Comparative assessment of pulse transit time–derived blood pressure and ambulatory blood pressure monitoring in patients with obstructive sleep apnea

Abstract

Study objectives: Nocturnal hypertension is common in patients with obstructive sleep apnea (OSA) and contributes to elevated cardiovascular risk. Pulse transit time (PTT) offers a noninvasive method to estimate nocturnal blood pressure (BP) during sleep, but its clinical validity in OSA remains unclear. This study aimed to assess the correlation between PTT-derived nocturnal BP (PTT-BP) and 24-hour ambulatory BP monitoring (ABPM-BP) in patients with suspected OSA. Methods: Adults undergoing full-night PSG for suspected OSA were prospectively enrolled and underwent 24-hour ABPM the following day. Nocturnal hypertension was defined as mean nighttime BP ≥ 120/70 mmHg. Exclusion criteria included positive airway pressure titration, arrhythmias affecting PTT accuracy, and incomplete ABPM data. PTT-BP and ABPM-BP were compared across OSA severity levels. Results: Sixty-six subjects (median age 47 years; 39.4% male) were analyzed. Prior hypertension was reported in 40.9%. OSA severity was mild in 28.8%, moderate in 37.9%, and severe in 28.8%. PTT-BP demonstrated a weak correlation with nocturnal ABPM-BP. Among patients with mild OSA, nocturnal PTT- BP was comparable to ABPM-BP. However, among patients with moderate to severe OSA, both systolic and diastolic PTT-BP exceeded ABPM-BP. Sensitivity and specificity of PTT-SBP ≥ 104 mmHg in detecting nocturnal hypertension were 85% and 39%, respectively. PTT-SBP ≥ 104 mmHg identified masked hypertension with 78% sensitivity and 48% specificity. Conclusions: PTT-derived BP tends to overestimate nocturnal BP in patients with moderate to severe OSA. The exact value from PTT can be significantly different from ambulatory blood pressure monitoring, which affects reliability. However, PTT-derived systolic BP may be useful in screening for nocturnal and masked hypertension.