Apnoea-Related Leg Movements May Signal CVD

Sayaka Aritake PhD of Tokyo Medical University in Japan together with colleagues has done a study to evaluate sleep apnoea and the risk for hypertension and cardiovascular disease.  The research was narrowed down to the comparative study of obstructive respiratory events which might end up producing leg movement and the risk of cardiovascular disease.

For the study, the researchers recruited 633 older men. This group had sleep apnoea and data regarding leg movements. The men in the study had an average age of 81.2 years and an apnoea hypopnea index of more than 10. The respiratory leg movement was defined as leg movement which lasts anything between 0.5 and 5 with the onset an average 2 seconds before and after a respiratory event.

The researchers used leg movement data collected using piezoelectric sensors as well as self-recorded data collected with an in-home, overnight or single night, unattended polysomnography. Other data was collected using and Chin EMG, ECG, inductance plethysmography, EEG, EOG, airflow, pulse oximetry, and body position.

Before commencement of the study, all the patients were questioned for any cardiovascular disease history and treatment in the 4 months prior to the study. The group was then split into three groups depending on data collected and data adjustment. One group was modeled on clinical site, BMI, age and race. The second group was modeled on anti-depressant use, history of diabetes, hypertension, apnoea hypopnea index, history of cardiovascular disease and smoking. The final group was modeled on the variables used for group two and coupled to periodic leg movement.

The group with variables such as BMI, age and race together with respiratory leg movements had a 58% increased risk of cardiovascular disease. The second group had a 71% increased risk of cardiovascular disease. Data from group three was discarded for its effect on outcome significance.

Sayaka Aritake reported that respiratory related leg movements predicted cardiovascular disease in older men. Obstructive respiratory conditions with leg movement produce greater increases in heart rate than those without leg movement. But it was unclear if the leg movement themselves confer risk or it is simply a marker of severe respiratory disease.

The only limitations of the study as reported by Aritake was that the findings could not be generalized to apply for younger men and women. Finally, the other limitation was the use of the piezoelectric sensors which might not be as good as electromyography in measuring leg movements.

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