Do you think everyone that walks around with high blood pressure is aware of it? Is there an obvious feeling that patients feel when their cholesterol is elevated? The obvious answer is no.
This may be the case for obstructive sleep apnea syndrome in many patients.
While a bed partner may identify loud snoring or pauses in respirations during sleep, the fact is that many patients simply tolerate the poor sleep quality (and sometimes quantity) from having OSA.
The question then is whether these patients need intervention and treatment given that they are asymptomatic.
This answer is an overwhelming yes! There has been ample literature in the recent few years demonstrating that obstructive sleep apnea syndrome is a significant risk factor for cardiac disease and even stroke.
Patients with more severe OSA with concomitant hypoxia are also more likely to have cardiac arrhythmias, congestive heart failure, and even sudden death.
While the risk of developing these conditions is directly correlative to the severity of their syndrome, it does not always correlate well with symptoms.
There have been two recent findings additionally reported that support these findings.
Researchers at University of California, San Diego (Dimsdale, et al.
Sleep 2006; 29:1531-1536) have demonstrated that in patients with OSA, there are findings of reduced cardiac output measured by impedance cardiography.
Interestingly, this correlated directly with reported hyper somnolence as measured by the Epworth Sleepiness Scale.
The more fatigued a patient was with OSA, the more reduced a cardiac output was found.
This implies that the symptoms of fatigue are complex, and not simply related to sleep deprivation only, but also cardiovascular effects secondarily.
Likewise, this may explain why patients who seem objectively to respond well to CPAP therapy continue to have a residual degree of fatigue often times.
Other researchers at Royal Prince Albert Hospital, Sydney (Lattimore, et al.
Thorax 2006; 61:459-460,491-495) reported that treatment with CPAP therapy in patients with Obstructive Sleep Apnea Syndrome resulted in a greater dilation and relaxation of endothelial cells (the inner lining cells) of blood vessels in response to acetyl choline infusion than prior to treatment.
This suggests that OSA syndrome results in a reduced responsiveness of these cells to dilate in response to appropriate triggers, and as a result increases the risk of blood vessel occlusion and heart attack.
Treatment of the OSA syndrome seems to improve this response and therefore reduces cardiac disease risk.
While the understanding between Obstructive Sleep Apnea Syndrome and cardiac disease is in its virgin stages, evidence now strongly supports that intervention and treatment is in everyone's best interest regardless of whether the patient has overt symptoms or not.
OSA has been well defined as a risk factor for cardiac disease, and a condition that if left untreated reduces life expectancy.
As more is understood, there well may be medication therapies to assist with residual cardiac effects left by OSA that improve fatigue and sleepiness.
Regardless, if obstructive sleep apnea syndrome is suspected, appropriate diagnostics and interventions seem prudent.