Contribution of arterial stiffness and stroke volume to peripheral pulse pressure in ICU patients: an arterial tonometry study.

OBJECTIVE: Peripheral arterial pulse pressure is increasingly used to assess hemodynamic status. Our aim was to test the respective influence of arterial stiffness, stroke volume, peripheral resistance, and various hemodynamic and demographic variables on peripheral pulse pressure in critically ill patients.

DESIGN: Prospective study.

SETTING: Medical intensive care unit of a university hospital.

INTERVENTIONS: None.

PATIENTS: 67 sinus rhythm patients (mean age 57+/-17 years) of whom 17 received vasoactive agents.

MEASUREMENTS AND RESULTS: The stroke volume was calculated by Doppler echocardiography. Radial pressures were calibrated from systolic and diastolic brachial cuff pressures. Central aortic pressure was estimated by radial applanation tonometry. The arterial compliance was estimated from the aortic pressure curve using the area method and the arterial stiffness was calculated as 1/compliance. The influences of age, body surface area, arterial stiffness, stroke volume, peripheral resistance, and time intervals on peripheral pulse pressure were tested using univariate and multivariate analyses. The mean arterial pressure ranged from 42 to 113 mmHg. Peripheral pulse pressure (59+/-17 mmHg) was higher than aortic pulse pressure (40+/-14 mmHg, p<0.001). In patients aged >or= 60 years whose mean arterial pressure was >or= 80 mmHg, peripheral pulse pressure was related to arterial stiffness (r2=0.41) and to stroke volume (multiple r2 =0.90). A similar but weaker relationship was observed in the overall population (multiple r2=0.52).

CONCLUSIONS: In critically ill patients, and especially in aged subjects with hemodynamic stability, peripheral pulse pressure mainly reflected the combined influences of arterial stiffness and stroke volume.