Apnea, hypoventilation and pulmonary hypertension: Pathology review

Joseph, a 42 year old man comes to the clinic because he’s been waking up many times at night, which makes him very sleepy during the day.

His partner also complains that Joseph has always snored but recently it’s louder than ever.

On physical examination he has a BMI of 35 kilograms per square meter, and has a blood pressure of 140 over 90 millimeters of mercury.

You decide to conduct a sleep study, which reveals a very low partial pressure of oxygen.

Later, a 35 year old woman called Robin also comes to the clinic.

She tells you that, lately, she’s been experiencing shortness of breath and fatigue.

Robin is quite worried, and mentions that she has a congenital heart defect.

On physical examination, she has a mean pulmonary arterial pressure of 28 millimeters of mercury.

You decide to perform an electrocardiogram or ECG test, and a chest X-ray, which show that Robin has right ventricular hypertrophy.

Based on the presentation, both cases seem to have some respiratory disease, associated with some cardiovascular issues.

Now, for your exams, some important conditions include sleep apnea, obesity hypoventilation syndrome, and pulmonary hypertension.

So, let’s begin with sleep apnea!

This is when a person, during their sleep, experiences recurrent and intermittent episodes in which they stop breathing for more than 10 seconds.

In addition, since fresh air is not getting into the lungs, individuals with sleep apnea will have nocturnal hypoxia.

This puts the body under stress, which in turn responds by releasing epinephrine.

Now, the recurrent epinephrine surges have several effects.

Firstly, this wakes up the person so that they can breathe again.

This causes disrupted sleep, which in turn leads to somnolence or sleepiness during the day or while awake.

Secondly, the body tries to compensate for the hypoxia by increasing the amount of red blood cells, or erythrocytes, available to carry the oxygen in blood to our tissues.