Clin Lab: Pulm Testing Flashcards
What are PFT?
series of measurements related to lung volumes, rate of airflow, & gas exchange
Indications of PFT
- symptoms of lung dz/dx of lung dz
- screening
- assess tx efficacy
-pre-op evaluation of lung function - monitoring for med SE
Contraindications for PFT.
- active or recent resp infx
- recent surgery
- recent or current heart issues
- known aneurysms in chest, abdomen, brain
Tidal volume (TV)
total volume of air inhaled/exhaled in one normal breath
Minute volume
tidal volume x # breaths/minute
IRV
volume that can be forcefully inhaled after normal tidal inspiration
IC
TV + IRV
ERV
volume that can be forcefully exhaled after normal tidal expiration
RV
volume of air left in lungs after all possible air exhaled
FRC
ERV + RV
Slow vital capacity
VC measured w/ slower, prolonged exhale
VC
total volume of air that can be exhaled after a maximum inspiration
Forced vital capacity
VC measured w/ forceful exhalation
TLC
VC + RV
List the 3 Forced vital capacities & describe?
- forced expiratory volume/time (FEV1, FEV2 etc): volume exhaled forcefully during a particular time period
- forced expiratory flow (FEF): rate of flow during FEV25% & FEV75%)
- Peak expiratory flow rate (PFER): maximum rate of flow during forceful exhalation
Types of pulmonary disorders
Obstructive, Restrictive, Pulmonary vasculature, breathing mechanics, neurologic control
Obstructive disorders are issues with
the airway & air flow issues
examples of fixed obstruction in upper airways
masses, mucus plug
Examples of variable Extrathoracic obstructions
- sleep apnea
- vocal cord issues
Examples of variable intrathoracic obstruction
- COPD
- asthma
Two categories of cause for restrictive pulm disorders
- loss of compliance/elasticity
- anatomical restrictions
Pulm disorders: pulm vasculature causes
- chronic PE
- chronic PHTN
Pulm disorders: breathing mechanics causes
- diaphragm/intercostals
Pulm disorders: Neurological control causes
- muscular dystrophy
- stroke
Measurements on specialized PFTs
- ABG
- Exercise oximetry “road test”
- 6-min walk test
- Peak flow
- Max inspiratory & expiratory pressure
What percentage of O2 will qualify a patient for home O2?
<88%
Spirometry procedure
- TV measured 3-5 times
- Forced exhalation for >6 secs measured 3 times
- Bronchodilator challenge (if done)
(BD inhaled; forced exhalations repeated to assess change
Usually, albuterol)
What other special test can be done? (spirometry slide)
- used when we suspect asthma*
- bronchoprovocation (methacoline/allergen,exercise)
- exercise testing
Results are based on predicted values for…
age, height, race, gender
On flow-volume loop, above the x-axis is…
exhalation
On flow-volume loop, below the x-axis is…
inhalation
What two things are being compared to the normal flow-volume loop?
shape & peak expiratory flow
What two things are being observed on the volume/time curve?
- where is the plateau?
- how long did it take to reach it?
Draw the spirometry volume/time chart
DONE
Draw flow-volume loops
DONE
GOLD criteria has a FEV1/FVC ratio of? Who is it used for?
70%
- middle-aged pts to assess COPD severity
ATS criteria has a FEV1/FVC ratio of? Who is it used for?
> 85%
- > 18yo
Low FEV1/FVC ratio & normal FVC is indicative of what?
Obstructive lung dz
How do you assess a bronchodilator test for obstructive lung dz?
- Ratio has >12% incr and FVC has >200 mL increase–> asthma (reversible)
- only one of the above criteria met–> COPD or bronchiectasis (irreversible)
Low FEV1/FVC ratio & low FVC is indicative of what?
Mixed disorder
How do you assess a bronchodilator test for a mixed disorder?
- FVC increases to >LLN–> obstruction w/ air trapping (emphysema)
- FVC does not increase to >LLN
mixed disorder
Possible methods for lung measurents.
- helium
- N2 washout
- body plethysmography
- radiographic measurements
When looking at lung volumes, what will restrictive patterns show.
low TLC confirms (the entire box is smaller)
What is DLCO?
measures capacity of diffusion across the alveolar-capillary membrane
Should CO normally be present in air/blood
No, & it has a very high affinity for Hgb
Causes for decreased DLCO
- interstitial lung dz
- emphysema
- PHTN
- Anemia
Causes for normal DLCO
- NM disorders affection resp system
- chronic bronchitis
- asthma
Study Slide 35 (full chart) 10 mins
DONE
What is A1AT?
inactivates enzyme that breaks down collagen
Deficiency of AAT leads to…
- early onset emphysema
- childhood cirrhosis
What is CF?
genetic disorder causing impaired Cl- transporter in cell membranes resulting in thick mucous
What test can be done to check for CF?
