The human airway allows for speaking, swallowing, and breathing. They are made up of muscles and soft tissues and do not contain any bony structure that allows them to be flexible. When this passageway collapses during sleep, it could be due to a loss of muscle tone or a framework defect, such as a buildup of fat around the tongue or soft palate. This causes the person to suffocate during sleep.
Obstructive sleep apnea (OSA) is a feeling of suffocation that occurs when lack of oxygen causes the body to repeatedly wake up and gasp to open the airways. This is a protection mechanism.
How does having OSA cause hypertension?
Many researchers have identified sleep apnea as a factor in high blood pressure. When there are low levels of oxygen in the body, the autonomic nervous and hormonal systems that are responsible for controlling BP are activated. Blood vessels begin to narrow and other bodily changes occur, leading to high blood pressure.
Nearly half of OSA patients develop hypertension. This link is so strong that it led the National Joint Committee on High Blood Pressure to cite sleep apnea as a cause of secondary hypertension.
Empirical evidence linking OSA with hypertension
A study published in the New England Journal of Medicine found that middle-aged adults who did not receive treatment for obstructive sleep apnea had a 2 to 3 times increased risk of developing high blood pressure over an 8-year period.
A Canadian study found that for every sleep apnea episode that occurred per hour, the chance of developing high blood pressure also increased by 1%. Furthermore, for every ten percent drop in oxygen levels overnight, the percentage of hypertension increased by 13%. Additionally, this Sleep Heart Health Study found that in severe cases of OSA, both systolic and diastolic blood pressure readings were higher, and consequently, nighttime blood pressure. The increase in high BP was proportional to the severity and presence of OSA. These individuals also had higher blood pressure levels during the day.
How does OSA treatment reduce the risk of developing hypertension?
The use of continuous positive airway pressure to treat OSA has a positive effect in reducing the risk of developing hypertension. In CPAP therapy, gentle streams of air are pumped into the airways, preventing them from collapsing during sleep. Many research studies have shown that people with moderate to severe sleep apnea who are treated with nasal CPAP had lower blood pressure readings during the day and at night.
In a multi-center HIPARCO trial study, patients with OSA and arterial hypertension unresponsive to conventional therapy received CPAP therapy for 12 weeks. This caused a reduction in diastolic blood pressure and in the 24-hour mean. It also improved blood pressure patterns at night. A 4-hour use of the CPAP machine each night is required to achieve a significant decrease in BP levels.
What are the benefits of using CPAP in hypertension?
The use of CPAP leads to a reduction in BP in all patients, regardless of whether they are using antihypertensive drugs. Patients who refuse CPAP and are offered supplemental oxygen instead do not experience the same benefits as those who use CPAP.
The use of CPAP effectively reduces symptoms related to sleep apnea and comorbidities such as type 2 diabetes and heart disease.
If you are experiencing high blood pressure levels and are unable to sleep well, you should visit a qualified sleep doctor to rule out sleep apnea.
