Peripheral pulse pressure responses to postural stress do not reflect those at the carotid artery

OBJECTIVE: Interpretation of baroreflex cardiovascular control requires accurate assessment of pulse pressure (PP) in central arteries under conditions of varying systemic or hydrostatic pressure. The objective of this study was to examine whether changes in PP during postural stress were similar in the peripheral versus carotid arteries. DESIGN: Protocol A: Pulse pressure was measured in both the left (Millar tonometer) and right (Colin Pilot) radial arteries, and in the finger (Finapres) in seated subjects (n = 7) who performed Valsalva's manoeuvre. Protocol B: PP was measured from the carotid (Millar tonometer), and from the finger and wrist kept at the level of the carotid artery, during supine and 60 degrees head-up postures. RESULTS: Protocol A: Pulse pressures during Valsalva's manoeuvre were highly correlated between all devices (r = 0.6-0.8). Protocol B: compared with supine, PP was reduced in both the finger and wrist during head-up-tilt (HUT) (P<0.05), but not in the carotid artery. CONCLUSIONS: During Valsalva manoeuvers the Millar and Colin tonometers similarly tracked PP over a wide range of rapidly changing pressures. This observation provided confidence for the further use of the hand-held device for central measurements during changes in posture. The results from Protocol B indicate that peripheral PP measurements are not suitable surrogates for carotid pulse pressures during HUT.