Cl- sweat test
Results of Cl- sweat test
- 29 or less –> CF unlikely
- 60 or high –> CF likely
- 30 to 59 –> inconclusive - repeat test & monitor
What does ACE stand for & what does it do?
- Angiotensin converting enzyme
- Angiotensin I (from liver)–> to angiotensin II (stimulates aldosterone [Na+ out of urine back into bloodstream] release)–> increases BP
Indications for ACE levels
- Sarcoidosis (elevated ACE)
Dx testing for A1AT & ACE
serum level measured
What does ANCA stand for & what do they do?
- Antineutrophil cytoplasmic antibodies
- attach WBC antigens causing inflammation & destruction of BVs w/ resultant lung damage
Hemoptysis w/ ANCA would be…
- Pneumonia
- Autoimmune dz
- Cancer
- TB
ANCA can have what vasculitides affect the lungs?
- granulomatosis w polyangiitis (GPA)
- Eosinophilic granulomatosis w/ polyangiitis (EGPA)
- Microscopic polyangiitis
Dx test for ANCA
Biopsy
- staining done for ANCA antibodies
Common resp pathogens: viruses
flu, paraflu, RSV, coronavirus, metapneumovirus
Common resp pathogens: bacteria
Bordetella pertussis, strep pneumo, s. aureus, mycoplasma, Legionella, Klebsiella, H. flu
Less common resp pathogens: bacteria
mycobacterium TB
Less common resp pathogens: fungi
histoplasmosis, aspergillus, pneumocystis
Hallmark symptoms that make you think Legionella.
pneumonia + GI symptoms
Outpt. diagnostics for pneumonia
- clinical dx (fever + productive cough)
- testing (CXR, labs, CBC/BMP)
ER diagnostics for pneumonia
- CXR
- Labs (CBC/BMP, +/- ABG, blood cultures, lactate)
On admission from ED diagnostics for pneumo
- Urine Antigen: strep pneumo & legionella
Blood antigen: mycoplasma pneumonia - Procalcitonin: elevated w/ bacterial infx, not w/ viral
- sputum culture (gram stain & culture
What is procalcitonin?
produced by lung parenchymal cells in response to bacterial toxins
What is considered a good sputum culture?
< 10 epithelial cells & >25 polymorphonuclear cells
Dx tesing for suspected TB
- CXR
- 3 sputum specimens, at least 8 hrs apart, at least 1 early am (acid-fast stain, NAAT, culture & sensitivities)
- skin test or IGRA–> TB antigens in vitro
Disorders that can cause a pleural effusion
- Lung infx, lung cancer, PE
- pancreatitis
- HF
- Cirrhosis
- Nephrotic syndrome
Two underlying for pleural effusions
- capillaries leaky (infx/cancer)
- increase rate of osmosis into tissues–> incr hydrostatic pressure or decr oncotic pressure
Describe exudative fluid & causes.
- PROs + cells
- think infection & cancer (lung)
Describe transudative & causes
- minimal PROs + cells
- Pancreatitis, HF, Cirrhosis, Nephrotic syndrome
Contraindications for thoracentesis
- bleeding disorder - relative
- skin infx at site
- low volume effusion
Complications of thoracentesis.
- pneumothorax
- Reactive pulm edema (if >1.5L removed)
what type of fluid analysis is done via thoracentesis?
- Gram stain & culture
- Cell count & differential
- PRO
- LDH
- Glucose
- Cytology
- Cholesterol
Light’s criteria: usually exudative if AT LEAST ONE of the following
- ratio of pleural fluid PRO to serum PRO is >0.5
- ration of pleural fluid LDH to serum LDH is >.45 (changed from 0.6)
- pleural fluid LDH level is > 0.6 x the normal upper limit of serum LDH
Does the new criteria need a serum sample?
NO, no blood needed
- a lot of cells means a lot of cholesterol
Imaging for PE
- CTA chest
- V/Q scan
- Venous US or legs (DVT?)
Labs for PE
D-dimer or EKG
Note
Use Wells’ criteria to help us decide whether to do a d-dimer or go straight to imaging
A D-dimer test has a cutoff that is related to what?
