Hypothesis: We hypothesized that baroreflex sensitivity is decreased during wakefulness and non-rapid eye movement sleep in normotensive, nonapneic snorers who are otherwise healthy. Moreover, we hypothesized that nocturnal alterations in baroreflex sensitivity are abolished during the application of nasal continuous positive airway pressure (nCPAP).
Design: The sequencing technique was used to measure baroreflex sensitivity in 16 normotensive nonapneic snorers and 16 control subjects matched for age, height, weight, gender, and race. Subsequently, baroreflex sensitivity was measured in 12 of 16 snorers and 14 of 16 control subjects during the application of nCPAP.
Results: Mean (± SE) baroreflex sensitivity was reduced during sleep in the nonapneic snoring group (wakefulness, 20.99 ± 1.46 ms/mm Hg; sleep, 15.85 ± 1.49 ms/mm Hg), but not in the control group (wakefulness, 21.82 ± 2.48 ms/mm Hg; sleep, 23.54 ± 2.18 ms/mm Hg). This reduction was abolished by the application of nCPAP in the snoring group (before nCPAP therapy, 16.30 ± 2.17 ms/mm Hg; during nCPAP therapy, 20.63 ± 2.40 ms/mm Hg). The application of nCPAP did not alter baroreflex sensitivity in the control group (before nCPAP therapy, 23.54 ± 2.18 ms/mm Hg; during nCPAP therapy, 22.56 ± 1.73 ms/mm Hg). BP was not significantly different between the snoring and control groups either before or during nCPAP application.
Conclusions: Our findings suggest that nocturnal alterations in baroreflex sensitivity may exist in nonapneic snoring subjects prior to alterations in other cardiovascular variables.