Measurement of digital arterial pressure in patients with essential hypertension

In 8 normotensive volunteers, digital blood pressure was determined, and the value was compared to direct brachial arterial pressure and to that measured by a conventional, indirect Korotkoff-method in the upper arm. The correlation coefficient was determined by changing blood pressure with intravenous administration of vasoconstrictors, sublingual nitroglycerin, and stress tests. Although the absolute value of the digital blood pressure was slightly lower than direct arterial pressure, the correlation between the two determinations was highly significant. The difference in readings between direct and digital arterial pressure was not significant even when the pressure was fluctuated with administration of vasoactive drugs and stress tests. In 2 of 6 volunteers the photosignals of the digital arterial pulses became too small to measure pressure 30 min after they entered in a cold room. However, the digital/brachial blood pressure difference did not alter even when the signals became small during the cold exposure in the remaining 4 subjects. Afterward, the subjects visited our outpatient clinic, where their digital blood pressure was taken. The value was compared with the indirect, contralateral brachial blood pressure. The absolute difference between the readings increased significantly when hypertension advanced. Among the patients (WHO, stage I) treated with antihypertensive drugs, the digital/arm pressure gap was the greatest in patients treated with beta-adrenergic blockers, diuretics and calcium channel blockers in decreasing order. These results indicate that digital blood pressure is influenced by the severity of hypertension and drugs; i.e., hypertensive vascular injury and/or atherosclerosis lowers the peripheral blood pressure leading to impaired peripheral tissue perfusion in the hypertensive patient, and beta-adrenergic blockers may deteriorate peripheral circulation in spite of their hypotensive effects.