Introduction: Obstructive sleep apnea (OSA) represents an independent risk factor for cardiovascular disorders. During sleep, the autonomic nervous system regulates the heart rate and blood pressure according to sleep stages and induces their cyclic variations.The heart rate variability is one of the expressions of the changes in autonomic tone. Respiratory polygraphy is a screening method for the diagnosis of obstructive sleep apnoea. During respiratory polygraphy, heart rate variability is also recorded – meaning how far from the average the values are spread.
Objective: To investigate the correlation between heart rate variability, minimal and maximal heart rates as indicators of cardiovascular function, and respiratory polygraphy parameters reflecting risk of OSA.
Methods: We conducted a retrospective study on 104 patients from Cardiology Outpatient Clinic who had undergone respiratory polygraphy, focusing on heart rate, the apnea-hypopnea index, desaturation index and time spent with arterial oxygen saturation below 90% (t90%). We performed the statistical data analysis using MedCalc Software, 12.2.1.0 version.Maxim 800 de caractere
Results: The patients included in the study have a mean age of 54.8±12.4, are mainly men (64%), and 68% of them have been diagnosed with moderate and severe OSA. The heart rate variability index is positively cor-related with the apnea-hypopnea index (AHI) (p=0.04) and also with the desaturation index (p=0.004). There is a statistically significant inverse correlation betwe-en the maximal heart rate and AHI. Using multiple regression, we identified a statistically significant mo-del, including heart rate variability, maximal heart rate, desaturation index and t90%. This model predicts the possibility that the patient may experience OSA as ex-pressed by the AHI, all these elements being in a posi-tive relationship with AHI except maximal heart rate. Another multiple regression model to be used for pa-tients with arterial hypertension to predict high AHI includes heart rate variance, age and maximal heart rate. In hypertensive patients, high AHI is positively correlated with heart rate variance after control of neck circumference and BMI (p<0.0001).
Conclusions: Heart rate variability is a parameter that can be easily recorded during sleep and aids the cardiologist in selecting OSA patients with high cardiovascular risk who require further investigations and appropriate treatment.Respiratory polygraphy is a valuable screening method for the diagnosis of patients with obstructive sleep apnea and high cardiovascular risk.