Flashcards in 6) Principles Of PFT & ABG Testing Deck (55):
Respiratory failure from too much CO2
Not enough O2 in the blood
Not enough O2 at the tissue level
What can lead to hypoxia?
Sense O2 content of blood
O2 dissolved in blood plasma
Can't get blow off CO2 so blood becomes acidic
Blow off too much CO2 so blood becomes basic
What is the physiologic mechanism of breathing?
1) Chemoreceptors in the carotid & aorta respond to changes in blood chem
2) Signals are sent to the medulla as PaO2 & PaCO2 change
3) Medulla sends signals to respiratory muscles to contract
4) Diaphragm contracts & thorax expands
5) Transpulmonary pressure changes
6) Air moves from AW into alveoli
Normal Vital Capacity
Normal Inspiratory Capacity
Normal Functional Residual Capacity
Primary measure of AW volume/obstruction over time
PFT Flow Measures
Peak expiratory flow rate; % of FVC exhaled in 1 sec
What % of FEV1 & FEF should PFT be?
Peak Flow Measurement
Measures max air flow during forced expiration
Who are peak flow measurements done on & why?
Pt's w/asthma to monitor AW tone to detect the onset of an attack so drugs can be properly adjusted
Approximates body's blood gases if pt can't exhale
Pattern for obstructive disorders
Decr flow & incr volume
Pattern for restrictive disorders
Incr flow & decr vol
Amount of air that diffuses through the lungs in 1 breath
What is the range for diffusion capacity?
When will diffusion capacity be low?
W/alveolar capillary membrane destruction
When will diffusion capacity be high?
Indications for PFT
*Measure lung vol, capacities, & flow for baseline & normal values
* Quantify level of lung dysfunction
*Measure pt tx response
O2 will diffuse from alveoli into blood when the PaO2 is in what range?
CO2 in blood will diffuse into alveoli when the PaCO2 is in what range?
Examples ventilatory & oxygenation abns:
*Ventilatory=Obstructive & Restrictive
*Oxygenative=Duffusion Deficit & Shunt (Atelectasis, ARDS)
Air taken in 1 normal breath
Normal Tidal Volume
Inspiratory Reserve Volume
Max amount of air that can be taken in after a normal inhale
Normal inspiratory reserve volume
Expiratory Reserve Volume
Amount of air that can let out after a normal exhale
Normal expiratory reserve volume
Air left in lungs after a max exhale (1.2L)
What is a capacity test?
Looks at 2+ volumes
Define total lung capacity
Amount of air in lungs after a max inhale
Examples of restrictive diseases
ABG's are done to determine:
*Adequacy of ventilations
*Adequacy of oxygenation
Where are ABG's usually drawn from & why?
Brachial or radial arteries bc they're easy to palpate & aren't near any major vessels
What is an Allen's Test?
Pinch off ulnar & radial arteries & release ulnar to check pt's collateral circulation
*<15sec is good
Normal pH range
Normal PCO2 range
Normal PO2 range
Normal HCO3 range
Normal base excess range
-2 to +2
Normal SpO2 range
Values for mild hypoxemia
PO2 of 67-75torr on room air
Values for moderate hypoxemia
PO2 of 50-65torr
Values for severe hypoxemia
Values for hyperoxia
What values put a pt in respiratory alkalosis?
What values put a pt in metabolic acidosis?
What values put a pt in respiratory acidosis?