Pseudohypertension and the measurement of blood pressure.

Riva-Rocci Korotkoff (RRK) blood pressure measurements may overestimate the intra-arterial pressure (IAP) in individual patients. To study pseudohypertension, defined as an overestimation larger than 10 mm Hg, we compared RRK and IAP measurements in 76 patients. These patients were considered to be at risk for pseudohypertension because of high age, hypertension, or vascular disease. RRK measurements underestimated simultaneously measured systolic IAP values by 6.0 +/- 6.5 (mean +/- SD) mm Hg, whereas simultaneous diastolic RRK readings overestimated the IAP by 1.9 +/- 5.6 mm Hg. Diastolic overestimation increased slightly with age. Vascular rigidity, as measured by counterpressure plethysmography, did not correlate with these errors. Systolic and diastolic pseudohypertension was observed in two and five patients, respectively. Pseudohypertension was only present in the group in which IAP was measured in the aorta. However, the number of patients with systolic and diastolic pseudohypertension could be increased to three and seven by using the average intra-arterial systolic and diastolic pressure during an RRK measurement or to six and 11 by using the IAP during a control period just before an RRK measurement rather than the IAP at the moment of appearance or disappearance of the Korotkoff sounds. The widely diverging prevalence of pseudohypertension described in the literature might be explained because of such different comparison techniques.