Does depth of squat-stand maneuver affect estimates of dynamic cerebral autoregulation?
Repeated squat-stand maneuvers (SSM) are an effective way of measuring dynamic cerebral autoregulation (dCA), but the depth of SSM required to improve dCA estimations has never been studied. We compared beat-to-beat cerebral hemodynamic parameters between maximal depth SSM (SSMD ) and a shallower alternative (SSMS ) in two age groups (younger [20-34 years] vs. older [50-71 years]) at a frequency of 0.05 Hz. Cerebral blood flow velocity, continuous blood pressure (BP) and end-tidal CO2 (EtCO2 ) were measured using transcranial Doppler ultrasound, the Finometer device, and capnography, respectively. Coherence (at 0.05 Hz) was significantly higher in both SSM recordings compared to spontaneous BP oscillations at baseline standing (BS ). Median (IQR) autoregulation index (ARI) was reduced during SSMD (4.46 [4.03-5.22], p < .01) compared to SSMS (5.96 [5.40-6.69]) and BS (6.03 [5.20-6.49], p < .01) with similar relative differences also observed for phase (at 0.05 Hz). End-tidal CO2 was increased in SSMD (38.3 ± 3.7 mmHg, p < .01) compared to both SSMS (36.6 ± 3.6 mmHg) and BS (35.5 ± 3.2 mmHg). The older group demonstrated significantly lower ARI and phase estimates during SSM and found SSMS more effortful than SSMD . In conclusion, both SSMD and SSMS are effective at estimating dCA, and dCA appears to be less efficient during maximal depth SSM compared to baseline rest or a shallower alternative.
['Batterham|Angus P|AP|', 'Panerai|Ronney B|RB|', 'Robinson|Thompson G|TG|', 'Haunton|Victoria J|VJ|0000-0001-6078-5469']
D000328:Adult D000368:Aged D000375:Aging D001783:Blood Flow Velocity D001794:Blood Pressure D002560:Cerebrovascular Circulation D005080:Exercise Test D005260:Female D006706:Homeostasis D006801:Humans D008297:Male D008875:Middle Aged D009068:Movement D017585:Ultrasonography, Doppler, Transcranial
squat-stand maneuvers cerebral hemodynamics transcranial Doppler ultrasound autoregulation index transfer function analysis