PFT & ABG Flashcards
What is the normal mechanism for breathing?
Chemoreceptors>medulla (PaCO2 and PaO2)>resp muscles contract>thorax expands and diaphragm contracts>transpulmonary pressure gradient change>air moves from AW to alveoli
What is the norm PaO2 for O2 in alveoli to diffuse into blood?
80-100 torr
What is the norm PaCO2 in blood to diffuse into alveoli?
35-45 torr
What is lung vol and capacitY?
-measure of AW and lung RESTRICTION
2+ vol= capacity
What is tidal volume? (VT)
How much you breath in and out during a breath
500 mL
What is insp reserve volume? IRV
Vol above normal inhalation
3.0L
What is exp reserve vol (ERV)?
Addl vol exhaled after normal exhalation
1.2 L
What is residual vol (RV)
Vol remaining in lungs after complete exh 1.2 L
TLC
IRV+VT+ERV+RV= 5 L
VC
IRV+VT+ERV= 4.8L
IC
IRV + VT= 3.5 L
FRC
2.4L how much is left in lungs to prevent from collapsing
What are examples of RD
Obesity
NM
CT disease
Occupational exposure
What is flow
Primary measure of AW OBSTUCTION
Flow= vol/time
PEFR
Peak expiratory flow rate
Good for asthma
If dropping=pt will get asthma attack
% of FEV exhaled in 1 sec
FEV1= 75-80% (blow as much air out in 1 sec)
FEV1 measures
Obstruction and progression of OD
Goes down= getting worse
FEF
Forced exp flow 25-75%, smaller AW
Speed of air moving out of lung during middle portion of forced exp
Once in here=sicker
PFT norms
80-110%
Below 80= no good
Peak flow measurement
Helps detect onset of asthma attack
**monitors AW tone
If drops=asthma attack
OD pattern
Decreased flow, increased volume/capacities
RD pattern
Decreased vol/capacities, normal/increased flow
FRC
Equilibrium point between lung and chest re-coil
Keeps ABGs normal
High level athlete= will change
Normal person=same
T/F: PFT provides specific dx and mainly IDs pattern of impairment
FALSE- doesnt provide specific dx, just OD or RD
How do you calculate % predicted and % change
It’s pre and post bronchodilator
Post-pre/pre
15% or more improvement post tx suggests reversible component
T/F: Emphysema diffusion capacity is high
False- it is low (obstructive d)
What are some upper airway obstructions
Obstructive sleep apnea
Tracheal stenosis
Extrinsic airway compression
RD of chest wall/pleura
Kyphoscoliosis
Obesity
RD of lung
Idiopathic pulm fibrosis
Sarcoidosis
Indications for ABGs
Adequate vent, oxygenation, and determine metabolic status
Where do you draw an ABG
Radial artery
Also a-line
ABG procedure
Modified Allen’s test (P/F)
<15 sec flush is good indication of collateral circulation
Norms for ABG
You should know it
Assessment of pH- less than 7.35
Resp if PCO2>45torr
Metab if HCO3<22meq
PH >7.45
Resp if PCO2<35torr
Metab if HCO3>26meq
PCO2>45torr
Acidosis
CO2 retention, hypoventilation, acidotic
PCO2<35torr
Alkalotic, hyperventilation
PH can be norm with abn PCO2 if kidneys compensate via increased HCO3
What is fully compensated respiratory acidosis
N pH
^CO2
^HCO3
T/F if HCO3 <22meq, it is compensatory metabolic acidosis
F, not compensatory
T/F: HCO3 >26meq, uncompensated resp alkalosis
F- metab alkalosis
Hypoxemia when ..
PO2<75-80torr
67-75 mild
50-65 mod
<50 severe
