T2: Pulmonary System (2) Flashcards
When does shunting occur?
when a portion of the VENOUS blood does not participate in gas exchange
Examples of conditions that may cause anatomic shunting:
- AVMs
- ARDS
- atelectasis
- pneumonia
- pulmonary edema
- pulmonary embolus
- vascular lung tumors
- intracardiac R to L shunt
Does increased FiO2 help when shunting occurs?
No
Does PCO2 change or stay the same when shunting occurs? Why?
stays the same
B/c compensation with increased RR
Venous blood that flows through the lungs w/o being oxygenated due to nonfunctioning alveoli:
intrapulmonary shunting
Intrapulmonary shunting:
____% is abnormal
____% is life-threatening
greater than 10% = abnormal
greater than 30% = life-threatening
What 2 methods can be used to measure shunting?
- Direct measurement
- Estimation
How do we directly measure shunting?
- Give 100% O2 for 15 min
- measure CaO2 and CvO2
CaO2 means ____.
CvO2 means ____.
CaO2 = O2 content of arterial blood CvO2 = O2 content of venous blood
CaO2 - CvO2 normal is ____ ml/dl.
5 ml/dl
How do we estimate shunting?
- PaO2 / PAO2 ratio
- Alveolar-arterial gradient
- PaO2 / FiO2 ratio
What is the A-a gradient?
The alveolar (PAO2) to arterial (PaO2) pressure difference
PAO2 means ____ pressure
PaO2 means ____ pressure
PAO2 = alveolar O2 pressure PaO2 = arterial O2 pressure
Why is the A-a gradient always positive?
You always have more O2 in the lungs than in the body tissue
What is a normal A-a gradient?
10-20 mmHg
increases within this range as the pt ages
What does A-a gradient show?
How efficiently the lung is managing pulmonary capillary O2 and alveolar O2
If the A-a gradient is large, this indicates a dysfunction in the ___.
lung
(it’s not picking up the O2 like it should
Issues that can lead to large A-a gradient:
- V/Q mismatching
- shunting
- diffusion abnormalities
What is the formula to find PAO2?
PAO2 = FiO2 (PB - PH2O) - PaCO2 / RQ
Abbreviation for fraction of inspired oxygen:
FiO2
Abbreviation for barometric pressure. What is normal?
PB
760 mmHg
Abbreviation for pressure of water vapor. What is normal?
PH2O
47 mmHg
Abbreviation for respiratory quotient. What is normal?
RQ
0.8
PaO2 / FiO2 normal value:
greater than 286
the lower the number, the worse the lung function
HYPOXEMIA caused by what 3 physiological problems:
- low inspire O2 tension
- alveolar hypoventilation
- V/Q mismatch
High _____ can cause LOW inspired O2 tension.
altitudes
Alveolar hypoventilation can be caused by disorders of the _____ center and _____ of the respiratory system.
respiratory
muscles
A-a gradient is NORMAL with _____ _____.
A-a gradient is INCREASED with _____ _____.
Normal = alveolar hypoventilation Increased = V/Q mismatch
What 5 things are checked by lab test regarding the pulmonary system?
1) Blood
2) Sputum
3) Chest
4) Ventilation and perfusion
5) Pulse oximetry
What BLOOD test is performed?
ABGs
What SPUTUM characteristics are observed?
Pathogens
abnormal cells
color, amount, consistency
What CHEST tests are performed?
CXR
Digital chest radiography
CT
What VENTILATION and PERFUSION test is performed?
V/Q scan
What noninvasive PULSE OXIMETRY test is performed?
SpO2
What areas do we ask about in a respiratory history assessment?
(Remember: SCAS HOG)
- Smoking history
- Childhood diseases
- Adult diseases
- Surgeries
- Hospitalizations
- Occupation/leisure activity
- Geographic area or travel
Pulmonary Function Test:
What does it look for?
Evaluates lung:
- VOLUME and CAPACITIES
- FLOW RATES
- DIFFUSION CAPACITY
- GAS EXCHANGE
- AIRWAY RESISTANCE
- DISTRIBUTION OF VENTILATION
Pulmonary Function Test:
No smoking for _____ hrs prior to test.
6 - 8 hrs
Pulmonary Function Test:
How many hours must bronchodilator drugs be held before test?
4 - 6 hrs
Capnometry and Capnography:
What does it measure?
Measures amount of CO2 present in EXHALED air
Remember you exhale to blow the “cap” off someone’s head
Capnometry:
What is the normal pressure of PETCO2?
between 20 and 40 mmHg
What is a capnometry device often used for?
Check for correct positioning of an ET tube
What 4 things can increase or decrease PETCO2?
Ventilation
Metabolism
Circulation
Error
What does exercise testing evaluate?
A 6 or 12 min walk test to see how short of breath, how far you can walk during that time
What do skin tests evaluate?
- allergens
- infectious diseases
What 3 things can be done during a bronchoscopy?
- visualize
- biopsy
- aspirate material
How many hours must a pt be NPO before a bronchoscopy? Why?
8 hrs
risk of aspiration
After a bronchoscopy, what must you assess for before allowing pt to drink?
Return of cough and gag reflex
What are 3 common complications with a bronchoscopy?
(Remember LAP)
- Laryngospasm
- Aspiration
- Pneumothorax
What is a THORACENTESIS?
aspiration of pleural FLUID or AIR from pleural space
What do we tell the pt a thoracentesis will feel like?
Stinging sensation and pressure; pt will feel better after excess fluid is pulled off lungs
What must the pt do during a thoracentesis?
Sit absolutely motionless in the correct position
What amount is typically the limit to aspirate in a thoracentesis? Why?
1000 mL
too much can cause complications from fluid shift
What 5 complications can be seen after a thoracentesis?
1) mediastinal shift
2) pneumothorax
3) bleeding
4) infection
5) subcutaneous emphysema
(**pneumothorax can cause the mediastinal shift)
What is subcutaneous emphysema? Is it dangerous?
trapped air under the skin that sounds like crackels (“Rice Crispies”)
Not dangerous, but the reason that caused it can be!
What does a lung biopsy look for?
obtains tissue for
- histologic analysis
- culture
- cytologic exam
Does a lung biopsy need to be performed in the OR?
No, can be done at the bedside
Follow-up care for lung biopsy:
- Assess VITALS, BREATH SOUNDS at least q4h for 24 hrs
- Assess for respiratory DISTRESS
- Report REDUCED/ABSENT breath sounds immediately
- Monitor for HEMOPTYSIS
