The LEARN and TEACH series of High Altitude Medicine
Case # 5233

We presume that this case report has disoriented our colleagues, because one of the questions was: Do you think this is a case of CMS ?. 

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Our comments follow below:

1) Ask yourself if this first chest x-rays shows you something important that justifies the increased hematocrit. 

There is a notorious dome elevation of the right hemidiaphragm. This may suggest hypoventilation in the right lung.

2) Do you think that the increased polycythemia will increase with aging or disease progression ? 

This is one possibility, however time has shown that it was not true. Also, aging in this case did not change significantly the increased polycythemia in twenty four years of residence in the city of La Paz 3510 m.

3) If you think the hematocrit will not increase, then try to explain why not.

Even though there is a gradually evolving ventilatory insufficiency of the right lung and vital capacity is reduced, there is ventilatory compensation in the left lung. 


Oxygen saturation changes and breath-holding (screen1),(screen2),(screen3), 

The breath holding time was 1 min 50 sec . Any comments ? 

The first screen shows an average SaO2 of 90 % (a normal value for this altitude is around 92%) with and ETCO2 of 27 mmHg (normal 30 mmHg for this altitude), which is explained by a temporary hyperventilation of the subject during the breath holding test. 

On the second screen a long breath holding time is observed (1 min 50 sec) because there is no CO2 retention, and slight hyperventilation during the test resulting in a post breath holding ETCO2 of 35 mmHg with CO2 retention which triggers rebreathing. Note that he is able to tolerate a SaO2 of 78% at the end of the breath holding.


The spirometry showed a reduced forced vital capacity of 53%, which confirms that during inspiration while the left hemidiaphagm goes down the right side goes up, due to paralysis. Unfortunately we were unable to measure ventilation and other ventilatory parameters in each lung independently. 


4) What is your diagnostic impression and what should be done ? 

There is a right lung hypoventilation secondary to right hemidiaphragmatic paralysis which is pushed up by the liver, with no resistance. An abdominal sonography showed no abnormalities in the liver.

5) Do you think this is a case of CMS ? 

This case is useful to analyze because it allows us to show that Chronic Mountain Sickness until now is not precisely defined since increased polycythemia is a common sign of many respiratory, cardiac or renal disease of different ethiopathogenesis. In this particular case, CMS is definitely due to right diaphragm paralysis in chronic hypoxic conditions.


According to our previous concept: all disease at high altitude is similar to that at sea level in ethiopathogenesis and evolution, but with a hypoxic physiognomy. In the present case the subject had a right side hemidiaphragmatic paralysis, that can also present at sea level, where comparatively hypoventilation with reduction of the ventilatory function does not necessarily lead to increased polycythemia, although there is dyspnea on effort. This due to the fact that the inspired oxygen tension (at sea level) is more than enough for an adequate saturation of hemoglobin at rest. In this case, hypoventilation progresses over a long period of time, decreasing ventilation in the right lung, but at the same time compensating by increasing ventilation in the left lung gradually however not completely (SaO2 = 84%) in order to achieve the normal saturation of blood which is 92 % at 3510 m.

As can be observed in the first chest x-rays there is an abnormal elevation of the right diaphragm with a descent of the left diaphragm and shift of the heart and the mediastinum to the left. The patient has suffered this alteration for over 24 years with moderate increased polycythemia (Ht = 65%; Hb = 21.7 mg%), that has not increased significantly and if conditions don’t change we presume that in the future they will remain static 

At present this mathematician is active for his age (76 years old), slightly cyanotic and with his exercise capacity reduced. He is performing respiratory exercises regularly, since that was the only possible treatment.


DIAGNOSIS: Idiopathic paralysis of the right hemidiaphragm at 3510 m in chronic hypoxia.

Any further comments or suggestions are welcome.


Prof. Dr. Gustavo Zubieta-Castillo (Sr)  & Dr. Gustavo Zubieta-Calleja

High Altitude Pathology Institute (IPPA)

We recently received Prof. Nakashima's comments which were:

Dear Drs.Gustavo-Zubieta Sr.and Jr.

This case is extraordinaly for me, the resident of sea level. I can not

diagnose this polycythemia is abnornal in La Paz or it comes or not from
aging or disease.
However, I would like to try to answer the questions.
1) The first chest film: It had seen already the elevation of right
diaphragm with fine scattered opacities in under field of right lung.
    Maybe, it is a sign of the begining of the paralysis of r.N.phrenics .
2) 3) I can not answer these questions because of luck of expeerience.

4) Paralysis of  right side N.phrenics with unknown cause. I do not think

chronic hypoxia concered with this. If so, not only N.phrenics but all sort
of paralysis might be more populer among high altitude rersidents.
5) I do not think so, though I have never seen CMS patients. He might be a
usual healthy man in La Paz and not a patient.

Michiro Nakashima, MD, JAPAN

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