Pulmonology Flashcards
Ultimate function of the lungs?
Maintain pO2 and pCO2 within normal physiologic range
What muscles are used to create negative thoracic pressure?
Diaphragm & accessory muscles (intercostals, SCM, pectorals
Conducting zone of the airway consists of:
Trachea, primary bronchus, brachial tree (terminal bronchioles?)
Respiratory zone of the airway consists of:
Respiratory bronchioles, alveolar sacs, and alveolus
Pulmonary arteries transport de-oxygenated blood ______ from the heart
Away
Pulmonary veins transport oxygenated blood ______ the heart
toward
What are the 2 types of cells that make up the alveolar epithelium? And how much is made up of each
Type I pneumocystis make up 95% of total alveolar area- they are large flattened squamous cells
Type II pneumocytes make up 5% of total alveolar area - they secrete surfactant (to decrease surface tension and prevent collapse)
What is the very thin layer of connective tissue which attaches capillary endothelial cells to alveolar cells called?
Basement membrane.
It contains elastin, collagen, and fibrin
Gas exchange at the alveolar level
respiration
Method to quantify gas diffusion across alveolar-capillary membranes, that typically measures CO.
Diffusion Capacity (DLCO)
Low DLCO means impaired gas transfer from alveoli to capillary blood.
How do we tell if lungs are getting enough O2 from air into the blood?
Use the A-A gradient, which is the measure of the difference between alveolar and arterial O2 pressures. These should have minimal differences.
If A-a is elevated, then the lungs are not getting adequate O2 (shunting is occurring)
A-a gradient normal? They are getting enough O2.
Pathologic condition in which alveoli are perfused with blood, but not ventilated.
Pulmonary shunting.
*most common cause of hypoxemia
Pulmonary vasculature attempts to minimize the effect of insufficient airflow through hypoxic pulmonary vasoconstriction. Often cannot compensate completely.
What is it called when low regional pO2 leads to pulmonary vascular smooth muscle constriction which leads to blood flow re-routed to areas of lung with better oxygenation
Hypoxic pulmonary vasoconstriction
In what way is Hypoxic pulmonary vasoconstriction good? How is it bad?
Good: shutting down an area of the lung that has an infection.
Bad: if extensive or bilateral low pO2, it can cause main pulmonary artery constriction leading to pulmonary HTN, which may lead to R heart failure from too much demand on the heart.
Alveolar destruction causes:
Loss of elastic recoil of the lungs
Sx of pulmonary disease
- Dyspnea/SOB/air hunger/exercise intolerance
- cough
- wheezing
- plus others like chest pain, headaches or lightheadedness, fever/chills, anorexia, anxiety or depression
Characteristics of obstructive lung disease
airways narrowed, stale air cannot escape the alveoli
Really full balloon but the hole is really small so cannot deflate
Characteristics of restrictive lung disease
Can’t get air into the lungs, often connected to thickening of alveolar-capillary membrane (or other things)
Balloon that you can’t inflate
How do we measure how quickly and efficiently the lungs are emptied and filled?
PFTs (pulmonary function tests):
Spirometry (O2 saturation in the blood), plethysmography (lung volume), DLCO.
Compare results to others of similar demographics. Results based on 1/3rd of inspired gas stays in conducting airways and 2/3rd reaches alveoli
In Spirometry, what do you call the amount exhaled in 1 sec
FEV1 (Forced Expiration Volume in 1 second)
In Spirometry, what do you call the volume capacity with forceful exhale not relaxed sigh
FVC (Forced Volume Capacity)
What percentage of Oxygen is in the air
21%
78% Nitrogen
1% CO2 and other gases
Why is it necessary to have Nitrogen in the air we breathe?
pure oxygen will diffuse across the capillary membrane and the alveolar will collapse (absorption atelectasis)
Benefits and limits of O2 saturation
Benefits: rapid, noninvasive, continuous, low cost, accurate =/- 2% of true O2 sat.
