Introduction:
Primary hypertension (PHT) has long ceased to be an adult problem. It commonly affects children and adolescents and is becoming a severe health care problem in many countries. In contrast to secondary hypertension, which occurs mainly in younger children with kidney, cardiovascular, and endocrine disorders, PHT affects older children and adolescents. Potential causes of PHT include being overweight, particularly obese, sleep apnea, and increased sympathetic nervous system (SNS) activity. Vegetative system activity is an essential factor in children’s blood pressure (BP). Those with excessive sympathetic system activity have increased heart rate, BP, and other parameters characterizing the positive chronotropic effect. In turn, one of the factors stimulating the SNS is blood desaturation (DES). This study investigates the relationship between ambulatory BP and oxygen DES rates.

Material and methods:
The degree and number of DES episodes were assessed by finger pulse oximetry during 24-h ambulatory monitoring in 54 boys and girls with PHT. Their results were compared to 52 healthy children without PHT.

Results:
Several disturbances in blood saturation were found in children with PHT. They had more episodes of DES and profound hypoxia (< 90%), their blood DES was significantly lower, and their DES time was longer. Additionally, higher systolic BP and higher diastolic pressure loads were observed throughout the day and night in children with longer DES times (> 60 s), who also had more DES episodes and lower baseline and average blood saturation.

Conclusions:
Children with PHT show significant disturbances in blood oxygenation, leading to overactive SNS activity, which may be a crucial element in PHT pathogenesis in children.