PFTs And ABGs Flashcards
What is abnormal increased CO2 level in the blood called?
Hypercarbia
What is decreased O2 in blood called?
Hypoxemia
PaO2 is the O2 in blood that is dissolved in what?
Plasma
The bulk of O2 is carried bound to ______
Hemoglobin
If you are not ventilating enough, and not blowing off enough Co2, CO2 goes ____ and pH goes ____
CO2 goes up
pH goes down
Respiratory acidosis is when the CO2 goes ___ and pH goes ____
Co2 goes up and pH goes down
Respiratory alkalosis is when you are hyperventilating, so pH goes ____
UP
6 steps of normal mechanism of breathing
1) Chemoreceptors (carotid arteries and aorta) respond to changes in blood chemicals
2) Signals sent to medulla as PaO2 and PaCO2 change
3) Medulla sends signal to respiratory muscles to contract C3-5 phrenic nerve –> innervates diaphragm
4) Thorax expands and diaphragm contracts
5) Transpulmonary pressure gradient changes
6) Air moves from a/w to alveoli
O2 in alveoli diffused into blood for PaO2 of ______ mmHg
80-100
CO2 in blood diffused into alveoli for PaCO2 of _____mmHg
35-45
Examples of restrictive defects are…
Neuromuscular, morbid obesity, and circumferential burns
Examples of obstructive defects are….
Asthma and COPD
Examples of diffusion deficits are…
Pulmonary Fibrosis (idiopathic)
Examples of shunt are….
Atelectasis, ARDS
When you are looking at lung volume and capacities, what kind of lung issues are you looking at?
Restriction
Tidal volume (VT) definition and what is the value?
Normal breath
Approx. 500 ml
Inspiratory reserve volume (IRV) definition and what is the value?
Volume above normal inhalation
Approx. 3 L
Expiratory reserve volume (ERV) definition and what is the value?
Addition volume exhaled after normal exhalation
1.2 L
Residual volume (RV) definition and what is the value?
Volume remaining in lungs after complete exhalation
1.2 L
What are the four measurements for volumes?
Tidal volume, inspiratory reserve volume, expiratory reserve volume, residual volume
What are the 4 capacity measurements?
Total lung capacity, vital capacity, inspiratory capacity, functional residual capacity
Total lung capacity (TLC) definition and values
IRV + VT + ERV + RV
Approx 5 L to 6
Vital capacity (VC/FVC/SVC) definition and values
IRV + VT + ERV
Approx. 4.8 L
Inspiratory capacity: definition and values
IRV + VT
Approx 3.5 L
Functional residual capacity: Definition and value
Ant left in lungs after normal respiration= approx 2.4 L
When using flows as your measurement, what kind of lung problem is this a primary measure of?
Obstruction
FEV1% definition and what value is considered obstructive?
% of FVC exhaled in 1 second –> maximal in, how much you can blow out
FEF definition
Forced Expiratory flow - 25-75% is normal, you are looking at middle capacity. Done in intervals: 0.5, 1, 2, 3 seconds
What is a body plethysmograph?
Used to estimate the residual volume
How is peak flow measurement measured?
The maximum flow during a forced expiration as measured by a handheld peak flow meter. Used to monitor asthma patients’ airway tone
What kind of disorder has decreased flow and increased volume/capacities (air trapping)
Obstructive
What kind of disorder has decreased volumes/capacities and normal or increased flows
Restrictive
With VT, RV, FRC, and TLC the values go ____ with obstructive and _____ with restrictive
Up
Down
Interpreting flows: Normal value for FVC
> 80
Interpreting flows: Normal value for FEV1/FVC%?
> 75
Interpreting flows: What happens to FVC with obstructive disease?
N or decreases
Interpreting flows: What happens to FEV1/FVC% with obstructive disease?
Decreases
Interpreting flows: What happens to FVC with restrictive disease?
Decreases
Interpreting flows: What happens to FEV1/FVC% with restrictive disease?
N or increases
What is DLCO?
Diffusion capacity of CO (small amounts- binds to hemoglobin very tightly
What is the normal value of DLCO?
25-30 mL CO/min/mmHg
What two things affect DLCO?
Hemoglobin and surface area
DLCO would be low with…
Destruction of alveolar capillary membrane
Pulmonary fibrosis and emphysema
People with emphysema have a decreased _____
Diffusing capacity
How do you calculate % predicted and % change?
Actual/normal x 100
For pre and post bronchodilator, what percent improvement post-Tx suggests a reversible component? And what percent is considered significant?
15%
10-20%
COPD is ______ reversible
Minimally
Asthma has a _____ component
Reversible
What are examples of upper/large airway obstruction?
Obstructive sleep apnea
Tracheal stenosis
Extrinsic airway compression (tumor)
What are some examples of restrictive diseases of the chest wall/pleura
Kyphoscoliosis
Obesity
What are some examples of restrictive LUNG diseases
Idiopathic pulmonary fibrosis and sarcoidosis
When the FEV1 is supposed to be 4.0 but you see that it is 2.0, is the disorder obstructive or restrictive?
Obstructive
When you see that the DLCO is 1/2 of normal value, what kind of disorder is it?
Restrictive
3 indications for ABGs
Determine:
1) Adequacy of ventilation
2) Adequacy of oxygenation
3) Metabolic status
What kind of disorders would you be determining adequacy of ventilation for?
Neuromuscular, COPD, “code”
What kind of disorders would you be determining adequacy of oxygenation for?
ARDS, PE, Pneumonia
What kind of disorders would you be determining metabolic status for?
Kidney failure, sepsis, ketoacidosis, S/P code blue
A status code blue: a patient is in full cardiac arrest, so what happens to CO2 and O2?
CO2 inc
O2 dec
Where would you draw an ABG in adults?
Radial artery
For the modified Allen’s test, how many seconds for a flush is a good indication of collateral circulation
15 seconds
When doing a modified allens test, how long does it take for the hand to turn pink again?
3-5 seconds
What is the typical representation in Pt record for ABGs?
PH/PCO2/Po2/HCO3/BE
Normal values of pH
7.35-7.45
Normal values of PCo2
35-45 torr
Normal values of PO2
80-100 torr
Normal values for HCO3
22-26 meq
Normal values for BE (base excess)?
-2 to +2
Normal values for SO2?
95-100%, same or similar to pulse Ox reading
What is the order that you should evaluate ABGs?
pH
PCO2
HCO3
Oxygenation Status
What is acidemia for pH?
<7.35
What is alkalemia for pH?
> 7.45
What is respiratory acidosis for PaCO2?
> 45
What is respiratory alkalosis for PaCO2?
<35
What is metabolic acidosis for HCO3?
<22
What is metabolic alkalosis for HCO3?
> 26
What is metabolic acidosis for BE?
< -2
What is metabolic alkalosis for BE?
> +2
If you have a PCO2 of >45 torr, what is going on?
Respiratory acidosis
CO2 retention
Hypoventilation
If you have a PCO2 of <35 torr, what is going on?
Respiratory alkalosis
Hyperventilation
Be is a function of what measure?
HCO3
If the initially change is increased PCO2, what happens to HCO3?
This is resp acidosis, and HCO3 increases also
If the initially change is decreased PCO2, what happens to HCO3?
This is resp alkalosis
HCO3 will also decrease
What values indicate hypoxemia?
PO2 = <75-80 torr
What are the mild hypoxemia values?
67-75 torr PO2
What are the moderate hypoxemia values?
PO2 of 50-65 torr
What are the severe hypoxemia values?
PO2 < 50 torr
Hyperoxia is indicated with what value?
100-120 torr
Uncompensated means?
pH is not in normal range