Diagnostic Testing Pt 2 Flashcards
Principles of Pulm Med Chapter 3 (previously assigned), Appendix B, and Appendix C 1. List and discuss the indications for arterial blood gases (ABGs), including the risks to the patient, cost effectiveness, and patient education. 2. When given a clinical scenario, correctly interpret ABG results. 3. Discuss the pathological changes occurring in the body as they relate to acidosis and alkalosis on ABG results. 4. List and discuss the indications for ventilation-perfusion scans (V/Q scans),
In practice, which two tests are very rarely completed these days?
VQ Scanning and Pulmonary Angiography, but they are still important to know about in limited resource areas.
This test evaluates the mismatches between ventilation and perfusion
Ventilation/Perfusion Scanning (VQ Scanning)
In VQ scanning where are radioactive chemicals inserted into the body?
- Inhaled
2. IV injections
After injective/inhalation of radioisotopes, what is done?
A scanner measures the gamma radiation in the blood flow and ventilation throughout the lungs
Segmental Anatomy of the Lungs are important and used for?
Analysis of VQ scanning to know where certain mismatching is occurring – indicating disease.
Three main phases of ventilation scanning:
- Wash-In
- Equilibrium
- Wash-out
During which phase of ventilation scanning would we be able to identify gas trapping if evident?
Wash out due to obstruction
**Commonly seen in COPD
The ventilation study is performed in the ________ projection to cut down on artifact created from soft tissues and to maximize the number of pulmonary segments seen.
Posterior.
This is also because the gas used (Xenon) is fat soluble and can be absorbed in the breast tissue, so posterior would avoid that.
Uptake of the tracer throughout the vasculature would indicate:
Healthy perfusion scan because it has gone through all the vasculature.
Tracer for Perfusion Scan
Albumin with radioactive particles
Tracers in perfusion scan are injected into the _____.
Venous system
True/False
Pulmonary arteries are primarily seen on the perfusion scan as opposed to bronchial arteries.
True
What would areas that are not perfused going to indicate?
Arteries blocked by clots
What are the results of a Perfusion Scanning?
- High Probabilty of PE
- Intermediate Probability of PE
- Low probability of PE
- Normal
What are the indications to perform a V/Q Scan?
- Diagnose PE
Assess lung function:
- Prior to resection for lung cancer
- Prior to lung volume reduction
- Prior to lung transplantation
High Probability for PE would
Greater than or equal to 2 segmental or larger perfusion defects with normal ventilations
Low Probability for PE would
Small or segmental perfusion defects, matched defects, radiographic abnormality larger than defect.
Normal
No perfusion defects
Most patients have _____ probability VQ scans.
Intermediate.
Likelihood of diagnosing PE with VQ scan
15-85%
In other words, it’s too variable to determine
What is the Gold Standard for diagnosis of Pulmonary Embolism?
Pulmonary Arteriography
What is a happening in a Pulmonary Arteriography?
Catheter is advanced into the right heart into the pulmonary artery. Contrast dye is injected during fluoroscopy.
This scan is commonly paired with V/Q scan when there is a clinical suspicion is high but it is not diagnostic.
Pulmonary Arteriography
Contradictions and Risks of Pulmonary Arteriography
- Increased bleeding risk (Coagulopathy)
- Renal Failure
- Left Bundle Branch Block - pt must me paced during the procedure to prevent heart block.
- This could also cause RBBB
Complications of Pulmonary Arteriography
- Death
- Severe Cardiopulmonary compromise requiring endotracheal intubation or CPR
- Renal Failure requiring hemodialysis
- Renal Failure not requiring hemodialysis
- Groin hematomas requiring transfusion of at least 2 units of blood
Complications are more likely in patients that are more ill - i.e. there is a higher complication rate inpatients referred from the ICU for arteriography