NIGHT-TIME BLOOD PRESSURE AND BLOOD PRESSURE VARIABILITY IN HYPERTENSIVE PATIENTS WITH OR WITHOUT INSOMNIA. A PILOT STUDY

Abstract

Objective: Recent studies found that insomnia is an independent risk factor for cardiovascular diseases, particularly arterial hypertension. Among the hypertensive population, insomnia could contribute to a worse blood pressure (BP) profile. In a sample of hypertensive patients, we compared those with and without insomnia with the aim of evaluating possible differences in BP, its variability, and breathing pattern. Design and method: We conducted a case-control study on patients with and without insomnia, based on the Insomnia Severity Index (ISI) questionnaire. Patients were recruited from the general practitioner's registry and were sent an invitation e-mail. All of them had long-lasting hypertension. One-hundred-and-fifty patients replied to the ISI questionnaire. Among them, twenty people with insomnia were selected (ISI greater than or equal to 15) and matched, based on their gender and age (±3 years), to 20 controls (with ISI lower than 15). All participants underwent night-time cardiorespiratory and 24-hour blood pressure monitoring by using a new cuff-less device that can estimate beat-to-beat BP (SomnoTouch-NIBP). Results: Comparing the two groups (insomnia vs. non-insomnia), no differences were observed in BP profile and all the respiratory indices, including the apnea-hypopnea index(AHI), the number of desaturations, and peripheral oxygen saturation (SpO2) values. Even the average BP and the indices of BP variability, such as the standard deviation (SD), the pressure coefficient of variation (CV), the BP dipping, and the nocturnal BP fluctuations (NBPF), were similar between the groups. Interestingly, to obtain the same average BP control, the insomnia group required a greater number of antihypertensive drugs (2,85 ± 0,88 vs. 1,95 ± 1,00 in the non-insomnia group; p<0.01). Conclusions: Patients with insomnia may need more antihypertensive medications to achieve the same average BP as patients without insomnia. Anyhow, they did not show, as expected, higher BP variability. How much beat-to-beat BP estimations are reliable compared to BP measurements by standard cuff-based devices is still under debate.