This was a simple suggestion made by Dr Arthur Guyton , to explain depressed resting respiration rates. in Medical Physiology by Arthur C Guyton , currently revised with the help of Dr John E. Hall.
This makes sense. Perhaps this is the nature of the damage to the networks communicating from the brain to skeletal muscles and sensors of the neck and torso and back again.
Axon dysfunction has caused many inherited and acquired neurological disorders which can affect both the peripheral and central neurons. Nerve fibers are classed into three types – group A nerve fibers, group B nerve fibers, and group C nerve fibers. Groups A and B are myelinated, and group C are unmyelinated. These groups include both sensory fibers and motor fibers. Another classification groups only the sensory fibers as Type I, Type II, Type III, and Type IV. {Wikipedia June 22 2021]
No one today seems aware that the ventilatory motor system of breathing can be damaged permanently in a non progressive manner, making respiratory acid base control more difficult.
Dr Guyton’s description of dyspnea as a mental anguish associated with inability to ventilate . is exactly what Paula experienced during her yearlong “depressive” episode. She was unable to describe the nature of her anguish and was only unremittingly and vaguely aware of her inability to ventilate during her attack of what seems to have been a kind of [hidden] respiratory failure.
Dr Guyton would have first hand knowledge of this kind of despair, he survived a bout of polio during his life.He understood suffering intimately.
This is why it is key to rule out insidious respiratory failure [with or without normal oxygenation as shown by pulse oximetry] by making sure that respiratory rate is within the norm, does not involve active exhaling or other kinds of effortful ventilation and can respond in the usual way to exercise and respiratory challenges and weakness due to having been sick from the flu or any other illness which causes loss of appetite, undernutrition and dehydration and muscle wasting.
Especially if a person suddenly experiences an altercation in their mental status, mood and/or locomotor activity and speed.
Measuring vital signs [respiratory rate will be the most sensitive to acute deterioration of any kind, including deterioration of function of the mind and the brain] is easy to do [in a focused, mindful accurate way] and it is the least we can do to avoid misdiagnosis of a condition that may be more common than we know.
Of Sound Mind 