[Relationship between respiratory event-related arousal and increased pulse rate in patients with obstructive sleep...

Objective: To investigate the relationship between respiratory event-related arousal and increased pulse rate in patients with obstructive sleep apnea (OSA), and to evaluate whether elevated pulse rate can be used as a surrogate marker of arousal. Methods: A total of 80 patients [40 males and 40 females, age range (18-63 years), mean age (37±13) years] who attended the Sleep Center of the Department of Respiratory and Critical Care Medicine, Tianjin Medical University General Hospital for polysomnography (PSG) from January 2021 to August 2022 were enrolled. Stable PSG recordings of non-rapid eye movement (NREM) sleep to compare the mean pulse rate (PR), the lowest PR 10 seconds before the onset of arousal, and the highest PR within 10 seconds after the end of arousal associated with each respiratory event. At the same time, the correlation between the arousal index and the pulse rate increase index (PRRI), as well as ΔPR₁ (highest PR-lowest PR) and ΔPR₂ (highest PR-mean PR), respectively, with the duration of respiratory events, the duration of arousal, the magnitude of pulse oximetry (SpO₂) decline, and the lowest SpO₂ was analyzed. Among the 53 patients, 10 events without arousal and 10 events with arousal (matched for the magnitude of SpO₂ decline) were selected for NREM in each of the 53 patients, and ΔPR before and after termination of respiratory events in the two groups was compared. In addition, 50 patients were simultaneously subjected to portable sleep monitoring (PM) and divided into non-severe OSA group (n=22) and severe OSA group (n=28), and ΔPR≥3 times,≥6 times,≥9 times, and≥12 times after respiratory events were used as surrogate markers of arousal, and ΔPR was scored manually and integrated into the respiratory event index (REI) of PM. Then, we compared the agreement between REI calculated from the four PR cut-off points and the apnea-hypopnea index (AHI_PSG) calculated by the gold standard PSG. Results: ΔPR₁ [(13±7)times/min] and ΔPR₂ [(11±6)times/min] were significantly higher in patients with severe OSA than in patients with non-OSA,mild and moderate OSA. The arousal index was positively correlated with the four PRRIs (r 0.968, 0.886, 0.773, 0.687, P<0.001, respectively), and the highest PR [(77±12) times/min] within 10 s after the end of arousal was significantly higher than the lowest PR [(65±10) times/min, t=113.24, P<0.001] and the mean PR [(67±11) times/min, t=103.02, P<0.001]. ΔPR₁ and ΔPR₂ were moderately correlated with the decrease in SpO₂ (r=0.490, 0.469, P<0.001). After matching the magnitude of SpO₂ decline, the ΔPR[(9±6)/min] before and after the termination of respiratory events with arousal was significantly higher than that of respiratory events without arousal [(6±5)/min, t=7.72, P<0.001]. The differences between REI+PRRI₃ and REI+PRRI₆ and AHI_PSG in the non-severe OSA group were not statistically significant (P values 0.055 and 0.442, respectively), and REI+PRRI₆ and AHI_PSG showed good agreement (the mean difference was 0.7 times/h, 95%CI 8.3-7.0 times/h). The four indicators of PM in the severe OSA group were statistically different from AHI_PSG (all P<0.05), and the agreement was poor. Conclusions: Respiratory event-related arousal in OSA patients is independently associated with increased PR, and frequent arousal may lead to increased frequency of PR fluctuations, and elevated PR may be used as a surrogate marker of arousal, especially in patients with non-severe OSA, where elevated PR≥6 times significantly improves the diagnostic agreement between PM and PSG.