Relationship between blood pressure fluctuations and ambient temperature variation in ischemic stroke patients with hypertension: a 5-year follow-up study

Abstract

Objective To explore the relationship between ambient temperature variation and blood pressure fluctuations in acute ischemic stroke patients. Methods Clinical data of 5 730 ischemic stroke patients hospitalized at the Departments of Neurology and Geriatrics of The Second Hospital of Tianjin Medical University and air temperature data during the corresponding period were retrospectively analyzed.The relationship between air temperature and blood pressure in patients with acute ischemic stroke was analyzed. Results Of 5 730 patients, 4 428(77.28%)had hypertension and most of them were male(56.26% 3 362 cases). The systolic and diastolic blood pressure levels were higher in hypertensive males than in hypertensive females〔(153.9±21.7)mmHg vs.(150.7±23.6)mmHg, (85.9±13.3)mmHg vs.(83.0±12.5)mmHg, 1 mm Hg=0.133 kPa, both P<0.05〕. The systolic pressure tended to increase and diastolic pressure tended to decrease with increasing age(both P<0.05). The systolic and diastolic blood pressure levels of patients were slightly higher in autumn and winter than in spring and summer (P<0.05). The mean monthly maximum and minimum temperature had negative correlations with the systolic blood pressure of patients.There was a linear positive correlation between the average monthly diurnal temperature range and the systolic and diastolic blood pressure.The systolic or diastolic blood pressure increased by 0.088 mmHg or 0.076 mmHg respectively with each 1 ℃ drop in the mean monthly maximum and minimum temperature.The systolic or diastolic blood pressure increased by 1.043 mmHg or 0.654 mmHg respectively with each 1 ℃ increase in the average monthly diurnal temperature range. Conclusions Hypertension is a risk factor for ischemic stroke, and ambient temperature variation is related to baseline blood pressure fluctuations in hypertensive patients with acute ischemic stroke.The temperature reduction and the increase of average diurnal temperature rang can lead to the elevation of blood pressure, which is more obvious in autumn and winter, especially in elderly patients. Key words: Brain ischemia; Stroke; Hypertension; Temperature