Dyspnea

Question 1

What’s thought to be responsible for generation of dyspnea?

Answer 1

Several sensory receptors located throughout the respiratory system (Afferent information from the sensory receptors is processed at the cortex along with the
respiratory motor command from the cortex and brainstem)

Question 2

Chemoreceptors:

Answer 2

the induction of hypercapnia or severe hypoxemia causes dyspnea (possibly)

Question 3

Chest wall mechanoreceptors:

Answer 3

Innervated by the anterior horn cells of the spinal motor neurons

Project to the somatosensory cortex

Question 4

Metaboreceptors:

Answer 4

Located in skeletal muscle

A source of afferent neurological signals that lead to a perception of dyspnea during exercise even without hypoxemia and hypercapnia

Question 5

Vagal receptors:

Answer 5

In lung parenchyma:
Slowly adapting stretch receptors (SARs)
Rapidly adapting stretch receptors (RARs)
C-fiber receptors

Question 6

SARS correspond to

Answer 6

the myelinated afferent nerve fibers in the vagus (furosemide can improve)

Question 7

Rapidly adapting stretch receptors known as

Answer 7

irritant receptors (adapt to maintain inflation or deflation of lungs); pneumothorax can stimulate

Question 8

A strong stimulator of c-fiber receptors is

Answer 8

pulmonary congestion (increased interstitial fluid outside the capillaries)

Question 9

Respiration is

Answer 9

1. A controller, which determines the rate and depth of breathing
2. A ventilatory pump, which facilitates the movement of gas into and out of the alveolus (increase 1 and 2, increased respiratory drive)
3. A gas exchanger, which consists of the pulmonary vasculature and the alveolus (responsible for increased effort or work of breathing)

Question 10

Chemoreceptor stim:

Answer 10

1. Conditions leading to acute hypoxemia
   Impaired gas exchanger (e.g., asthma, pulmonary embolism, pneumonia, congestive heart failure)
   Environmental hypoxia (e.g., altitude, contained space with fire)
2. Conditions leading to increased dead space and/or acute hypercapnia
   Impaired gas exchanger (e.g., acute severe asthma, exacerbations of COPD, severe pulmonary edema)
   Impaired ventilatory pump (e.g., muscle weakness like ALS, airflow obstruction)
3. Metabolic Acidosis
   Renal disease (renal failure, renal tubular acidosis)
4. Decreased oxygen carrying capacity (e.g., anemia)
5. Decreased release of oxygen to tissues (e.g., hemoglobinopathy)
6. Decreased cardiac output

Question 11

Other factors contributing to dyspnea:

Answer 11

behavioral factors, muscle weakness, decreased compliance of the chest wall, airflow obstruction

Question 12

Dyspnea may be due to diseases

Answer 12

in virtually any organ system, whether caused by interference with breathing, increased demand for breathing, or weakening of the respiratory pump. In most cases, however, one is dealing with a disorder of the respiratory or cardiovascular system

Question 13

Diagnosis of dyspnea requires

Answer 13

a comprehensive history, detailed physical examination, laboratory testing and diagnostic tests. Cardiopulmonary exercise testing may be particularly useful when a patient has concomitant cardiopulmonary diseases or when cardiovascular deconditioning is suspected

Question 14

Orthopnea; platynea:

Answer 14

Dyspnea in the recumbent position (diaphragm problems, LV failure);
Dyspnea that worsens in the upright position (orthodeoxia, or decrease in arterial O2 pressure in upright position, like cirrhosis, pulmonary AV malformation, interatrial shunts)

Question 15

For physical exam:

Answer 15

Consider walking the patient in a corridor near the examination room to elicit his or her symptoms.

When dyspnea occurs, observe the patient, repeat the vital signs, reexamine the chest and heart, and check the oxygen saturation with pulse oximetry.

Question 16

When the cause is not obvious,

Answer 16

a series of studies analyzing cardiopulmonary function at rest and with exercise usually uncovers a specific diagnosis;

Sophisticated studies of the heart, pulmonary vascular bed, lung parenchyma, and even esophagus may be necessary.

Question 17

A combination of; but in far-advanced disease,

Answer 17

education, exercise training, oxygen, and muscle strengthening aids most patients (moee);
compassion may require the use of agents that directly blunt the sensation even though they may shorten life (think an opiate).