Ambulatory blood pressure monitoring.

IN this issue Pickering and Harshfield review the use of invasive and noninvasive arterial blood pressure monitoring in ambulant humans. Their review is well balanced and comprehensive but is limited to the discussion of patients with hypertension. Although it is true that the Framingham Study, the Hypertension Detection and Follow-up Program, and the insurance industry data all show the powerful predictive value of casual office arterial pressure readings, evidence is accumulating that there is an even stronger relation between ambulatory blood pressure results and prognosis. Although Pickering and Harshfield state that fully automatic portable recorders can reliably monitor changes in arterial pressure, I do not believe this statement would extend to all the commercially available equipment. Indeed, the Del Mar Avionics recorder used by their laboratory has had considerable adverse criticism compared with the Remler device used by Perloff, Sokolow, and Cowan. The problem with all these devices is that the editing out of artifacts is very much a subjective assessment. All these semiautomatic or automatic machines and all the electronic home sphygmomanometers are reasonably accurate for systolic pressure but are not reliable for diastolic pressure, which is generally overestimated. In our hands, intra-arterial recordings usually have shown lower pressures at home than in the hospital, but in a carefully controlled study, Young and colleagues surprisingly recorded higher pressures at home than in the hospital. Pickering and Harshfield, in a comment on home versus hospital recordings, suggest that the patient may be more relaxed at home — though this, of course, may not always be true. The production and development of home blood pressure recording devices, whether ambulatory, automatic, or self-recorded, is clearly a growing industry. Before embracing the technology wholeheartedly we need to evaluate carefully the accuracy of each device. Nielsen and colleagues in Copenhagen have already performed preliminary assessment of five or six commercially available devices. Gould and colleagues compared home cuff blood pressure recordings with simultaneous direct intra-arterial ambulatory recordings using F.D. Stotts's "Oxford" system. They found good agreement except that diastolic pressures were again overestimated by the cuff recorders. Intra-arterial recordings remain the gold standard, but because they are invasive they are not widely applicable. They are invaluable for the recognition of very transient changes (e.g., the hypotensive pacemaker syndrome seen in patients with ventricular paced and ventricular inhibited [VVI] pacemakers that switch suddenly from sinus rhythm to ventricular pacing with loss of atrial systole).