Supplemental oxygen eliminates the rise in morning blood pressure experienced by obstructive sleep apnea (OSA) patients who stop using continuous positive airway pressure (CPAP), the standard treatment for OSA.
According to a new research, co-authors reported that in patients with moderate to severe OSA, supplemental oxygen prevented the rise in systolic and diastolic blood pressure, and the increase in oxygen desaturations that were seen in the control arm of the study after CPAP was withdrawn.
Twenty-five adults living in the United Kingdom participated in the study. All had been using CPAP successfully for over a year.
Many studies have demonstrated an association between OSA, hypertension and cardiovascular disease.Some of these studies have linked the acute rises in blood pressure that OSA patients experience while sleeping to the constant need to wake up when their breathing stops or is partially blocked.
The authors of the current study wanted to find out if these recurrent arousals were also responsible for higher blood pressure in OSA patients during the day or whether intermittent hypoxia (low oxygen levels), resulting from interrupted breathing during sleep, caused a rise in blood pressure during the day.It is hoped that with this discovery a simple test to identify salt sensitivity of BP during a clinical visit can be developed.
High blood pressure (hypertension) impacts nearly one of every two adults in the U.S. and is the leading global non-communicable cause of death. It is projected to be the primary global cause of death and disability by 2020.
Salt sensitivity in blood pressure is a major risk factor for hypertension and increased cardiovascular risk and is highly relevant given that 99 percent of U.S. adults exceed the recommended daily intake for salt.”Our data highlights a potential genetic method to screen for the salt sensitivity of blood pressure that may identify patients who exhibit the salt sensitivity of blood pressure. Possessing this specific marker makes you three times more likely to be salt sensitive than people who don’t have the marker,” explained corresponding author Richard Wainford, Ph.D., associate professor of Pharmacology & Experimental Therapeutics at Boston University School of Medicine (BUSM).
The researchers looked at two groups of patients. The first group had no change in blood pressure in response to high dietary salt intake (meaning they were salt resistant). The second group of patients had an increase in blood pressure in response to high dietary salt intake (salt sensitive). Both groups were then screened for genetic variation in the GNAI2 gene. Those patients with the gene variation were more likely to be salt sensitive.
“Developing a simple diagnostic biomarker of individual salt-sensitivity of BP would aid in identifying individuals at risk for developing salt sensitivity related complications (hypertension, cardiac, renal and cerebral diseases), and in risk stratification and treatment decisions in individuals with established salt-sensitive conditions.”
The study found that supplemental oxygen substantially reduced intermittent hypoxia, but had minimal effect on two markers of arousal: the apnea-hypopnea index, a measure of sleep apnea severity that takes into account episodes of paused and shallow breathing.
However, before supplemental oxygen can be used as an alternative to CPAP, the authors write that more research must be done to prove it is safe.The full findings are present in the American Journal of Respiratory and Critical Care Medicine.
