LAUSR

The present study tests the hypothesis that individuals who develop sleep apnea due to saline infusion during sleep will experience autonomic dysregulation, compared to those without saline-induced sleep apnea. Twenty-one normotensive, nonobese (mean BMI 24.5 kg/m 2 ) men (mean age 37 years) underwent a sleep study. Through random assignment, participants were infused with saline during sleep at the minimum rate to keep the vein open (control) or as a bolus of 22 ml/kg body weight (intervention). Participants crossed over to the other study arm one week later. Heart rate variability (HRV) measurements were computed from continuous electrocardiographic recordings pre- and post-saline infusion in the intervention arm. HRV measures computed were: standard deviation of the RR interval (SDRR), and low (LF) and high frequency (HF) power. Eight participants had increased apnea-hypopnea index by saline infusion (AHI+), and 13 had no change in apnea-hypopnea index by saline infusion (AHI−). Changes in LF power from pre- to post-infusion were not different between the groups. However, while pre-saline infusion values were similar, post-saline infusion values of SDRR and HF power were lower in the AHI+, compared to the AHI− group (Figure 1, P