Obstructive sleep apnea can have adverse vascular effects.

FORT LAUDERDALE, FLA. -- Children are not immune to effects of obstructive sleep apnea on the vasculature, including an increased risk of systemic diastolic hypertension and decreased left ventricular contractility, according to a pediatric pulmonologist/sleep medicine researcher.

"Sleep apnea may directly affect the vasculature and indirectly affect the diseases we typically see later in life," Dr. David Gozal said at a pediatric pulmonology meeting sponsored by the American College of Chest Physicians.

"The clinical prototypic pediatric patient of the early 1990s has been insidiously replaced by a different phenotypic presentation that strikingly resembles that of adults afflicted by the disease," Dr. Gozal and colleagues wrote in a recent study (Proc. Am. Thorac. Soc. 2008;5:274-82).

Treatment of sleep apnea in pediatric patients permits them to grow to be healthy adults, Dr. Gozal said. He and others are studying the adverse vascular and cardiovascular effects of obstructive sleep apnea (OSA). For example, a study in press indicates increases in LDL cholesterol and decreases in HDL cholesterol among all children with OSA. Based on that finding, "now we take a blood test in the morning for all our children, even those with mild sleep apnea," he said.

Studies to date primarily include obese and nonobese children. However, "we are currently looking at the interaction between obesity and sleep apnea, and expect to see an explosion in the effect they can have on the vasculature," said Dr. Gozal, professor and vice chair of research in the department of pediatrics at the University of Louisville (Ky.).

Even mild OSA reduces quality of life for children (Sleep 2004;27:1131-8). Significant decreases in some measures of health-related quality of life and increased symptoms of depression were detected among children with sleep-disordered breathing, including those with a mild condition, and more particularly among obese children.

"The magnitude of the quality of life decrease for those with severe OSA is in range of those with juvenile rheumatoid arthritis, severe asthma, or those on chemotherapy," said Dr. Gozal, who is also a respiratory/ sleep physiologist in the division of sleep medicine at Kosair Children's Hospital Research Institute, also in Louisville.

Severe OSA also can induce daytime and nighttime systemic diastolic hypertension for children, Dr. Gozal said. Increases in tonic-sympathetic activity that continue from nighttime to daytime and persist at high levels also are possible in that population (Sleep 2005;28:747-52). That could be associated with an increase in vascular resistance, he said. Indeed, children with OSA may have an increased response to any challenge to their sympathetic system, Dr. Gozal said.

The investigators did a noninvasive test in nonobese children with OSA. They measured pulse arterial tonometry responses to a sigh in 28 boys and girls (mean age 10 years) and 29 controls matched for age and gender. Among those with OSA, the vital capacity breath response led to increased blood flow reductions, which also lasted longer than controls. "And these were nonobese children with no other morbidity," he added.

Dr. Gozal and his associates also examined OSA effects on endothelial function (Circulation 2007;116:2307-14). "We do a simple occlusion of the brachial artery and allow for reperfusion," he explained. "In normal children, you get nice reperfusion that is reproducible over time." In contrast, in the majority of children with sleep apnea--the nonobese without hypertension--"you get a delayed reperfusion, suggesting that the vascular bed is sick."

Treatment may reverse that effect for most children. "When you treat a nonobese child with OSA [with tonsillectomy and adenoidectomy], you get normalization, suggesting the endothelium can heal," Dr. Gozal said.

"However, for about 25% we found no evidence of improvement after 6 months," he added. "This was very concerning to us. The only difference we could find is that the nonresponders had significant family history of cardiovascular disease."

Increased left ventricular mass and higher pulmonary artery pressure are potential adverse cardiovascular effects, Dr. Raouf Amin reported (Hypertension 2008;51:84-91). In addition, there is decreased left ventricular contractility, Dr. Gozal said.

"So it's not just the right side of the heart," he cautioned. "We have to start thinking about the left side of the heart in terms of morbidity too, and conceptualize that all the elements of the cardiovascular system might be involved."

BY DAMIAN McNAMARA

Miami Bureau