Abstract 2587: New Non-Invasive Oxygen Desaturation-Triggered Blood Pressure Monitoring System Successfully Detected Midnight Surge in Blood Pressure and its Association with Severity of Sleep Apnea Syndrome
Background Patients with obstructive sleep apnea (SA) syndrome are known to have greater risk for cardiovascular events, and midnight surge in blood pressure (BP) may be a potential mechanism of this SA-related cardiovascular risk.
Method We developed an experimental system to detect SA-related short-term BP surge based on BP measurement triggered by peripheral (finger-tip) oxygen desaturation, and monitored BP during sleep period in 16 patients with obstructive SA. The time rate (TR) (velocity) of BP surge was calculated as follows: TR(i) =[BP(i) - BP(i-1)]/[T(i) - T(i-1)], where, BP(i) and BP(i-1) are two consecutive BP readings, and T(i) and T(i-1) are the corresponding times when the 2 BPs were measured.
Results This new system successfully detected BP surges during each SA episode. The SA-related peak SBP (the average of the highest 3 values) was significantly correlated positively with the apnea-hypopnea index (AHI) (r=0.53, p=0.03) (figure⇓, left), while the correlation between the average of SBP during total sleep period and AHI was not significant. The maximum (the average of the highest 3 values) time rates (velocity) of SA-related surges of SBP(r=0.86, p<0.0001) (figure⇓, right), diastolic BP (r=0.74, p=0.001) and pulse rate (r=0.58, p=0.02) were strongly correlated positively with AHI.
Conclusion We developed a non-invasive oxygen desaturation-triggered BP monitoring system, which could successfully detect sleep apnea-related BP surge. Midnight BP surge and time rate of BP variation detected by this new system were significantly correlated with the severity of obstructive sleep apnea syndrome.