HLK Week 3 Flashcards
Definition of ventilation:
Movement of air between alveoli and atmosphere by BULK FLOW. A mechanical process.
Definition of respiration:
Movement of gases into and out of the body. Ventilation is part of the process but not exactly synonymous with it. Not to be confused with cellular respiration.
Discuss anatomical vs. physiological dead space:
Anatomical:
- Refers to the amount of air that is always left inside the airways. Must be subtracted from tidal volume to obtain true alveolar ventilation.
Physiological:
- Refers to the amount of air that reaches the alveoli but which doesn’t participate in gas exchange because, e.g., of non-uniform capillary distribution in the alveoli.
What does immediate orthopnea in an otherwise “healthy” person indicate?
Bilateral diaphragmatic weakness or paralysis
Define trepopnea:
Dyspnea only in a lateral decubitus position
Define platypnea:
Dyspnea only in an upright position
What is the definition of ventilation/perfusion (V/Q) ratio?
The ratio of the amount of air reaching the alveoli (ventilation) to the amount of blood reaching the alveoli (perfusion).
What is the classic imaging finding in a patient with acute hemoptysis?
Ground glass appearance on CXR
What’s the mechanism of action of albuterol and other SABA drugs?
Stimulates beta 2 receptors, relaxing bronchial smooth muscle and promoting bronchodilation.
According to lecture, what are the recommendations for theophylline?
Not recommended. Does not appear to control asthma but may be prescribed due to affordability.
Discuss restrictive vs. obstructive diseases in regards to vital capacity and the FEV1 test:
Restrictive:
- Not due to airway narrowing but rather lung expansion
- Therefore, normal FEV1 but decreased vital capacity
Obstructive:
- Due to airway narrowing
- Therefore normal vital capacity but reduced FEV1
The most common reason for inadequate oxygen movement between alveoli and capillaries:
Ventilation/perfusion inequality:
- Some alveoli may not be adequately ventilated, despite adequate blood supply (e.g., alveolar collapse)
- Some alveoli may be well ventilated but w/o adequate blood supply (e.g., due to a clot)
Which is more affected by V/Q mismatch, O2 or CO2 transfer?
O2
The neurons of the dorsal respiratory group (DRG) are responsible for which phase of respiration?
Inspiration
What is the function of the ventral respiratory group (VRG) on respiration?
- Cells of the respiratory rhythm generator are located in the pre-Botzinger complex in the VRG. They set the basal respiratory rate.
- VRG neurons also control active expiration.
What is the role of the pons in regulating breathing?
The apneustic and pneumotaxic centers fine tune the DRG’s activity and smooth the transition from inspiration to expiration
How to airway stretch receptors affect breathing?
Hering-Breuer reflex occurs when stretch receptors are activated by inflated lungs, sending afferent signals that inhibit DRG activity
Which chemoreceptors are most responsible for the regulation of breathing, and what are they most sensitive to?
- Carotid bodies (part of the peripheral chemoreceptors)
- H+, usually as a result of an increase in arterial CO2
What is the primary spirometric tool used to diagnose obstructive lung disease?
FEV1/FVC ratio
In a methylcholine (bronchoprovocation test) challenge, what result indicates asthma in a patient with normal pulmonary function tests?
At least a 20% reduction in FEV1.
A few things to go on the DDx for a patient with dyspnea:
Obstructive: asthma, copd, cystic fibrosis
Infectious: pneumonia
Restrictive: obesity, interstitial lung disease, pleural effusion
Other: metabolic acidosis, PE, CHF, anemia
Explain why hypoxia is more common in V/Q mismatch than hypercapnea?
The body can compensate for CO2 excess by increasing ventilation, causing you to blow off excess CO2. With low O2, increasing the ventilation only works when O2 is very low (this puts you on the steep part of the sat/PO2 curve). Plus, because O2 diffuses more slowly than CO2, increased ventilation can’t increase the alveolar PO2 enough to offset the V/Q mismatch happening elsewhere.
Some common causes of pulsus paradoxus:
- Cardiac tamponade
- Pericarditis
- Asthma/COPD
Examples of restrictive lung diseases/conditions:
- 2-ary to obesity
- Sarcoidosis
- Neuromuscular diseases
- Pleural effusion/pneumothorax
- Interstitial lung disease
- Pulmonary fibrosis
Examples of obstructive lung diseases/conditions:
- Asthma
- COPD
- Bronchiectasis
- Cystic fibrosis
Complications of COPD:
- Cor pulmonale as a result of pulmonary HTN
- Chronic respiratory failure
- Right heart failure
Describe the results of the FEV1/FVC test with respect to obstructive and restrictive diseases:
Obstructive: lower than normal ratio due to decreased ability to force air out.
Restrictive: normal to higher than normal ratio due to lower vital capacity.
Things that put cystic fibrosis on your differential:
- Chronic cough with thick sputum
- Chronic respiratory infections
- Chronic GI, liver, pancreas issues and malnourishment
- Azoospermia
- Bronchiectasis and scarring on CXR
- Increased chloride in sweat
Treatment for COPD:
- Oxygen therapy
- Anticholinergic inhaler (ipratropium)
- Inhaled or oral steroids for exacerbations
- Quit smoking
Things that put bronchiectasis on your differential:
- Chronic productive cough
- CXR showing dilated, thickened airways (tram tracks)
- Hx of cystic fibrosis
Treatment for cystic fibrosis:
- Lung transplant
- Inhaled bronchodilators
- Chest percussion and postural drainage
- Nutritional support
- Abx for infections
True or false: Asthma patients without sputum eosinophilia may be less responsive to steroids.
True
Obesity hypoventilation syndrome treatment:
- Weight loss
- Respiratory stimulants such as theophylline
- Treatment of comorbid sleep apnea
Acute respiratory distress syndrome (ARDS):
- Acute hypoxemic respiratory failure following pulmonary or systemic insult in the absence of heart failure.
- Tx underlying cause
