Dyspnea (includes pulmonary edema) Flashcards
What is dyspnea?
Subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity.
Is dyspnea a sign or symptom?
It’s a symptom, and should be distinguished from signs of increased work of breathing.
Increased airway resistance or stiffness is associated with…
a sense of increased effort to breathe.
Chemoreceptors: where are they & what do they sense?
What sensation do they cause when activated?
Where: carotid bodies
What they sense: hypoxemia, acute hypercapnia, acidemia
Sensation: air hunger
Mechanoreceptors: where are they & what do they sense?
What sensation do they cause when activated?
Where: lungs
What they sense: bronchospasm
Sensation: chest tightness
J-receptors: where are they & what do they sense?
What sensation do they cause when activated?
Where: lungs
What they sense: interstitial edema
Sensation: air hunger
Pulmonary vascular receptors: where are they & what do they sense?
What sensation do they cause when activated?
Where: lungs
What they sense: acute changes in pulmonary artery pressure
Sensation: Air hunger
What sensation is associated with hyperinflation of the lungs?
An inability to get a deep breath; unsatisfying breaths
Metaboreceptors: where are they & what do they sense?
What sensation do they cause when activated?
Where: skeletal muscle
What they sense: biochemical changes during exercise
Sensation: breathing discomfort
How might anxiety contribute to dyspnea?
1) By altering the interpretation of sensory data
2) by leading to breathing patterns that heighten physiologic abnormalities
What pathophysiology is often associated with chest tightness or constriction?
1) bronchoconstriction
2) interstitial edema (asthma, MI)
What pathophysiology is often associated with increased effort to breathe?
1) airway obstruction
2) Neuromuscular disease (COPD, mod-to-severe asthma, myopathy, kyphoscoliosis)
What pathophysiology is often associated with air hunger?
1) Increased drive to breathe (CHF, PE, airflow obstruction)
What pathophysiology is often associated with the inability to get a deep breath?
1) Hyperinflation (asthma, COPD)
2) Restricted tidal volume (pulmonary fibrosis, chest wall restriction)
What pathophysiology is often associated with heavy or rapid breathing?
Deconditioning
Most diseases of the respiratory system produce dyspnea by…
…mechanical alterations of lungs or chest wall.
Most diseases of the cardiovascular system produce dyspnea by…
…causing gas exchange abnormalities or stimulating pulmonary/vascular receptors.
Asthma & COPD are what type of lung disease?
Obstructive
What does chronic airway obstruction cause to happen to the lungs?
Air trapping & hyperinflation
Which is more common: hypoxemia or hypercapnia?
Hypoxemia
Diseases of lung parenchyma (AKA interstitial lung diseases) may be caused by:
1) Infection
2) Occupational exposure
3) Autoimmune disorders
Disease of lung parenchyma result in:
1) increased stiffness (decreased compliance) of lungs & increased work of breathing
2) hypoxemia & increased drive (bc of V/Q mismatch & destruction of alveolar-capillary interface)
Diseases of the left heart result in:
1) Greater LV end-diastolic volume & pressure, which
2) Increased pulmonary capillary pressures, which lead to
3) Interstitial edema, which
4) Stimulates pulmonary receptors, causing
5) Dyspnea!
Examples of diseases of the pulmonary vasculature
1) PE
2) primary pulmonary hypertension
3) pulmonary vasculitis
Diseases of pulmonary vasculature result in:
1) Increased pulmonary artery pressure
2) Stimulation of pulmonary receptors
3) Hyperventilation & hypoxemia are common & not affected by supplemental O2
Diseases of the pericardium result in what effect on the lungs?
1) Increased intracardiac pressure leads to
2) Increased pulmonary vascular pressure, causing
3) Dyspnea! Surprise!
What is a good way to distinguish cardiac dyspnea from respiratory-based dyspnea?
Exercise stress test.
Respiratory cause: patient achieves max ventilation, demonstrates increase in hypoxemia or dead space, or develops bronchospasm
Cardiac cause: HR > 85% of predicted max, anaerobic threshold occurs early, BP excessively high or low, O2 pulse falls, or ischemic changes on ECG
Common Causes of Noncardiogenic Pulmonary Edema: Direct Injury to Lung Edition!
1) Chest trauma, pulmonary contusion
2) Aspiration
3) Smoke inhalation
4) Pneumonia
5) O2 toxicity
6) Pulmonary embolism/reperfusion
Common Causes of Noncardiogenic Pulmonary Edema:
Hematogenous Injury to Lung Edition!
1) Sepsis
2) Pancreatitis
3) Non-thoracic trauma
4) Leukoagglutination reactions
5) Multiple transfusions
6) IV drug use (just say no, kids!)
7) Cardiopulmonary bypass
Common Causes of Noncardiogenic Pulmonary Edema:
Possible Lung Injury Plus Elevated Hydrostatic Pressures Edition!
1) High-altitude pulmonary edema
2) Neurogenic pulmonary edema
3) Re-expansion pulmonary edema
