Pulmonary Function Tests - Quiz 7 Flashcards
What is the FEV1 for High Risk Patients?
< 2 L
What is the FEV1/FVC for High Risk Patients?
< 0.5
What is the VC for High Risk Adults and Children?
Adult: <15 cc/kg
Child: < 10 cc/kg
or
VC < 40-50% than predicted
What is the PreOP Goal of PFTs?
Optimize Patient by treating Reversible Conditions
Important for Pts. w/ > 15% improvement after treatment
EX: Bronchodilators, Antibiotics, Diuretics
How do you manage the Ventilator Intraoperatively
- Emphysema needs longer expiratory time (change I:E)
- Monitor PIP
- Keep EtCO2 near patient’s baseline
How do you manage Bronchospams Intraoperatively?
Neb Treatment
Avoid Histamine Releasing Drugs
What are some Histamine Releasing Drugs?
Pentothal (STP)
Morphine
Atracurium
Mivacurium
Neostigmine
ABX
How would an FEV1 > 50% predicted effect extubation?
Extubation will not be effected
How would an FEV1 of 25-50% + some hypoxemia & hypercarbia effect extubation?
Probable Prolonged Intubation
What considerations should you take for a patient with an FEV1 < 25% predicted?
Only perform Life-Saving Procedures
Regional Anesthesia
Long Term Vent
Poss. Trach
Extubation Criteria
- VSS, Awake & Alert
- 40% FiO2 = PaO2 > 70 & PaCO2 < 55
- NIF < -20cm H2O
- VC > 15 cc/kg
What criteria would be considered Respiratory Failure requiring Intubation?
- RR > 35
- PaCO2 > 55 mmHg
- PaO2 < 70 on 40% FiO2
What A-a gradient would you consider Intubating?
A-a Gradient > 350 mmHg on 100% FiO2
At what Vital Capacity would you consider Intubating?
VC < 15 cc/kg
< 10 cc/kg for kids
At what ratio of Dead Space to Tidal Volume would you consider intubating?
Vd/Vt > 0.6
List A-I
(I is not Depicted)
A: Airway
B: Bone
C: Cardiac Silouette
D: Diaphragm
E & F: Equal Lung Fields
G: Gastric Bubble
H: Hilum (and Medastinum)
I: Invasive Lines (Not Shown)
Whats the most fundamental test of all PFTs?
Arterial Blood Gas
How soon much the blood ABG be measured after being drawn?
Within 15 min or glycolysis due to lacic acid
=
↓pH + ↑CO2
How long can you store an ABG for?
1-2 Hours on Ice
How does Heparin effect an ABG?
Lowers PCO2 by dilution
(Especially in Kids)
An increase in PCO2 by 10 mmHg would decrease in pH by ________
PCO2 increase by 10 = pH decrease of 0.8
What does the A-a Gradient measure?
A-a measures the difference b/t oxygen concentration in alveoli & arterial system
How do you treat abnormal A-a gradients?
Treat Underlying Cause
O2, Adjust Ventilation, PEEP
A decrease in Bicarb by 10 mmoles decreases pH by _________
Decrease of Bicarb by 10 decreases pH by 0.15
Replace Bicarb by half of deficit
What can cause Respiratory Alkalosis?
Pregnancy
Artificial Ventilation
Hypoxic Respiration
Anxiety
Kidneys partially fix pH
What can cause Metabolic Acidosis?
Low pH & Low HCO3-
Lactic Acidosis
DKA
ASA Ingestion
Diarrhea
What can cause Metabolic Alkalosis?
Loss of H+ from Vomiting/NGT Suctioning
Giving too much Bicarb
What is Tidal Volume?
Volume Inspired/Expired w/ each normal breath
500 mL
What is Inspiratory Reserve Volume?
Extra Volume inspired above normal breathing.
3000 mL
What is Expiratory Reserve Volume?
The extra volume after normal expiration
1100 mL
What is Residual Volume?
Volume of air remaining after max expiration.
1200 mL
What is the Inspiratory Capacity
The maximum amount of air that a person can breathe in.
Tidal Volume + Inspiratory Volume Reserve
3500 mL
What is Functional Residual Capacity?
The air in the lungs after normal expiration
Expiratory Reserve Volume + Residual Volume
2300 mL
What is Vital Capacity?
The max amount of air a person can blow out after taking the biggest breath they can.
Inspiratory Reserve Volume + Tidal Volume + Expiratory Reserve Volume
4600 mL
What is Total Lung Capacity?
The max volume of air the a person can breath in
Vital Capacity + Residual Volume
5800 mL
Normally, how much is the FRC in comparison to the TLC?
40% of TLC
What are the techniques used to measure FRC and which is the most accurate?
- Helium Dilution
- Nitrogen Washout
- Body Plethysmography - sit in a sealed box and try to inhale through closed mouthpiece - more accurate
What is Forced Vital Capacity (FVC)?
The max amount of air a person can forcibly blow out after taking the biggest breath they can.
What is FEV1?
Volume of air forcibly exhaled in the first second.
3-5 L
What is FEV1%?
Ratio of FEV1 to FVC
Normal: > 75%
How does Airway Obstruction and Constricted Lungs compare to normal Flow Volumes?
- Both have reduced Total Lung Capacity & Residual Volume
- Airway Obstruction - harder to get air out
How are FVC’s different between a healthy person and a person with lung disease?
Total Volumes are not much different.
Major difference Amount of air each person can expire per second
What is the most important clinical tool in assessing the Severity of Obstructive Airway Disease?
FEV1
What is the approximate FEV1% for a person with serious airway obstruction?
47%
Acute Asthma: < 20%
An abnormal FEV1 can indicate ______ disease, while an abnormal FVC can indicate ________ disease
Abnormal FEV1 = Obstructive
Abnormal FVC = Restrictive
Degree of risk in Obstructive Lung Disease
FEV1/FVC
Normal: > 75%
Mild: 60-75%
Moderate 45-60%
Severe 35-45%
Extreme < 35%
What helps distinguish b/t upper airway obstruction (extrathoracic) and generalized pulmonary disease (intrathoracic)?
Flow-Volume Loops
Extrathoracic obstruction decreases _______ flow, while Intrathoracic obstruction decreases ________ flow
Extrathoractic decreases inspiratory flow
Intrathoracic decreases expiratory flow
Which type of lung disease when FEV1 < FVC and the FEV1/FVC ratio is decreased?
Obstructive Lung Disease
Which type of lung disease when FVC < FEV1 and the FEV1/FVC ratio is increased?
Restrictive Lung Disease
What is FEF25-75%?
Forced Expiratory Flow
or
Mid-Expiratory Flow Rate
- Effort Dependent = Highly Variable
- Indicator of Early Airway Obstruction
What is the “Will to Live” test?
Max Voluntary Ventilation or Max Breathing Capacity
Patient breathes as hard and fast as possible x 12 seconds
Extremely Effort Dependent
What does the Max Voluntary Ventilation (MVV) test for?
Breathing Motivation, Mechanics, Strength, and Endurance
Low MVV = ↑Morbidty & ↑Mortality for thoracic Sx
