What is Obesity Hypoventilation Syndrome?
When people imagine obstructive sleep apnea, they tend to think of it as represented by the infamous “fat boy” Joe (pictured left), a character in Charles Dickens’ The Posthumous Papers of the Pickwick Club. Joe was known for falling asleep during the day and choking in his sleep at night.
The assumption is reasonable. It’s widely believed that the Dickens character was probably the first recorded observation of a sleep breathing disorder (well before such conditions were actually identified and diagnosed by physicians). However, Joe more likely suffered from obesity hypoventilation syndrome (OHS), a specific kind of sleep disorder related to obesity, with sleep apnea as a secondary problem.
What’s the difference between OHS and sleep apnea?
Also known as Pickwickian Syndrome, OHS occurs when obesity leads to poor breathing mechanics.
OHS is a condition which affects the sufferer at all hours of day, not only at night. The result of OHS is too much carbon dioxide (hypoventilation) and too low a concentration of oxygen (hypoxemia) in the bloodstream. When these occur, the body generates inflammation and stress hormones surge in order to correct the imbalance.
Untreated OHS leads to a multitude of other chronic and dangerous health problems. These include type 2 diabetes, pulmonary hypertension, swollen ankles, a heart condition known as cor pulmonale, and secondary erythrocytosis (red blood cell overproduction which leads to concerns about bruising, bleeding, and clotting).
OHS and sleep apnea
People with OHS frequently develop obstructive sleep apnea (OSA) as well. This can greatly aggravate their already precarious health situation.
When you are awake and you suffer from hypoventilation and hypoxemia, you are able to voluntarily alter your breathing patterns to adjust these imbalances. However, while asleep, your respiratory function relies on the brain to manage breathing. Because OHS is a 24-hour condition, those bloodstream imbalances in carbon dioxide and oxygen are ever present, making sleep difficult. Excessive daytime sleepiness is one symptom of OHS, as a result of fragmented sleep caused by this condition.
Sleeping only makes things worse for those who are obese. The added weight around the neck and fluid retained in the tissues causes apneas—pauses in breathing that last more than 10 seconds. Even in healthy individuals, apneas also lead to problems with hypoventilation and hypoxemia. For someone with OHS, apnea further worsens their respiratory outcomes.
Obesity is not the only cause of sleep apnea
Another distinction between OHS and OSA is less obvious: while people who have OHS are more likely to develop OSA, people with OSA do not have to be obese to suffer from sleep apnea.
In fact, this is one of the greatest misunderstandings among patients suspected of having OSA. If they don’t believe they fit the image of Pickwickian Joe, how is it possible that they could have OSA?
The answer is simple: OSA occurs in people of all ages, genders, and BMI measurements.
Denial among thin, otherwise healthy people who still suffer from OSA complicates treatment. Why? These patients may find it harder to be compliant to therapy if they don’t believe they actually have a sleep breathing disorder, even if a sleep study objectively proves so otherwise.
3 links related to OHS in SleepyHeadCentral
- What happens when school kids don’t get enough quality sleep? (Aug 8, 2017)
- Sleep Hygiene Tip of the Week: Follow your heart (Feb 15, 2016)
- Just Breathe || Sleep Breathing Disorder basics (Apr 4, 2015)