Pulmonary Diagnostics Flashcards
What vaccine can interfere with a TST?
Bacille Calmette-Guerin (BCG for TB)
TST:
Tuberculin Skin Testing:
- intradermal injection on forearm, evaluate at 48-72 hrs.
- 5mm (HIV, recent TB exposure), 10 (pts with risk factors for TB, 15 (those without risk factors)
- TB exposure has to be at least 6 weeks prior to TST
- CXR as needed if positive
- Non-rxn maybe due to bacterial infection, viral infection, or immunosuppressive drugs (steroids) overwhelming TB
What test can be performed on people w/ BCG vaccine?
Quantiferon Gold TB test
Quantiferon Gold TB test:
- blood test can diagnose latent or active TB
- Highly specific, single visit
- stimulates T cell response
TB Testing AFB Smear & culture:
- detects mycobacterium infections
- Pulmonary infection: collect 3-5 sputum samples
- can have false negative smears
- need culture for definitive confirmation
- slow growing days to weeks to months
- susceptibility testing is extremely important for TB due to resistance
NAAT TB testing:
- inconjunction with smear
- more sensitive
MODS
- Microscopic-Observation Drug-Susceptibility
- For TB
- 7 days - rapid
Pulmonary Function Testing (PFTs)
-assesses respiratory function, abnormalities and disease severity
Indications of PFTs:
- Differentiate type and severity of lung dysfunction
- Monitor Therapy and disease progression
- Evaluate lung function function prior to a surgical procedure
- Determine lungs gas diffusing ability
Full PFTs:
Spirometry/ volumes/ capacities
Things to consider with PFTs:
age, hgt, wgt, gender, ethnicity, pt ability, clinical context
Spirometry:
- measures volumes and airflow rates
- results are compared to predicted values
- if values are greater than 80% of predicted then its normal
Forced Vital capacity (FVC)
- part of spirometry
- amount exhaled after max inspiration
- this is diminished in obstructive and restrictive diseases
Forced Expiratory Volume 1 Sec (FEV1)
-1st sec of FVC
FEV1/FVC ratio:
- results relatively normal in restrictive disease and markedly lower in obstructive
- 80% or greater is normal
Inspiratory reserve volume (IRV)
-volume remaining after forced exhale
Expiratory Reserve Volume (ERV)
-Max volume exhaled after normal expiration
Obstructive diseases show _______ volumes.
hyperinflated/increased
Restrictive diseases show all ________ volumes and capacities.
low
Volumes are needed for _____
DLCO
-diffusing capacity of the lung
Volume is determined by…
finding FRC and calculating other values based on spirometer IC and ERV
VT-
tidal volume - quiet breathing
Lung Diffusing Capacity (DLco)
- measures lungs ability to exchange gasses and saturate RBCs w/ O2
- single breath of CO and Helium measured by gas chromatograph
- normal= little CO returned (75-120% of predicted)
- interstitual lung dz, pneumonia, tomur, PE, emphysema
PFTs in restrictive diseases=
- FEV1=
- FVC, low
- FEV1/FVC=
- TLC-RV-FRC, low
PFTs in Obstructive diseases=
FEV1, low FVC=/low FEV1/FVC, low TLC=/^ RV=/^ FRC,^
Who do you do ABGs on?
-sicker ventilated pts, non-ventilated pts, and pre-op
what else do you obtain with ABG?
serum blood chemistry to compare values
acidemia=
<7.35
Alkalemia=
> 7.45
Anion Gap [Na-(Cl+HCO3)]
-difference measured between anions and cations
Anion gap uses
- determining a DDx of various metabolic acidemia
- Normal= 12+/- 4 (normally HCO3 loss)
D-dimer
- tests intravascular clotting
- Looks for plasmin activity on a fibrin clot
- high sensitivity for amount of clot breakdown, but not any one pathology
- Normal values= ‘none’
- tests for DIC, DVT, PE, general fibrinolysis
- elevated after surgery, cancer, pregnancy or sickle cell
Alpha 1 antitrypsin (AAT)
- used if you suspect familial component of emphysema which occurs early in life
- non-specific marker for inflammation so must use with clinical workup
Sweat Chloride Test
- diagnostic for Cystic Fibrosis (>60 men/L)
- Performed on children w/ FTT, malabsorption, early asthma, ongoing respiratory infections, presence of meconium ileus at birth.
- screen siblings with CF
- must have 2 positive tests
Chest Computed Tomography (CT) scan
-used for- tumor, PNA, abscess, lung dz, aortic dz, bony dz, upper GI dz, mediastinal dz
Number 1 modality to identify pulmonary embolism-
Spiral CT with contrast
When is chest CT contraindicated?
- instable pt
- pregnancy
- profound claustrophobia
- No IV contrast w/ iodine- shellfish allergy
Chest CT complications:
Acute Renal failure
- allergic rxn
- interaction w/ metformin precipitating acidosis or hypoglycemia
Spiculated nodule=
not round or nice, stuff moving from it
= cancer
Ventilation/Perfusion Scan (VQ)
- used for diagnosis of suspected PE
- Dx categories: negative, low probability, high probability, positive.
- *used less than spiral test CT, but negative scan rules out a PE
What is the gold standard test when a VQ is equivocal?
Pulmonary Angiography
Pulmonary Angiography
- essentially replaced by spiral chest CT
- its more invasive
- takes longer
- potential for cardiac arrhythmias
Thoracentesis
Needle insertion into the pleural space to remove excess fluid for treatment and diagnosis.
Done with or without ultrasound guidance.
Specimens sent for: cytology, cell count, gm stain, cultures, protein, glucose, TB, fungus.
Differentiate between transudate and exudate effusions.
Transudates: CHF, cirrhosis, nephrotic syndrome
Exudates: malignancy, infection or inflammation
Bronchoscopy
Endoscopic modality to directly visualize the larynx, trachea and bronchi.
Flexible fiberoptic or rigid scope.
Diagnosis or treatment.
Rigid: removal of larger FB under GETA.
Flexible: more commonly used because of flexibility and ability to reach smaller airways.
Obtain sputum samples, biopsy lesions, assess airways, look at larynx, stop bleeding,
Tube Thoracostomy (chest tube)
Remove air or fluid
Therapy for introducing sclerosing agents
Video Assisted Thoracic Surgery (VATS)
Laproscopic thoracic surgery for diagnosis and treatment
Thoracotomy
- Open thoracic surgery both diagnostic and therapuetic
- Most commonly used for lung resection due to malignancy
- extremely painful
