[Effect of suppression of apnea on arterial pressure and plasma catecholamines in normotensive patients with sleep apnea].

BACKGROUND

The association of high blood pressure (HBP) and the sleep apnea syndrome (SPS) and the beneficial effect of SAS treatment on HBP are well known. The direct effect of the continuous nocturnal administration of positive air pressure (CPAP) on blood pressure is not, however, well known. The aim of this study was to evaluate the blood pressure (BP), plasma catecholamines (PC) and urinary derivatives of catecholamines (UDC) in 17 normotensive subjects (4 females; age 49 +/- 11 years) with SAS, prior to and after correction of apnea with CPAP.

METHODS

Twenty-four hour outpatient registry of blood pressure (OPRBP) and after nocturnal polysomnography were performed both basal and during CPAP administration for two nights. Urine was collected over these 24 hour period for measurement of UDC. At 7 hours a blood sample was collected for measurement of PC.

RESULTS

SAS was corrected by CPAP in all the patients with a reduction in mean BP (24 h: 87 +/- 6 vs 84 +/- 6 mmHg, p < 0.05, diurnal, 90 +/- 6 vs 87 +/- 6 mmHg, p < 0.05, nocturnal, 84 +/- 6 vs 82 +/- 7 mmHg, NS) and the percentage of diastolic BP > 90 mmHg (24 h: 10 +/- 7 mmHg vs 6.5 +/- 6 mmHg, p < 0.01, diurnal, 15 +/- 10 vs 10 +/- 10 mmHg, p < 0.05, nocturnal 5.2 vs 5 vs 3 +/- 4 mmHg, p < 0.05). The plasma catecholamines tended to reduce, although not significantly, without changes of urinary metabolites.

CONCLUSIONS

There is a significant decrease in blood pressure with the administration of continuous positive air pressure even in normotensive patients. An early correction of sleep apnea syndrome may reduce the high prevalence of hypertension associated with this syndrome.