New York, Dec 7 : Researchers have found that a simple blood test can help identify people with obstructive sleep apnea (OSA) who are at higher risk of cardiovascular problems because of a phenomenon called "reverse dipping" that causes blood pressure to rise rather than lower during sleep.
Most people experience lower blood pressure at night.
The new study, published in the European Respiratory Journal suggests a potential cause for reverse dipping that may help patients with sleep apnea get the help they need before cardiovascular disease develops.
"We can now identify those with OSA at the highest risk of cardiovascular problems in order to prevent them from developing additional complications," said David Gozal from the University of Missouri School of Medicine in the US.
"We can treat those patients more aggressively to ensure they adhere to therapy and use their continuous positive airway pressure device (CPAP) properly," Gozal said.
The researchers studied 46 patients diagnosed with OSA. They ranged in age from 18 to 70. Fifteen participants were identified to have a rise in blood pressure during sleep, while the remaining 31 participants had blood pressure readings that either remained the same or declined at night.
The researchers collected a blood sample from each participant to study the messages cells produce and send to each other through microscopic packages called exosomes.
"We found that the cell messages coming from participants with night-time elevated blood pressure were different than those transmitted in subjects with normal blood pressure," Gozal said.
"The altered messages caused the cells that line the blood vessels to become dysfunctional. Those disturbed vessels allowed inflammatory cells to enter the vessels' walls, causing hardening of those vessels and leading to cardiovascular disease."
Gozal said the cell message discovery will help clinicians personalise treatment for each patient diagnosed with OSA.
A simple blood test administered at the beginning of a sleep study could indicate each patient's cardiovascular risk, said the study.