Limits: Can’t distinguish O2 from other molecules (like CO), inaccurate if poor perfusion (cold hands), cannot assess ventilation (CO2 level), less accurate is O2 sats <70%
Low partial pressure of O2 in the blood
Hypoxemia
insufficient O2 delivery to tissues
Hypoxia
Adequate breathing requires both adequate oxygenation and _________
Ventilation
PEEP stands for:
Positive end expiratory pressure
-heated high flow, vent, bypass
What decreases pCO2?
increasing respiratory rate
increasing tidal volume (amount of air moved with each breath)
In Arterial Blood Gas readings, what is normal pH?
7.35-7.45
In Arterial Blood Gas readings, what is normal PaCO2?
35-45 mmHg
In Arterial Blood Gas readings, what is normal PaO2?
80-100 mmHg
In Arterial Blood Gas readings, what is normal HCO3?
22-26 mEq/L
In Arterial Blood Gas readings, what is normal O2 saturation?
95-100%
Pros and cons of Arterial Blood Gas (ABG) testing
Pros: low to moderate cost, more accurate than pulse oximetry, measures CO2, allows determination of cause of acid/base imbalance (metabolic vs rest)
Cons: invasive, painful, not continuous so requires rechecks
Blood pH of <7.35
Acidosis
Blood pH of >7.45
Alkalosis
How is blood pH regulated?
A bicarbonate buffer system of CO2 ( in the lungs) and bicarbonate (in the kidneys)
Continuous, noninvasive measurement and graphical display of end-tidal carbon dioxide
Waveform Capnography or ETCO2 or PETCO2
A sensor is attached to endotracheal tube or Bipap to detect CO2 in expired air
When is a CXR indicated?
shortness of breath cough (severe or chronic) chest pain chest wall trauma chest wall deformities hypoxia foreign body aspiration
When is CT indicated
Sx unexplained by a CXR concern for PE Pulmonary nodules/masses mediastinal or hilar adenopathy loculated or unilateral pleural effusion, pleural thickening
What is “technique difference” on a radiology report
When the same nodule looks different in size when imaged several times because it may be captured at a different level
What test might you order to rule in a PE?
ventilation/perfusion scan aka V/Q scan
- does not rule out PE
- can be used in pts with renal failure or other contraindications for IV contrast
- reported as “low” “moderate” or “high-probability” of PE
What is it called when a flexible scope is passed into the brachial tree?
Flexible Bronchoscopy
aka Bronch
- may be used to visualize a mass or nodule, non resolving pneumonia, mediastinal adenopathy
- $$$
- allows for direct visualization of airways, can obtain a biopsy or cultures, perform interventions
- risks include pneumothorax, bleeding, death
When trouble-shooting breathing problems, what would you think about when the patient isn’t breathing?
- Is your equipment working? (When in doubt, check vitals yourself)
- CNS respiratory drive (toxins, opioids, brainstem tumor or stroke or TBI)
- Is air composition appropriate? (carbon monoxide, low atmospheric pressure)
When trouble-shooting breathing problems, what would you think about if fresh air isn’t getting in and out of the alveoli?
- Airway dz (eg bronchospasm, bronchial thickening/inflammation, mucous plugging, infection, obstructive lung dz/air trapping, foreign body, tumor)
- Musculoskeletal (obesity, chest wall trauma, kyphosis, congenital chest wall deformity, diaphragm dysfunction)
- Extrinsic restriction (pleural effusion, pneumothorax, neck tumor)
When trouble-shooting breathing problems, what would you think about if oxygen can’t cross the alveolar-capillary membrane?
- Interstitial disease, pulmonary fibrosis, pulmonary vasculitis
- Loss of alveolar surface area (emphysema/COPD)
When trouble-shooting breathing problems, what would you think about if the capillary isn’t adequately perfused?
PE, CHF, low cardiac output, cardiac arrhythmia/arrest
