"Although the relationship between hypertension and sleep apnea is well established, our results suggest that the occurrence of WCH could lead to overdiagnosis of hypertension among patients with sleep apnea, thereby leading to potentially flawed conclusions regarding the causative association of hypertension and sleep apnea," said lead researcher Francisco Garcia-Rio, PhD, La Paz University Hospital, Madrid, Spain.
Researchers from La Paz University Hospital observed the frequency of WCH in patients with sleep apnea and the characteristics of patients with both conditions. Ninety-nine patients with sleep apnea and 20 healthy patients (control group) were included in the study. Of the patients with sleep apnea, 45 patients were physician-diagnosed with hypertension, and the remaining patients were considered to have normal blood pressure levels. During a 24-hour period, all patients underwent regular intervals of ambulatory blood pressure monitoring, polysomnography, and blood and urine testing. Results showed that in patients with sleep apnea initially diagnosed with hypertension, 30 patients were confirmed to have sustained hypertension, while the remaining 15 patients had normal blood pressure readings. All other patients presented normal blood pressure readings. Further analysis revealed that patients with WCH took three times as long to fall asleep and had longer periods of wakefulness after sleep onset than patients with sustained hypertension. No other differences in sleep characteristics, lung function data, or urinary hormone levels were found between the groups with sleep apnea. In addition, there were no significant differences in gender, age, body mass index, or smoking habits between sleep apnea and control groups.
"The medical community should be cautious in utilizing these data in clinical practice, since it is preliminary in nature. However, the potential importance of sleep apnea as a secondary or correctable cause of hypertension should alert the clinicians in pursuing the diagnosis of sleep apnea, especially in patients in whom blood pressure can not be controlled medically," said the author of a corresponding editorial, Hector O. Ventura, MD, Cardiomyopathy and Heart Transplantation Center, Ochsner Clinical Foundation, New Orleans, LA.
"It is important for physicians to recognize the severe effects hypertension and sleep apnea can have on a patient's health," said Richard S. Irwin, MD, FCCP, President of the American College of Chest Physicians. "Although the prevalence of both hypertension and sleep apnea may be overestimated, more research is needed to understand WCH and its relationship with sleep disorders."
CHEST is a peer-reviewed journal published by the ACCP. It is available online each month at www.chestjournal.org. ACCP represents more than 15,700 members who provide clinical, respiratory, and cardiothoracic patient care in the United States and throughout the world. ACCP's mission is to promote the prevention and treatment of diseases of the chest through leadership, education, research, and communication.