Respiratory Sensations and Dyspnea

Question 1

Many inputs to the respiratory controller that increase the drive to breathe are also associated with ___.

Answer 1

Many inputs to the respiratory controller that increase the drive to breathe are also associated with dyspnea

Question 2

Types of stimulation associated with dyspnea

Answer 2

1. Chemoreceptor stimulation (hypoxia, hypercapnia, abnormal pH)
2. Stimulation of pulmonary receptors (stretch receptors, irritant receptors, pulmonary vascular receptors)
3. Acute bronchoconstriction (patients report “chest tightness”)
4. Acute pulmonary edema (feeling of “suffocating”)

Question 3

Sensations that accompany increases in the drive to breathe are often described as. . .

Answer 3

“air hunger,” “need for more air”, “can’t get enough air”

Question 4

Things that may trigger irritant receptors

Answer 4

inflammation, inhalation of toxic substances

Question 5

Things that trigger pulmonary vascular receptors

Answer 5

acute increases in pulmonary vascular pressure

Question 6

Differential for increased work of breathing

Answer 6

• Muscle weakness (may be myogenic or neurogenic)
• Reduced compliance of lungs and/or chest wall
• Increased airway resistance
• Hyperinflation
• Tachypnea secondary to acidemia, hypoxia, etc.
• Ventilation/perfusion mismatch

Question 7

Dynamic hyperinflation

Answer 7

The increase in end expiratory volume with increasing ventilation in patients with increased expiratory airway resistance. Associated with flow limitation and elevated end expiratory volume. May produce a sensation of “not able to get a deep breath” as the inspiratory capacity progressively gets smaller.

Question 8

The sensation of air hunger seems to arise from. . .

Answer 8

. . . direct communication between the chemoreceptors and sensory cortex.

Question 9

Corollary discharge

Answer 9

When a signal is sent to muscles to have them fire, a corollary discharge message is also sent to the sensory cortex. This helps the sensory cortex ‘monitor’ the activity of the motor cortex.

Question 10

Inhalation of ___ relieves the feeling of shortness of breath, without really improving empirical symptoms.

Answer 10

Inhalation of lidocaine relieves the feeling of shortness of breath, without really improving empirical symptoms.

Question 11

____ contributes to the feeling of burning reported by many acute bronchitis patients.

Answer 11

Stimulation of C fibres and rapidly adapting receptors (RARs) contributes to the feeling of burning reported by many acute bronchitis patients.

Question 12

‘reafferent’

Answer 12

Afferent signals that are sent in response to efferent signals.

Question 13

Efferent-reafferent dissociation

Answer 13

Mismatch between incoming and outgoing signals may result in air hunger and increased work-of-breathing.

Question 14

Voluntary hyperpnea is . . .

Answer 14

. . . not associated with the same sensation of dyspnea as that from hyperventilation initiated by the central or peripheral chemoreceptors. It does not generate a corollary discharge

Question 15

Physiological sources of resiratory symptoms (table)

Answer 15

Question 16

Dyspnea

Answer 16

Describes the feeling of breathing discomfort

Question 17

Pulsus paradoxus

Answer 17

<10 mmHg in a healthy patient

Question 18

People with ___ are the people who will have abnormally increased pulsus paradoxus.

Answer 18

People with abnormally high airway resistance or cardiac tamponade are the people who will have abnormally increased pulsus paradoxus.

Question 19

Pulsus paradoxus physiology diagram

Answer 19

Question 20

___ may cause lung diffusion to appear worse than it really is on a diffusion test.

Answer 20

Anemia may cause lung diffusion to appear worse than it really is on a diffusion test.