposits, obstructive sleep apnea
Normal venous blood gas PCO2
44-46mmHg
Reasons for an increase in compliance
Emphysema
Loss of elastic fibers (w/ age sometimes)
Lung becomes easier to inflate
PV curve shifts left and TLC is increased
Sitting or standing leaning forward in respiratory distress. With upper body with hands on knees for support
Tripod stance
An abnormally low FEV1 is highly diagnostic of a patient with
Obstructive pulmonary disease
FEV1 basically tells you airway resistance, because max expiratory flow rates are largely effort INdependent
Compared to a person who is standing, the FRC of a supine person is ______
Less
Gut is pushing into diaphragm in supine
What happens to FRC as a person grows older?
FRC increases
Obstructions in which the cross-sectional area of the obstruction is dependent on inspiratory and expiratory effort
Variable obstructions
Variable intrathoracic lesions will be affected to a greater extent by _________
Expiration
