Lecture 1: Diagnostic & Therapeutic Skills Flashcards
At what age is PFT indicated?
5 and older.
What is acrocyanosis?
Cyanosis of the extremities
What kind of condition is PFT usually tested in?
- Chronic lung conditions with respiratory symptoms.
- Rib fracture
Generally not for things like pneumonia.
Can be done for things like a rib fracture, which are acute but can impair pulmonary function as a secondary complication.
What is a normal total lung capacity? (TLC)
6L
How are lung reserve volumes calculated?
IRV: Air inspired ABOVE the tidal volume.
ERV: Air exhaled BELOW the tidal volume.
Neither calculation includes tidal volume itself.
What is spirometry generally indicated for?
- Diagnosis/monitoring of lung/neuromuscular disease.
- Preventing post-surgical pulmonary complications.
Encourages people to take deep breath to prevent alveolar collapse.
What people should avoid spirometry?
- Recent abdominal/intracranial/eye surgery or pneumothorax
- Aneurysms
- Unstable angina/recent MI
- Acute severe asthma, acute respiratory distress, active TB
Mimics valsalva, which can open abdominal wounds or increase ICP.
What is a normal FEV1/FVC ratio?
70% or more.
Less than 0.7 generally implies COPD.
Normal implies normal or restrictive lung disease.
What is gold standard testing for PFTs? Indication?
Plethysmography
Decreased FVC on spirometry.
Why is plethysmography used?
Measures TLC because the chamber is enclosed and the residual lung volume can be measured as well.
Define obstructive vs restrictive lung disease.
- Obstructive: Difficulty EXHALING air.
- Restrictive: Difficulty INHALING air.
For an adult, what increases imply a positive response to bronchodilator therapy? Child?
- Increases in FEV1 > 12%
- Increases in FVC > 0.2L
Both must be present.
5-18: Does not require FVC change.
How do flow volume loops differ between obstructive and restrictive lung disease?
- Obstructive: expiration flow rate should be LOW. Inspiration is partially impaired.
- Restrictive: Inspiration flow rate should be LOW. Expiration is partially impaired. Impaired TLC.
What factor is restrictive lung disease graded by?
TLC
What factor is obstructive lung disease graded by?
FEV1
How is diffusing capacity measured? (DLco)
Inhalation of carbon monoxide and tracer. Amount exhaled = did not diffuse.
Example: 15% exhaled = 85% diffusing capacity.
What is the most sensitive PFT?
DLco
What is considered a passing 6MWT?
Flat surface walking for 6 minutes at 95%+ pulse ox with 1200-2300 ft walked.
What is peak flow used for?
Monitoring asthmatic’s peak expiratory flow rate to determine asthma control.
Non-invasive, simple, at home.
Why is ETCO2 preferred over O2 sats?
ETCO2 will rise almost 1 minute prior to O2 drop, which can signal hypoxia sooner.
What are the 4 phases of a CO2 waveform?
- Dead space ventilation
- Ascending phase (exhalation)
- Alveolar phase (uniform exhalation)
- Inspiration (inhaling)
What does elevated ETCO2 imply?
Hypercapnia.
Implies hypoventilation.
How is an asthmatic’s CO2 waveform altered?
Rounded part in ascending phase and an upward sloping alveolar plateau.
Shark-fin deformity
When are sputum cultures indicated for pneumonia?
- IP admission for pneumonia
- OP failure of empiric ABX for pneumonia
What is the primary disadvantage of CT scanning?
Radiation exposure is much higher with a CT than with a single XR.
mSv
Example: CXR: 0.1 mSv (10 days of natural radiation)
CT Chest: 7 mSv (2 years of natural radiation)
What food allergy should be checked prior to contrast injection?
Seafood/shellfish because iodine is often a contrast agent.
What is the difference between a CTA and a CT Chest with contrast?
CTA only highlights vascular structures.
CT Chest with contrast will show both tissue and vascular structures.
When is a VQ scan indicated?
R/o PE when CT is contraindicated.
AKA CT is PREFERRED first-line test.
It is not more sensitive. It is primarily in pregnant patients.
What exactly does a VQ scan measure?
Detects poor blood flow in pulmonary vasculature (perfusion) and uneven air distribution (ventilation).
Describe the VQ scan procedure.
- Inhalation of radioactive material to image airflow in lungs. (ventilation)
- Injection of radioactive material to assess vasculature. (perfusion)
What would a VQ scan look like for a suspected PE?
What is the main pitfall of a VQ scan?
Unable to identify a blood clot. It simply reveals that blood flow is impaired in general.
Describe the 3 types of abnormal VQ scans.
- Abnormal ventilation, normal perfusion: COPD or asthma.
- Normal ventilation, abnormal perfusion: PE.
- Abnormal ventilation, abnormal perfusion: Any of above + pneumonia.
What are the biggest risks with a VQ scan?
- Radioactive breastmilk for 24 hours.
- Allergic reaction: MC urticaria
What is the definitive/gold standard test for acute PE?
Pulmonary angiography.
Invasive test, not indicated first-line.
What does a negative pulmonary angiography indicate?
Excludes clinically relevant PEs.
When is pulmonary angiography indicated over CTA?
- Nondiagnostic CTA.
- Gold standard for PE.
Otherwise, CTA is preferred.
What are the two types of bronchoscopes and the differences?
- Flexible: MC, using procedural sedation.
- Rigid: using general anesthesia
When is bronchoscopy indicated?
- Evaluation and removal of airway foreign bodies
- Diagnosing and staging bronchogenic carcinoma
- Hemoptysis
- Pulmonary infections
- Transbronchial lung biopsy
- Bronchoalveolar lavage
What is the main contraindication to bronchoscopy?
Severe bronchospasms or bleeding diathesis.
Diathesis = tendency to suffer from a medical condition.
