I think that this is a real possibility. Getting an arterial blood gas test for first episode bipolar patients would answer this question. Mild suffocation caused by hypercapnic respiratory failure would explain the distress and anguish described by such patients and would explain the mental fog they experience and the lethargy and psychomotor retardation.
CNS injury/defects interfering with motor mechanisms needed for the normal exchange of air in and out of the body , especially during periods of increased metabolism – due to infection, blood loss, internal bleeding and/or injury – could overwhelm a compromised ventilatory system. And cause episodes of hypercapnic respiratory failure and alveolar hypoventilation.
The patient will feel the effects of respiratory failure but be unaware of having an episode of respiratory failure.
It would be up to the doctor to think of this diagnosis and to test for it.
This should be something that every doctor and psychiatrist should be aware of.
Stereotypic behavior change is common in toxicology and difficulties breathing air, even if lungs are entirely normal, can result in the kind of changes seen in delirium and in bipolar illness [an extended delirium] which is invisible unless arterial blood gas studies are done.
We need to understand a lot more about carbon dioxide retention and acid base changes affecting the blood and the tissues, especially the tissues of the blood. Understanding the nuances of the motor act of breathing in respiratory acidosis and respiratory alkalosis is the future of psychiatry and the key to effective treatment for manic depressive insanity.