Reduced baroreceptor reflex sensitivity and increased blood pressure variability at 2400 m simulated cabin altitude.
In a hypobaric chamber nine healthy volunteers were exposed to an atmospheric pressure corresponding to 2400 m above sea level. This is similar to the lowest air pressure encountered inside pressurized commercial airplanes. Heart rate and blood pressure were monitored beat-to-beat in the supine position with a non-invasive device. Blood pressure variability and heart rate variability were measured in the mid-frequency band; subsequently, baroreceptor reflex sensitivity (BRS) was calculated with the transfer-function method. Compared with baseline, there were reduced BRS and increased blood pressure variability at 2400 m (16.5 +/- 3.1 vs. 13.2 +/- 2.0 ms x mm Hg(-1) and 5.4 +/- 1.3 vs. 8.2 +/- 1.1 mm Hg, respectively; p < 0.05). We conclude that autonomic cardiovascular control was disturbed during acute exposure to an air pressure corresponding to 2400 m.
Department of Cardiology, Ullevål University Hospital, Oslo, Norway. knut.sevre@ioks.uio.no
Knut
K
Sevre
Bjørn
B
Bendz
Morten
M
Rostrup
D000328:Adult; D000337:Aerospace Medicine; D000531:Altitude; D000704:Analysis of Variance; D001341:Autonomic Nervous System / Q000502:physiology; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic; D011311:Pressoreceptors / Q000502:physiology*; D013997:Time Factors