Inducers of post-apneic blood pressure fluctuation monitored by pulse transfer time measurement in obstructive sleep apnea varied with syndrome severity

Up-to-date advance in the relationship between OSA and stroke: a narrative review

PURPOSE

Obstructive sleep apnea (OSA) and stroke affect each other. In this review, we summarized the effect of OSA on the onset and recurrence of stroke, the prognosis, and the treatment of poststroke patients with OSA.

METHODS

Pubmed/MEDLINE were searched through May 2023 to explore the relationship between OSA and stroke. The relevant papers included OSA and stroke, OSA and recurrent stroke, and the prognosis and treatment of poststroke patients with OSA.

RESULTS

The results showed that OSA can promote the onset and recurrence of stroke and that OSA may adversely affect the prognosis of poststroke patients. The application of continuous positive airway pressure (CPAP) and other treatments may benefit poststroke patients with OSA, though the long term effects of treatment are not well documented.

CONCLUSION

Both the onset and recurrence of stroke closely correlated with OSA, but the specific mechanisms remain unclear. Further studies should be carried out to explore effective treatments in patients with stroke and OSA.

Effects of Continuous Positive Airway Pressure Therapy on Nocturnal Blood Pressure Fluctuation Patterns in Patients with Obstructive Sleep Apnea

This retrospective study was designed to evaluate the effects of continuous positive airway pressure (CPAP) therapy, a well-established treatment for obstructive sleep apnea (OSA), on nocturnal blood pressure fluctuations (NBPFs) during rapid eye movement (REM) and non-REM sleep, and to evaluate the NBPF patterns in patients with OSA. We included 34 patients with moderate-to-severe OSA who underwent polysomnography using pulse transit time before and at 3−6 months after CPAP therapy. Nocturnal BP and NBPF frequency in REM and non-REM sleep were investigated, as well as NBPF pattern changes after receiving CPAP therapy. CPAP therapy resulted in significant reductions in the apnea−hypopnea index (AHI), arousal index, nocturnal systolic and diastolic BP, and NBPF frequency in REM and non-REM sleep (all p < 0.01). A higher AHI before CPAP resulted in lower nocturnal systolic BP (r = 0.40, p = 0.019) and NBPFs (r = 0.51, p = 0.002) after CPAP. However, 58.8% of patients showed no change in NBPF patterns with CPAP therapy. CPAP therapy significantly improved almost all sleep-related parameters, nocturnal BP, and NBPF frequency in REM and non-REM sleep periods, but NBPF patterns showed various changes post-CPAP therapy. These results suggest that factors other than OSA influence changes in NBPF patterns.

Nocturnal blood pressure and nocturnal blood pressure fluctuations: the effect of short-term CPAP therapy and their association with the severity of obstructive sleep apnea

STUDY OBJECTIVES

We determined the relationship of cardiovascular risk factors, cardiovascular diseases, nocturnal blood pressure (NBP), and NBP fluctuations (NBPFs) with the severity of obstructive sleep apnea (OSA). We also investigated the effect of short-term continuous positive airway pressure therapy on NBP parameters.

METHODS

This retrospective study included 548 patients from our cardiac clinic with suspected OSA. Patients underwent polysomnography and continuous NBP measurement using the pulse transit time. According to their apnea-hypopnea index (AHI), patients were subclassified as controls (AHI < 5 events/h), mild (AHI 5 to < 15 events/h), moderate (AHI 15 to < 30 events/h), and severe OSA (AHI ≥ 30 events/h); 294 patients received continuous positive airway pressure therapy.

RESULTS

Analysis of covariance showed that NBP and the frequency of NBPFs were the highest in severe followed by moderate and mild OSA (all P < .001). Multivariable regression analysis revealed a significant association of NBPFs with AHI, body mass index, systolic NBP, and lowest SpO₂. The severity of OSA is also associated with the frequency of obesity, hypertension, diabetes mellitus, atrial fibrillation, heart failure (all P < .001), and coronary artery disease (P = .035). Short-term continuous positive airway pressure decreased the frequency of NBPFs in all OSA groups and the systolic NBP in severe and moderate but not in mild OSA.

CONCLUSIONS

The severity of OSA is associated with an increase in NBP and NBPFs. Continuous positive airway pressure reduces NBP parameters already after the first night. In addition to BP, the diagnosis and therapy of NBPFs should be considered in patients with OSA.

CLINICAL TRIAL REGISTRATION

Registry: German Clinical Trials Register; Name: Nocturnal blood pressure and nocturnal blood pressure fluctuations associated with the severity of obstructive sleep apnea; URL: https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00024087; Identifier: DRKS00024087.

CITATION

Picard F, Panagiotidou P, Tammen A-B, et al. Nocturnal blood pressure and nocturnal blood pressure fluctuations: the effect of short-term CPAP therapy and their association with the severity of obstructive sleep apnea. J Clin Sleep Med. 2022;18(2):361-371.

ANALYSIS OF PHOTOPLETHYSMOGRAPHIC MORPHOLOGY IN SLEEP APNEA SYNDROME PATIENTS USING CURVE FITTING AND SUPPORT VECTOR MACHINE

This paper develops a time-saving, simple, and comfortable method for detecting Sleep Apnea Syndrome (SAS). Seventy SAS patients and 17 healthy persons were randomly selected in this study, and nine analytical parameters (i.e., [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] of healthy persons and SAS patients during five sleep stages (i.e., W, R, N1, N2, and N3) were obtained to construct a SAS classification model based on logarithmic normal analytical parameters using the Support Vector Machine (SVM) method to fit Photoplethysmographic (PPG) signals. The results show that there were no statistical differences among the five sleep stages for either the healthy or SAS patients. However, there were significant differences in the measured logarithmic normal analytical parameters between the healthy persons and the SAS patients in each of the five sleep stages. The accuracies of the SAS classification model were 95.00%, 90.00%, 84.00%, 94.67%, and 90.77%, corresponding to the five sleep stages, respectively. The SAS classification model based on the SVM method of logarithmic normal analysis parameters can achieve higher classification accuracy for each of the five sleep stages. It can be considered to collect the patient’s pulse wave during the awake period, but not necessarily during the sleep period to classify and identify the SAS; it provides an idea for a convenient and comfortable SAS detection.

[Pulmonary insufficiency in acute stroke: risk factors and mechanisms of development]

Various degrees of pulmonary insufficiency (PI) (PaO₂ ≤60 mm Hg, SaO₂ ≤90%) are diagnosed in most of patients with severe acute stroke (AS). Frequency and severity of PI positively correlates with the severity of AS. PI worsens patient's condition, prolongs the hospitalization period, and increases the probability of fatal outcome. Early clinical signs of PI may be undiagnosed due to the severity of stroke and thus not treated. The initiating pathogenic mechanism of PI is stress-related activation of sympathetic nervous system (SNS) and systemic immunosuppression. In severe stroke with mass effect, the rapid and significant increase in intracranial pressure may additionally activate the SNS. Risk factors of PI include older age, previous pulmonary disease, prolonged supine position, respiratory muscle dysfunction, apnea, and concomitant somatic diseases. Decompensation of somatic diseases leads to multiple stage reactions with facilitation of functional and morphologic changes in the pulmonary system, hypoxemia and hypoxia, promotes infectious complications and multiple organ failure and worsens neurological outcome. Diagnosis and treatment of PI in AS decreases mortality and improves rehabilitation prognosis.