Arterial Pressure Variability in Patients With Ischemic Stroke and the Concomitant Syndrome of Obstructive Sleep Apnea

Introduction. Cerebral stroke is a significant medical-social problem today, which remains the second leading cause of death in the world and is the dominant cause of permanent incapacity for work and disability. Among the many factors that have a negative impact on the development and course of a stroke, more and more attention is paid to breathing disorders during sleep – obstructive sleep apnea syndrome (OSAS), which causes nocturnal hypoxemia, hypercapnia, arterial dystonia, sleep fragmentation, etc. Systemic hypoxemia, caused by OSAS, reduces oxygen delivery to tissues, causing a secondary negative effect on the ischemia-affected brain, thereby worsening the course and results of stroke treatment. The above pathological changes are regarded as a favorable background for a stroke. The study of arterial pressure (AP) absolute values, as well as its variability, attracts an increasing attention of scientists. Average values of AP variation coefficient may differ depending on age, gender, country of residence, measurement method, concomitant pathology, and medication. Maintaining stable values of AP in patients with ischemic stroke and concomitant OSAS is advisable not only by drug correction, but also by eliminating night breathing disorders. The application of various strategies of non-invasive respiratory support, primarily continuous positive airway pressure (CPAP), аccording to a number of researchers, is potentially able to eliminate negative trigger factors of hemodynamic instability; this causes significant scientific interest in this problem and justifies the relevance of further scientific research in this regard. Objective: To assess the effect of non-invasive CPAP-support on the arterial pressure indices and its variability in the treatment of patients with ischemic stroke and the concomitant syndrome of obstructive sleep apnea. Materials and methods. 60 patients with mild (1–5 points) and moderate (6–13 points) stroke severity were selected for further participation in the study. Criteria for inclusion into the study were: signed informed consent, verified ischemic stroke with the severity of 1–13 points according to the NIHSS scale, snoring, polysomomnographically confirmed obstructive sleep apnea syndrome (OSAS) with an apnea/hypopnea index (AHI) > 15/hour. Exclusion criteria were: diabetes mellitus, bulbar syndrome, sopor, bronchial asthma, chronic obstructive pulmonary disease, rhinosinusopathy, signs of respiratory infection, predicted necessity for mechanical ventilation, tracheostomy, presence of a nasogastric tube. The patients were divided into two groups: group I (control one, n=30) – patients with OSAS who were offered respiratory support, but who, for various reasons, did not want to use the offered method of treatment: they were given treatment and rehabilitation according to the traditional scheme of the unified clinical protocols. For patients included into the group II (experimental one, n=30) with OSAS, a traditional treatment and rehabilitation scheme and additional CPAP during night sleep were used. To evaluate the effect of two treatment strategies on the blood pressure level and its variability, daily monitoring was performed using the “ABPM-50” device (Contec, China) during the 2nd day from the moment of admission into the hospital (initial values), and at the end of the 7th day of treatment. Average daily values of systolic (SAP) and diastolic (DAP) arterial pressure and coefficient of variation (CV) during the day were chosen for statistical analysis. Statistical analysis of the data obtained was performed using the licensed STATISTICA 12 program (StatSoft Inc., USA). Research results. At the initial stage, the average values of SAP in patients of the group I were 157.96±15.84 mm Hg, and DAP – 90.63±13.03 mm Hg, and in patients of group II – 161.23±11.32 mm Hg and 94.46±12.93 mm Hg, respectively. During the 7th day of observation, under the influence of standard treatment, there were no changes in the average systolic and diastolic blood pressure in patients of the group I; on the other hand, in the patients of group II, under the influence of CPAP-therapy during 7 nights, a decrease was noted in the average SAP by 7.3% and the average DAT by 12% compared to the initial values. The coefficient of variation of SAP was 17.88±2.98%, and DAP – 13.93±2.84% in patients of the group I, and 18.37±3.77% and 14.58±2.78%, respectively, in the patients of the group II. After 7 days of treatment, the coefficients of variability in the comparison groups decreased towards normal values. In particular, in patients of CV group I, SAP decreased at 14.8% (p<0.004), and diastolic blood pressure decreased at 24.9% (p<0.0001), compared to the initial values. At this time, in patients of the group II, whose standard treatment was supplemented with CPAP-therapy, the CV of SAP decreased by 42.2% (p<0.00001) and DAP by 40.7% (p<0.00001) compared to the initial level and both indices were within the limits of physiological fluctuations. Comparing CV of SAP at the end of the 7th day of treatment between the groups, it was found that they differed 1.4-fold (by 30.3%; p<0.00001), and CV of DAT – 1.2-fold, respectively (17.4%; p<0.00001; p=0.002). Conclusion. 1. Routine monitoring of blood pressure indices has insufficient clinical informativeness, especially in patients with ischemic stroke and concomitant obstructive sleep apnea syndrome, and needs to be added to. 2. Variable indices of arterial pressure, first of all – coefficients of variation of systolic and diastolic blood pressure, during daily monitoring significantly supplement the patient’s hemodynamic status, serve as a basis for changing therapeutic effects and are a method of objective assessment of their effectiveness. 3. In patients with ischemic stroke against the background of OSAS, an initial high variability of arterial pressure at the level of 18% was found. At a standard approach to the treatment and rehabilitation of patients, the variability of SAP and DAP significantly decreased by 14.8% and 24.9%, respectively. When using CPAP to correct the manifestations of OSAS, the variability of SAP and DAP decreased from the initial values at 42.2% and 40.7%, respectively, and approached the limit of physiological fluctuations. 4. The use of CPAP in the complex treatment of patients with ischemic stroke and concomitant OSAS helps not only eliminate obstructive events and respiratory disorders, but also normalize the initially increased variability of the AP – an independent risk factor for the repeated stroke.