Student:  The Airways are connected to the Pulmonary Stretch Receptors that are connected to the Vagal Nerves. Then they are connected to what next?

Professor:  Before we get to the your intriguing question, let’s consider all the ‘inputs’:

• Airway smooth muscle
• Diaphragm skeletal muscle
• Chest wall skeletal muscle
• Lung airways and tissue

Shown below are two models for dyspnea; the left is Davenport (2007) and the right is Weiser, Mahler, et al. (1993). The bottom of BOTH diagrams displays the lung inputs that can become the signals for uncomfortable breathing:

Student: BOTH models’ bottom loops are almost IDENTICAL.

Professor: And in another review, Davenport & Vovk (2009) show a similar diagram, which we will see shortly. And in it, they show an earlier structural model that is hierarchical and is divided into three levels:

• Cortical Processing,
• Sub-cortical Central Nervous Processing, and
• Sensory Signal Transduction.

Click link to read more

Student: Is the “Clustering of Dyspnea Symptoms” done statistically or phenomenologically?

Professor: Both!

According to Lansing, Gracely, and Banzett (2009),

“There are at least three separable ‘qualities’ of uncomfortable breathing sensations”:

• ‘Work’,
• ‘Air hunger’, and
• ‘Tightness’.

“The division into different kinds of sensation classification is not based on perceptual quality alone. To be classed as distinct, the perception must have a different afferent source; this is most easily demonstrated by applying stimulus combinations that excite different afferents demonstrating that the sensations can vary independently.”

Sense of Work / Effort
Student: I can sense that this is like, “Breathing is hard work.” Or, “I am huffing and puffing to get up this hill.”

Click here to read more

Student: A lot of dust on this Dyspnea diagram. Where did you get it?

Professor: The schematic diagram I got from a very old backup disk of manuscripts written in the early 1990s. Notice that the diagram is an attempt to place uncomfortable subjective qualities, i.e., symptoms, for breathing into a hierarchy as shown below:

Dyspnea Model 1992

Student: Hmm. From the top down, the hierarchy seems to be:

• Conceptual Symptom of BREATHING DISCOMFORT (“Dyspnea”)
• Subconceptual Symptom of INSCREASED BREATHING WORK (“Breathing Effort”)
• Discrete Symptom of  VENTILITORY MUSCLE TENSION (“Breathing Deep”)

Click here to read more

Student: Mile high Denver! You were there from 1968 to 1981.

Professor: Yes, I was assigned to the Nut Lab, that is, to the US Army Medical and Nutrition Laboratory. That’s near where Eisenhower went and did his cardiac rehabilitation.

From: http://www.endurance-education.com/

Click here to read more