Ambulatory blood pressure — direct and indirect

Ambulatory blood pressures help characterise the behavior of blood pressure away from the hospital environment and may aid in the diagnosis and management of hypertensive patients. These measurements have been obtained either by patient-recorded blood pressures or with automated recorders such as the Remler M2000 and Avionics 1978 Pressurometer. We have evaluated these techniques against indirect pressures measured with the random zero sphygmomanometer and intraarterial blood pressures recorded with the “Oxford” sytem for ambulatory monitoring. The mean discrepancy for home BP-intra arterial BP was 0/3 mmHg whilst for clinic BP-intra-arterial BP it was −13/1 mmHg. There was a mean error of 3/2 mmHg for Remler-intra-arterial BP and of −2/4 for clinic BP-Remler. There was a mean error of −2/11 mmHg for Avionics -intra-arterial BP and of 3/8 mmHg for clinic BP-Avionics. Morning and evening self-recorded blood pressures (as used by epidemiologists) did not relate well to mean daytime ambulatory pressures. During a clinical trial the observed reductions in blood-pressure, as recorded by intra-arterial and self-recorded pressures, showed good agreement for a group of patients but not for the individual.