- age
- d-dimer tend to go up w/ age
what is mostly commonly seen on EKG if pt. has a pulmonary embolism?
sinus tachycardia
What is the more uncommon things seen on EKG in PEs?
S1Q3T3 pattern
Measure of hypoxemia on ABG: Normal PaO2
80 - 100
Measure of hypoxemia on ABG: Mild
60 - 79
Measure of hypoxemia on ABG: Moderate
40 - 59
Measure of hypoxemia on ABG: Severe
< 40
Hypoxemia means there a problem b/t
the nose & alveoli
1. ventilation issue
2. gas exchange issue
If the etiology of hypoxemia is unclear, what can help narrow the list of causes?
A-a gradient
PAO2 means:
partial pressure of O2 in the ALVEOLI
PaO2 means:
partial pressure of O2 in the blood (arteries)
Does the A-a gradient vary w/age?
YES
A-a gradient calculated vs expected: normal (close to equal) is what type of issue?
ventilation issue
A-a gradient calculated vs expected: elevated (calc > expected) is what type of issue?
gas exchange issue
What is a bronchoscopy?
endoscopic procedure to visualize trachea & major bronchi
Where can a bronchoscopy be done?
bedside or endoscopy suite
unilateral wheezing: we should be concerned w/?
FB
What part of the anatomy can we perform a bronchoscopy?
central or close to the bronchus
What part of the anatomy can we NOT perform a bronchoscopy?
more peripheral: beyond the bronchus (further away; deeper)
Bronchoscopy complications
- perforation or injury
- pneumothorax
- problems w/ anesthesia
What special procedures can be done during a bronchoscopy?
- bronchoalveolar lavage
- Bronchial brushing
- Biopsy
Types of biopsies that can be done during bronchoscopy
- Endotracheal or endobronchial
- Transbronchial needle aspiration (TBNA) of lesions outside of bronchi [often ultrasound guided]
Describe Mediastinoscopy
endoscopic procedure to examine mediastinum
Mediastinoscopy indications
Lymph node biopsy
- lung cancer staging
- Sarcoidosis
- TB
- Lymphoma
Mediastinoscopy complications
- Pneumothorax
- Bleeding
- Esophageal injury
What is the entry point for a mediastinoscopy?
- sternal notch
outside tubing of the lungs but inside chest (mediastinum)
Indication for biopsy
evaluation of mass or lesion
Approach for centrally located mass or lesion
bronchoscopy
Approach for peripheral mass or lesion
transthoracic needle aspiration (TTNA)
CT or US guided done by interventional radiology
If you are at risk for having lung cancer what is the screening plan?
annual low dose CT
What makes a person high risk for lung cancer?
- 55-80yo
- 20+ pk-yr
- hx of smoking
- smoker or quit < 15yo ago
- in reasonable health
What patients call for a more aggressive workup?
- known primary cancer
- immunocompromised
- significant smoking history
- FHx of cancer
- suspicious morphology
Describe suspicious morphology for lung nodule
> 8mm in size
- irregular borders
- semi-solid appearance
- upper lobes
What criteria do providers use to assess when a patient needs to do repeat imaging?
Fleischer society
NOTE
cancers tend to double in volume every 100-300 days
Considerations for lung nodules
- solid vs semi-solid nodules
- Size
- Single vs multiple
- RFs
What is a Pancoast tumor?
upper lobe of lungs put pressure on lungs/nerves & you get shoulder pain that doesn’t change w/ movement
Other symptoms of Pancoast tumors
same side of face
- small pupil
- lack of sweating (Horner’s syndrome)
Paraneoplastic syndrome
symptoms from secreting hormones (ADH) & ^ Ca++
- rashes
- fluid retention
- v Na+ (hyponatremia)
- ISADH
Dx for a more concerning nodule
- sputum cytology
- bronchoalveolar lavage
- bronchoalveolar brushings
- transbronchial needle or transthoracic needle aspiration
- lymph node biopsy
- surgical biopsy
What measurement is used to determine obstructive sleep apnea?
apnea/hypopnea index (AHI)
How long must a sleep study be?
2 hours
How many events must you have to have Obstructive Sleep Apnea?
5 or more apnea/hypopnea events/hour
What is mild sleep apnea?
5-15
What is moderate sleep apnea?
16-30
What is severe sleep apnea?
> 30
Obstructive sleep apnea tx
CPAP
What can obstructive sleep apnea cause?
HTN