Normal brain function [and that of the mind] requires the ability to move air in and out of the body. Moving air in and out in correct ratio’s and amounts requires the work of ordinary skeletal muscles. “Muscle fiber atrophy and weakness that occurs in respiratory muscles along with systemic skeletal muscle with age is known as respiratory sarcopenia” It can happen at any age as a result of illness, malnutrition, neuromuscular conditions or traumatic [ physical ] injury ...[and thus affect minute ventilation at any age]. Nagano, A., Wakabayashi, H., Maeda, K. et al. Respiratory Sarcopenia and Sarcopenic Respiratory Disability: Concepts, Diagnosis, and Treatment. J Nutr Health Aging25, 507–515 (2021). https://doi.org/10.1007/s12603-021-1587-5
Skeletal muscle, as well as the lungs are key to the complex motor act of breathing. The complex motor act of breathing is key to the function of the brain and to the function of mind, we think. Not breathing normally due to acute or gradual skeletal muscle weakness is not hard to detect if the baseline respiratory rate at rest is carefully measured. That is why measuring respiratory rate[ at rest] many times to establish a baseline rate and pattern at rest is so important. Because by measuring respiratory rate and pattern you are taking a major step in establishing the strength of the respiratory skeletal muscles. The average rate of breathing is 12-18 breaths per minute. Rates below 8 breaths per minute or higher then 20 should be investigated further, especially if accompanied by changes in locomotor behaviour and changes in mood [inadequate breathing causes major anxiety and distress, while it is occurring] , and the person cannot know that their minute ventilation is abnormal, so if respiratory rate is abnormal then minute ventilation must be evaluated by a health provider, as it is a physical sign.] . Other posts have already explained the noninvasive measurement of minute ventilation.
Acute onset of abnormal mood [depression, dysphoric mood, anguish, distress, anxiety, euphoria, irritability, combativeness ] accompanied by psychomotor retardation or psychomotor excitement [or the locomotor subtypes of delirium] must be taken seriously even if the patient cannot tell you what to look for and even if psychological distress is obvious. The presence of what you may think of as psychological distress does not tell you whether or not there is a number of hidden physical and mechanical stressors. Damage to the brain is very unpleasant and likely to present as immense distress. Damage to the brain in depression, bipolar illness and psychosis, is what is now seen when imaging is done now that we have new and improved technology.
The immediate protocol for depression, bipolar depression, mania, psychosis, delirium [all locomotor subtypes] and dementia should be to check for pathophysiology by checking the basic baseline vital signs to see if anything physiological is obviously amiss. Measurement is key in scientific investigation. The 4 main vital signs are basic indicators of physiology and possible pathophysiology.
Respiratory rate is easy to check manually and reliably; but not the way doctors and nurses currently do it. Skeletal muscle weakness will make abnormal respiratory patterns hard to detect because often the patient will not show any respiratory distress or shortness of breath even though they may be experiencing both without realizing what the cause is.
Simply tell the patient to lie down with eyes open so you can watch them breath for a full minute , using a stopwatch, while they relax a minute. This is a very reliable way to count the respiratory rate, especially in someone who is not taking any medication. a stopwatch helps with precision, especially if the respiratory rate is too slow or fast or chaotic [ Cheynes Stokes].. When the person lies down it is easier to see if they use any accessory muscles, especially abdominal muscles.
When Paula had recovered, we measured Paula’s respiratory rate this way and always got the same result. We checked our result with a respiratory plethysmograph [embedded in a Hexoskin smart shirt] and got the same result. Lying down, it was obvious that she used her abdominal muscles to actively exhale and squeeze air out in order to help increase her tidal volume. Both inhaling and exhaling took a lot of work and this was abnormal.
Later on we got spirometry tests [which showed that her tidal volume was better than normal] and we were able to get her minute ventilation. When well, her minute ventilation was adequate [said the doctor] adequate enough to support normal brain function and circulation, pH and body temperature. Paula increased tidal volume instead of respiratory rate at rest and increased both during exercise [her respiratory rate increased sluggishly though. So Paula relies a lot on her strong tidal volume and would run into difficulty if she had problems with her upper airway or her lungs or if she had an illness/injury related episode of further sarcopenia affecting her already damaged respiratory muscles. At least we suspect that she has sustained injury and weakness affecting some of her respiratory muscles during her birth. [she was born asphyxiated and not breathing and required medical intervention to recover]. In health, Paula’s blood pressure, heart rate and body temperature were normal, despite her depressed breathing rate.
We also measured Paula’s respiratory rate when she was ill and looked depressed, her baseline respiratory rate at rest did not change, in fact it declined very slightly, and the rest of her vital signs became extremely abnormal in response. This was 20 years ago and no one would help us then; doctors did not listen and were not interested in anything but her “psychological” depression so we stopped telling them.
Twenty years later, we understand a lot more about the importance of the skeletal muscles in the complex motor act of breathing, even when the lungs are fine [as they are in Paula]. We understand that because of her ventilatory defect and inability to increase her breathing rate normally during a homeostatic crisis, that Paula is more at risk for ventilatory failure and increased levels of hypercapnia.
Respiratory acidosis or alkalosis will result when normal respiratory skeletal reflexes are overwhelmed by disease of injury, and will occur more frequently if the muscles have already been weakened during on’e life.
This explains the level of mental confusion experienced by Paula when this happened to her 20 years ago, she experienced partial amnesia .