Hidden Neurological Injury and Reduced Quality of life after Surgery or after Intubation

Dear Researchers,

I wanted to suggest that you think of the possible hidden neural complications in survivors of Covid 19 after life saving procedures.

I would like to have you think about possible damage to the peripheral nervous system causing acquired control of breathing problems, resulting in ongoing depressive mood and anxiety. This is common  after acute respiratory failure and treatment , in any condition involving intubation, including heart surgery and covid-19.   

There is a lot of research being done on quiet delirium after heart surgery. I think that quiet delirium after surgery [ which the patient is unable to recognize or communicate because of their mental anguish and silent mental confusion] ,   may be due to hidden hypercapnia- an insidious type of respiratory failure.  

Hypercapnia can occur , even with normal 02 and HC03.  Carbon dioxide is a normal product of cellular respiration and metabolism and needs to be exhaled in the proper ratio’s. The brain stem and the autonomic nervous system are used to dealing with endogenous C02 and acid base balance.  

Measuring baseline respiratory rate before and after surgery [without medication  if possible – medication changes breathing] can suggest the need for arterial blood gas tests, especially if the patient is not themselves.  Abnormal breathing at rest can suggest the need for an arterial blood gas test in mentally confused patients.  Arterial blood gases are invasive and it is hard to get serial measurements, so abnormal respiratory rates along with mental anguish and confusion would help predict when they are necessary.
Even mild Hypercapnia can cause huge anxiety and distress…and maybe even intoxication [dysphoria, euphoria, restlessness, irritability, cognitive impairment] and often does not progress to death, only disability and lower quality of life.  

 Luckily the effects of carbon dioxide imbalance in the blood are completely reversible; but only if the patient gets noninvasive respiratory supports [eg. removal of secretions, , other pulmonary rehabilitation, bronchodilators to open the airways, antibiotics for secondary hidden infection and possible a non invasive machine to reduce the work of breathing.]
These measures will surely reduce delirium [quiet, wild and mixed] in post intubation and post surgery most patients with invisible and unsuspected trouble moving air in and out of their bodies.

This hypothesis is easy to test, and if true  –  would cut health care costs for these patients by a lot, I predict and would improve their lives..

A life saving procedure may occur any time in the life of the individual, potentially causing peripheral nervous system damage, affecting breathing rate and depth at rest.

It is because of my friend and co-worker Paula that we became interested in the complex motor control of breathing and mechanical problems with this system and PC02.

We think that Paula’s [hidden] too slow respiratory rate might relate to the patients described in studies suggesting persistent neurological problems in some of the more seriously ill covid 19 survivors.   Respiratory failure that goes unrecognized looks very similar to depression and involves a lot of anxiety; the person cannot breath and does not know it and it is not visible except by measuring respiratory rate and then obtaining PCO2 measure by arterial blood gas. Pulse oximetry will not pick this up. O2 is often perfectly normal [or not]. This tool is sensitive for hypoxia not hypercapnia.

We discuss what happened to Paula and what we learned over the past 25 years since she learnt about her own abnormal baseline breathing. She had no idea and was profoundly shocked. In our blog we cite research on hypercapnia, the importance of CO2 as a cerebral vasodilator, and the brain stem’s importance to consciousness states and production of mind.and lots more.

Paula found out , accidentally, in her 40th  year, that she had a very slow breathing rate at rest , when healthy and fit.  She found out that she feels no respiratory distress in health or in illness. We figure that  those nerve fibres in throat and torso are fried.

We also found out that, the few times she has been quite physically ill, her breathing became even slower…. not faster as would be normal; so she is at risk for hidden respiratory failure with hypercapnia.  Only an arterial blood gas can tell you the PC02 levels in the blood.  [her 02 and HC03 are normal – her lungs are normal] .
see Respiratory Failure, by  C. Roussous,   Lung and Critical Care Doctor and clinical Researcher.

Acquired injury  to nerves and sensors affecting the neural control of breathing seems to be the problem. We think that this kind of acquired injury can happen any time during life, especially after any intubation and life saving intervention. These peripheral nervous system injuries make it harder to breathe in or out without a lot of effort. This effort is NOT visible to the eye. 

The person accommodates and this becomes their new normal, of which they will be unaware.   I also think that respiratory rate and pattern is involuntary and unconscious, it is set by the brain stem…..no one feels their own respiratory rate and pattern at rest….it just feels normal even when it is far from normal, like that of Paula’s.

The explanation for Paula’s too slow baseline, is in her birth history ; we discovered this by talking to her much older [lol] brother,. My friend Paula was born not breathing…… [she got stuck in birth canal-made crooked by poverty- related Rickets in mother] and was successfully resuscitated and transfused and thrived from then till now. Her then nine year old brother and the entire family were waiting [she was born in Paris in a modern 1955 clinic] by the phone [on pins and needles] to see if the newborn [Paula] would live or die.

Paula survived so well and met all her milestones so perfectly, her Mom never even worried about the toddler’s long term outcome. It was clear that she was average or above, in all ways.

It is a inspiring story, really. And a forgotten story, since she only found out when she asked about her birth history after finding out about her slow breathing in health. She was so normal her family kind of forgot about her rough entry into the world.

A real triumph of modern paediatrics!


Endotracheal intubation to resuscitate neonates was used by Scheel in 1798. A century before endotracheal anesthesia was developed, inventive obstetricians constructed devices for endotracheal intubation of infants and mastered their insertion, localization, and airtight sealing. Fell’s laryngoscope, Magill’s intubation forceps and tissue-friendly materials were significant contributions of the 20th century to endotracheal intubation of the newborn. The striking absence of scientific studies on the most efficient resuscitation techniques for neonates can be explained by the difficulty to adjust for the personal skills of the resuscitator.

History of neonatal resuscitation – part 3: endotracheal intubation Obladen M1.

Paula is not the only healthy person to have abnormal breathing rate at rest when awake.  Studies done in the 1940’s showed that, in healthy adults, there was a wide range of respiratory rates- from as low as 5 breathes per minute to 28 breathes per minute-  in healthy adults. The brain stem co-ordinates tidal volume in order to circulate enough air to manage the ratio’s of carbon dioxide in the blood and thus primary acid base balance.  this is all automatic and unconscious and co-ordinated with body temperature and the other vital signs.

Still,  breathing rates at rest at either extreme  too slow, too fast] will  complicate things a lot for the brain stem, especially during and after any physical illness or surgical procedure.
Doctors seem never to measure minute volume or respiratory rate, so abnormal control of breathing is almost never diagnosed, yet the patient might need help breathing and clearing the airway from time to time.  This is basic first aid, which is not part of the tradition of medicine:  

Basic First Aid is helpful in identifying medical emergencies. It is easy and fast   

1] check airway   [for obstruction including secretions] 

2]  measure breathing rate at rest [takes a stop watch and one minute]  and 

3] check the circulation  [is the patient grey, are the hands, feet, and lips pale, cold, even blue?  Is there vasoconstriction? 

Doctors never do this, in my experience, and so miss potentially treatable medical emergencies.


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